/* Low level interface to ptrace, for the remote server for GDB. Copyright (C) 1995-2021 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include "server.h" #include "linux-low.h" #include "nat/linux-osdata.h" #include "gdbsupport/agent.h" #include "tdesc.h" #include "gdbsupport/rsp-low.h" #include "gdbsupport/signals-state-save-restore.h" #include "nat/linux-nat.h" #include "nat/linux-waitpid.h" #include "gdbsupport/gdb_wait.h" #include "nat/gdb_ptrace.h" #include "nat/linux-ptrace.h" #include "nat/linux-procfs.h" #include "nat/linux-personality.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include "gdbsupport/filestuff.h" #include "tracepoint.h" #include #include "gdbsupport/common-inferior.h" #include "nat/fork-inferior.h" #include "gdbsupport/environ.h" #include "gdbsupport/gdb-sigmask.h" #include "gdbsupport/scoped_restore.h" #ifndef ELFMAG0 /* Don't include here. If it got included by gdb_proc_service.h then ELFMAG0 will have been defined. If it didn't get included by gdb_proc_service.h then including it will likely introduce a duplicate definition of elf_fpregset_t. */ #include #endif #include "nat/linux-namespaces.h" #ifndef O_LARGEFILE #define O_LARGEFILE 0 #endif #ifndef AT_HWCAP2 #define AT_HWCAP2 26 #endif /* Some targets did not define these ptrace constants from the start, so gdbserver defines them locally here. In the future, these may be removed after they are added to asm/ptrace.h. */ #if !(defined(PT_TEXT_ADDR) \ || defined(PT_DATA_ADDR) \ || defined(PT_TEXT_END_ADDR)) #if defined(__mcoldfire__) /* These are still undefined in 3.10 kernels. */ #define PT_TEXT_ADDR 49*4 #define PT_DATA_ADDR 50*4 #define PT_TEXT_END_ADDR 51*4 /* These are still undefined in 3.10 kernels. */ #elif defined(__TMS320C6X__) #define PT_TEXT_ADDR (0x10000*4) #define PT_DATA_ADDR (0x10004*4) #define PT_TEXT_END_ADDR (0x10008*4) #endif #endif #if (defined(__UCLIBC__) \ && defined(HAS_NOMMU) \ && defined(PT_TEXT_ADDR) \ && defined(PT_DATA_ADDR) \ && defined(PT_TEXT_END_ADDR)) #define SUPPORTS_READ_OFFSETS #endif #ifdef HAVE_LINUX_BTRACE # include "nat/linux-btrace.h" # include "gdbsupport/btrace-common.h" #endif #ifndef HAVE_ELF32_AUXV_T /* Copied from glibc's elf.h. */ typedef struct { uint32_t a_type; /* Entry type */ union { uint32_t a_val; /* Integer value */ /* We use to have pointer elements added here. We cannot do that, though, since it does not work when using 32-bit definitions on 64-bit platforms and vice versa. */ } a_un; } Elf32_auxv_t; #endif #ifndef HAVE_ELF64_AUXV_T /* Copied from glibc's elf.h. */ typedef struct { uint64_t a_type; /* Entry type */ union { uint64_t a_val; /* Integer value */ /* We use to have pointer elements added here. We cannot do that, though, since it does not work when using 32-bit definitions on 64-bit platforms and vice versa. */ } a_un; } Elf64_auxv_t; #endif /* Does the current host support PTRACE_GETREGSET? */ int have_ptrace_getregset = -1; /* LWP accessors. */ /* See nat/linux-nat.h. */ ptid_t ptid_of_lwp (struct lwp_info *lwp) { return ptid_of (get_lwp_thread (lwp)); } /* See nat/linux-nat.h. */ void lwp_set_arch_private_info (struct lwp_info *lwp, struct arch_lwp_info *info) { lwp->arch_private = info; } /* See nat/linux-nat.h. */ struct arch_lwp_info * lwp_arch_private_info (struct lwp_info *lwp) { return lwp->arch_private; } /* See nat/linux-nat.h. */ int lwp_is_stopped (struct lwp_info *lwp) { return lwp->stopped; } /* See nat/linux-nat.h. */ enum target_stop_reason lwp_stop_reason (struct lwp_info *lwp) { return lwp->stop_reason; } /* See nat/linux-nat.h. */ int lwp_is_stepping (struct lwp_info *lwp) { return lwp->stepping; } /* A list of all unknown processes which receive stop signals. Some other process will presumably claim each of these as forked children momentarily. */ struct simple_pid_list { /* The process ID. */ int pid; /* The status as reported by waitpid. */ int status; /* Next in chain. */ struct simple_pid_list *next; }; static struct simple_pid_list *stopped_pids; /* Trivial list manipulation functions to keep track of a list of new stopped processes. */ static void add_to_pid_list (struct simple_pid_list **listp, int pid, int status) { struct simple_pid_list *new_pid = XNEW (struct simple_pid_list); new_pid->pid = pid; new_pid->status = status; new_pid->next = *listp; *listp = new_pid; } static int pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp) { struct simple_pid_list **p; for (p = listp; *p != NULL; p = &(*p)->next) if ((*p)->pid == pid) { struct simple_pid_list *next = (*p)->next; *statusp = (*p)->status; xfree (*p); *p = next; return 1; } return 0; } enum stopping_threads_kind { /* Not stopping threads presently. */ NOT_STOPPING_THREADS, /* Stopping threads. */ STOPPING_THREADS, /* Stopping and suspending threads. */ STOPPING_AND_SUSPENDING_THREADS }; /* This is set while stop_all_lwps is in effect. */ static stopping_threads_kind stopping_threads = NOT_STOPPING_THREADS; /* FIXME make into a target method? */ int using_threads = 1; /* True if we're presently stabilizing threads (moving them out of jump pads). */ static int stabilizing_threads; static void unsuspend_all_lwps (struct lwp_info *except); static void mark_lwp_dead (struct lwp_info *lwp, int wstat); static int lwp_is_marked_dead (struct lwp_info *lwp); static int kill_lwp (unsigned long lwpid, int signo); static void enqueue_pending_signal (struct lwp_info *lwp, int signal, siginfo_t *info); static int linux_low_ptrace_options (int attached); static int check_ptrace_stopped_lwp_gone (struct lwp_info *lp); /* When the event-loop is doing a step-over, this points at the thread being stepped. */ static ptid_t step_over_bkpt; bool linux_process_target::low_supports_breakpoints () { return false; } CORE_ADDR linux_process_target::low_get_pc (regcache *regcache) { return 0; } void linux_process_target::low_set_pc (regcache *regcache, CORE_ADDR newpc) { gdb_assert_not_reached ("linux target op low_set_pc is not implemented"); } std::vector linux_process_target::low_get_next_pcs (regcache *regcache) { gdb_assert_not_reached ("linux target op low_get_next_pcs is not " "implemented"); } int linux_process_target::low_decr_pc_after_break () { return 0; } /* True if LWP is stopped in its stepping range. */ static int lwp_in_step_range (struct lwp_info *lwp) { CORE_ADDR pc = lwp->stop_pc; return (pc >= lwp->step_range_start && pc < lwp->step_range_end); } /* The read/write ends of the pipe registered as waitable file in the event loop. */ static int linux_event_pipe[2] = { -1, -1 }; /* True if we're currently in async mode. */ #define target_is_async_p() (linux_event_pipe[0] != -1) static void send_sigstop (struct lwp_info *lwp); /* Return non-zero if HEADER is a 64-bit ELF file. */ static int elf_64_header_p (const Elf64_Ehdr *header, unsigned int *machine) { if (header->e_ident[EI_MAG0] == ELFMAG0 && header->e_ident[EI_MAG1] == ELFMAG1 && header->e_ident[EI_MAG2] == ELFMAG2 && header->e_ident[EI_MAG3] == ELFMAG3) { *machine = header->e_machine; return header->e_ident[EI_CLASS] == ELFCLASS64; } *machine = EM_NONE; return -1; } /* Return non-zero if FILE is a 64-bit ELF file, zero if the file is not a 64-bit ELF file, and -1 if the file is not accessible or doesn't exist. */ static int elf_64_file_p (const char *file, unsigned int *machine) { Elf64_Ehdr header; int fd; fd = open (file, O_RDONLY); if (fd < 0) return -1; if (read (fd, &header, sizeof (header)) != sizeof (header)) { close (fd); return 0; } close (fd); return elf_64_header_p (&header, machine); } /* Accepts an integer PID; Returns true if the executable PID is running is a 64-bit ELF file.. */ int linux_pid_exe_is_elf_64_file (int pid, unsigned int *machine) { char file[PATH_MAX]; sprintf (file, "/proc/%d/exe", pid); return elf_64_file_p (file, machine); } void linux_process_target::delete_lwp (lwp_info *lwp) { struct thread_info *thr = get_lwp_thread (lwp); if (debug_threads) debug_printf ("deleting %ld\n", lwpid_of (thr)); remove_thread (thr); low_delete_thread (lwp->arch_private); delete lwp; } void linux_process_target::low_delete_thread (arch_lwp_info *info) { /* Default implementation should be overridden if architecture-specific info is being used. */ gdb_assert (info == nullptr); } process_info * linux_process_target::add_linux_process (int pid, int attached) { struct process_info *proc; proc = add_process (pid, attached); proc->priv = XCNEW (struct process_info_private); proc->priv->arch_private = low_new_process (); return proc; } arch_process_info * linux_process_target::low_new_process () { return nullptr; } void linux_process_target::low_delete_process (arch_process_info *info) { /* Default implementation must be overridden if architecture-specific info exists. */ gdb_assert (info == nullptr); } void linux_process_target::low_new_fork (process_info *parent, process_info *child) { /* Nop. */ } void linux_process_target::arch_setup_thread (thread_info *thread) { struct thread_info *saved_thread; saved_thread = current_thread; current_thread = thread; low_arch_setup (); current_thread = saved_thread; } int linux_process_target::handle_extended_wait (lwp_info **orig_event_lwp, int wstat) { client_state &cs = get_client_state (); struct lwp_info *event_lwp = *orig_event_lwp; int event = linux_ptrace_get_extended_event (wstat); struct thread_info *event_thr = get_lwp_thread (event_lwp); struct lwp_info *new_lwp; gdb_assert (event_lwp->waitstatus.kind () == TARGET_WAITKIND_IGNORE); /* All extended events we currently use are mid-syscall. Only PTRACE_EVENT_STOP is delivered more like a signal-stop, but you have to be using PTRACE_SEIZE to get that. */ event_lwp->syscall_state = TARGET_WAITKIND_SYSCALL_ENTRY; if ((event == PTRACE_EVENT_FORK) || (event == PTRACE_EVENT_VFORK) || (event == PTRACE_EVENT_CLONE)) { ptid_t ptid; unsigned long new_pid; int ret, status; /* Get the pid of the new lwp. */ ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_thr), (PTRACE_TYPE_ARG3) 0, &new_pid); /* If we haven't already seen the new PID stop, wait for it now. */ if (!pull_pid_from_list (&stopped_pids, new_pid, &status)) { /* The new child has a pending SIGSTOP. We can't affect it until it hits the SIGSTOP, but we're already attached. */ ret = my_waitpid (new_pid, &status, __WALL); if (ret == -1) perror_with_name ("waiting for new child"); else if (ret != new_pid) warning ("wait returned unexpected PID %d", ret); else if (!WIFSTOPPED (status)) warning ("wait returned unexpected status 0x%x", status); } if (event == PTRACE_EVENT_FORK || event == PTRACE_EVENT_VFORK) { struct process_info *parent_proc; struct process_info *child_proc; struct lwp_info *child_lwp; struct thread_info *child_thr; ptid = ptid_t (new_pid, new_pid); if (debug_threads) { debug_printf ("HEW: Got fork event from LWP %ld, " "new child is %d\n", ptid_of (event_thr).lwp (), ptid.pid ()); } /* Add the new process to the tables and clone the breakpoint lists of the parent. We need to do this even if the new process will be detached, since we will need the process object and the breakpoints to remove any breakpoints from memory when we detach, and the client side will access registers. */ child_proc = add_linux_process (new_pid, 0); gdb_assert (child_proc != NULL); child_lwp = add_lwp (ptid); gdb_assert (child_lwp != NULL); child_lwp->stopped = 1; child_lwp->must_set_ptrace_flags = 1; child_lwp->status_pending_p = 0; child_thr = get_lwp_thread (child_lwp); child_thr->last_resume_kind = resume_stop; child_thr->last_status.set_stopped (GDB_SIGNAL_0); /* If we're suspending all threads, leave this one suspended too. If the fork/clone parent is stepping over a breakpoint, all other threads have been suspended already. Leave the child suspended too. */ if (stopping_threads == STOPPING_AND_SUSPENDING_THREADS || event_lwp->bp_reinsert != 0) { if (debug_threads) debug_printf ("HEW: leaving child suspended\n"); child_lwp->suspended = 1; } parent_proc = get_thread_process (event_thr); child_proc->attached = parent_proc->attached; if (event_lwp->bp_reinsert != 0 && supports_software_single_step () && event == PTRACE_EVENT_VFORK) { /* If we leave single-step breakpoints there, child will hit it, so uninsert single-step breakpoints from parent (and child). Once vfork child is done, reinsert them back to parent. */ uninsert_single_step_breakpoints (event_thr); } clone_all_breakpoints (child_thr, event_thr); target_desc_up tdesc = allocate_target_description (); copy_target_description (tdesc.get (), parent_proc->tdesc); child_proc->tdesc = tdesc.release (); /* Clone arch-specific process data. */ low_new_fork (parent_proc, child_proc); /* Save fork info in the parent thread. */ if (event == PTRACE_EVENT_FORK) event_lwp->waitstatus.set_forked (ptid); else if (event == PTRACE_EVENT_VFORK) event_lwp->waitstatus.set_vforked (ptid); /* The status_pending field contains bits denoting the extended event, so when the pending event is handled, the handler will look at lwp->waitstatus. */ event_lwp->status_pending_p = 1; event_lwp->status_pending = wstat; /* Link the threads until the parent event is passed on to higher layers. */ event_lwp->fork_relative = child_lwp; child_lwp->fork_relative = event_lwp; /* If the parent thread is doing step-over with single-step breakpoints, the list of single-step breakpoints are cloned from the parent's. Remove them from the child process. In case of vfork, we'll reinsert them back once vforked child is done. */ if (event_lwp->bp_reinsert != 0 && supports_software_single_step ()) { /* The child process is forked and stopped, so it is safe to access its memory without stopping all other threads from other processes. */ delete_single_step_breakpoints (child_thr); gdb_assert (has_single_step_breakpoints (event_thr)); gdb_assert (!has_single_step_breakpoints (child_thr)); } /* Report the event. */ return 0; } if (debug_threads) debug_printf ("HEW: Got clone event " "from LWP %ld, new child is LWP %ld\n", lwpid_of (event_thr), new_pid); ptid = ptid_t (pid_of (event_thr), new_pid); new_lwp = add_lwp (ptid); /* Either we're going to immediately resume the new thread or leave it stopped. resume_one_lwp is a nop if it thinks the thread is currently running, so set this first before calling resume_one_lwp. */ new_lwp->stopped = 1; /* If we're suspending all threads, leave this one suspended too. If the fork/clone parent is stepping over a breakpoint, all other threads have been suspended already. Leave the child suspended too. */ if (stopping_threads == STOPPING_AND_SUSPENDING_THREADS || event_lwp->bp_reinsert != 0) new_lwp->suspended = 1; /* Normally we will get the pending SIGSTOP. But in some cases we might get another signal delivered to the group first. If we do get another signal, be sure not to lose it. */ if (WSTOPSIG (status) != SIGSTOP) { new_lwp->stop_expected = 1; new_lwp->status_pending_p = 1; new_lwp->status_pending = status; } else if (cs.report_thread_events) { new_lwp->waitstatus.set_thread_created (); new_lwp->status_pending_p = 1; new_lwp->status_pending = status; } #ifdef USE_THREAD_DB thread_db_notice_clone (event_thr, ptid); #endif /* Don't report the event. */ return 1; } else if (event == PTRACE_EVENT_VFORK_DONE) { event_lwp->waitstatus.set_vfork_done (); if (event_lwp->bp_reinsert != 0 && supports_software_single_step ()) { reinsert_single_step_breakpoints (event_thr); gdb_assert (has_single_step_breakpoints (event_thr)); } /* Report the event. */ return 0; } else if (event == PTRACE_EVENT_EXEC && cs.report_exec_events) { struct process_info *proc; std::vector syscalls_to_catch; ptid_t event_ptid; pid_t event_pid; if (debug_threads) { debug_printf ("HEW: Got exec event from LWP %ld\n", lwpid_of (event_thr)); } /* Get the event ptid. */ event_ptid = ptid_of (event_thr); event_pid = event_ptid.pid (); /* Save the syscall list from the execing process. */ proc = get_thread_process (event_thr); syscalls_to_catch = std::move (proc->syscalls_to_catch); /* Delete the execing process and all its threads. */ mourn (proc); current_thread = NULL; /* Create a new process/lwp/thread. */ proc = add_linux_process (event_pid, 0); event_lwp = add_lwp (event_ptid); event_thr = get_lwp_thread (event_lwp); gdb_assert (current_thread == event_thr); arch_setup_thread (event_thr); /* Set the event status. */ event_lwp->waitstatus.set_execd (make_unique_xstrdup (linux_proc_pid_to_exec_file (lwpid_of (event_thr)))); /* Mark the exec status as pending. */ event_lwp->stopped = 1; event_lwp->status_pending_p = 1; event_lwp->status_pending = wstat; event_thr->last_resume_kind = resume_continue; event_thr->last_status.set_ignore (); /* Update syscall state in the new lwp, effectively mid-syscall too. */ event_lwp->syscall_state = TARGET_WAITKIND_SYSCALL_ENTRY; /* Restore the list to catch. Don't rely on the client, which is free to avoid sending a new list when the architecture doesn't change. Also, for ANY_SYSCALL, the architecture doesn't really matter. */ proc->syscalls_to_catch = std::move (syscalls_to_catch); /* Report the event. */ *orig_event_lwp = event_lwp; return 0; } internal_error (__FILE__, __LINE__, _("unknown ptrace event %d"), event); } CORE_ADDR linux_process_target::get_pc (lwp_info *lwp) { struct thread_info *saved_thread; struct regcache *regcache; CORE_ADDR pc; if (!low_supports_breakpoints ()) return 0; saved_thread = current_thread; current_thread = get_lwp_thread (lwp); regcache = get_thread_regcache (current_thread, 1); pc = low_get_pc (regcache); if (debug_threads) debug_printf ("pc is 0x%lx\n", (long) pc); current_thread = saved_thread; return pc; } void linux_process_target::get_syscall_trapinfo (lwp_info *lwp, int *sysno) { struct thread_info *saved_thread; struct regcache *regcache; saved_thread = current_thread; current_thread = get_lwp_thread (lwp); regcache = get_thread_regcache (current_thread, 1); low_get_syscall_trapinfo (regcache, sysno); if (debug_threads) debug_printf ("get_syscall_trapinfo sysno %d\n", *sysno); current_thread = saved_thread; } void linux_process_target::low_get_syscall_trapinfo (regcache *regcache, int *sysno) { /* By default, report an unknown system call number. */ *sysno = UNKNOWN_SYSCALL; } bool linux_process_target::save_stop_reason (lwp_info *lwp) { CORE_ADDR pc; CORE_ADDR sw_breakpoint_pc; struct thread_info *saved_thread; #if USE_SIGTRAP_SIGINFO siginfo_t siginfo; #endif if (!low_supports_breakpoints ()) return false; pc = get_pc (lwp); sw_breakpoint_pc = pc - low_decr_pc_after_break (); /* breakpoint_at reads from the current thread. */ saved_thread = current_thread; current_thread = get_lwp_thread (lwp); #if USE_SIGTRAP_SIGINFO if (ptrace (PTRACE_GETSIGINFO, lwpid_of (current_thread), (PTRACE_TYPE_ARG3) 0, &siginfo) == 0) { if (siginfo.si_signo == SIGTRAP) { if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code) && GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code)) { /* The si_code is ambiguous on this arch -- check debug registers. */ if (!check_stopped_by_watchpoint (lwp)) lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT; } else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code)) { /* If we determine the LWP stopped for a SW breakpoint, trust it. Particularly don't check watchpoint registers, because at least on s390, we'd find stopped-by-watchpoint as long as there's a watchpoint set. */ lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT; } else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code)) { /* This can indicate either a hardware breakpoint or hardware watchpoint. Check debug registers. */ if (!check_stopped_by_watchpoint (lwp)) lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT; } else if (siginfo.si_code == TRAP_TRACE) { /* We may have single stepped an instruction that triggered a watchpoint. In that case, on some architectures (such as x86), instead of TRAP_HWBKPT, si_code indicates TRAP_TRACE, and we need to check the debug registers separately. */ if (!check_stopped_by_watchpoint (lwp)) lwp->stop_reason = TARGET_STOPPED_BY_SINGLE_STEP; } } } #else /* We may have just stepped a breakpoint instruction. E.g., in non-stop mode, GDB first tells the thread A to step a range, and then the user inserts a breakpoint inside the range. In that case we need to report the breakpoint PC. */ if ((!lwp->stepping || lwp->stop_pc == sw_breakpoint_pc) && low_breakpoint_at (sw_breakpoint_pc)) lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT; if (hardware_breakpoint_inserted_here (pc)) lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT; if (lwp->stop_reason == TARGET_STOPPED_BY_NO_REASON) check_stopped_by_watchpoint (lwp); #endif if (lwp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT) { if (debug_threads) { struct thread_info *thr = get_lwp_thread (lwp); debug_printf ("CSBB: %s stopped by software breakpoint\n", target_pid_to_str (ptid_of (thr)).c_str ()); } /* Back up the PC if necessary. */ if (pc != sw_breakpoint_pc) { struct regcache *regcache = get_thread_regcache (current_thread, 1); low_set_pc (regcache, sw_breakpoint_pc); } /* Update this so we record the correct stop PC below. */ pc = sw_breakpoint_pc; } else if (lwp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT) { if (debug_threads) { struct thread_info *thr = get_lwp_thread (lwp); debug_printf ("CSBB: %s stopped by hardware breakpoint\n", target_pid_to_str (ptid_of (thr)).c_str ()); } } else if (lwp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT) { if (debug_threads) { struct thread_info *thr = get_lwp_thread (lwp); debug_printf ("CSBB: %s stopped by hardware watchpoint\n", target_pid_to_str (ptid_of (thr)).c_str ()); } } else if (lwp->stop_reason == TARGET_STOPPED_BY_SINGLE_STEP) { if (debug_threads) { struct thread_info *thr = get_lwp_thread (lwp); debug_printf ("CSBB: %s stopped by trace\n", target_pid_to_str (ptid_of (thr)).c_str ()); } } lwp->stop_pc = pc; current_thread = saved_thread; return true; } lwp_info * linux_process_target::add_lwp (ptid_t ptid) { lwp_info *lwp = new lwp_info; lwp->thread = add_thread (ptid, lwp); low_new_thread (lwp); return lwp; } void linux_process_target::low_new_thread (lwp_info *info) { /* Nop. */ } /* Callback to be used when calling fork_inferior, responsible for actually initiating the tracing of the inferior. */ static void linux_ptrace_fun () { if (ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0) < 0) trace_start_error_with_name ("ptrace"); if (setpgid (0, 0) < 0) trace_start_error_with_name ("setpgid"); /* If GDBserver is connected to gdb via stdio, redirect the inferior's stdout to stderr so that inferior i/o doesn't corrupt the connection. Also, redirect stdin to /dev/null. */ if (remote_connection_is_stdio ()) { if (close (0) < 0) trace_start_error_with_name ("close"); if (open ("/dev/null", O_RDONLY) < 0) trace_start_error_with_name ("open"); if (dup2 (2, 1) < 0) trace_start_error_with_name ("dup2"); if (write (2, "stdin/stdout redirected\n", sizeof ("stdin/stdout redirected\n") - 1) < 0) { /* Errors ignored. */; } } } /* Start an inferior process and returns its pid. PROGRAM is the name of the program to be started, and PROGRAM_ARGS are its arguments. */ int linux_process_target::create_inferior (const char *program, const std::vector &program_args) { client_state &cs = get_client_state (); struct lwp_info *new_lwp; int pid; ptid_t ptid; { maybe_disable_address_space_randomization restore_personality (cs.disable_randomization); std::string str_program_args = construct_inferior_arguments (program_args); pid = fork_inferior (program, str_program_args.c_str (), get_environ ()->envp (), linux_ptrace_fun, NULL, NULL, NULL, NULL); } add_linux_process (pid, 0); ptid = ptid_t (pid, pid); new_lwp = add_lwp (ptid); new_lwp->must_set_ptrace_flags = 1; post_fork_inferior (pid, program); return pid; } /* Implement the post_create_inferior target_ops method. */ void linux_process_target::post_create_inferior () { struct lwp_info *lwp = get_thread_lwp (current_thread); low_arch_setup (); if (lwp->must_set_ptrace_flags) { struct process_info *proc = current_process (); int options = linux_low_ptrace_options (proc->attached); linux_enable_event_reporting (lwpid_of (current_thread), options); lwp->must_set_ptrace_flags = 0; } } int linux_process_target::attach_lwp (ptid_t ptid) { struct lwp_info *new_lwp; int lwpid = ptid.lwp (); if (ptrace (PTRACE_ATTACH, lwpid, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0) != 0) return errno; new_lwp = add_lwp (ptid); /* We need to wait for SIGSTOP before being able to make the next ptrace call on this LWP. */ new_lwp->must_set_ptrace_flags = 1; if (linux_proc_pid_is_stopped (lwpid)) { if (debug_threads) debug_printf ("Attached to a stopped process\n"); /* The process is definitely stopped. It is in a job control stop, unless the kernel predates the TASK_STOPPED / TASK_TRACED distinction, in which case it might be in a ptrace stop. Make sure it is in a ptrace stop; from there we can kill it, signal it, et cetera. First make sure there is a pending SIGSTOP. Since we are already attached, the process can not transition from stopped to running without a PTRACE_CONT; so we know this signal will go into the queue. The SIGSTOP generated by PTRACE_ATTACH is probably already in the queue (unless this kernel is old enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP is not an RT signal, it can only be queued once. */ kill_lwp (lwpid, SIGSTOP); /* Finally, resume the stopped process. This will deliver the SIGSTOP (or a higher priority signal, just like normal PTRACE_ATTACH), which we'll catch later on. */ ptrace (PTRACE_CONT, lwpid, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); } /* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH brings it to a halt. There are several cases to consider here: 1) gdbserver has already attached to the process and is being notified of a new thread that is being created. In this case we should ignore that SIGSTOP and resume the process. This is handled below by setting stop_expected = 1, and the fact that add_thread sets last_resume_kind == resume_continue. 2) This is the first thread (the process thread), and we're attaching to it via attach_inferior. In this case we want the process thread to stop. This is handled by having linux_attach set last_resume_kind == resume_stop after we return. If the pid we are attaching to is also the tgid, we attach to and stop all the existing threads. Otherwise, we attach to pid and ignore any other threads in the same group as this pid. 3) GDB is connecting to gdbserver and is requesting an enumeration of all existing threads. In this case we want the thread to stop. FIXME: This case is currently not properly handled. We should wait for the SIGSTOP but don't. Things work apparently because enough time passes between when we ptrace (ATTACH) and when gdb makes the next ptrace call on the thread. On the other hand, if we are currently trying to stop all threads, we should treat the new thread as if we had sent it a SIGSTOP. This works because we are guaranteed that the add_lwp call above added us to the end of the list, and so the new thread has not yet reached wait_for_sigstop (but will). */ new_lwp->stop_expected = 1; return 0; } /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not already attached. Returns true if a new LWP is found, false otherwise. */ static int attach_proc_task_lwp_callback (ptid_t ptid) { /* Is this a new thread? */ if (find_thread_ptid (ptid) == NULL) { int lwpid = ptid.lwp (); int err; if (debug_threads) debug_printf ("Found new lwp %d\n", lwpid); err = the_linux_target->attach_lwp (ptid); /* Be quiet if we simply raced with the thread exiting. EPERM is returned if the thread's task still exists, and is marked as exited or zombie, as well as other conditions, so in that case, confirm the status in /proc/PID/status. */ if (err == ESRCH || (err == EPERM && linux_proc_pid_is_gone (lwpid))) { if (debug_threads) { debug_printf ("Cannot attach to lwp %d: " "thread is gone (%d: %s)\n", lwpid, err, safe_strerror (err)); } } else if (err != 0) { std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); warning (_("Cannot attach to lwp %d: %s"), lwpid, reason.c_str ()); } return 1; } return 0; } static void async_file_mark (void); /* Attach to PID. If PID is the tgid, attach to it and all of its threads. */ int linux_process_target::attach (unsigned long pid) { struct process_info *proc; struct thread_info *initial_thread; ptid_t ptid = ptid_t (pid, pid); int err; proc = add_linux_process (pid, 1); /* Attach to PID. We will check for other threads soon. */ err = attach_lwp (ptid); if (err != 0) { remove_process (proc); std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); error ("Cannot attach to process %ld: %s", pid, reason.c_str ()); } /* Don't ignore the initial SIGSTOP if we just attached to this process. It will be collected by wait shortly. */ initial_thread = find_thread_ptid (ptid_t (pid, pid)); initial_thread->last_resume_kind = resume_stop; /* We must attach to every LWP. If /proc is mounted, use that to find them now. On the one hand, the inferior may be using raw clone instead of using pthreads. On the other hand, even if it is using pthreads, GDB may not be connected yet (thread_db needs to do symbol lookups, through qSymbol). Also, thread_db walks structures in the inferior's address space to find the list of threads/LWPs, and those structures may well be corrupted. Note that once thread_db is loaded, we'll still use it to list threads and associate pthread info with each LWP. */ linux_proc_attach_tgid_threads (pid, attach_proc_task_lwp_callback); /* GDB will shortly read the xml target description for this process, to figure out the process' architecture. But the target description is only filled in when the first process/thread in the thread group reports its initial PTRACE_ATTACH SIGSTOP. Do that now, otherwise, if GDB is fast enough, it could read the target description _before_ that initial stop. */ if (non_stop) { struct lwp_info *lwp; int wstat, lwpid; ptid_t pid_ptid = ptid_t (pid); lwpid = wait_for_event_filtered (pid_ptid, pid_ptid, &wstat, __WALL); gdb_assert (lwpid > 0); lwp = find_lwp_pid (ptid_t (lwpid)); if (!WIFSTOPPED (wstat) || WSTOPSIG (wstat) != SIGSTOP) { lwp->status_pending_p = 1; lwp->status_pending = wstat; } initial_thread->last_resume_kind = resume_continue; async_file_mark (); gdb_assert (proc->tdesc != NULL); } return 0; } static int last_thread_of_process_p (int pid) { bool seen_one = false; thread_info *thread = find_thread (pid, [&] (thread_info *thr_arg) { if (!seen_one) { /* This is the first thread of this process we see. */ seen_one = true; return false; } else { /* This is the second thread of this process we see. */ return true; } }); return thread == NULL; } /* Kill LWP. */ static void linux_kill_one_lwp (struct lwp_info *lwp) { struct thread_info *thr = get_lwp_thread (lwp); int pid = lwpid_of (thr); /* PTRACE_KILL is unreliable. After stepping into a signal handler, there is no signal context, and ptrace(PTRACE_KILL) (or ptrace(PTRACE_CONT, SIGKILL), pretty much the same) acts like ptrace(CONT, pid, 0,0) and just resumes the tracee. A better alternative is to kill with SIGKILL. We only need one SIGKILL per process, not one for each thread. But since we still support support debugging programs using raw clone without CLONE_THREAD, we send one for each thread. For years, we used PTRACE_KILL only, so we're being a bit paranoid about some old kernels where PTRACE_KILL might work better (dubious if there are any such, but that's why it's paranoia), so we try SIGKILL first, PTRACE_KILL second, and so we're fine everywhere. */ errno = 0; kill_lwp (pid, SIGKILL); if (debug_threads) { int save_errno = errno; debug_printf ("LKL: kill_lwp (SIGKILL) %s, 0, 0 (%s)\n", target_pid_to_str (ptid_of (thr)).c_str (), save_errno ? safe_strerror (save_errno) : "OK"); } errno = 0; ptrace (PTRACE_KILL, pid, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); if (debug_threads) { int save_errno = errno; debug_printf ("LKL: PTRACE_KILL %s, 0, 0 (%s)\n", target_pid_to_str (ptid_of (thr)).c_str (), save_errno ? safe_strerror (save_errno) : "OK"); } } /* Kill LWP and wait for it to die. */ static void kill_wait_lwp (struct lwp_info *lwp) { struct thread_info *thr = get_lwp_thread (lwp); int pid = ptid_of (thr).pid (); int lwpid = ptid_of (thr).lwp (); int wstat; int res; if (debug_threads) debug_printf ("kwl: killing lwp %d, for pid: %d\n", lwpid, pid); do { linux_kill_one_lwp (lwp); /* Make sure it died. Notes: - The loop is most likely unnecessary. - We don't use wait_for_event as that could delete lwps while we're iterating over them. We're not interested in any pending status at this point, only in making sure all wait status on the kernel side are collected until the process is reaped. - We don't use __WALL here as the __WALL emulation relies on SIGCHLD, and killing a stopped process doesn't generate one, nor an exit status. */ res = my_waitpid (lwpid, &wstat, 0); if (res == -1 && errno == ECHILD) res = my_waitpid (lwpid, &wstat, __WCLONE); } while (res > 0 && WIFSTOPPED (wstat)); /* Even if it was stopped, the child may have already disappeared. E.g., if it was killed by SIGKILL. */ if (res < 0 && errno != ECHILD) perror_with_name ("kill_wait_lwp"); } /* Callback for `for_each_thread'. Kills an lwp of a given process, except the leader. */ static void kill_one_lwp_callback (thread_info *thread, int pid) { struct lwp_info *lwp = get_thread_lwp (thread); /* We avoid killing the first thread here, because of a Linux kernel (at least 2.6.0-test7 through 2.6.8-rc4) bug; if we kill the parent before the children get a chance to be reaped, it will remain a zombie forever. */ if (lwpid_of (thread) == pid) { if (debug_threads) debug_printf ("lkop: is last of process %s\n", target_pid_to_str (thread->id).c_str ()); return; } kill_wait_lwp (lwp); } int linux_process_target::kill (process_info *process) { int pid = process->pid; /* If we're killing a running inferior, make sure it is stopped first, as PTRACE_KILL will not work otherwise. */ stop_all_lwps (0, NULL); for_each_thread (pid, [&] (thread_info *thread) { kill_one_lwp_callback (thread, pid); }); /* See the comment in linux_kill_one_lwp. We did not kill the first thread in the list, so do so now. */ lwp_info *lwp = find_lwp_pid (ptid_t (pid)); if (lwp == NULL) { if (debug_threads) debug_printf ("lk_1: cannot find lwp for pid: %d\n", pid); } else kill_wait_lwp (lwp); mourn (process); /* Since we presently can only stop all lwps of all processes, we need to unstop lwps of other processes. */ unstop_all_lwps (0, NULL); return 0; } /* Get pending signal of THREAD, for detaching purposes. This is the signal the thread last stopped for, which we need to deliver to the thread when detaching, otherwise, it'd be suppressed/lost. */ static int get_detach_signal (struct thread_info *thread) { client_state &cs = get_client_state (); enum gdb_signal signo = GDB_SIGNAL_0; int status; struct lwp_info *lp = get_thread_lwp (thread); if (lp->status_pending_p) status = lp->status_pending; else { /* If the thread had been suspended by gdbserver, and it stopped cleanly, then it'll have stopped with SIGSTOP. But we don't want to deliver that SIGSTOP. */ if (thread->last_status.kind () != TARGET_WAITKIND_STOPPED || thread->last_status.sig () == GDB_SIGNAL_0) return 0; /* Otherwise, we may need to deliver the signal we intercepted. */ status = lp->last_status; } if (!WIFSTOPPED (status)) { if (debug_threads) debug_printf ("GPS: lwp %s hasn't stopped: no pending signal\n", target_pid_to_str (ptid_of (thread)).c_str ()); return 0; } /* Extended wait statuses aren't real SIGTRAPs. */ if (WSTOPSIG (status) == SIGTRAP && linux_is_extended_waitstatus (status)) { if (debug_threads) debug_printf ("GPS: lwp %s had stopped with extended " "status: no pending signal\n", target_pid_to_str (ptid_of (thread)).c_str ()); return 0; } signo = gdb_signal_from_host (WSTOPSIG (status)); if (cs.program_signals_p && !cs.program_signals[signo]) { if (debug_threads) debug_printf ("GPS: lwp %s had signal %s, but it is in nopass state\n", target_pid_to_str (ptid_of (thread)).c_str (), gdb_signal_to_string (signo)); return 0; } else if (!cs.program_signals_p /* If we have no way to know which signals GDB does not want to have passed to the program, assume SIGTRAP/SIGINT, which is GDB's default. */ && (signo == GDB_SIGNAL_TRAP || signo == GDB_SIGNAL_INT)) { if (debug_threads) debug_printf ("GPS: lwp %s had signal %s, " "but we don't know if we should pass it. " "Default to not.\n", target_pid_to_str (ptid_of (thread)).c_str (), gdb_signal_to_string (signo)); return 0; } else { if (debug_threads) debug_printf ("GPS: lwp %s has pending signal %s: delivering it.\n", target_pid_to_str (ptid_of (thread)).c_str (), gdb_signal_to_string (signo)); return WSTOPSIG (status); } } void linux_process_target::detach_one_lwp (lwp_info *lwp) { struct thread_info *thread = get_lwp_thread (lwp); int sig; int lwpid; /* If there is a pending SIGSTOP, get rid of it. */ if (lwp->stop_expected) { if (debug_threads) debug_printf ("Sending SIGCONT to %s\n", target_pid_to_str (ptid_of (thread)).c_str ()); kill_lwp (lwpid_of (thread), SIGCONT); lwp->stop_expected = 0; } /* Pass on any pending signal for this thread. */ sig = get_detach_signal (thread); /* Preparing to resume may try to write registers, and fail if the lwp is zombie. If that happens, ignore the error. We'll handle it below, when detach fails with ESRCH. */ try { /* Flush any pending changes to the process's registers. */ regcache_invalidate_thread (thread); /* Finally, let it resume. */ low_prepare_to_resume (lwp); } catch (const gdb_exception_error &ex) { if (!check_ptrace_stopped_lwp_gone (lwp)) throw; } lwpid = lwpid_of (thread); if (ptrace (PTRACE_DETACH, lwpid, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) (long) sig) < 0) { int save_errno = errno; /* We know the thread exists, so ESRCH must mean the lwp is zombie. This can happen if one of the already-detached threads exits the whole thread group. In that case we're still attached, and must reap the lwp. */ if (save_errno == ESRCH) { int ret, status; ret = my_waitpid (lwpid, &status, __WALL); if (ret == -1) { warning (_("Couldn't reap LWP %d while detaching: %s"), lwpid, safe_strerror (errno)); } else if (!WIFEXITED (status) && !WIFSIGNALED (status)) { warning (_("Reaping LWP %d while detaching " "returned unexpected status 0x%x"), lwpid, status); } } else { error (_("Can't detach %s: %s"), target_pid_to_str (ptid_of (thread)).c_str (), safe_strerror (save_errno)); } } else if (debug_threads) { debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)\n", target_pid_to_str (ptid_of (thread)).c_str (), strsignal (sig)); } delete_lwp (lwp); } int linux_process_target::detach (process_info *process) { struct lwp_info *main_lwp; /* As there's a step over already in progress, let it finish first, otherwise nesting a stabilize_threads operation on top gets real messy. */ complete_ongoing_step_over (); /* Stop all threads before detaching. First, ptrace requires that the thread is stopped to successfully detach. Second, thread_db may need to uninstall thread event breakpoints from memory, which only works with a stopped process anyway. */ stop_all_lwps (0, NULL); #ifdef USE_THREAD_DB thread_db_detach (process); #endif /* Stabilize threads (move out of jump pads). */ target_stabilize_threads (); /* Detach from the clone lwps first. If the thread group exits just while we're detaching, we must reap the clone lwps before we're able to reap the leader. */ for_each_thread (process->pid, [this] (thread_info *thread) { /* We don't actually detach from the thread group leader just yet. If the thread group exits, we must reap the zombie clone lwps before we're able to reap the leader. */ if (thread->id.pid () == thread->id.lwp ()) return; lwp_info *lwp = get_thread_lwp (thread); detach_one_lwp (lwp); }); main_lwp = find_lwp_pid (ptid_t (process->pid)); detach_one_lwp (main_lwp); mourn (process); /* Since we presently can only stop all lwps of all processes, we need to unstop lwps of other processes. */ unstop_all_lwps (0, NULL); return 0; } /* Remove all LWPs that belong to process PROC from the lwp list. */ void linux_process_target::mourn (process_info *process) { struct process_info_private *priv; #ifdef USE_THREAD_DB thread_db_mourn (process); #endif for_each_thread (process->pid, [this] (thread_info *thread) { delete_lwp (get_thread_lwp (thread)); }); /* Freeing all private data. */ priv = process->priv; low_delete_process (priv->arch_private); free (priv); process->priv = NULL; remove_process (process); } void linux_process_target::join (int pid) { int status, ret; do { ret = my_waitpid (pid, &status, 0); if (WIFEXITED (status) || WIFSIGNALED (status)) break; } while (ret != -1 || errno != ECHILD); } /* Return true if the given thread is still alive. */ bool linux_process_target::thread_alive (ptid_t ptid) { struct lwp_info *lwp = find_lwp_pid (ptid); /* We assume we always know if a thread exits. If a whole process exited but we still haven't been able to report it to GDB, we'll hold on to the last lwp of the dead process. */ if (lwp != NULL) return !lwp_is_marked_dead (lwp); else return 0; } bool linux_process_target::thread_still_has_status_pending (thread_info *thread) { struct lwp_info *lp = get_thread_lwp (thread); if (!lp->status_pending_p) return 0; if (thread->last_resume_kind != resume_stop && (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT || lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT)) { struct thread_info *saved_thread; CORE_ADDR pc; int discard = 0; gdb_assert (lp->last_status != 0); pc = get_pc (lp); saved_thread = current_thread; current_thread = thread; if (pc != lp->stop_pc) { if (debug_threads) debug_printf ("PC of %ld changed\n", lwpid_of (thread)); discard = 1; } #if !USE_SIGTRAP_SIGINFO else if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT && !low_breakpoint_at (pc)) { if (debug_threads) debug_printf ("previous SW breakpoint of %ld gone\n", lwpid_of (thread)); discard = 1; } else if (lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT && !hardware_breakpoint_inserted_here (pc)) { if (debug_threads) debug_printf ("previous HW breakpoint of %ld gone\n", lwpid_of (thread)); discard = 1; } #endif current_thread = saved_thread; if (discard) { if (debug_threads) debug_printf ("discarding pending breakpoint status\n"); lp->status_pending_p = 0; return 0; } } return 1; } /* Returns true if LWP is resumed from the client's perspective. */ static int lwp_resumed (struct lwp_info *lwp) { struct thread_info *thread = get_lwp_thread (lwp); if (thread->last_resume_kind != resume_stop) return 1; /* Did gdb send us a `vCont;t', but we haven't reported the corresponding stop to gdb yet? If so, the thread is still resumed/running from gdb's perspective. */ if (thread->last_resume_kind == resume_stop && thread->last_status.kind () == TARGET_WAITKIND_IGNORE) return 1; return 0; } bool linux_process_target::status_pending_p_callback (thread_info *thread, ptid_t ptid) { struct lwp_info *lp = get_thread_lwp (thread); /* Check if we're only interested in events from a specific process or a specific LWP. */ if (!thread->id.matches (ptid)) return 0; if (!lwp_resumed (lp)) return 0; if (lp->status_pending_p && !thread_still_has_status_pending (thread)) { resume_one_lwp (lp, lp->stepping, GDB_SIGNAL_0, NULL); return 0; } return lp->status_pending_p; } struct lwp_info * find_lwp_pid (ptid_t ptid) { thread_info *thread = find_thread ([&] (thread_info *thr_arg) { int lwp = ptid.lwp () != 0 ? ptid.lwp () : ptid.pid (); return thr_arg->id.lwp () == lwp; }); if (thread == NULL) return NULL; return get_thread_lwp (thread); } /* Return the number of known LWPs in the tgid given by PID. */ static int num_lwps (int pid) { int count = 0; for_each_thread (pid, [&] (thread_info *thread) { count++; }); return count; } /* See nat/linux-nat.h. */ struct lwp_info * iterate_over_lwps (ptid_t filter, gdb::function_view callback) { thread_info *thread = find_thread (filter, [&] (thread_info *thr_arg) { lwp_info *lwp = get_thread_lwp (thr_arg); return callback (lwp); }); if (thread == NULL) return NULL; return get_thread_lwp (thread); } void linux_process_target::check_zombie_leaders () { for_each_process ([this] (process_info *proc) { pid_t leader_pid = pid_of (proc); struct lwp_info *leader_lp; leader_lp = find_lwp_pid (ptid_t (leader_pid)); if (debug_threads) debug_printf ("leader_pid=%d, leader_lp!=NULL=%d, " "num_lwps=%d, zombie=%d\n", leader_pid, leader_lp!= NULL, num_lwps (leader_pid), linux_proc_pid_is_zombie (leader_pid)); if (leader_lp != NULL && !leader_lp->stopped /* Check if there are other threads in the group, as we may have raced with the inferior simply exiting. */ && !last_thread_of_process_p (leader_pid) && linux_proc_pid_is_zombie (leader_pid)) { /* A leader zombie can mean one of two things: - It exited, and there's an exit status pending available, or only the leader exited (not the whole program). In the latter case, we can't waitpid the leader's exit status until all other threads are gone. - There are 3 or more threads in the group, and a thread other than the leader exec'd. On an exec, the Linux kernel destroys all other threads (except the execing one) in the thread group, and resets the execing thread's tid to the tgid. No exit notification is sent for the execing thread -- from the ptracer's perspective, it appears as though the execing thread just vanishes. Until we reap all other threads except the leader and the execing thread, the leader will be zombie, and the execing thread will be in `D (disc sleep)'. As soon as all other threads are reaped, the execing thread changes it's tid to the tgid, and the previous (zombie) leader vanishes, giving place to the "new" leader. We could try distinguishing the exit and exec cases, by waiting once more, and seeing if something comes out, but it doesn't sound useful. The previous leader _does_ go away, and we'll re-add the new one once we see the exec event (which is just the same as what would happen if the previous leader did exit voluntarily before some other thread execs). */ if (debug_threads) debug_printf ("CZL: Thread group leader %d zombie " "(it exited, or another thread execd).\n", leader_pid); delete_lwp (leader_lp); } }); } /* Callback for `find_thread'. Returns the first LWP that is not stopped. */ static bool not_stopped_callback (thread_info *thread, ptid_t filter) { if (!thread->id.matches (filter)) return false; lwp_info *lwp = get_thread_lwp (thread); return !lwp->stopped; } /* Increment LWP's suspend count. */ static void lwp_suspended_inc (struct lwp_info *lwp) { lwp->suspended++; if (debug_threads && lwp->suspended > 4) { struct thread_info *thread = get_lwp_thread (lwp); debug_printf ("LWP %ld has a suspiciously high suspend count," " suspended=%d\n", lwpid_of (thread), lwp->suspended); } } /* Decrement LWP's suspend count. */ static void lwp_suspended_decr (struct lwp_info *lwp) { lwp->suspended--; if (lwp->suspended < 0) { struct thread_info *thread = get_lwp_thread (lwp); internal_error (__FILE__, __LINE__, "unsuspend LWP %ld, suspended=%d\n", lwpid_of (thread), lwp->suspended); } } /* This function should only be called if the LWP got a SIGTRAP. Handle any tracepoint steps or hits. Return true if a tracepoint event was handled, 0 otherwise. */ static int handle_tracepoints (struct lwp_info *lwp) { struct thread_info *tinfo = get_lwp_thread (lwp); int tpoint_related_event = 0; gdb_assert (lwp->suspended == 0); /* If this tracepoint hit causes a tracing stop, we'll immediately uninsert tracepoints. To do this, we temporarily pause all threads, unpatch away, and then unpause threads. We need to make sure the unpausing doesn't resume LWP too. */ lwp_suspended_inc (lwp); /* And we need to be sure that any all-threads-stopping doesn't try to move threads out of the jump pads, as it could deadlock the inferior (LWP could be in the jump pad, maybe even holding the lock.) */ /* Do any necessary step collect actions. */ tpoint_related_event |= tracepoint_finished_step (tinfo, lwp->stop_pc); tpoint_related_event |= handle_tracepoint_bkpts (tinfo, lwp->stop_pc); /* See if we just hit a tracepoint and do its main collect actions. */ tpoint_related_event |= tracepoint_was_hit (tinfo, lwp->stop_pc); lwp_suspended_decr (lwp); gdb_assert (lwp->suspended == 0); gdb_assert (!stabilizing_threads || (lwp->collecting_fast_tracepoint != fast_tpoint_collect_result::not_collecting)); if (tpoint_related_event) { if (debug_threads) debug_printf ("got a tracepoint event\n"); return 1; } return 0; } fast_tpoint_collect_result linux_process_target::linux_fast_tracepoint_collecting (lwp_info *lwp, fast_tpoint_collect_status *status) { CORE_ADDR thread_area; struct thread_info *thread = get_lwp_thread (lwp); /* Get the thread area address. This is used to recognize which thread is which when tracing with the in-process agent library. We don't read anything from the address, and treat it as opaque; it's the address itself that we assume is unique per-thread. */ if (low_get_thread_area (lwpid_of (thread), &thread_area) == -1) return fast_tpoint_collect_result::not_collecting; return fast_tracepoint_collecting (thread_area, lwp->stop_pc, status); } int linux_process_target::low_get_thread_area (int lwpid, CORE_ADDR *addrp) { return -1; } bool linux_process_target::maybe_move_out_of_jump_pad (lwp_info *lwp, int *wstat) { struct thread_info *saved_thread; saved_thread = current_thread; current_thread = get_lwp_thread (lwp); if ((wstat == NULL || (WIFSTOPPED (*wstat) && WSTOPSIG (*wstat) != SIGTRAP)) && supports_fast_tracepoints () && agent_loaded_p ()) { struct fast_tpoint_collect_status status; if (debug_threads) debug_printf ("Checking whether LWP %ld needs to move out of the " "jump pad.\n", lwpid_of (current_thread)); fast_tpoint_collect_result r = linux_fast_tracepoint_collecting (lwp, &status); if (wstat == NULL || (WSTOPSIG (*wstat) != SIGILL && WSTOPSIG (*wstat) != SIGFPE && WSTOPSIG (*wstat) != SIGSEGV && WSTOPSIG (*wstat) != SIGBUS)) { lwp->collecting_fast_tracepoint = r; if (r != fast_tpoint_collect_result::not_collecting) { if (r == fast_tpoint_collect_result::before_insn && lwp->exit_jump_pad_bkpt == NULL) { /* Haven't executed the original instruction yet. Set breakpoint there, and wait till it's hit, then single-step until exiting the jump pad. */ lwp->exit_jump_pad_bkpt = set_breakpoint_at (status.adjusted_insn_addr, NULL); } if (debug_threads) debug_printf ("Checking whether LWP %ld needs to move out of " "the jump pad...it does\n", lwpid_of (current_thread)); current_thread = saved_thread; return true; } } else { /* If we get a synchronous signal while collecting, *and* while executing the (relocated) original instruction, reset the PC to point at the tpoint address, before reporting to GDB. Otherwise, it's an IPA lib bug: just report the signal to GDB, and pray for the best. */ lwp->collecting_fast_tracepoint = fast_tpoint_collect_result::not_collecting; if (r != fast_tpoint_collect_result::not_collecting && (status.adjusted_insn_addr <= lwp->stop_pc && lwp->stop_pc < status.adjusted_insn_addr_end)) { siginfo_t info; struct regcache *regcache; /* The si_addr on a few signals references the address of the faulting instruction. Adjust that as well. */ if ((WSTOPSIG (*wstat) == SIGILL || WSTOPSIG (*wstat) == SIGFPE || WSTOPSIG (*wstat) == SIGBUS || WSTOPSIG (*wstat) == SIGSEGV) && ptrace (PTRACE_GETSIGINFO, lwpid_of (current_thread), (PTRACE_TYPE_ARG3) 0, &info) == 0 /* Final check just to make sure we don't clobber the siginfo of non-kernel-sent signals. */ && (uintptr_t) info.si_addr == lwp->stop_pc) { info.si_addr = (void *) (uintptr_t) status.tpoint_addr; ptrace (PTRACE_SETSIGINFO, lwpid_of (current_thread), (PTRACE_TYPE_ARG3) 0, &info); } regcache = get_thread_regcache (current_thread, 1); low_set_pc (regcache, status.tpoint_addr); lwp->stop_pc = status.tpoint_addr; /* Cancel any fast tracepoint lock this thread was holding. */ force_unlock_trace_buffer (); } if (lwp->exit_jump_pad_bkpt != NULL) { if (debug_threads) debug_printf ("Cancelling fast exit-jump-pad: removing bkpt. " "stopping all threads momentarily.\n"); stop_all_lwps (1, lwp); delete_breakpoint (lwp->exit_jump_pad_bkpt); lwp->exit_jump_pad_bkpt = NULL; unstop_all_lwps (1, lwp); gdb_assert (lwp->suspended >= 0); } } } if (debug_threads) debug_printf ("Checking whether LWP %ld needs to move out of the " "jump pad...no\n", lwpid_of (current_thread)); current_thread = saved_thread; return false; } /* Enqueue one signal in the "signals to report later when out of the jump pad" list. */ static void enqueue_one_deferred_signal (struct lwp_info *lwp, int *wstat) { struct thread_info *thread = get_lwp_thread (lwp); if (debug_threads) debug_printf ("Deferring signal %d for LWP %ld.\n", WSTOPSIG (*wstat), lwpid_of (thread)); if (debug_threads) { for (const auto &sig : lwp->pending_signals_to_report) debug_printf (" Already queued %d\n", sig.signal); debug_printf (" (no more currently queued signals)\n"); } /* Don't enqueue non-RT signals if they are already in the deferred queue. (SIGSTOP being the easiest signal to see ending up here twice) */ if (WSTOPSIG (*wstat) < __SIGRTMIN) { for (const auto &sig : lwp->pending_signals_to_report) { if (sig.signal == WSTOPSIG (*wstat)) { if (debug_threads) debug_printf ("Not requeuing already queued non-RT signal %d" " for LWP %ld\n", sig.signal, lwpid_of (thread)); return; } } } lwp->pending_signals_to_report.emplace_back (WSTOPSIG (*wstat)); ptrace (PTRACE_GETSIGINFO, lwpid_of (thread), (PTRACE_TYPE_ARG3) 0, &lwp->pending_signals_to_report.back ().info); } /* Dequeue one signal from the "signals to report later when out of the jump pad" list. */ static int dequeue_one_deferred_signal (struct lwp_info *lwp, int *wstat) { struct thread_info *thread = get_lwp_thread (lwp); if (!lwp->pending_signals_to_report.empty ()) { const pending_signal &p_sig = lwp->pending_signals_to_report.front (); *wstat = W_STOPCODE (p_sig.signal); if (p_sig.info.si_signo != 0) ptrace (PTRACE_SETSIGINFO, lwpid_of (thread), (PTRACE_TYPE_ARG3) 0, &p_sig.info); lwp->pending_signals_to_report.pop_front (); if (debug_threads) debug_printf ("Reporting deferred signal %d for LWP %ld.\n", WSTOPSIG (*wstat), lwpid_of (thread)); if (debug_threads) { for (const auto &sig : lwp->pending_signals_to_report) debug_printf (" Still queued %d\n", sig.signal); debug_printf (" (no more queued signals)\n"); } return 1; } return 0; } bool linux_process_target::check_stopped_by_watchpoint (lwp_info *child) { struct thread_info *saved_thread = current_thread; current_thread = get_lwp_thread (child); if (low_stopped_by_watchpoint ()) { child->stop_reason = TARGET_STOPPED_BY_WATCHPOINT; child->stopped_data_address = low_stopped_data_address (); } current_thread = saved_thread; return child->stop_reason == TARGET_STOPPED_BY_WATCHPOINT; } bool linux_process_target::low_stopped_by_watchpoint () { return false; } CORE_ADDR linux_process_target::low_stopped_data_address () { return 0; } /* Return the ptrace options that we want to try to enable. */ static int linux_low_ptrace_options (int attached) { client_state &cs = get_client_state (); int options = 0; if (!attached) options |= PTRACE_O_EXITKILL; if (cs.report_fork_events) options |= PTRACE_O_TRACEFORK; if (cs.report_vfork_events) options |= (PTRACE_O_TRACEVFORK | PTRACE_O_TRACEVFORKDONE); if (cs.report_exec_events) options |= PTRACE_O_TRACEEXEC; options |= PTRACE_O_TRACESYSGOOD; return options; } void linux_process_target::filter_event (int lwpid, int wstat) { client_state &cs = get_client_state (); struct lwp_info *child; struct thread_info *thread; int have_stop_pc = 0; child = find_lwp_pid (ptid_t (lwpid)); /* Check for stop events reported by a process we didn't already know about - anything not already in our LWP list. If we're expecting to receive stopped processes after fork, vfork, and clone events, then we'll just add the new one to our list and go back to waiting for the event to be reported - the stopped process might be returned from waitpid before or after the event is. But note the case of a non-leader thread exec'ing after the leader having exited, and gone from our lists (because check_zombie_leaders deleted it). The non-leader thread changes its tid to the tgid. */ if (WIFSTOPPED (wstat) && child == NULL && WSTOPSIG (wstat) == SIGTRAP && linux_ptrace_get_extended_event (wstat) == PTRACE_EVENT_EXEC) { ptid_t child_ptid; /* A multi-thread exec after we had seen the leader exiting. */ if (debug_threads) { debug_printf ("LLW: Re-adding thread group leader LWP %d" "after exec.\n", lwpid); } child_ptid = ptid_t (lwpid, lwpid); child = add_lwp (child_ptid); child->stopped = 1; current_thread = child->thread; } /* If we didn't find a process, one of two things presumably happened: - A process we started and then detached from has exited. Ignore it. - A process we are controlling has forked and the new child's stop was reported to us by the kernel. Save its PID. */ if (child == NULL && WIFSTOPPED (wstat)) { add_to_pid_list (&stopped_pids, lwpid, wstat); return; } else if (child == NULL) return; thread = get_lwp_thread (child); child->stopped = 1; child->last_status = wstat; /* Check if the thread has exited. */ if ((WIFEXITED (wstat) || WIFSIGNALED (wstat))) { if (debug_threads) debug_printf ("LLFE: %d exited.\n", lwpid); if (finish_step_over (child)) { /* Unsuspend all other LWPs, and set them back running again. */ unsuspend_all_lwps (child); } /* If there is at least one more LWP, then the exit signal was not the end of the debugged application and should be ignored, unless GDB wants to hear about thread exits. */ if (cs.report_thread_events || last_thread_of_process_p (pid_of (thread))) { /* Since events are serialized to GDB core, and we can't report this one right now. Leave the status pending for the next time we're able to report it. */ mark_lwp_dead (child, wstat); return; } else { delete_lwp (child); return; } } gdb_assert (WIFSTOPPED (wstat)); if (WIFSTOPPED (wstat)) { struct process_info *proc; /* Architecture-specific setup after inferior is running. */ proc = find_process_pid (pid_of (thread)); if (proc->tdesc == NULL) { if (proc->attached) { /* This needs to happen after we have attached to the inferior and it is stopped for the first time, but before we access any inferior registers. */ arch_setup_thread (thread); } else { /* The process is started, but GDBserver will do architecture-specific setup after the program stops at the first instruction. */ child->status_pending_p = 1; child->status_pending = wstat; return; } } } if (WIFSTOPPED (wstat) && child->must_set_ptrace_flags) { struct process_info *proc = find_process_pid (pid_of (thread)); int options = linux_low_ptrace_options (proc->attached); linux_enable_event_reporting (lwpid, options); child->must_set_ptrace_flags = 0; } /* Always update syscall_state, even if it will be filtered later. */ if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SYSCALL_SIGTRAP) { child->syscall_state = (child->syscall_state == TARGET_WAITKIND_SYSCALL_ENTRY ? TARGET_WAITKIND_SYSCALL_RETURN : TARGET_WAITKIND_SYSCALL_ENTRY); } else { /* Almost all other ptrace-stops are known to be outside of system calls, with further exceptions in handle_extended_wait. */ child->syscall_state = TARGET_WAITKIND_IGNORE; } /* Be careful to not overwrite stop_pc until save_stop_reason is called. */ if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP && linux_is_extended_waitstatus (wstat)) { child->stop_pc = get_pc (child); if (handle_extended_wait (&child, wstat)) { /* The event has been handled, so just return without reporting it. */ return; } } if (linux_wstatus_maybe_breakpoint (wstat)) { if (save_stop_reason (child)) have_stop_pc = 1; } if (!have_stop_pc) child->stop_pc = get_pc (child); if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGSTOP && child->stop_expected) { if (debug_threads) debug_printf ("Expected stop.\n"); child->stop_expected = 0; if (thread->last_resume_kind == resume_stop) { /* We want to report the stop to the core. Treat the SIGSTOP as a normal event. */ if (debug_threads) debug_printf ("LLW: resume_stop SIGSTOP caught for %s.\n", target_pid_to_str (ptid_of (thread)).c_str ()); } else if (stopping_threads != NOT_STOPPING_THREADS) { /* Stopping threads. We don't want this SIGSTOP to end up pending. */ if (debug_threads) debug_printf ("LLW: SIGSTOP caught for %s " "while stopping threads.\n", target_pid_to_str (ptid_of (thread)).c_str ()); return; } else { /* This is a delayed SIGSTOP. Filter out the event. */ if (debug_threads) debug_printf ("LLW: %s %s, 0, 0 (discard delayed SIGSTOP)\n", child->stepping ? "step" : "continue", target_pid_to_str (ptid_of (thread)).c_str ()); resume_one_lwp (child, child->stepping, 0, NULL); return; } } child->status_pending_p = 1; child->status_pending = wstat; return; } bool linux_process_target::maybe_hw_step (thread_info *thread) { if (supports_hardware_single_step ()) return true; else { /* GDBserver must insert single-step breakpoint for software single step. */ gdb_assert (has_single_step_breakpoints (thread)); return false; } } void linux_process_target::resume_stopped_resumed_lwps (thread_info *thread) { struct lwp_info *lp = get_thread_lwp (thread); if (lp->stopped && !lp->suspended && !lp->status_pending_p && thread->last_status.kind () == TARGET_WAITKIND_IGNORE) { int step = 0; if (thread->last_resume_kind == resume_step) step = maybe_hw_step (thread); if (debug_threads) debug_printf ("RSRL: resuming stopped-resumed LWP %s at %s: step=%d\n", target_pid_to_str (ptid_of (thread)).c_str (), paddress (lp->stop_pc), step); resume_one_lwp (lp, step, GDB_SIGNAL_0, NULL); } } int linux_process_target::wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, int *wstatp, int options) { struct thread_info *event_thread; struct lwp_info *event_child, *requested_child; sigset_t block_mask, prev_mask; retry: /* N.B. event_thread points to the thread_info struct that contains event_child. Keep them in sync. */ event_thread = NULL; event_child = NULL; requested_child = NULL; /* Check for a lwp with a pending status. */ if (filter_ptid == minus_one_ptid || filter_ptid.is_pid ()) { event_thread = find_thread_in_random ([&] (thread_info *thread) { return status_pending_p_callback (thread, filter_ptid); }); if (event_thread != NULL) event_child = get_thread_lwp (event_thread); if (debug_threads && event_thread) debug_printf ("Got a pending child %ld\n", lwpid_of (event_thread)); } else if (filter_ptid != null_ptid) { requested_child = find_lwp_pid (filter_ptid); if (stopping_threads == NOT_STOPPING_THREADS && requested_child->status_pending_p && (requested_child->collecting_fast_tracepoint != fast_tpoint_collect_result::not_collecting)) { enqueue_one_deferred_signal (requested_child, &requested_child->status_pending); requested_child->status_pending_p = 0; requested_child->status_pending = 0; resume_one_lwp (requested_child, 0, 0, NULL); } if (requested_child->suspended && requested_child->status_pending_p) { internal_error (__FILE__, __LINE__, "requesting an event out of a" " suspended child?"); } if (requested_child->status_pending_p) { event_child = requested_child; event_thread = get_lwp_thread (event_child); } } if (event_child != NULL) { if (debug_threads) debug_printf ("Got an event from pending child %ld (%04x)\n", lwpid_of (event_thread), event_child->status_pending); *wstatp = event_child->status_pending; event_child->status_pending_p = 0; event_child->status_pending = 0; current_thread = event_thread; return lwpid_of (event_thread); } /* But if we don't find a pending event, we'll have to wait. We only enter this loop if no process has a pending wait status. Thus any action taken in response to a wait status inside this loop is responding as soon as we detect the status, not after any pending events. */ /* Make sure SIGCHLD is blocked until the sigsuspend below. Block all signals while here. */ sigfillset (&block_mask); gdb_sigmask (SIG_BLOCK, &block_mask, &prev_mask); /* Always pull all events out of the kernel. We'll randomly select an event LWP out of all that have events, to prevent starvation. */ while (event_child == NULL) { pid_t ret = 0; /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace quirks: - If the thread group leader exits while other threads in the thread group still exist, waitpid(TGID, ...) hangs. That waitpid won't return an exit status until the other threads in the group are reaped. - When a non-leader thread execs, that thread just vanishes without reporting an exit (so we'd hang if we waited for it explicitly in that case). The exec event is reported to the TGID pid. */ errno = 0; ret = my_waitpid (-1, wstatp, options | WNOHANG); if (debug_threads) debug_printf ("LWFE: waitpid(-1, ...) returned %d, %s\n", ret, errno ? safe_strerror (errno) : "ERRNO-OK"); if (ret > 0) { if (debug_threads) { debug_printf ("LLW: waitpid %ld received %s\n", (long) ret, status_to_str (*wstatp).c_str ()); } /* Filter all events. IOW, leave all events pending. We'll randomly select an event LWP out of all that have events below. */ filter_event (ret, *wstatp); /* Retry until nothing comes out of waitpid. A single SIGCHLD can indicate more than one child stopped. */ continue; } /* Now that we've pulled all events out of the kernel, resume LWPs that don't have an interesting event to report. */ if (stopping_threads == NOT_STOPPING_THREADS) for_each_thread ([this] (thread_info *thread) { resume_stopped_resumed_lwps (thread); }); /* ... and find an LWP with a status to report to the core, if any. */ event_thread = find_thread_in_random ([&] (thread_info *thread) { return status_pending_p_callback (thread, filter_ptid); }); if (event_thread != NULL) { event_child = get_thread_lwp (event_thread); *wstatp = event_child->status_pending; event_child->status_pending_p = 0; event_child->status_pending = 0; break; } /* Check for zombie thread group leaders. Those can't be reaped until all other threads in the thread group are. */ check_zombie_leaders (); auto not_stopped = [&] (thread_info *thread) { return not_stopped_callback (thread, wait_ptid); }; /* If there are no resumed children left in the set of LWPs we want to wait for, bail. We can't just block in waitpid/sigsuspend, because lwps might have been left stopped in trace-stop state, and we'd be stuck forever waiting for their status to change (which would only happen if we resumed them). Even if WNOHANG is set, this return code is preferred over 0 (below), as it is more detailed. */ if (find_thread (not_stopped) == NULL) { if (debug_threads) debug_printf ("LLW: exit (no unwaited-for LWP)\n"); gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); return -1; } /* No interesting event to report to the caller. */ if ((options & WNOHANG)) { if (debug_threads) debug_printf ("WNOHANG set, no event found\n"); gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); return 0; } /* Block until we get an event reported with SIGCHLD. */ if (debug_threads) debug_printf ("sigsuspend'ing\n"); sigsuspend (&prev_mask); gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); goto retry; } gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); current_thread = event_thread; return lwpid_of (event_thread); } int linux_process_target::wait_for_event (ptid_t ptid, int *wstatp, int options) { return wait_for_event_filtered (ptid, ptid, wstatp, options); } /* Select one LWP out of those that have events pending. */ static void select_event_lwp (struct lwp_info **orig_lp) { struct thread_info *event_thread = NULL; /* In all-stop, give preference to the LWP that is being single-stepped. There will be at most one, and it's the LWP that the core is most interested in. If we didn't do this, then we'd have to handle pending step SIGTRAPs somehow in case the core later continues the previously-stepped thread, otherwise we'd report the pending SIGTRAP, and the core, not having stepped the thread, wouldn't understand what the trap was for, and therefore would report it to the user as a random signal. */ if (!non_stop) { event_thread = find_thread ([] (thread_info *thread) { lwp_info *lp = get_thread_lwp (thread); return (thread->last_status.kind () == TARGET_WAITKIND_IGNORE && thread->last_resume_kind == resume_step && lp->status_pending_p); }); if (event_thread != NULL) { if (debug_threads) debug_printf ("SEL: Select single-step %s\n", target_pid_to_str (ptid_of (event_thread)).c_str ()); } } if (event_thread == NULL) { /* No single-stepping LWP. Select one at random, out of those which have had events. */ event_thread = find_thread_in_random ([&] (thread_info *thread) { lwp_info *lp = get_thread_lwp (thread); /* Only resumed LWPs that have an event pending. */ return (thread->last_status.kind () == TARGET_WAITKIND_IGNORE && lp->status_pending_p); }); } if (event_thread != NULL) { struct lwp_info *event_lp = get_thread_lwp (event_thread); /* Switch the event LWP. */ *orig_lp = event_lp; } } /* Decrement the suspend count of all LWPs, except EXCEPT, if non NULL. */ static void unsuspend_all_lwps (struct lwp_info *except) { for_each_thread ([&] (thread_info *thread) { lwp_info *lwp = get_thread_lwp (thread); if (lwp != except) lwp_suspended_decr (lwp); }); } static bool lwp_running (thread_info *thread); /* Stabilize threads (move out of jump pads). If a thread is midway collecting a fast tracepoint, we need to finish the collection and move it out of the jump pad before reporting the signal. This avoids recursion while collecting (when a signal arrives midway, and the signal handler itself collects), which would trash the trace buffer. In case the user set a breakpoint in a signal handler, this avoids the backtrace showing the jump pad, etc.. Most importantly, there are certain things we can't do safely if threads are stopped in a jump pad (or in its callee's). For example: - starting a new trace run. A thread still collecting the previous run, could trash the trace buffer when resumed. The trace buffer control structures would have been reset but the thread had no way to tell. The thread could even midway memcpy'ing to the buffer, which would mean that when resumed, it would clobber the trace buffer that had been set for a new run. - we can't rewrite/reuse the jump pads for new tracepoints safely. Say you do tstart while a thread is stopped midway while collecting. When the thread is later resumed, it finishes the collection, and returns to the jump pad, to execute the original instruction that was under the tracepoint jump at the time the older run had been started. If the jump pad had been rewritten since for something else in the new run, the thread would now execute the wrong / random instructions. */ void linux_process_target::stabilize_threads () { thread_info *thread_stuck = find_thread ([this] (thread_info *thread) { return stuck_in_jump_pad (thread); }); if (thread_stuck != NULL) { if (debug_threads) debug_printf ("can't stabilize, LWP %ld is stuck in jump pad\n", lwpid_of (thread_stuck)); return; } thread_info *saved_thread = current_thread; stabilizing_threads = 1; /* Kick 'em all. */ for_each_thread ([this] (thread_info *thread) { move_out_of_jump_pad (thread); }); /* Loop until all are stopped out of the jump pads. */ while (find_thread (lwp_running) != NULL) { struct target_waitstatus ourstatus; struct lwp_info *lwp; int wstat; /* Note that we go through the full wait even loop. While moving threads out of jump pad, we need to be able to step over internal breakpoints and such. */ wait_1 (minus_one_ptid, &ourstatus, 0); if (ourstatus.kind () == TARGET_WAITKIND_STOPPED) { lwp = get_thread_lwp (current_thread); /* Lock it. */ lwp_suspended_inc (lwp); if (ourstatus.sig () != GDB_SIGNAL_0 || current_thread->last_resume_kind == resume_stop) { wstat = W_STOPCODE (gdb_signal_to_host (ourstatus.sig ())); enqueue_one_deferred_signal (lwp, &wstat); } } } unsuspend_all_lwps (NULL); stabilizing_threads = 0; current_thread = saved_thread; if (debug_threads) { thread_stuck = find_thread ([this] (thread_info *thread) { return stuck_in_jump_pad (thread); }); if (thread_stuck != NULL) debug_printf ("couldn't stabilize, LWP %ld got stuck in jump pad\n", lwpid_of (thread_stuck)); } } /* Convenience function that is called when the kernel reports an event that is not passed out to GDB. */ static ptid_t ignore_event (struct target_waitstatus *ourstatus) { /* If we got an event, there may still be others, as a single SIGCHLD can indicate more than one child stopped. This forces another target_wait call. */ async_file_mark (); ourstatus->set_ignore (); return null_ptid; } ptid_t linux_process_target::filter_exit_event (lwp_info *event_child, target_waitstatus *ourstatus) { client_state &cs = get_client_state (); struct thread_info *thread = get_lwp_thread (event_child); ptid_t ptid = ptid_of (thread); if (!last_thread_of_process_p (pid_of (thread))) { if (cs.report_thread_events) ourstatus->set_thread_exited (0); else ourstatus->set_ignore (); delete_lwp (event_child); } return ptid; } /* Returns 1 if GDB is interested in any event_child syscalls. */ static int gdb_catching_syscalls_p (struct lwp_info *event_child) { struct thread_info *thread = get_lwp_thread (event_child); struct process_info *proc = get_thread_process (thread); return !proc->syscalls_to_catch.empty (); } bool linux_process_target::gdb_catch_this_syscall (lwp_info *event_child) { int sysno; struct thread_info *thread = get_lwp_thread (event_child); struct process_info *proc = get_thread_process (thread); if (proc->syscalls_to_catch.empty ()) return false; if (proc->syscalls_to_catch[0] == ANY_SYSCALL) return true; get_syscall_trapinfo (event_child, &sysno); for (int iter : proc->syscalls_to_catch) if (iter == sysno) return true; return false; } ptid_t linux_process_target::wait_1 (ptid_t ptid, target_waitstatus *ourstatus, target_wait_flags target_options) { client_state &cs = get_client_state (); int w; struct lwp_info *event_child; int options; int pid; int step_over_finished; int bp_explains_trap; int maybe_internal_trap; int report_to_gdb; int trace_event; int in_step_range; int any_resumed; if (debug_threads) { debug_enter (); debug_printf ("wait_1: [%s]\n", target_pid_to_str (ptid).c_str ()); } /* Translate generic target options into linux options. */ options = __WALL; if (target_options & TARGET_WNOHANG) options |= WNOHANG; bp_explains_trap = 0; trace_event = 0; in_step_range = 0; ourstatus->set_ignore (); auto status_pending_p_any = [&] (thread_info *thread) { return status_pending_p_callback (thread, minus_one_ptid); }; auto not_stopped = [&] (thread_info *thread) { return not_stopped_callback (thread, minus_one_ptid); }; /* Find a resumed LWP, if any. */ if (find_thread (status_pending_p_any) != NULL) any_resumed = 1; else if (find_thread (not_stopped) != NULL) any_resumed = 1; else any_resumed = 0; if (step_over_bkpt == null_ptid) pid = wait_for_event (ptid, &w, options); else { if (debug_threads) debug_printf ("step_over_bkpt set [%s], doing a blocking wait\n", target_pid_to_str (step_over_bkpt).c_str ()); pid = wait_for_event (step_over_bkpt, &w, options & ~WNOHANG); } if (pid == 0 || (pid == -1 && !any_resumed)) { gdb_assert (target_options & TARGET_WNOHANG); if (debug_threads) { debug_printf ("wait_1 ret = null_ptid, " "TARGET_WAITKIND_IGNORE\n"); debug_exit (); } ourstatus->set_ignore (); return null_ptid; } else if (pid == -1) { if (debug_threads) { debug_printf ("wait_1 ret = null_ptid, " "TARGET_WAITKIND_NO_RESUMED\n"); debug_exit (); } ourstatus->set_no_resumed (); return null_ptid; } event_child = get_thread_lwp (current_thread); /* wait_for_event only returns an exit status for the last child of a process. Report it. */ if (WIFEXITED (w) || WIFSIGNALED (w)) { if (WIFEXITED (w)) { ourstatus->set_exited (WEXITSTATUS (w)); if (debug_threads) { debug_printf ("wait_1 ret = %s, exited with " "retcode %d\n", target_pid_to_str (ptid_of (current_thread)).c_str (), WEXITSTATUS (w)); debug_exit (); } } else { ourstatus->set_signalled (gdb_signal_from_host (WTERMSIG (w))); if (debug_threads) { debug_printf ("wait_1 ret = %s, terminated with " "signal %d\n", target_pid_to_str (ptid_of (current_thread)).c_str (), WTERMSIG (w)); debug_exit (); } } if (ourstatus->kind () == TARGET_WAITKIND_EXITED) return filter_exit_event (event_child, ourstatus); return ptid_of (current_thread); } /* If step-over executes a breakpoint instruction, in the case of a hardware single step it means a gdb/gdbserver breakpoint had been planted on top of a permanent breakpoint, in the case of a software single step it may just mean that gdbserver hit the reinsert breakpoint. The PC has been adjusted by save_stop_reason to point at the breakpoint address. So in the case of the hardware single step advance the PC manually past the breakpoint and in the case of software single step advance only if it's not the single_step_breakpoint we are hitting. This avoids that a program would keep trapping a permanent breakpoint forever. */ if (step_over_bkpt != null_ptid && event_child->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT && (event_child->stepping || !single_step_breakpoint_inserted_here (event_child->stop_pc))) { int increment_pc = 0; int breakpoint_kind = 0; CORE_ADDR stop_pc = event_child->stop_pc; breakpoint_kind = breakpoint_kind_from_current_state (&stop_pc); sw_breakpoint_from_kind (breakpoint_kind, &increment_pc); if (debug_threads) { debug_printf ("step-over for %s executed software breakpoint\n", target_pid_to_str (ptid_of (current_thread)).c_str ()); } if (increment_pc != 0) { struct regcache *regcache = get_thread_regcache (current_thread, 1); event_child->stop_pc += increment_pc; low_set_pc (regcache, event_child->stop_pc); if (!low_breakpoint_at (event_child->stop_pc)) event_child->stop_reason = TARGET_STOPPED_BY_NO_REASON; } } /* If this event was not handled before, and is not a SIGTRAP, we report it. SIGILL and SIGSEGV are also treated as traps in case a breakpoint is inserted at the current PC. If this target does not support internal breakpoints at all, we also report the SIGTRAP without further processing; it's of no concern to us. */ maybe_internal_trap = (low_supports_breakpoints () && (WSTOPSIG (w) == SIGTRAP || ((WSTOPSIG (w) == SIGILL || WSTOPSIG (w) == SIGSEGV) && low_breakpoint_at (event_child->stop_pc)))); if (maybe_internal_trap) { /* Handle anything that requires bookkeeping before deciding to report the event or continue waiting. */ /* First check if we can explain the SIGTRAP with an internal breakpoint, or if we should possibly report the event to GDB. Do this before anything that may remove or insert a breakpoint. */ bp_explains_trap = breakpoint_inserted_here (event_child->stop_pc); /* We have a SIGTRAP, possibly a step-over dance has just finished. If so, tweak the state machine accordingly, reinsert breakpoints and delete any single-step breakpoints. */ step_over_finished = finish_step_over (event_child); /* Now invoke the callbacks of any internal breakpoints there. */ check_breakpoints (event_child->stop_pc); /* Handle tracepoint data collecting. This may overflow the trace buffer, and cause a tracing stop, removing breakpoints. */ trace_event = handle_tracepoints (event_child); if (bp_explains_trap) { if (debug_threads) debug_printf ("Hit a gdbserver breakpoint.\n"); } } else { /* We have some other signal, possibly a step-over dance was in progress, and it should be cancelled too. */ step_over_finished = finish_step_over (event_child); } /* We have all the data we need. Either report the event to GDB, or resume threads and keep waiting for more. */ /* If we're collecting a fast tracepoint, finish the collection and move out of the jump pad before delivering a signal. See linux_stabilize_threads. */ if (WIFSTOPPED (w) && WSTOPSIG (w) != SIGTRAP && supports_fast_tracepoints () && agent_loaded_p ()) { if (debug_threads) debug_printf ("Got signal %d for LWP %ld. Check if we need " "to defer or adjust it.\n", WSTOPSIG (w), lwpid_of (current_thread)); /* Allow debugging the jump pad itself. */ if (current_thread->last_resume_kind != resume_step && maybe_move_out_of_jump_pad (event_child, &w)) { enqueue_one_deferred_signal (event_child, &w); if (debug_threads) debug_printf ("Signal %d for LWP %ld deferred (in jump pad)\n", WSTOPSIG (w), lwpid_of (current_thread)); resume_one_lwp (event_child, 0, 0, NULL); if (debug_threads) debug_exit (); return ignore_event (ourstatus); } } if (event_child->collecting_fast_tracepoint != fast_tpoint_collect_result::not_collecting) { if (debug_threads) debug_printf ("LWP %ld was trying to move out of the jump pad (%d). " "Check if we're already there.\n", lwpid_of (current_thread), (int) event_child->collecting_fast_tracepoint); trace_event = 1; event_child->collecting_fast_tracepoint = linux_fast_tracepoint_collecting (event_child, NULL); if (event_child->collecting_fast_tracepoint != fast_tpoint_collect_result::before_insn) { /* No longer need this breakpoint. */ if (event_child->exit_jump_pad_bkpt != NULL) { if (debug_threads) debug_printf ("No longer need exit-jump-pad bkpt; removing it." "stopping all threads momentarily.\n"); /* Other running threads could hit this breakpoint. We don't handle moribund locations like GDB does, instead we always pause all threads when removing breakpoints, so that any step-over or decr_pc_after_break adjustment is always taken care of while the breakpoint is still inserted. */ stop_all_lwps (1, event_child); delete_breakpoint (event_child->exit_jump_pad_bkpt); event_child->exit_jump_pad_bkpt = NULL; unstop_all_lwps (1, event_child); gdb_assert (event_child->suspended >= 0); } } if (event_child->collecting_fast_tracepoint == fast_tpoint_collect_result::not_collecting) { if (debug_threads) debug_printf ("fast tracepoint finished " "collecting successfully.\n"); /* We may have a deferred signal to report. */ if (dequeue_one_deferred_signal (event_child, &w)) { if (debug_threads) debug_printf ("dequeued one signal.\n"); } else { if (debug_threads) debug_printf ("no deferred signals.\n"); if (stabilizing_threads) { ourstatus->set_stopped (GDB_SIGNAL_0); if (debug_threads) { debug_printf ("wait_1 ret = %s, stopped " "while stabilizing threads\n", target_pid_to_str (ptid_of (current_thread)).c_str ()); debug_exit (); } return ptid_of (current_thread); } } } } /* Check whether GDB would be interested in this event. */ /* Check if GDB is interested in this syscall. */ if (WIFSTOPPED (w) && WSTOPSIG (w) == SYSCALL_SIGTRAP && !gdb_catch_this_syscall (event_child)) { if (debug_threads) { debug_printf ("Ignored syscall for LWP %ld.\n", lwpid_of (current_thread)); } resume_one_lwp (event_child, event_child->stepping, 0, NULL); if (debug_threads) debug_exit (); return ignore_event (ourstatus); } /* If GDB is not interested in this signal, don't stop other threads, and don't report it to GDB. Just resume the inferior right away. We do this for threading-related signals as well as any that GDB specifically requested we ignore. But never ignore SIGSTOP if we sent it ourselves, and do not ignore signals when stepping - they may require special handling to skip the signal handler. Also never ignore signals that could be caused by a breakpoint. */ if (WIFSTOPPED (w) && current_thread->last_resume_kind != resume_step && ( #if defined (USE_THREAD_DB) && !defined (__ANDROID__) (current_process ()->priv->thread_db != NULL && (WSTOPSIG (w) == __SIGRTMIN || WSTOPSIG (w) == __SIGRTMIN + 1)) || #endif (cs.pass_signals[gdb_signal_from_host (WSTOPSIG (w))] && !(WSTOPSIG (w) == SIGSTOP && current_thread->last_resume_kind == resume_stop) && !linux_wstatus_maybe_breakpoint (w)))) { siginfo_t info, *info_p; if (debug_threads) debug_printf ("Ignored signal %d for LWP %ld.\n", WSTOPSIG (w), lwpid_of (current_thread)); if (ptrace (PTRACE_GETSIGINFO, lwpid_of (current_thread), (PTRACE_TYPE_ARG3) 0, &info) == 0) info_p = &info; else info_p = NULL; if (step_over_finished) { /* We cancelled this thread's step-over above. We still need to unsuspend all other LWPs, and set them back running again while the signal handler runs. */ unsuspend_all_lwps (event_child); /* Enqueue the pending signal info so that proceed_all_lwps doesn't lose it. */ enqueue_pending_signal (event_child, WSTOPSIG (w), info_p); proceed_all_lwps (); } else { resume_one_lwp (event_child, event_child->stepping, WSTOPSIG (w), info_p); } if (debug_threads) debug_exit (); return ignore_event (ourstatus); } /* Note that all addresses are always "out of the step range" when there's no range to begin with. */ in_step_range = lwp_in_step_range (event_child); /* If GDB wanted this thread to single step, and the thread is out of the step range, we always want to report the SIGTRAP, and let GDB handle it. Watchpoints should always be reported. So should signals we can't explain. A SIGTRAP we can't explain could be a GDB breakpoint --- we may or not support Z0 breakpoints. If we do, we're be able to handle GDB breakpoints on top of internal breakpoints, by handling the internal breakpoint and still reporting the event to GDB. If we don't, we're out of luck, GDB won't see the breakpoint hit. If we see a single-step event but the thread should be continuing, don't pass the trap to gdb. That indicates that we had previously finished a single-step but left the single-step pending -- see complete_ongoing_step_over. */ report_to_gdb = (!maybe_internal_trap || (current_thread->last_resume_kind == resume_step && !in_step_range) || event_child->stop_reason == TARGET_STOPPED_BY_WATCHPOINT || (!in_step_range && !bp_explains_trap && !trace_event && !step_over_finished && !(current_thread->last_resume_kind == resume_continue && event_child->stop_reason == TARGET_STOPPED_BY_SINGLE_STEP)) || (gdb_breakpoint_here (event_child->stop_pc) && gdb_condition_true_at_breakpoint (event_child->stop_pc) && gdb_no_commands_at_breakpoint (event_child->stop_pc)) || event_child->waitstatus.kind () != TARGET_WAITKIND_IGNORE); run_breakpoint_commands (event_child->stop_pc); /* We found no reason GDB would want us to stop. We either hit one of our own breakpoints, or finished an internal step GDB shouldn't know about. */ if (!report_to_gdb) { if (debug_threads) { if (bp_explains_trap) debug_printf ("Hit a gdbserver breakpoint.\n"); if (step_over_finished) debug_printf ("Step-over finished.\n"); if (trace_event) debug_printf ("Tracepoint event.\n"); if (lwp_in_step_range (event_child)) debug_printf ("Range stepping pc 0x%s [0x%s, 0x%s).\n", paddress (event_child->stop_pc), paddress (event_child->step_range_start), paddress (event_child->step_range_end)); } /* We're not reporting this breakpoint to GDB, so apply the decr_pc_after_break adjustment to the inferior's regcache ourselves. */ if (low_supports_breakpoints ()) { struct regcache *regcache = get_thread_regcache (current_thread, 1); low_set_pc (regcache, event_child->stop_pc); } if (step_over_finished) { /* If we have finished stepping over a breakpoint, we've stopped and suspended all LWPs momentarily except the stepping one. This is where we resume them all again. We're going to keep waiting, so use proceed, which handles stepping over the next breakpoint. */ unsuspend_all_lwps (event_child); } else { /* Remove the single-step breakpoints if any. Note that there isn't single-step breakpoint if we finished stepping over. */ if (supports_software_single_step () && has_single_step_breakpoints (current_thread)) { stop_all_lwps (0, event_child); delete_single_step_breakpoints (current_thread); unstop_all_lwps (0, event_child); } } if (debug_threads) debug_printf ("proceeding all threads.\n"); proceed_all_lwps (); if (debug_threads) debug_exit (); return ignore_event (ourstatus); } if (debug_threads) { if (event_child->waitstatus.kind () != TARGET_WAITKIND_IGNORE) { std::string str = target_waitstatus_to_string (&event_child->waitstatus); debug_printf ("LWP %ld: extended event with waitstatus %s\n", lwpid_of (get_lwp_thread (event_child)), str.c_str ()); } if (current_thread->last_resume_kind == resume_step) { if (event_child->step_range_start == event_child->step_range_end) debug_printf ("GDB wanted to single-step, reporting event.\n"); else if (!lwp_in_step_range (event_child)) debug_printf ("Out of step range, reporting event.\n"); } if (event_child->stop_reason == TARGET_STOPPED_BY_WATCHPOINT) debug_printf ("Stopped by watchpoint.\n"); else if (gdb_breakpoint_here (event_child->stop_pc)) debug_printf ("Stopped by GDB breakpoint.\n"); if (debug_threads) debug_printf ("Hit a non-gdbserver trap event.\n"); } /* Alright, we're going to report a stop. */ /* Remove single-step breakpoints. */ if (supports_software_single_step ()) { /* Remove single-step breakpoints or not. It it is true, stop all lwps, so that other threads won't hit the breakpoint in the staled memory. */ int remove_single_step_breakpoints_p = 0; if (non_stop) { remove_single_step_breakpoints_p = has_single_step_breakpoints (current_thread); } else { /* In all-stop, a stop reply cancels all previous resume requests. Delete all single-step breakpoints. */ find_thread ([&] (thread_info *thread) { if (has_single_step_breakpoints (thread)) { remove_single_step_breakpoints_p = 1; return true; } return false; }); } if (remove_single_step_breakpoints_p) { /* If we remove single-step breakpoints from memory, stop all lwps, so that other threads won't hit the breakpoint in the staled memory. */ stop_all_lwps (0, event_child); if (non_stop) { gdb_assert (has_single_step_breakpoints (current_thread)); delete_single_step_breakpoints (current_thread); } else { for_each_thread ([] (thread_info *thread){ if (has_single_step_breakpoints (thread)) delete_single_step_breakpoints (thread); }); } unstop_all_lwps (0, event_child); } } if (!stabilizing_threads) { /* In all-stop, stop all threads. */ if (!non_stop) stop_all_lwps (0, NULL); if (step_over_finished) { if (!non_stop) { /* If we were doing a step-over, all other threads but the stepping one had been paused in start_step_over, with their suspend counts incremented. We don't want to do a full unstop/unpause, because we're in all-stop mode (so we want threads stopped), but we still need to unsuspend the other threads, to decrement their `suspended' count back. */ unsuspend_all_lwps (event_child); } else { /* If we just finished a step-over, then all threads had been momentarily paused. In all-stop, that's fine, we want threads stopped by now anyway. In non-stop, we need to re-resume threads that GDB wanted to be running. */ unstop_all_lwps (1, event_child); } } /* If we're not waiting for a specific LWP, choose an event LWP from among those that have had events. Giving equal priority to all LWPs that have had events helps prevent starvation. */ if (ptid == minus_one_ptid) { event_child->status_pending_p = 1; event_child->status_pending = w; select_event_lwp (&event_child); /* current_thread and event_child must stay in sync. */ current_thread = get_lwp_thread (event_child); event_child->status_pending_p = 0; w = event_child->status_pending; } /* Stabilize threads (move out of jump pads). */ if (!non_stop) target_stabilize_threads (); } else { /* If we just finished a step-over, then all threads had been momentarily paused. In all-stop, that's fine, we want threads stopped by now anyway. In non-stop, we need to re-resume threads that GDB wanted to be running. */ if (step_over_finished) unstop_all_lwps (1, event_child); } if (event_child->waitstatus.kind () != TARGET_WAITKIND_IGNORE) { /* If the reported event is an exit, fork, vfork or exec, let GDB know. */ /* Break the unreported fork relationship chain. */ if (event_child->waitstatus.kind () == TARGET_WAITKIND_FORKED || event_child->waitstatus.kind () == TARGET_WAITKIND_VFORKED) { event_child->fork_relative->fork_relative = NULL; event_child->fork_relative = NULL; } *ourstatus = event_child->waitstatus; /* Clear the event lwp's waitstatus since we handled it already. */ event_child->waitstatus.set_ignore (); } else { /* The actual stop signal is overwritten below. */ ourstatus->set_stopped (GDB_SIGNAL_0); } /* Now that we've selected our final event LWP, un-adjust its PC if it was a software breakpoint, and the client doesn't know we can adjust the breakpoint ourselves. */ if (event_child->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT && !cs.swbreak_feature) { int decr_pc = low_decr_pc_after_break (); if (decr_pc != 0) { struct regcache *regcache = get_thread_regcache (current_thread, 1); low_set_pc (regcache, event_child->stop_pc + decr_pc); } } if (WSTOPSIG (w) == SYSCALL_SIGTRAP) { int syscall_number; get_syscall_trapinfo (event_child, &syscall_number); if (event_child->syscall_state == TARGET_WAITKIND_SYSCALL_ENTRY) ourstatus->set_syscall_entry (syscall_number); else if (event_child->syscall_state == TARGET_WAITKIND_SYSCALL_RETURN) ourstatus->set_syscall_return (syscall_number); else gdb_assert_not_reached ("unexpected syscall state"); } else if (current_thread->last_resume_kind == resume_stop && WSTOPSIG (w) == SIGSTOP) { /* A thread that has been requested to stop by GDB with vCont;t, and it stopped cleanly, so report as SIG0. The use of SIGSTOP is an implementation detail. */ ourstatus->set_stopped (GDB_SIGNAL_0); } else if (current_thread->last_resume_kind == resume_stop && WSTOPSIG (w) != SIGSTOP) { /* A thread that has been requested to stop by GDB with vCont;t, but, it stopped for other reasons. */ ourstatus->set_stopped (gdb_signal_from_host (WSTOPSIG (w))); } else if (ourstatus->kind () == TARGET_WAITKIND_STOPPED) ourstatus->set_stopped (gdb_signal_from_host (WSTOPSIG (w))); gdb_assert (step_over_bkpt == null_ptid); if (debug_threads) { debug_printf ("wait_1 ret = %s, %d, %d\n", target_pid_to_str (ptid_of (current_thread)).c_str (), ourstatus->kind (), ourstatus->sig ()); debug_exit (); } if (ourstatus->kind () == TARGET_WAITKIND_EXITED) return filter_exit_event (event_child, ourstatus); return ptid_of (current_thread); } /* Get rid of any pending event in the pipe. */ static void async_file_flush (void) { int ret; char buf; do ret = read (linux_event_pipe[0], &buf, 1); while (ret >= 0 || (ret == -1 && errno == EINTR)); } /* Put something in the pipe, so the event loop wakes up. */ static void async_file_mark (void) { int ret; async_file_flush (); do ret = write (linux_event_pipe[1], "+", 1); while (ret == 0 || (ret == -1 && errno == EINTR)); /* Ignore EAGAIN. If the pipe is full, the event loop will already be awakened anyway. */ } ptid_t linux_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus, target_wait_flags target_options) { ptid_t event_ptid; /* Flush the async file first. */ if (target_is_async_p ()) async_file_flush (); do { event_ptid = wait_1 (ptid, ourstatus, target_options); } while ((target_options & TARGET_WNOHANG) == 0 && event_ptid == null_ptid && ourstatus->kind () == TARGET_WAITKIND_IGNORE); /* If at least one stop was reported, there may be more. A single SIGCHLD can signal more than one child stop. */ if (target_is_async_p () && (target_options & TARGET_WNOHANG) != 0 && event_ptid != null_ptid) async_file_mark (); return event_ptid; } /* Send a signal to an LWP. */ static int kill_lwp (unsigned long lwpid, int signo) { int ret; errno = 0; ret = syscall (__NR_tkill, lwpid, signo); if (errno == ENOSYS) { /* If tkill fails, then we are not using nptl threads, a configuration we no longer support. */ perror_with_name (("tkill")); } return ret; } void linux_stop_lwp (struct lwp_info *lwp) { send_sigstop (lwp); } static void send_sigstop (struct lwp_info *lwp) { int pid; pid = lwpid_of (get_lwp_thread (lwp)); /* If we already have a pending stop signal for this process, don't send another. */ if (lwp->stop_expected) { if (debug_threads) debug_printf ("Have pending sigstop for lwp %d\n", pid); return; } if (debug_threads) debug_printf ("Sending sigstop to lwp %d\n", pid); lwp->stop_expected = 1; kill_lwp (pid, SIGSTOP); } static void send_sigstop (thread_info *thread, lwp_info *except) { struct lwp_info *lwp = get_thread_lwp (thread); /* Ignore EXCEPT. */ if (lwp == except) return; if (lwp->stopped) return; send_sigstop (lwp); } /* Increment the suspend count of an LWP, and stop it, if not stopped yet. */ static void suspend_and_send_sigstop (thread_info *thread, lwp_info *except) { struct lwp_info *lwp = get_thread_lwp (thread); /* Ignore EXCEPT. */ if (lwp == except) return; lwp_suspended_inc (lwp); send_sigstop (thread, except); } static void mark_lwp_dead (struct lwp_info *lwp, int wstat) { /* Store the exit status for later. */ lwp->status_pending_p = 1; lwp->status_pending = wstat; /* Store in waitstatus as well, as there's nothing else to process for this event. */ if (WIFEXITED (wstat)) lwp->waitstatus.set_exited (WEXITSTATUS (wstat)); else if (WIFSIGNALED (wstat)) lwp->waitstatus.set_signalled (gdb_signal_from_host (WTERMSIG (wstat))); /* Prevent trying to stop it. */ lwp->stopped = 1; /* No further stops are expected from a dead lwp. */ lwp->stop_expected = 0; } /* Return true if LWP has exited already, and has a pending exit event to report to GDB. */ static int lwp_is_marked_dead (struct lwp_info *lwp) { return (lwp->status_pending_p && (WIFEXITED (lwp->status_pending) || WIFSIGNALED (lwp->status_pending))); } void linux_process_target::wait_for_sigstop () { struct thread_info *saved_thread; ptid_t saved_tid; int wstat; int ret; saved_thread = current_thread; if (saved_thread != NULL) saved_tid = saved_thread->id; else saved_tid = null_ptid; /* avoid bogus unused warning */ if (debug_threads) debug_printf ("wait_for_sigstop: pulling events\n"); /* Passing NULL_PTID as filter indicates we want all events to be left pending. Eventually this returns when there are no unwaited-for children left. */ ret = wait_for_event_filtered (minus_one_ptid, null_ptid, &wstat, __WALL); gdb_assert (ret == -1); if (saved_thread == NULL || mythread_alive (saved_tid)) current_thread = saved_thread; else { if (debug_threads) debug_printf ("Previously current thread died.\n"); /* We can't change the current inferior behind GDB's back, otherwise, a subsequent command may apply to the wrong process. */ current_thread = NULL; } } bool linux_process_target::stuck_in_jump_pad (thread_info *thread) { struct lwp_info *lwp = get_thread_lwp (thread); if (lwp->suspended != 0) { internal_error (__FILE__, __LINE__, "LWP %ld is suspended, suspended=%d\n", lwpid_of (thread), lwp->suspended); } gdb_assert (lwp->stopped); /* Allow debugging the jump pad, gdb_collect, etc.. */ return (supports_fast_tracepoints () && agent_loaded_p () && (gdb_breakpoint_here (lwp->stop_pc) || lwp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT || thread->last_resume_kind == resume_step) && (linux_fast_tracepoint_collecting (lwp, NULL) != fast_tpoint_collect_result::not_collecting)); } void linux_process_target::move_out_of_jump_pad (thread_info *thread) { struct thread_info *saved_thread; struct lwp_info *lwp = get_thread_lwp (thread); int *wstat; if (lwp->suspended != 0) { internal_error (__FILE__, __LINE__, "LWP %ld is suspended, suspended=%d\n", lwpid_of (thread), lwp->suspended); } gdb_assert (lwp->stopped); /* For gdb_breakpoint_here. */ saved_thread = current_thread; current_thread = thread; wstat = lwp->status_pending_p ? &lwp->status_pending : NULL; /* Allow debugging the jump pad, gdb_collect, etc. */ if (!gdb_breakpoint_here (lwp->stop_pc) && lwp->stop_reason != TARGET_STOPPED_BY_WATCHPOINT && thread->last_resume_kind != resume_step && maybe_move_out_of_jump_pad (lwp, wstat)) { if (debug_threads) debug_printf ("LWP %ld needs stabilizing (in jump pad)\n", lwpid_of (thread)); if (wstat) { lwp->status_pending_p = 0; enqueue_one_deferred_signal (lwp, wstat); if (debug_threads) debug_printf ("Signal %d for LWP %ld deferred " "(in jump pad)\n", WSTOPSIG (*wstat), lwpid_of (thread)); } resume_one_lwp (lwp, 0, 0, NULL); } else lwp_suspended_inc (lwp); current_thread = saved_thread; } static bool lwp_running (thread_info *thread) { struct lwp_info *lwp = get_thread_lwp (thread); if (lwp_is_marked_dead (lwp)) return false; return !lwp->stopped; } void linux_process_target::stop_all_lwps (int suspend, lwp_info *except) { /* Should not be called recursively. */ gdb_assert (stopping_threads == NOT_STOPPING_THREADS); if (debug_threads) { debug_enter (); debug_printf ("stop_all_lwps (%s, except=%s)\n", suspend ? "stop-and-suspend" : "stop", (except != NULL ? target_pid_to_str (ptid_of (get_lwp_thread (except))).c_str () : "none")); } stopping_threads = (suspend ? STOPPING_AND_SUSPENDING_THREADS : STOPPING_THREADS); if (suspend) for_each_thread ([&] (thread_info *thread) { suspend_and_send_sigstop (thread, except); }); else for_each_thread ([&] (thread_info *thread) { send_sigstop (thread, except); }); wait_for_sigstop (); stopping_threads = NOT_STOPPING_THREADS; if (debug_threads) { debug_printf ("stop_all_lwps done, setting stopping_threads " "back to !stopping\n"); debug_exit (); } } /* Enqueue one signal in the chain of signals which need to be delivered to this process on next resume. */ static void enqueue_pending_signal (struct lwp_info *lwp, int signal, siginfo_t *info) { lwp->pending_signals.emplace_back (signal); if (info == nullptr) memset (&lwp->pending_signals.back ().info, 0, sizeof (siginfo_t)); else lwp->pending_signals.back ().info = *info; } void linux_process_target::install_software_single_step_breakpoints (lwp_info *lwp) { struct thread_info *thread = get_lwp_thread (lwp); struct regcache *regcache = get_thread_regcache (thread, 1); scoped_restore save_current_thread = make_scoped_restore (¤t_thread); current_thread = thread; std::vector next_pcs = low_get_next_pcs (regcache); for (CORE_ADDR pc : next_pcs) set_single_step_breakpoint (pc, current_ptid); } int linux_process_target::single_step (lwp_info* lwp) { int step = 0; if (supports_hardware_single_step ()) { step = 1; } else if (supports_software_single_step ()) { install_software_single_step_breakpoints (lwp); step = 0; } else { if (debug_threads) debug_printf ("stepping is not implemented on this target"); } return step; } /* The signal can be delivered to the inferior if we are not trying to finish a fast tracepoint collect. Since signal can be delivered in the step-over, the program may go to signal handler and trap again after return from the signal handler. We can live with the spurious double traps. */ static int lwp_signal_can_be_delivered (struct lwp_info *lwp) { return (lwp->collecting_fast_tracepoint == fast_tpoint_collect_result::not_collecting); } void linux_process_target::resume_one_lwp_throw (lwp_info *lwp, int step, int signal, siginfo_t *info) { struct thread_info *thread = get_lwp_thread (lwp); struct thread_info *saved_thread; int ptrace_request; struct process_info *proc = get_thread_process (thread); /* Note that target description may not be initialised (proc->tdesc == NULL) at this point because the program hasn't stopped at the first instruction yet. It means GDBserver skips the extra traps from the wrapper program (see option --wrapper). Code in this function that requires register access should be guarded by proc->tdesc == NULL or something else. */ if (lwp->stopped == 0) return; gdb_assert (lwp->waitstatus.kind () == TARGET_WAITKIND_IGNORE); fast_tpoint_collect_result fast_tp_collecting = lwp->collecting_fast_tracepoint; gdb_assert (!stabilizing_threads || (fast_tp_collecting != fast_tpoint_collect_result::not_collecting)); /* Cancel actions that rely on GDB not changing the PC (e.g., the user used the "jump" command, or "set $pc = foo"). */ if (thread->while_stepping != NULL && lwp->stop_pc != get_pc (lwp)) { /* Collecting 'while-stepping' actions doesn't make sense anymore. */ release_while_stepping_state_list (thread); } /* If we have pending signals or status, and a new signal, enqueue the signal. Also enqueue the signal if it can't be delivered to the inferior right now. */ if (signal != 0 && (lwp->status_pending_p || !lwp->pending_signals.empty () || !lwp_signal_can_be_delivered (lwp))) { enqueue_pending_signal (lwp, signal, info); /* Postpone any pending signal. It was enqueued above. */ signal = 0; } if (lwp->status_pending_p) { if (debug_threads) debug_printf ("Not resuming lwp %ld (%s, stop %s);" " has pending status\n", lwpid_of (thread), step ? "step" : "continue", lwp->stop_expected ? "expected" : "not expected"); return; } saved_thread = current_thread; current_thread = thread; /* This bit needs some thinking about. If we get a signal that we must report while a single-step reinsert is still pending, we often end up resuming the thread. It might be better to (ew) allow a stack of pending events; then we could be sure that the reinsert happened right away and not lose any signals. Making this stack would also shrink the window in which breakpoints are uninserted (see comment in linux_wait_for_lwp) but not enough for complete correctness, so it won't solve that problem. It may be worthwhile just to solve this one, however. */ if (lwp->bp_reinsert != 0) { if (debug_threads) debug_printf (" pending reinsert at 0x%s\n", paddress (lwp->bp_reinsert)); if (supports_hardware_single_step ()) { if (fast_tp_collecting == fast_tpoint_collect_result::not_collecting) { if (step == 0) warning ("BAD - reinserting but not stepping."); if (lwp->suspended) warning ("BAD - reinserting and suspended(%d).", lwp->suspended); } } step = maybe_hw_step (thread); } if (fast_tp_collecting == fast_tpoint_collect_result::before_insn) { if (debug_threads) debug_printf ("lwp %ld wants to get out of fast tracepoint jump pad" " (exit-jump-pad-bkpt)\n", lwpid_of (thread)); } else if (fast_tp_collecting == fast_tpoint_collect_result::at_insn) { if (debug_threads) debug_printf ("lwp %ld wants to get out of fast tracepoint jump pad" " single-stepping\n", lwpid_of (thread)); if (supports_hardware_single_step ()) step = 1; else { internal_error (__FILE__, __LINE__, "moving out of jump pad single-stepping" " not implemented on this target"); } } /* If we have while-stepping actions in this thread set it stepping. If we have a signal to deliver, it may or may not be set to SIG_IGN, we don't know. Assume so, and allow collecting while-stepping into a signal handler. A possible smart thing to do would be to set an internal breakpoint at the signal return address, continue, and carry on catching this while-stepping action only when that breakpoint is hit. A future enhancement. */ if (thread->while_stepping != NULL) { if (debug_threads) debug_printf ("lwp %ld has a while-stepping action -> forcing step.\n", lwpid_of (thread)); step = single_step (lwp); } if (proc->tdesc != NULL && low_supports_breakpoints ()) { struct regcache *regcache = get_thread_regcache (current_thread, 1); lwp->stop_pc = low_get_pc (regcache); if (debug_threads) { debug_printf (" %s from pc 0x%lx\n", step ? "step" : "continue", (long) lwp->stop_pc); } } /* If we have pending signals, consume one if it can be delivered to the inferior. */ if (!lwp->pending_signals.empty () && lwp_signal_can_be_delivered (lwp)) { const pending_signal &p_sig = lwp->pending_signals.front (); signal = p_sig.signal; if (p_sig.info.si_signo != 0) ptrace (PTRACE_SETSIGINFO, lwpid_of (thread), (PTRACE_TYPE_ARG3) 0, &p_sig.info); lwp->pending_signals.pop_front (); } if (debug_threads) debug_printf ("Resuming lwp %ld (%s, signal %d, stop %s)\n", lwpid_of (thread), step ? "step" : "continue", signal, lwp->stop_expected ? "expected" : "not expected"); low_prepare_to_resume (lwp); regcache_invalidate_thread (thread); errno = 0; lwp->stepping = step; if (step) ptrace_request = PTRACE_SINGLESTEP; else if (gdb_catching_syscalls_p (lwp)) ptrace_request = PTRACE_SYSCALL; else ptrace_request = PTRACE_CONT; ptrace (ptrace_request, lwpid_of (thread), (PTRACE_TYPE_ARG3) 0, /* Coerce to a uintptr_t first to avoid potential gcc warning of coercing an 8 byte integer to a 4 byte pointer. */ (PTRACE_TYPE_ARG4) (uintptr_t) signal); current_thread = saved_thread; if (errno) perror_with_name ("resuming thread"); /* Successfully resumed. Clear state that no longer makes sense, and mark the LWP as running. Must not do this before resuming otherwise if that fails other code will be confused. E.g., we'd later try to stop the LWP and hang forever waiting for a stop status. Note that we must not throw after this is cleared, otherwise handle_zombie_lwp_error would get confused. */ lwp->stopped = 0; lwp->stop_reason = TARGET_STOPPED_BY_NO_REASON; } void linux_process_target::low_prepare_to_resume (lwp_info *lwp) { /* Nop. */ } /* Called when we try to resume a stopped LWP and that errors out. If the LWP is no longer in ptrace-stopped state (meaning it's zombie, or about to become), discard the error, clear any pending status the LWP may have, and return true (we'll collect the exit status soon enough). Otherwise, return false. */ static int check_ptrace_stopped_lwp_gone (struct lwp_info *lp) { struct thread_info *thread = get_lwp_thread (lp); /* If we get an error after resuming the LWP successfully, we'd confuse !T state for the LWP being gone. */ gdb_assert (lp->stopped); /* We can't just check whether the LWP is in 'Z (Zombie)' state, because even if ptrace failed with ESRCH, the tracee may be "not yet fully dead", but already refusing ptrace requests. In that case the tracee has 'R (Running)' state for a little bit (observed in Linux 3.18). See also the note on ESRCH in the ptrace(2) man page. Instead, check whether the LWP has any state other than ptrace-stopped. */ /* Don't assume anything if /proc/PID/status can't be read. */ if (linux_proc_pid_is_trace_stopped_nowarn (lwpid_of (thread)) == 0) { lp->stop_reason = TARGET_STOPPED_BY_NO_REASON; lp->status_pending_p = 0; return 1; } return 0; } void linux_process_target::resume_one_lwp (lwp_info *lwp, int step, int signal, siginfo_t *info) { try { resume_one_lwp_throw (lwp, step, signal, info); } catch (const gdb_exception_error &ex) { if (!check_ptrace_stopped_lwp_gone (lwp)) throw; } } /* This function is called once per thread via for_each_thread. We look up which resume request applies to THREAD and mark it with a pointer to the appropriate resume request. This algorithm is O(threads * resume elements), but resume elements is small (and will remain small at least until GDB supports thread suspension). */ static void linux_set_resume_request (thread_info *thread, thread_resume *resume, size_t n) { struct lwp_info *lwp = get_thread_lwp (thread); for (int ndx = 0; ndx < n; ndx++) { ptid_t ptid = resume[ndx].thread; if (ptid == minus_one_ptid || ptid == thread->id /* Handle both 'pPID' and 'pPID.-1' as meaning 'all threads of PID'. */ || (ptid.pid () == pid_of (thread) && (ptid.is_pid () || ptid.lwp () == -1))) { if (resume[ndx].kind == resume_stop && thread->last_resume_kind == resume_stop) { if (debug_threads) debug_printf ("already %s LWP %ld at GDB's request\n", (thread->last_status.kind () == TARGET_WAITKIND_STOPPED) ? "stopped" : "stopping", lwpid_of (thread)); continue; } /* Ignore (wildcard) resume requests for already-resumed threads. */ if (resume[ndx].kind != resume_stop && thread->last_resume_kind != resume_stop) { if (debug_threads) debug_printf ("already %s LWP %ld at GDB's request\n", (thread->last_resume_kind == resume_step) ? "stepping" : "continuing", lwpid_of (thread)); continue; } /* Don't let wildcard resumes resume fork children that GDB does not yet know are new fork children. */ if (lwp->fork_relative != NULL) { struct lwp_info *rel = lwp->fork_relative; if (rel->status_pending_p && (rel->waitstatus.kind () == TARGET_WAITKIND_FORKED || rel->waitstatus.kind () == TARGET_WAITKIND_VFORKED)) { if (debug_threads) debug_printf ("not resuming LWP %ld: has queued stop reply\n", lwpid_of (thread)); continue; } } /* If the thread has a pending event that has already been reported to GDBserver core, but GDB has not pulled the event out of the vStopped queue yet, likewise, ignore the (wildcard) resume request. */ if (in_queued_stop_replies (thread->id)) { if (debug_threads) debug_printf ("not resuming LWP %ld: has queued stop reply\n", lwpid_of (thread)); continue; } lwp->resume = &resume[ndx]; thread->last_resume_kind = lwp->resume->kind; lwp->step_range_start = lwp->resume->step_range_start; lwp->step_range_end = lwp->resume->step_range_end; /* If we had a deferred signal to report, dequeue one now. This can happen if LWP gets more than one signal while trying to get out of a jump pad. */ if (lwp->stopped && !lwp->status_pending_p && dequeue_one_deferred_signal (lwp, &lwp->status_pending)) { lwp->status_pending_p = 1; if (debug_threads) debug_printf ("Dequeueing deferred signal %d for LWP %ld, " "leaving status pending.\n", WSTOPSIG (lwp->status_pending), lwpid_of (thread)); } return; } } /* No resume action for this thread. */ lwp->resume = NULL; } bool linux_process_target::resume_status_pending (thread_info *thread) { struct lwp_info *lwp = get_thread_lwp (thread); /* LWPs which will not be resumed are not interesting, because we might not wait for them next time through linux_wait. */ if (lwp->resume == NULL) return false; return thread_still_has_status_pending (thread); } bool linux_process_target::thread_needs_step_over (thread_info *thread) { struct lwp_info *lwp = get_thread_lwp (thread); struct thread_info *saved_thread; CORE_ADDR pc; struct process_info *proc = get_thread_process (thread); /* GDBserver is skipping the extra traps from the wrapper program, don't have to do step over. */ if (proc->tdesc == NULL) return false; /* LWPs which will not be resumed are not interesting, because we might not wait for them next time through linux_wait. */ if (!lwp->stopped) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Ignoring, not stopped\n", lwpid_of (thread)); return false; } if (thread->last_resume_kind == resume_stop) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Ignoring, should remain" " stopped\n", lwpid_of (thread)); return false; } gdb_assert (lwp->suspended >= 0); if (lwp->suspended) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Ignoring, suspended\n", lwpid_of (thread)); return false; } if (lwp->status_pending_p) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Ignoring, has pending" " status.\n", lwpid_of (thread)); return false; } /* Note: PC, not STOP_PC. Either GDB has adjusted the PC already, or we have. */ pc = get_pc (lwp); /* If the PC has changed since we stopped, then don't do anything, and let the breakpoint/tracepoint be hit. This happens if, for instance, GDB handled the decr_pc_after_break subtraction itself, GDB is OOL stepping this thread, or the user has issued a "jump" command, or poked thread's registers herself. */ if (pc != lwp->stop_pc) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Cancelling, PC was changed. " "Old stop_pc was 0x%s, PC is now 0x%s\n", lwpid_of (thread), paddress (lwp->stop_pc), paddress (pc)); return false; } /* On software single step target, resume the inferior with signal rather than stepping over. */ if (supports_software_single_step () && !lwp->pending_signals.empty () && lwp_signal_can_be_delivered (lwp)) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? Ignoring, has pending" " signals.\n", lwpid_of (thread)); return false; } saved_thread = current_thread; current_thread = thread; /* We can only step over breakpoints we know about. */ if (breakpoint_here (pc) || fast_tracepoint_jump_here (pc)) { /* Don't step over a breakpoint that GDB expects to hit though. If the condition is being evaluated on the target's side and it evaluate to false, step over this breakpoint as well. */ if (gdb_breakpoint_here (pc) && gdb_condition_true_at_breakpoint (pc) && gdb_no_commands_at_breakpoint (pc)) { if (debug_threads) debug_printf ("Need step over [LWP %ld]? yes, but found" " GDB breakpoint at 0x%s; skipping step over\n", lwpid_of (thread), paddress (pc)); current_thread = saved_thread; return false; } else { if (debug_threads) debug_printf ("Need step over [LWP %ld]? yes, " "found breakpoint at 0x%s\n", lwpid_of (thread), paddress (pc)); /* We've found an lwp that needs stepping over --- return 1 so that find_thread stops looking. */ current_thread = saved_thread; return true; } } current_thread = saved_thread; if (debug_threads) debug_printf ("Need step over [LWP %ld]? No, no breakpoint found" " at 0x%s\n", lwpid_of (thread), paddress (pc)); return false; } void linux_process_target::start_step_over (lwp_info *lwp) { struct thread_info *thread = get_lwp_thread (lwp); struct thread_info *saved_thread; CORE_ADDR pc; int step; if (debug_threads) debug_printf ("Starting step-over on LWP %ld. Stopping all threads\n", lwpid_of (thread)); stop_all_lwps (1, lwp); if (lwp->suspended != 0) { internal_error (__FILE__, __LINE__, "LWP %ld suspended=%d\n", lwpid_of (thread), lwp->suspended); } if (debug_threads) debug_printf ("Done stopping all threads for step-over.\n"); /* Note, we should always reach here with an already adjusted PC, either by GDB (if we're resuming due to GDB's request), or by our caller, if we just finished handling an internal breakpoint GDB shouldn't care about. */ pc = get_pc (lwp); saved_thread = current_thread; current_thread = thread; lwp->bp_reinsert = pc; uninsert_breakpoints_at (pc); uninsert_fast_tracepoint_jumps_at (pc); step = single_step (lwp); current_thread = saved_thread; resume_one_lwp (lwp, step, 0, NULL); /* Require next event from this LWP. */ step_over_bkpt = thread->id; } bool linux_process_target::finish_step_over (lwp_info *lwp) { if (lwp->bp_reinsert != 0) { struct thread_info *saved_thread = current_thread; if (debug_threads) debug_printf ("Finished step over.\n"); current_thread = get_lwp_thread (lwp); /* Reinsert any breakpoint at LWP->BP_REINSERT. Note that there may be no breakpoint to reinsert there by now. */ reinsert_breakpoints_at (lwp->bp_reinsert); reinsert_fast_tracepoint_jumps_at (lwp->bp_reinsert); lwp->bp_reinsert = 0; /* Delete any single-step breakpoints. No longer needed. We don't have to worry about other threads hitting this trap, and later not being able to explain it, because we were stepping over a breakpoint, and we hold all threads but LWP stopped while doing that. */ if (!supports_hardware_single_step ()) { gdb_assert (has_single_step_breakpoints (current_thread)); delete_single_step_breakpoints (current_thread); } step_over_bkpt = null_ptid; current_thread = saved_thread; return true; } else return false; } void linux_process_target::complete_ongoing_step_over () { if (step_over_bkpt != null_ptid) { struct lwp_info *lwp; int wstat; int ret; if (debug_threads) debug_printf ("detach: step over in progress, finish it first\n"); /* Passing NULL_PTID as filter indicates we want all events to be left pending. Eventually this returns when there are no unwaited-for children left. */ ret = wait_for_event_filtered (minus_one_ptid, null_ptid, &wstat, __WALL); gdb_assert (ret == -1); lwp = find_lwp_pid (step_over_bkpt); if (lwp != NULL) { finish_step_over (lwp); /* If we got our step SIGTRAP, don't leave it pending, otherwise we would report it to GDB as a spurious SIGTRAP. */ gdb_assert (lwp->status_pending_p); if (WIFSTOPPED (lwp->status_pending) && WSTOPSIG (lwp->status_pending) == SIGTRAP) { thread_info *thread = get_lwp_thread (lwp); if (thread->last_resume_kind != resume_step) { if (debug_threads) debug_printf ("detach: discard step-over SIGTRAP\n"); lwp->status_pending_p = 0; lwp->status_pending = 0; resume_one_lwp (lwp, lwp->stepping, 0, NULL); } else { if (debug_threads) debug_printf ("detach: resume_step, " "not discarding step-over SIGTRAP\n"); } } } step_over_bkpt = null_ptid; unsuspend_all_lwps (lwp); } } void linux_process_target::resume_one_thread (thread_info *thread, bool leave_all_stopped) { struct lwp_info *lwp = get_thread_lwp (thread); int leave_pending; if (lwp->resume == NULL) return; if (lwp->resume->kind == resume_stop) { if (debug_threads) debug_printf ("resume_stop request for LWP %ld\n", lwpid_of (thread)); if (!lwp->stopped) { if (debug_threads) debug_printf ("stopping LWP %ld\n", lwpid_of (thread)); /* Stop the thread, and wait for the event asynchronously, through the event loop. */ send_sigstop (lwp); } else { if (debug_threads) debug_printf ("already stopped LWP %ld\n", lwpid_of (thread)); /* The LWP may have been stopped in an internal event that was not meant to be notified back to GDB (e.g., gdbserver breakpoint), so we should be reporting a stop event in this case too. */ /* If the thread already has a pending SIGSTOP, this is a no-op. Otherwise, something later will presumably resume the thread and this will cause it to cancel any pending operation, due to last_resume_kind == resume_stop. If the thread already has a pending status to report, we will still report it the next time we wait - see status_pending_p_callback. */ /* If we already have a pending signal to report, then there's no need to queue a SIGSTOP, as this means we're midway through moving the LWP out of the jumppad, and we will report the pending signal as soon as that is finished. */ if (lwp->pending_signals_to_report.empty ()) send_sigstop (lwp); } /* For stop requests, we're done. */ lwp->resume = NULL; thread->last_status.set_ignore (); return; } /* If this thread which is about to be resumed has a pending status, then don't resume it - we can just report the pending status. Likewise if it is suspended, because e.g., another thread is stepping past a breakpoint. Make sure to queue any signals that would otherwise be sent. In all-stop mode, we do this decision based on if *any* thread has a pending status. If there's a thread that needs the step-over-breakpoint dance, then don't resume any other thread but that particular one. */ leave_pending = (lwp->suspended || lwp->status_pending_p || leave_all_stopped); /* If we have a new signal, enqueue the signal. */ if (lwp->resume->sig != 0) { siginfo_t info, *info_p; /* If this is the same signal we were previously stopped by, make sure to queue its siginfo. */ if (WIFSTOPPED (lwp->last_status) && WSTOPSIG (lwp->last_status) == lwp->resume->sig && ptrace (PTRACE_GETSIGINFO, lwpid_of (thread), (PTRACE_TYPE_ARG3) 0, &info) == 0) info_p = &info; else info_p = NULL; enqueue_pending_signal (lwp, lwp->resume->sig, info_p); } if (!leave_pending) { if (debug_threads) debug_printf ("resuming LWP %ld\n", lwpid_of (thread)); proceed_one_lwp (thread, NULL); } else { if (debug_threads) debug_printf ("leaving LWP %ld stopped\n", lwpid_of (thread)); } thread->last_status.set_ignore (); lwp->resume = NULL; } void linux_process_target::resume (thread_resume *resume_info, size_t n) { struct thread_info *need_step_over = NULL; if (debug_threads) { debug_enter (); debug_printf ("linux_resume:\n"); } for_each_thread ([&] (thread_info *thread) { linux_set_resume_request (thread, resume_info, n); }); /* If there is a thread which would otherwise be resumed, which has a pending status, then don't resume any threads - we can just report the pending status. Make sure to queue any signals that would otherwise be sent. In non-stop mode, we'll apply this logic to each thread individually. We consume all pending events before considering to start a step-over (in all-stop). */ bool any_pending = false; if (!non_stop) any_pending = find_thread ([this] (thread_info *thread) { return resume_status_pending (thread); }) != nullptr; /* If there is a thread which would otherwise be resumed, which is stopped at a breakpoint that needs stepping over, then don't resume any threads - have it step over the breakpoint with all other threads stopped, then resume all threads again. Make sure to queue any signals that would otherwise be delivered or queued. */ if (!any_pending && low_supports_breakpoints ()) need_step_over = find_thread ([this] (thread_info *thread) { return thread_needs_step_over (thread); }); bool leave_all_stopped = (need_step_over != NULL || any_pending); if (debug_threads) { if (need_step_over != NULL) debug_printf ("Not resuming all, need step over\n"); else if (any_pending) debug_printf ("Not resuming, all-stop and found " "an LWP with pending status\n"); else debug_printf ("Resuming, no pending status or step over needed\n"); } /* Even if we're leaving threads stopped, queue all signals we'd otherwise deliver. */ for_each_thread ([&] (thread_info *thread) { resume_one_thread (thread, leave_all_stopped); }); if (need_step_over) start_step_over (get_thread_lwp (need_step_over)); if (debug_threads) { debug_printf ("linux_resume done\n"); debug_exit (); } /* We may have events that were pending that can/should be sent to the client now. Trigger a linux_wait call. */ if (target_is_async_p ()) async_file_mark (); } void linux_process_target::proceed_one_lwp (thread_info *thread, lwp_info *except) { struct lwp_info *lwp = get_thread_lwp (thread); int step; if (lwp == except) return; if (debug_threads) debug_printf ("proceed_one_lwp: lwp %ld\n", lwpid_of (thread)); if (!lwp->stopped) { if (debug_threads) debug_printf (" LWP %ld already running\n", lwpid_of (thread)); return; } if (thread->last_resume_kind == resume_stop && thread->last_status.kind () != TARGET_WAITKIND_IGNORE) { if (debug_threads) debug_printf (" client wants LWP to remain %ld stopped\n", lwpid_of (thread)); return; } if (lwp->status_pending_p) { if (debug_threads) debug_printf (" LWP %ld has pending status, leaving stopped\n", lwpid_of (thread)); return; } gdb_assert (lwp->suspended >= 0); if (lwp->suspended) { if (debug_threads) debug_printf (" LWP %ld is suspended\n", lwpid_of (thread)); return; } if (thread->last_resume_kind == resume_stop && lwp->pending_signals_to_report.empty () && (lwp->collecting_fast_tracepoint == fast_tpoint_collect_result::not_collecting)) { /* We haven't reported this LWP as stopped yet (otherwise, the last_status.kind check above would catch it, and we wouldn't reach here. This LWP may have been momentarily paused by a stop_all_lwps call while handling for example, another LWP's step-over. In that case, the pending expected SIGSTOP signal that was queued at vCont;t handling time will have already been consumed by wait_for_sigstop, and so we need to requeue another one here. Note that if the LWP already has a SIGSTOP pending, this is a no-op. */ if (debug_threads) debug_printf ("Client wants LWP %ld to stop. " "Making sure it has a SIGSTOP pending\n", lwpid_of (thread)); send_sigstop (lwp); } if (thread->last_resume_kind == resume_step) { if (debug_threads) debug_printf (" stepping LWP %ld, client wants it stepping\n", lwpid_of (thread)); /* If resume_step is requested by GDB, install single-step breakpoints when the thread is about to be actually resumed if the single-step breakpoints weren't removed. */ if (supports_software_single_step () && !has_single_step_breakpoints (thread)) install_software_single_step_breakpoints (lwp); step = maybe_hw_step (thread); } else if (lwp->bp_reinsert != 0) { if (debug_threads) debug_printf (" stepping LWP %ld, reinsert set\n", lwpid_of (thread)); step = maybe_hw_step (thread); } else step = 0; resume_one_lwp (lwp, step, 0, NULL); } void linux_process_target::unsuspend_and_proceed_one_lwp (thread_info *thread, lwp_info *except) { struct lwp_info *lwp = get_thread_lwp (thread); if (lwp == except) return; lwp_suspended_decr (lwp); proceed_one_lwp (thread, except); } void linux_process_target::proceed_all_lwps () { struct thread_info *need_step_over; /* If there is a thread which would otherwise be resumed, which is stopped at a breakpoint that needs stepping over, then don't resume any threads - have it step over the breakpoint with all other threads stopped, then resume all threads again. */ if (low_supports_breakpoints ()) { need_step_over = find_thread ([this] (thread_info *thread) { return thread_needs_step_over (thread); }); if (need_step_over != NULL) { if (debug_threads) debug_printf ("proceed_all_lwps: found " "thread %ld needing a step-over\n", lwpid_of (need_step_over)); start_step_over (get_thread_lwp (need_step_over)); return; } } if (debug_threads) debug_printf ("Proceeding, no step-over needed\n"); for_each_thread ([this] (thread_info *thread) { proceed_one_lwp (thread, NULL); }); } void linux_process_target::unstop_all_lwps (int unsuspend, lwp_info *except) { if (debug_threads) { debug_enter (); if (except) debug_printf ("unstopping all lwps, except=(LWP %ld)\n", lwpid_of (get_lwp_thread (except))); else debug_printf ("unstopping all lwps\n"); } if (unsuspend) for_each_thread ([&] (thread_info *thread) { unsuspend_and_proceed_one_lwp (thread, except); }); else for_each_thread ([&] (thread_info *thread) { proceed_one_lwp (thread, except); }); if (debug_threads) { debug_printf ("unstop_all_lwps done\n"); debug_exit (); } } #ifdef HAVE_LINUX_REGSETS #define use_linux_regsets 1 /* Returns true if REGSET has been disabled. */ static int regset_disabled (struct regsets_info *info, struct regset_info *regset) { return (info->disabled_regsets != NULL && info->disabled_regsets[regset - info->regsets]); } /* Disable REGSET. */ static void disable_regset (struct regsets_info *info, struct regset_info *regset) { int dr_offset; dr_offset = regset - info->regsets; if (info->disabled_regsets == NULL) info->disabled_regsets = (char *) xcalloc (1, info->num_regsets); info->disabled_regsets[dr_offset] = 1; } static int regsets_fetch_inferior_registers (struct regsets_info *regsets_info, struct regcache *regcache) { struct regset_info *regset; int saw_general_regs = 0; int pid; struct iovec iov; pid = lwpid_of (current_thread); for (regset = regsets_info->regsets; regset->size >= 0; regset++) { void *buf, *data; int nt_type, res; if (regset->size == 0 || regset_disabled (regsets_info, regset)) continue; buf = xmalloc (regset->size); nt_type = regset->nt_type; if (nt_type) { iov.iov_base = buf; iov.iov_len = regset->size; data = (void *) &iov; } else data = buf; #ifndef __sparc__ res = ptrace (regset->get_request, pid, (PTRACE_TYPE_ARG3) (long) nt_type, data); #else res = ptrace (regset->get_request, pid, data, nt_type); #endif if (res < 0) { if (errno == EIO || (errno == EINVAL && regset->type == OPTIONAL_REGS)) { /* If we get EIO on a regset, or an EINVAL and the regset is optional, do not try it again for this process mode. */ disable_regset (regsets_info, regset); } else if (errno == ENODATA) { /* ENODATA may be returned if the regset is currently not "active". This can happen in normal operation, so suppress the warning in this case. */ } else if (errno == ESRCH) { /* At this point, ESRCH should mean the process is already gone, in which case we simply ignore attempts to read its registers. */ } else { char s[256]; sprintf (s, "ptrace(regsets_fetch_inferior_registers) PID=%d", pid); perror (s); } } else { if (regset->type == GENERAL_REGS) saw_general_regs = 1; regset->store_function (regcache, buf); } free (buf); } if (saw_general_regs) return 0; else return 1; } static int regsets_store_inferior_registers (struct regsets_info *regsets_info, struct regcache *regcache) { struct regset_info *regset; int saw_general_regs = 0; int pid; struct iovec iov; pid = lwpid_of (current_thread); for (regset = regsets_info->regsets; regset->size >= 0; regset++) { void *buf, *data; int nt_type, res; if (regset->size == 0 || regset_disabled (regsets_info, regset) || regset->fill_function == NULL) continue; buf = xmalloc (regset->size); /* First fill the buffer with the current register set contents, in case there are any items in the kernel's regset that are not in gdbserver's regcache. */ nt_type = regset->nt_type; if (nt_type) { iov.iov_base = buf; iov.iov_len = regset->size; data = (void *) &iov; } else data = buf; #ifndef __sparc__ res = ptrace (regset->get_request, pid, (PTRACE_TYPE_ARG3) (long) nt_type, data); #else res = ptrace (regset->get_request, pid, data, nt_type); #endif if (res == 0) { /* Then overlay our cached registers on that. */ regset->fill_function (regcache, buf); /* Only now do we write the register set. */ #ifndef __sparc__ res = ptrace (regset->set_request, pid, (PTRACE_TYPE_ARG3) (long) nt_type, data); #else res = ptrace (regset->set_request, pid, data, nt_type); #endif } if (res < 0) { if (errno == EIO || (errno == EINVAL && regset->type == OPTIONAL_REGS)) { /* If we get EIO on a regset, or an EINVAL and the regset is optional, do not try it again for this process mode. */ disable_regset (regsets_info, regset); } else if (errno == ESRCH) { /* At this point, ESRCH should mean the process is already gone, in which case we simply ignore attempts to change its registers. See also the related comment in resume_one_lwp. */ free (buf); return 0; } else { perror ("Warning: ptrace(regsets_store_inferior_registers)"); } } else if (regset->type == GENERAL_REGS) saw_general_regs = 1; free (buf); } if (saw_general_regs) return 0; else return 1; } #else /* !HAVE_LINUX_REGSETS */ #define use_linux_regsets 0 #define regsets_fetch_inferior_registers(regsets_info, regcache) 1 #define regsets_store_inferior_registers(regsets_info, regcache) 1 #endif /* Return 1 if register REGNO is supported by one of the regset ptrace calls or 0 if it has to be transferred individually. */ static int linux_register_in_regsets (const struct regs_info *regs_info, int regno) { unsigned char mask = 1 << (regno % 8); size_t index = regno / 8; return (use_linux_regsets && (regs_info->regset_bitmap == NULL || (regs_info->regset_bitmap[index] & mask) != 0)); } #ifdef HAVE_LINUX_USRREGS static int register_addr (const struct usrregs_info *usrregs, int regnum) { int addr; if (regnum < 0 || regnum >= usrregs->num_regs) error ("Invalid register number %d.", regnum); addr = usrregs->regmap[regnum]; return addr; } void linux_process_target::fetch_register (const usrregs_info *usrregs, regcache *regcache, int regno) { CORE_ADDR regaddr; int i, size; char *buf; int pid; if (regno >= usrregs->num_regs) return; if (low_cannot_fetch_register (regno)) return; regaddr = register_addr (usrregs, regno); if (regaddr == -1) return; size = ((register_size (regcache->tdesc, regno) + sizeof (PTRACE_XFER_TYPE) - 1) & -sizeof (PTRACE_XFER_TYPE)); buf = (char *) alloca (size); pid = lwpid_of (current_thread); for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE)) { errno = 0; *(PTRACE_XFER_TYPE *) (buf + i) = ptrace (PTRACE_PEEKUSER, pid, /* Coerce to a uintptr_t first to avoid potential gcc warning of coercing an 8 byte integer to a 4 byte pointer. */ (PTRACE_TYPE_ARG3) (uintptr_t) regaddr, (PTRACE_TYPE_ARG4) 0); regaddr += sizeof (PTRACE_XFER_TYPE); if (errno != 0) { /* Mark register REGNO unavailable. */ supply_register (regcache, regno, NULL); return; } } low_supply_ptrace_register (regcache, regno, buf); } void linux_process_target::store_register (const usrregs_info *usrregs, regcache *regcache, int regno) { CORE_ADDR regaddr; int i, size; char *buf; int pid; if (regno >= usrregs->num_regs) return; if (low_cannot_store_register (regno)) return; regaddr = register_addr (usrregs, regno); if (regaddr == -1) return; size = ((register_size (regcache->tdesc, regno) + sizeof (PTRACE_XFER_TYPE) - 1) & -sizeof (PTRACE_XFER_TYPE)); buf = (char *) alloca (size); memset (buf, 0, size); low_collect_ptrace_register (regcache, regno, buf); pid = lwpid_of (current_thread); for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE)) { errno = 0; ptrace (PTRACE_POKEUSER, pid, /* Coerce to a uintptr_t first to avoid potential gcc warning about coercing an 8 byte integer to a 4 byte pointer. */ (PTRACE_TYPE_ARG3) (uintptr_t) regaddr, (PTRACE_TYPE_ARG4) *(PTRACE_XFER_TYPE *) (buf + i)); if (errno != 0) { /* At this point, ESRCH should mean the process is already gone, in which case we simply ignore attempts to change its registers. See also the related comment in resume_one_lwp. */ if (errno == ESRCH) return; if (!low_cannot_store_register (regno)) error ("writing register %d: %s", regno, safe_strerror (errno)); } regaddr += sizeof (PTRACE_XFER_TYPE); } } #endif /* HAVE_LINUX_USRREGS */ void linux_process_target::low_collect_ptrace_register (regcache *regcache, int regno, char *buf) { collect_register (regcache, regno, buf); } void linux_process_target::low_supply_ptrace_register (regcache *regcache, int regno, const char *buf) { supply_register (regcache, regno, buf); } void linux_process_target::usr_fetch_inferior_registers (const regs_info *regs_info, regcache *regcache, int regno, int all) { #ifdef HAVE_LINUX_USRREGS struct usrregs_info *usr = regs_info->usrregs; if (regno == -1) { for (regno = 0; regno < usr->num_regs; regno++) if (all || !linux_register_in_regsets (regs_info, regno)) fetch_register (usr, regcache, regno); } else fetch_register (usr, regcache, regno); #endif } void linux_process_target::usr_store_inferior_registers (const regs_info *regs_info, regcache *regcache, int regno, int all) { #ifdef HAVE_LINUX_USRREGS struct usrregs_info *usr = regs_info->usrregs; if (regno == -1) { for (regno = 0; regno < usr->num_regs; regno++) if (all || !linux_register_in_regsets (regs_info, regno)) store_register (usr, regcache, regno); } else store_register (usr, regcache, regno); #endif } void linux_process_target::fetch_registers (regcache *regcache, int regno) { int use_regsets; int all = 0; const regs_info *regs_info = get_regs_info (); if (regno == -1) { if (regs_info->usrregs != NULL) for (regno = 0; regno < regs_info->usrregs->num_regs; regno++) low_fetch_register (regcache, regno); all = regsets_fetch_inferior_registers (regs_info->regsets_info, regcache); if (regs_info->usrregs != NULL) usr_fetch_inferior_registers (regs_info, regcache, -1, all); } else { if (low_fetch_register (regcache, regno)) return; use_regsets = linux_register_in_regsets (regs_info, regno); if (use_regsets) all = regsets_fetch_inferior_registers (regs_info->regsets_info, regcache); if ((!use_regsets || all) && regs_info->usrregs != NULL) usr_fetch_inferior_registers (regs_info, regcache, regno, 1); } } void linux_process_target::store_registers (regcache *regcache, int regno) { int use_regsets; int all = 0; const regs_info *regs_info = get_regs_info (); if (regno == -1) { all = regsets_store_inferior_registers (regs_info->regsets_info, regcache); if (regs_info->usrregs != NULL) usr_store_inferior_registers (regs_info, regcache, regno, all); } else { use_regsets = linux_register_in_regsets (regs_info, regno); if (use_regsets) all = regsets_store_inferior_registers (regs_info->regsets_info, regcache); if ((!use_regsets || all) && regs_info->usrregs != NULL) usr_store_inferior_registers (regs_info, regcache, regno, 1); } } bool linux_process_target::low_fetch_register (regcache *regcache, int regno) { return false; } /* A wrapper for the read_memory target op. */ static int linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len) { return the_target->read_memory (memaddr, myaddr, len); } /* Copy LEN bytes from inferior's memory starting at MEMADDR to debugger memory starting at MYADDR. */ int linux_process_target::read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len) { int pid = lwpid_of (current_thread); PTRACE_XFER_TYPE *buffer; CORE_ADDR addr; int count; char filename[64]; int i; int ret; int fd; /* Try using /proc. Don't bother for one word. */ if (len >= 3 * sizeof (long)) { int bytes; /* We could keep this file open and cache it - possibly one per thread. That requires some juggling, but is even faster. */ sprintf (filename, "/proc/%d/mem", pid); fd = open (filename, O_RDONLY | O_LARGEFILE); if (fd == -1) goto no_proc; /* If pread64 is available, use it. It's faster if the kernel supports it (only one syscall), and it's 64-bit safe even on 32-bit platforms (for instance, SPARC debugging a SPARC64 application). */ #ifdef HAVE_PREAD64 bytes = pread64 (fd, myaddr, len, memaddr); #else bytes = -1; if (lseek (fd, memaddr, SEEK_SET) != -1) bytes = read (fd, myaddr, len); #endif close (fd); if (bytes == len) return 0; /* Some data was read, we'll try to get the rest with ptrace. */ if (bytes > 0) { memaddr += bytes; myaddr += bytes; len -= bytes; } } no_proc: /* Round starting address down to longword boundary. */ addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE); /* Round ending address up; get number of longwords that makes. */ count = ((((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1) / sizeof (PTRACE_XFER_TYPE)); /* Allocate buffer of that many longwords. */ buffer = XALLOCAVEC (PTRACE_XFER_TYPE, count); /* Read all the longwords */ errno = 0; for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE)) { /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning about coercing an 8 byte integer to a 4 byte pointer. */ buffer[i] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, (PTRACE_TYPE_ARG4) 0); if (errno) break; } ret = errno; /* Copy appropriate bytes out of the buffer. */ if (i > 0) { i *= sizeof (PTRACE_XFER_TYPE); i -= memaddr & (sizeof (PTRACE_XFER_TYPE) - 1); memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), i < len ? i : len); } return ret; } /* Copy LEN bytes of data from debugger memory at MYADDR to inferior's memory at MEMADDR. On failure (cannot write to the inferior) returns the value of errno. Always succeeds if LEN is zero. */ int linux_process_target::write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len) { int i; /* Round starting address down to longword boundary. */ CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE); /* Round ending address up; get number of longwords that makes. */ int count = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1) / sizeof (PTRACE_XFER_TYPE); /* Allocate buffer of that many longwords. */ PTRACE_XFER_TYPE *buffer = XALLOCAVEC (PTRACE_XFER_TYPE, count); int pid = lwpid_of (current_thread); if (len == 0) { /* Zero length write always succeeds. */ return 0; } if (debug_threads) { /* Dump up to four bytes. */ char str[4 * 2 + 1]; char *p = str; int dump = len < 4 ? len : 4; for (i = 0; i < dump; i++) { sprintf (p, "%02x", myaddr[i]); p += 2; } *p = '\0'; debug_printf ("Writing %s to 0x%08lx in process %d\n", str, (long) memaddr, pid); } /* Fill start and end extra bytes of buffer with existing memory data. */ errno = 0; /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning about coercing an 8 byte integer to a 4 byte pointer. */ buffer[0] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, (PTRACE_TYPE_ARG4) 0); if (errno) return errno; if (count > 1) { errno = 0; buffer[count - 1] = ptrace (PTRACE_PEEKTEXT, pid, /* Coerce to a uintptr_t first to avoid potential gcc warning about coercing an 8 byte integer to a 4 byte pointer. */ (PTRACE_TYPE_ARG3) (uintptr_t) (addr + (count - 1) * sizeof (PTRACE_XFER_TYPE)), (PTRACE_TYPE_ARG4) 0); if (errno) return errno; } /* Copy data to be written over corresponding part of buffer. */ memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), myaddr, len); /* Write the entire buffer. */ for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE)) { errno = 0; ptrace (PTRACE_POKETEXT, pid, /* Coerce to a uintptr_t first to avoid potential gcc warning about coercing an 8 byte integer to a 4 byte pointer. */ (PTRACE_TYPE_ARG3) (uintptr_t) addr, (PTRACE_TYPE_ARG4) buffer[i]); if (errno) return errno; } return 0; } void linux_process_target::look_up_symbols () { #ifdef USE_THREAD_DB struct process_info *proc = current_process (); if (proc->priv->thread_db != NULL) return; thread_db_init (); #endif } void linux_process_target::request_interrupt () { /* Send a SIGINT to the process group. This acts just like the user typed a ^C on the controlling terminal. */ ::kill (-signal_pid, SIGINT); } bool linux_process_target::supports_read_auxv () { return true; } /* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET to debugger memory starting at MYADDR. */ int linux_process_target::read_auxv (CORE_ADDR offset, unsigned char *myaddr, unsigned int len) { char filename[PATH_MAX]; int fd, n; int pid = lwpid_of (current_thread); xsnprintf (filename, sizeof filename, "/proc/%d/auxv", pid); fd = open (filename, O_RDONLY); if (fd < 0) return -1; if (offset != (CORE_ADDR) 0 && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset) n = -1; else n = read (fd, myaddr, len); close (fd); return n; } int linux_process_target::insert_point (enum raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { if (type == raw_bkpt_type_sw) return insert_memory_breakpoint (bp); else return low_insert_point (type, addr, size, bp); } int linux_process_target::low_insert_point (raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { /* Unsupported (see target.h). */ return 1; } int linux_process_target::remove_point (enum raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { if (type == raw_bkpt_type_sw) return remove_memory_breakpoint (bp); else return low_remove_point (type, addr, size, bp); } int linux_process_target::low_remove_point (raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { /* Unsupported (see target.h). */ return 1; } /* Implement the stopped_by_sw_breakpoint target_ops method. */ bool linux_process_target::stopped_by_sw_breakpoint () { struct lwp_info *lwp = get_thread_lwp (current_thread); return (lwp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT); } /* Implement the supports_stopped_by_sw_breakpoint target_ops method. */ bool linux_process_target::supports_stopped_by_sw_breakpoint () { return USE_SIGTRAP_SIGINFO; } /* Implement the stopped_by_hw_breakpoint target_ops method. */ bool linux_process_target::stopped_by_hw_breakpoint () { struct lwp_info *lwp = get_thread_lwp (current_thread); return (lwp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT); } /* Implement the supports_stopped_by_hw_breakpoint target_ops method. */ bool linux_process_target::supports_stopped_by_hw_breakpoint () { return USE_SIGTRAP_SIGINFO; } /* Implement the supports_hardware_single_step target_ops method. */ bool linux_process_target::supports_hardware_single_step () { return true; } bool linux_process_target::stopped_by_watchpoint () { struct lwp_info *lwp = get_thread_lwp (current_thread); return lwp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT; } CORE_ADDR linux_process_target::stopped_data_address () { struct lwp_info *lwp = get_thread_lwp (current_thread); return lwp->stopped_data_address; } /* This is only used for targets that define PT_TEXT_ADDR, PT_DATA_ADDR and PT_TEXT_END_ADDR. If those are not defined, supposedly the target has different ways of acquiring this information, like loadmaps. */ bool linux_process_target::supports_read_offsets () { #ifdef SUPPORTS_READ_OFFSETS return true; #else return false; #endif } /* Under uClinux, programs are loaded at non-zero offsets, which we need to tell gdb about. */ int linux_process_target::read_offsets (CORE_ADDR *text_p, CORE_ADDR *data_p) { #ifdef SUPPORTS_READ_OFFSETS unsigned long text, text_end, data; int pid = lwpid_of (current_thread); errno = 0; text = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_TYPE_ARG3) PT_TEXT_ADDR, (PTRACE_TYPE_ARG4) 0); text_end = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_TYPE_ARG3) PT_TEXT_END_ADDR, (PTRACE_TYPE_ARG4) 0); data = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_TYPE_ARG3) PT_DATA_ADDR, (PTRACE_TYPE_ARG4) 0); if (errno == 0) { /* Both text and data offsets produced at compile-time (and so used by gdb) are relative to the beginning of the program, with the data segment immediately following the text segment. However, the actual runtime layout in memory may put the data somewhere else, so when we send gdb a data base-address, we use the real data base address and subtract the compile-time data base-address from it (which is just the length of the text segment). BSS immediately follows data in both cases. */ *text_p = text; *data_p = data - (text_end - text); return 1; } return 0; #else gdb_assert_not_reached ("target op read_offsets not supported"); #endif } bool linux_process_target::supports_get_tls_address () { #ifdef USE_THREAD_DB return true; #else return false; #endif } int linux_process_target::get_tls_address (thread_info *thread, CORE_ADDR offset, CORE_ADDR load_module, CORE_ADDR *address) { #ifdef USE_THREAD_DB return thread_db_get_tls_address (thread, offset, load_module, address); #else return -1; #endif } bool linux_process_target::supports_qxfer_osdata () { return true; } int linux_process_target::qxfer_osdata (const char *annex, unsigned char *readbuf, unsigned const char *writebuf, CORE_ADDR offset, int len) { return linux_common_xfer_osdata (annex, readbuf, offset, len); } void linux_process_target::siginfo_fixup (siginfo_t *siginfo, gdb_byte *inf_siginfo, int direction) { bool done = low_siginfo_fixup (siginfo, inf_siginfo, direction); /* If there was no callback, or the callback didn't do anything, then just do a straight memcpy. */ if (!done) { if (direction == 1) memcpy (siginfo, inf_siginfo, sizeof (siginfo_t)); else memcpy (inf_siginfo, siginfo, sizeof (siginfo_t)); } } bool linux_process_target::low_siginfo_fixup (siginfo_t *native, gdb_byte *inf, int direction) { return false; } bool linux_process_target::supports_qxfer_siginfo () { return true; } int linux_process_target::qxfer_siginfo (const char *annex, unsigned char *readbuf, unsigned const char *writebuf, CORE_ADDR offset, int len) { int pid; siginfo_t siginfo; gdb_byte inf_siginfo[sizeof (siginfo_t)]; if (current_thread == NULL) return -1; pid = lwpid_of (current_thread); if (debug_threads) debug_printf ("%s siginfo for lwp %d.\n", readbuf != NULL ? "Reading" : "Writing", pid); if (offset >= sizeof (siginfo)) return -1; if (ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, &siginfo) != 0) return -1; /* When GDBSERVER is built as a 64-bit application, ptrace writes into SIGINFO an object with 64-bit layout. Since debugging a 32-bit inferior with a 64-bit GDBSERVER should look the same as debugging it with a 32-bit GDBSERVER, we need to convert it. */ siginfo_fixup (&siginfo, inf_siginfo, 0); if (offset + len > sizeof (siginfo)) len = sizeof (siginfo) - offset; if (readbuf != NULL) memcpy (readbuf, inf_siginfo + offset, len); else { memcpy (inf_siginfo + offset, writebuf, len); /* Convert back to ptrace layout before flushing it out. */ siginfo_fixup (&siginfo, inf_siginfo, 1); if (ptrace (PTRACE_SETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, &siginfo) != 0) return -1; } return len; } /* SIGCHLD handler that serves two purposes: In non-stop/async mode, so we notice when children change state; as the handler for the sigsuspend in my_waitpid. */ static void sigchld_handler (int signo) { int old_errno = errno; if (debug_threads) { do { /* Use the async signal safe debug function. */ if (debug_write ("sigchld_handler\n", sizeof ("sigchld_handler\n") - 1) < 0) break; /* just ignore */ } while (0); } if (target_is_async_p ()) async_file_mark (); /* trigger a linux_wait */ errno = old_errno; } bool linux_process_target::supports_non_stop () { return true; } bool linux_process_target::async (bool enable) { bool previous = target_is_async_p (); if (debug_threads) debug_printf ("linux_async (%d), previous=%d\n", enable, previous); if (previous != enable) { sigset_t mask; sigemptyset (&mask); sigaddset (&mask, SIGCHLD); gdb_sigmask (SIG_BLOCK, &mask, NULL); if (enable) { if (pipe (linux_event_pipe) == -1) { linux_event_pipe[0] = -1; linux_event_pipe[1] = -1; gdb_sigmask (SIG_UNBLOCK, &mask, NULL); warning ("creating event pipe failed."); return previous; } fcntl (linux_event_pipe[0], F_SETFL, O_NONBLOCK); fcntl (linux_event_pipe[1], F_SETFL, O_NONBLOCK); /* Register the event loop handler. */ add_file_handler (linux_event_pipe[0], handle_target_event, NULL, "linux-low"); /* Always trigger a linux_wait. */ async_file_mark (); } else { delete_file_handler (linux_event_pipe[0]); close (linux_event_pipe[0]); close (linux_event_pipe[1]); linux_event_pipe[0] = -1; linux_event_pipe[1] = -1; } gdb_sigmask (SIG_UNBLOCK, &mask, NULL); } return previous; } int linux_process_target::start_non_stop (bool nonstop) { /* Register or unregister from event-loop accordingly. */ target_async (nonstop); if (target_is_async_p () != (nonstop != false)) return -1; return 0; } bool linux_process_target::supports_multi_process () { return true; } /* Check if fork events are supported. */ bool linux_process_target::supports_fork_events () { return linux_supports_tracefork (); } /* Check if vfork events are supported. */ bool linux_process_target::supports_vfork_events () { return linux_supports_tracefork (); } /* Check if exec events are supported. */ bool linux_process_target::supports_exec_events () { return linux_supports_traceexec (); } /* Target hook for 'handle_new_gdb_connection'. Causes a reset of the ptrace flags for all inferiors. This is in case the new GDB connection doesn't support the same set of events that the previous one did. */ void linux_process_target::handle_new_gdb_connection () { /* Request that all the lwps reset their ptrace options. */ for_each_thread ([] (thread_info *thread) { struct lwp_info *lwp = get_thread_lwp (thread); if (!lwp->stopped) { /* Stop the lwp so we can modify its ptrace options. */ lwp->must_set_ptrace_flags = 1; linux_stop_lwp (lwp); } else { /* Already stopped; go ahead and set the ptrace options. */ struct process_info *proc = find_process_pid (pid_of (thread)); int options = linux_low_ptrace_options (proc->attached); linux_enable_event_reporting (lwpid_of (thread), options); lwp->must_set_ptrace_flags = 0; } }); } int linux_process_target::handle_monitor_command (char *mon) { #ifdef USE_THREAD_DB return thread_db_handle_monitor_command (mon); #else return 0; #endif } int linux_process_target::core_of_thread (ptid_t ptid) { return linux_common_core_of_thread (ptid); } bool linux_process_target::supports_disable_randomization () { return true; } bool linux_process_target::supports_agent () { return true; } bool linux_process_target::supports_range_stepping () { if (supports_software_single_step ()) return true; return low_supports_range_stepping (); } bool linux_process_target::low_supports_range_stepping () { return false; } bool linux_process_target::supports_pid_to_exec_file () { return true; } const char * linux_process_target::pid_to_exec_file (int pid) { return linux_proc_pid_to_exec_file (pid); } bool linux_process_target::supports_multifs () { return true; } int linux_process_target::multifs_open (int pid, const char *filename, int flags, mode_t mode) { return linux_mntns_open_cloexec (pid, filename, flags, mode); } int linux_process_target::multifs_unlink (int pid, const char *filename) { return linux_mntns_unlink (pid, filename); } ssize_t linux_process_target::multifs_readlink (int pid, const char *filename, char *buf, size_t bufsiz) { return linux_mntns_readlink (pid, filename, buf, bufsiz); } #if defined PT_GETDSBT || defined PTRACE_GETFDPIC struct target_loadseg { /* Core address to which the segment is mapped. */ Elf32_Addr addr; /* VMA recorded in the program header. */ Elf32_Addr p_vaddr; /* Size of this segment in memory. */ Elf32_Word p_memsz; }; # if defined PT_GETDSBT struct target_loadmap { /* Protocol version number, must be zero. */ Elf32_Word version; /* Pointer to the DSBT table, its size, and the DSBT index. */ unsigned *dsbt_table; unsigned dsbt_size, dsbt_index; /* Number of segments in this map. */ Elf32_Word nsegs; /* The actual memory map. */ struct target_loadseg segs[/*nsegs*/]; }; # define LINUX_LOADMAP PT_GETDSBT # define LINUX_LOADMAP_EXEC PTRACE_GETDSBT_EXEC # define LINUX_LOADMAP_INTERP PTRACE_GETDSBT_INTERP # else struct target_loadmap { /* Protocol version number, must be zero. */ Elf32_Half version; /* Number of segments in this map. */ Elf32_Half nsegs; /* The actual memory map. */ struct target_loadseg segs[/*nsegs*/]; }; # define LINUX_LOADMAP PTRACE_GETFDPIC # define LINUX_LOADMAP_EXEC PTRACE_GETFDPIC_EXEC # define LINUX_LOADMAP_INTERP PTRACE_GETFDPIC_INTERP # endif bool linux_process_target::supports_read_loadmap () { return true; } int linux_process_target::read_loadmap (const char *annex, CORE_ADDR offset, unsigned char *myaddr, unsigned int len) { int pid = lwpid_of (current_thread); int addr = -1; struct target_loadmap *data = NULL; unsigned int actual_length, copy_length; if (strcmp (annex, "exec") == 0) addr = (int) LINUX_LOADMAP_EXEC; else if (strcmp (annex, "interp") == 0) addr = (int) LINUX_LOADMAP_INTERP; else return -1; if (ptrace (LINUX_LOADMAP, pid, addr, &data) != 0) return -1; if (data == NULL) return -1; actual_length = sizeof (struct target_loadmap) + sizeof (struct target_loadseg) * data->nsegs; if (offset < 0 || offset > actual_length) return -1; copy_length = actual_length - offset < len ? actual_length - offset : len; memcpy (myaddr, (char *) data + offset, copy_length); return copy_length; } #endif /* defined PT_GETDSBT || defined PTRACE_GETFDPIC */ bool linux_process_target::supports_catch_syscall () { return (low_supports_catch_syscall () && linux_supports_tracesysgood ()); } bool linux_process_target::low_supports_catch_syscall () { return false; } CORE_ADDR linux_process_target::read_pc (regcache *regcache) { if (!low_supports_breakpoints ()) return 0; return low_get_pc (regcache); } void linux_process_target::write_pc (regcache *regcache, CORE_ADDR pc) { gdb_assert (low_supports_breakpoints ()); low_set_pc (regcache, pc); } bool linux_process_target::supports_thread_stopped () { return true; } bool linux_process_target::thread_stopped (thread_info *thread) { return get_thread_lwp (thread)->stopped; } /* This exposes stop-all-threads functionality to other modules. */ void linux_process_target::pause_all (bool freeze) { stop_all_lwps (freeze, NULL); } /* This exposes unstop-all-threads functionality to other gdbserver modules. */ void linux_process_target::unpause_all (bool unfreeze) { unstop_all_lwps (unfreeze, NULL); } int linux_process_target::prepare_to_access_memory () { /* Neither ptrace nor /proc/PID/mem allow accessing memory through a running LWP. */ if (non_stop) target_pause_all (true); return 0; } void linux_process_target::done_accessing_memory () { /* Neither ptrace nor /proc/PID/mem allow accessing memory through a running LWP. */ if (non_stop) target_unpause_all (true); } /* Extract &phdr and num_phdr in the inferior. Return 0 on success. */ static int get_phdr_phnum_from_proc_auxv (const int pid, const int is_elf64, CORE_ADDR *phdr_memaddr, int *num_phdr) { char filename[PATH_MAX]; int fd; const int auxv_size = is_elf64 ? sizeof (Elf64_auxv_t) : sizeof (Elf32_auxv_t); char buf[sizeof (Elf64_auxv_t)]; /* The larger of the two. */ xsnprintf (filename, sizeof filename, "/proc/%d/auxv", pid); fd = open (filename, O_RDONLY); if (fd < 0) return 1; *phdr_memaddr = 0; *num_phdr = 0; while (read (fd, buf, auxv_size) == auxv_size && (*phdr_memaddr == 0 || *num_phdr == 0)) { if (is_elf64) { Elf64_auxv_t *const aux = (Elf64_auxv_t *) buf; switch (aux->a_type) { case AT_PHDR: *phdr_memaddr = aux->a_un.a_val; break; case AT_PHNUM: *num_phdr = aux->a_un.a_val; break; } } else { Elf32_auxv_t *const aux = (Elf32_auxv_t *) buf; switch (aux->a_type) { case AT_PHDR: *phdr_memaddr = aux->a_un.a_val; break; case AT_PHNUM: *num_phdr = aux->a_un.a_val; break; } } } close (fd); if (*phdr_memaddr == 0 || *num_phdr == 0) { warning ("Unexpected missing AT_PHDR and/or AT_PHNUM: " "phdr_memaddr = %ld, phdr_num = %d", (long) *phdr_memaddr, *num_phdr); return 2; } return 0; } /* Return &_DYNAMIC (via PT_DYNAMIC) in the inferior, or 0 if not present. */ static CORE_ADDR get_dynamic (const int pid, const int is_elf64) { CORE_ADDR phdr_memaddr, relocation; int num_phdr, i; unsigned char *phdr_buf; const int phdr_size = is_elf64 ? sizeof (Elf64_Phdr) : sizeof (Elf32_Phdr); if (get_phdr_phnum_from_proc_auxv (pid, is_elf64, &phdr_memaddr, &num_phdr)) return 0; gdb_assert (num_phdr < 100); /* Basic sanity check. */ phdr_buf = (unsigned char *) alloca (num_phdr * phdr_size); if (linux_read_memory (phdr_memaddr, phdr_buf, num_phdr * phdr_size)) return 0; /* Compute relocation: it is expected to be 0 for "regular" executables, non-zero for PIE ones. */ relocation = -1; for (i = 0; relocation == -1 && i < num_phdr; i++) if (is_elf64) { Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size); if (p->p_type == PT_PHDR) relocation = phdr_memaddr - p->p_vaddr; } else { Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size); if (p->p_type == PT_PHDR) relocation = phdr_memaddr - p->p_vaddr; } if (relocation == -1) { /* PT_PHDR is optional, but necessary for PIE in general. Fortunately any real world executables, including PIE executables, have always PT_PHDR present. PT_PHDR is not present in some shared libraries or in fpc (Free Pascal 2.4) binaries but neither of those have a need for or present DT_DEBUG anyway (fpc binaries are statically linked). Therefore if there exists DT_DEBUG there is always also PT_PHDR. GDB could find RELOCATION also from AT_ENTRY - e_entry. */ return 0; } for (i = 0; i < num_phdr; i++) { if (is_elf64) { Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size); if (p->p_type == PT_DYNAMIC) return p->p_vaddr + relocation; } else { Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size); if (p->p_type == PT_DYNAMIC) return p->p_vaddr + relocation; } } return 0; } /* Return &_r_debug in the inferior, or -1 if not present. Return value can be 0 if the inferior does not yet have the library list initialized. We look for DT_MIPS_RLD_MAP first. MIPS executables use this instead of DT_DEBUG, although they sometimes contain an unused DT_DEBUG entry too. */ static CORE_ADDR get_r_debug (const int pid, const int is_elf64) { CORE_ADDR dynamic_memaddr; const int dyn_size = is_elf64 ? sizeof (Elf64_Dyn) : sizeof (Elf32_Dyn); unsigned char buf[sizeof (Elf64_Dyn)]; /* The larger of the two. */ CORE_ADDR map = -1; dynamic_memaddr = get_dynamic (pid, is_elf64); if (dynamic_memaddr == 0) return map; while (linux_read_memory (dynamic_memaddr, buf, dyn_size) == 0) { if (is_elf64) { Elf64_Dyn *const dyn = (Elf64_Dyn *) buf; #if defined DT_MIPS_RLD_MAP || defined DT_MIPS_RLD_MAP_REL union { Elf64_Xword map; unsigned char buf[sizeof (Elf64_Xword)]; } rld_map; #endif #ifdef DT_MIPS_RLD_MAP if (dyn->d_tag == DT_MIPS_RLD_MAP) { if (linux_read_memory (dyn->d_un.d_val, rld_map.buf, sizeof (rld_map.buf)) == 0) return rld_map.map; else break; } #endif /* DT_MIPS_RLD_MAP */ #ifdef DT_MIPS_RLD_MAP_REL if (dyn->d_tag == DT_MIPS_RLD_MAP_REL) { if (linux_read_memory (dyn->d_un.d_val + dynamic_memaddr, rld_map.buf, sizeof (rld_map.buf)) == 0) return rld_map.map; else break; } #endif /* DT_MIPS_RLD_MAP_REL */ if (dyn->d_tag == DT_DEBUG && map == -1) map = dyn->d_un.d_val; if (dyn->d_tag == DT_NULL) break; } else { Elf32_Dyn *const dyn = (Elf32_Dyn *) buf; #if defined DT_MIPS_RLD_MAP || defined DT_MIPS_RLD_MAP_REL union { Elf32_Word map; unsigned char buf[sizeof (Elf32_Word)]; } rld_map; #endif #ifdef DT_MIPS_RLD_MAP if (dyn->d_tag == DT_MIPS_RLD_MAP) { if (linux_read_memory (dyn->d_un.d_val, rld_map.buf, sizeof (rld_map.buf)) == 0) return rld_map.map; else break; } #endif /* DT_MIPS_RLD_MAP */ #ifdef DT_MIPS_RLD_MAP_REL if (dyn->d_tag == DT_MIPS_RLD_MAP_REL) { if (linux_read_memory (dyn->d_un.d_val + dynamic_memaddr, rld_map.buf, sizeof (rld_map.buf)) == 0) return rld_map.map; else break; } #endif /* DT_MIPS_RLD_MAP_REL */ if (dyn->d_tag == DT_DEBUG && map == -1) map = dyn->d_un.d_val; if (dyn->d_tag == DT_NULL) break; } dynamic_memaddr += dyn_size; } return map; } /* Read one pointer from MEMADDR in the inferior. */ static int read_one_ptr (CORE_ADDR memaddr, CORE_ADDR *ptr, int ptr_size) { int ret; /* Go through a union so this works on either big or little endian hosts, when the inferior's pointer size is smaller than the size of CORE_ADDR. It is assumed the inferior's endianness is the same of the superior's. */ union { CORE_ADDR core_addr; unsigned int ui; unsigned char uc; } addr; ret = linux_read_memory (memaddr, &addr.uc, ptr_size); if (ret == 0) { if (ptr_size == sizeof (CORE_ADDR)) *ptr = addr.core_addr; else if (ptr_size == sizeof (unsigned int)) *ptr = addr.ui; else gdb_assert_not_reached ("unhandled pointer size"); } return ret; } bool linux_process_target::supports_qxfer_libraries_svr4 () { return true; } struct link_map_offsets { /* Offset and size of r_debug.r_version. */ int r_version_offset; /* Offset and size of r_debug.r_map. */ int r_map_offset; /* Offset to l_addr field in struct link_map. */ int l_addr_offset; /* Offset to l_name field in struct link_map. */ int l_name_offset; /* Offset to l_ld field in struct link_map. */ int l_ld_offset; /* Offset to l_next field in struct link_map. */ int l_next_offset; /* Offset to l_prev field in struct link_map. */ int l_prev_offset; }; /* Construct qXfer:libraries-svr4:read reply. */ int linux_process_target::qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, unsigned const char *writebuf, CORE_ADDR offset, int len) { struct process_info_private *const priv = current_process ()->priv; char filename[PATH_MAX]; int pid, is_elf64; static const struct link_map_offsets lmo_32bit_offsets = { 0, /* r_version offset. */ 4, /* r_debug.r_map offset. */ 0, /* l_addr offset in link_map. */ 4, /* l_name offset in link_map. */ 8, /* l_ld offset in link_map. */ 12, /* l_next offset in link_map. */ 16 /* l_prev offset in link_map. */ }; static const struct link_map_offsets lmo_64bit_offsets = { 0, /* r_version offset. */ 8, /* r_debug.r_map offset. */ 0, /* l_addr offset in link_map. */ 8, /* l_name offset in link_map. */ 16, /* l_ld offset in link_map. */ 24, /* l_next offset in link_map. */ 32 /* l_prev offset in link_map. */ }; const struct link_map_offsets *lmo; unsigned int machine; int ptr_size; CORE_ADDR lm_addr = 0, lm_prev = 0; CORE_ADDR l_name, l_addr, l_ld, l_next, l_prev; int header_done = 0; if (writebuf != NULL) return -2; if (readbuf == NULL) return -1; pid = lwpid_of (current_thread); xsnprintf (filename, sizeof filename, "/proc/%d/exe", pid); is_elf64 = elf_64_file_p (filename, &machine); lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets; ptr_size = is_elf64 ? 8 : 4; while (annex[0] != '\0') { const char *sep; CORE_ADDR *addrp; int name_len; sep = strchr (annex, '='); if (sep == NULL) break; name_len = sep - annex; if (name_len == 5 && startswith (annex, "start")) addrp = &lm_addr; else if (name_len == 4 && startswith (annex, "prev")) addrp = &lm_prev; else { annex = strchr (sep, ';'); if (annex == NULL) break; annex++; continue; } annex = decode_address_to_semicolon (addrp, sep + 1); } if (lm_addr == 0) { int r_version = 0; if (priv->r_debug == 0) priv->r_debug = get_r_debug (pid, is_elf64); /* We failed to find DT_DEBUG. Such situation will not change for this inferior - do not retry it. Report it to GDB as E01, see for the reasons at the GDB solib-svr4.c side. */ if (priv->r_debug == (CORE_ADDR) -1) return -1; if (priv->r_debug != 0) { if (linux_read_memory (priv->r_debug + lmo->r_version_offset, (unsigned char *) &r_version, sizeof (r_version)) != 0 || r_version < 1) { warning ("unexpected r_debug version %d", r_version); } else if (read_one_ptr (priv->r_debug + lmo->r_map_offset, &lm_addr, ptr_size) != 0) { warning ("unable to read r_map from 0x%lx", (long) priv->r_debug + lmo->r_map_offset); } } } std::string document = "l_name_offset, &l_name, ptr_size) == 0 && read_one_ptr (lm_addr + lmo->l_addr_offset, &l_addr, ptr_size) == 0 && read_one_ptr (lm_addr + lmo->l_ld_offset, &l_ld, ptr_size) == 0 && read_one_ptr (lm_addr + lmo->l_prev_offset, &l_prev, ptr_size) == 0 && read_one_ptr (lm_addr + lmo->l_next_offset, &l_next, ptr_size) == 0) { unsigned char libname[PATH_MAX]; if (lm_prev != l_prev) { warning ("Corrupted shared library list: 0x%lx != 0x%lx", (long) lm_prev, (long) l_prev); break; } /* Ignore the first entry even if it has valid name as the first entry corresponds to the main executable. The first entry should not be skipped if the dynamic loader was loaded late by a static executable (see solib-svr4.c parameter ignore_first). But in such case the main executable does not have PT_DYNAMIC present and this function already exited above due to failed get_r_debug. */ if (lm_prev == 0) string_appendf (document, " main-lm=\"0x%lx\"", (unsigned long) lm_addr); else { /* Not checking for error because reading may stop before we've got PATH_MAX worth of characters. */ libname[0] = '\0'; linux_read_memory (l_name, libname, sizeof (libname) - 1); libname[sizeof (libname) - 1] = '\0'; if (libname[0] != '\0') { if (!header_done) { /* Terminate `", (unsigned long) lm_addr, (unsigned long) l_addr, (unsigned long) l_ld); } } lm_prev = lm_addr; lm_addr = l_next; } if (!header_done) { /* Empty list; terminate ` document_len) len = document_len; memcpy (readbuf, document.data () + offset, len); return len; } #ifdef HAVE_LINUX_BTRACE btrace_target_info * linux_process_target::enable_btrace (ptid_t ptid, const btrace_config *conf) { return linux_enable_btrace (ptid, conf); } /* See to_disable_btrace target method. */ int linux_process_target::disable_btrace (btrace_target_info *tinfo) { enum btrace_error err; err = linux_disable_btrace (tinfo); return (err == BTRACE_ERR_NONE ? 0 : -1); } /* Encode an Intel Processor Trace configuration. */ static void linux_low_encode_pt_config (struct buffer *buffer, const struct btrace_data_pt_config *config) { buffer_grow_str (buffer, "\n"); switch (config->cpu.vendor) { case CV_INTEL: buffer_xml_printf (buffer, "\n", config->cpu.family, config->cpu.model, config->cpu.stepping); break; default: break; } buffer_grow_str (buffer, "\n"); } /* Encode a raw buffer. */ static void linux_low_encode_raw (struct buffer *buffer, const gdb_byte *data, unsigned int size) { if (size == 0) return; /* We use hex encoding - see gdbsupport/rsp-low.h. */ buffer_grow_str (buffer, "\n"); while (size-- > 0) { char elem[2]; elem[0] = tohex ((*data >> 4) & 0xf); elem[1] = tohex (*data++ & 0xf); buffer_grow (buffer, elem, 2); } buffer_grow_str (buffer, "\n"); } /* See to_read_btrace target method. */ int linux_process_target::read_btrace (btrace_target_info *tinfo, buffer *buffer, enum btrace_read_type type) { struct btrace_data btrace; enum btrace_error err; err = linux_read_btrace (&btrace, tinfo, type); if (err != BTRACE_ERR_NONE) { if (err == BTRACE_ERR_OVERFLOW) buffer_grow_str0 (buffer, "E.Overflow."); else buffer_grow_str0 (buffer, "E.Generic Error."); return -1; } switch (btrace.format) { case BTRACE_FORMAT_NONE: buffer_grow_str0 (buffer, "E.No Trace."); return -1; case BTRACE_FORMAT_BTS: buffer_grow_str (buffer, "\n"); buffer_grow_str (buffer, "\n"); for (const btrace_block &block : *btrace.variant.bts.blocks) buffer_xml_printf (buffer, "\n", paddress (block.begin), paddress (block.end)); buffer_grow_str0 (buffer, "\n"); break; case BTRACE_FORMAT_PT: buffer_grow_str (buffer, "\n"); buffer_grow_str (buffer, "\n"); buffer_grow_str (buffer, "\n"); linux_low_encode_pt_config (buffer, &btrace.variant.pt.config); linux_low_encode_raw (buffer, btrace.variant.pt.data, btrace.variant.pt.size); buffer_grow_str (buffer, "\n"); buffer_grow_str0 (buffer, "\n"); break; default: buffer_grow_str0 (buffer, "E.Unsupported Trace Format."); return -1; } return 0; } /* See to_btrace_conf target method. */ int linux_process_target::read_btrace_conf (const btrace_target_info *tinfo, buffer *buffer) { const struct btrace_config *conf; buffer_grow_str (buffer, "\n"); buffer_grow_str (buffer, "\n"); conf = linux_btrace_conf (tinfo); if (conf != NULL) { switch (conf->format) { case BTRACE_FORMAT_NONE: break; case BTRACE_FORMAT_BTS: buffer_xml_printf (buffer, "bts.size); buffer_xml_printf (buffer, " />\n"); break; case BTRACE_FORMAT_PT: buffer_xml_printf (buffer, "pt.size); buffer_xml_printf (buffer, "/>\n"); break; } } buffer_grow_str0 (buffer, "\n"); return 0; } #endif /* HAVE_LINUX_BTRACE */ /* See nat/linux-nat.h. */ ptid_t current_lwp_ptid (void) { return ptid_of (current_thread); } const char * linux_process_target::thread_name (ptid_t thread) { return linux_proc_tid_get_name (thread); } #if USE_THREAD_DB bool linux_process_target::thread_handle (ptid_t ptid, gdb_byte **handle, int *handle_len) { return thread_db_thread_handle (ptid, handle, handle_len); } #endif /* Default implementation of linux_target_ops method "set_pc" for 32-bit pc register which is literally named "pc". */ void linux_set_pc_32bit (struct regcache *regcache, CORE_ADDR pc) { uint32_t newpc = pc; supply_register_by_name (regcache, "pc", &newpc); } /* Default implementation of linux_target_ops method "get_pc" for 32-bit pc register which is literally named "pc". */ CORE_ADDR linux_get_pc_32bit (struct regcache *regcache) { uint32_t pc; collect_register_by_name (regcache, "pc", &pc); if (debug_threads) debug_printf ("stop pc is 0x%" PRIx32 "\n", pc); return pc; } /* Default implementation of linux_target_ops method "set_pc" for 64-bit pc register which is literally named "pc". */ void linux_set_pc_64bit (struct regcache *regcache, CORE_ADDR pc) { uint64_t newpc = pc; supply_register_by_name (regcache, "pc", &newpc); } /* Default implementation of linux_target_ops method "get_pc" for 64-bit pc register which is literally named "pc". */ CORE_ADDR linux_get_pc_64bit (struct regcache *regcache) { uint64_t pc; collect_register_by_name (regcache, "pc", &pc); if (debug_threads) debug_printf ("stop pc is 0x%" PRIx64 "\n", pc); return pc; } /* See linux-low.h. */ int linux_get_auxv (int wordsize, CORE_ADDR match, CORE_ADDR *valp) { gdb_byte *data = (gdb_byte *) alloca (2 * wordsize); int offset = 0; gdb_assert (wordsize == 4 || wordsize == 8); while (the_target->read_auxv (offset, data, 2 * wordsize) == 2 * wordsize) { if (wordsize == 4) { uint32_t *data_p = (uint32_t *) data; if (data_p[0] == match) { *valp = data_p[1]; return 1; } } else { uint64_t *data_p = (uint64_t *) data; if (data_p[0] == match) { *valp = data_p[1]; return 1; } } offset += 2 * wordsize; } return 0; } /* See linux-low.h. */ CORE_ADDR linux_get_hwcap (int wordsize) { CORE_ADDR hwcap = 0; linux_get_auxv (wordsize, AT_HWCAP, &hwcap); return hwcap; } /* See linux-low.h. */ CORE_ADDR linux_get_hwcap2 (int wordsize) { CORE_ADDR hwcap2 = 0; linux_get_auxv (wordsize, AT_HWCAP2, &hwcap2); return hwcap2; } #ifdef HAVE_LINUX_REGSETS void initialize_regsets_info (struct regsets_info *info) { for (info->num_regsets = 0; info->regsets[info->num_regsets].size >= 0; info->num_regsets++) ; } #endif void initialize_low (void) { struct sigaction sigchld_action; memset (&sigchld_action, 0, sizeof (sigchld_action)); set_target_ops (the_linux_target); linux_ptrace_init_warnings (); linux_proc_init_warnings (); sigchld_action.sa_handler = sigchld_handler; sigemptyset (&sigchld_action.sa_mask); sigchld_action.sa_flags = SA_RESTART; sigaction (SIGCHLD, &sigchld_action, NULL); initialize_low_arch (); linux_check_ptrace_features (); }