diff options
Diffstat (limited to 'gdb')
| -rw-r--r-- | gdb/gdbserver/ChangeLog | 28 | ||||
| -rw-r--r-- | gdb/gdbserver/inferiors.h | 22 | ||||
| -rw-r--r-- | gdb/gdbserver/linux-low.c | 852 | ||||
| -rw-r--r-- | gdb/gdbserver/server.c | 18 |
4 files changed, 568 insertions, 352 deletions
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 8eb3e28..eab7e8d 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,31 @@ +2014-02-27 Pedro Alves <palves@redhat.com> + + PR 12702 + * inferiors.h (A_I_NEXT, ALL_INFERIORS_TYPE, ALL_PROCESSES): New + macros. + * linux-low.c (delete_lwp, handle_extended_wait): Add debug + output. + (last_thread_of_process_p): Take a PID argument instead of a + thread pointer. + (linux_wait_for_lwp): Delete. + (num_lwps, check_zombie_leaders, not_stopped_callback): New + functions. + (linux_low_filter_event): New function, party factored out from + linux_wait_for_event. + (linux_wait_for_event): Rename to ... + (linux_wait_for_event_filtered): ... this. Add new filter ptid + argument. Partly rewrite. Always use waitpid(-1, WNOHANG) and + sigsuspend. Check for zombie leaders. + (linux_wait_for_event): Reimplement as wrapper around + linux_wait_for_event_filtered. + (linux_wait_1): Handle TARGET_WAITKIND_NO_RESUMED. Assume that if + a normal or signal exit is seen, it's the whole process exiting. + (wait_for_sigstop): No longer a for_each_inferior callback. + Rewrite on top of linux_wait_for_event_filtered. + (stop_all_lwps): Call wait_for_sigstop directly. + * server.c (resume, handle_target_event): Handle + TARGET_WAITKIND_NO_RESUMED. + 2014-02-26 Joel Brobecker <brobecker@adacore.com> * win32-low.c (psapi_get_dll_name, diff --git a/gdb/gdbserver/inferiors.h b/gdb/gdbserver/inferiors.h index 9ea55df..f584339 100644 --- a/gdb/gdbserver/inferiors.h +++ b/gdb/gdbserver/inferiors.h @@ -99,6 +99,28 @@ void clear_inferior_list (struct inferior_list *list); int one_inferior_p (struct inferior_list *list); +/* Helper for ALL_INFERIORS_TYPE. Gets the next element starting at + CUR, if CUR is not NULL. */ +#define A_I_NEXT(type, list, cur) \ + ((cur) != NULL \ + ? (type *) ((struct inferior_list_entry *) cur)->next \ + : NULL) + +/* Iterate over all inferiors of type TYPE in LIST, open loop + style. */ +#define ALL_INFERIORS_TYPE(type, list, cur, tmp) \ + for ((cur) = (type *) (list)->head, (tmp) = A_I_NEXT (type, list, cur); \ + (cur) != NULL; \ + (cur) = (tmp), (tmp) = A_I_NEXT (type, list, cur)) + +/* Iterate over all inferiors in LIST, open loop style. */ +#define ALL_INFERIORS(list, cur, tmp) \ + ALL_INFERIORS_TYPE (struct inferior_list_entry, list, cur, tmp) + +/* Iterate over all processes, open loop style. */ +#define ALL_PROCESSES(cur, tmp) \ + ALL_INFERIORS_TYPE (struct process_info, &all_processes, cur, tmp) + extern struct thread_info *current_inferior; void remove_inferior (struct inferior_list *list, struct inferior_list_entry *entry); diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 923ee14..2d8d5f5 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -214,6 +214,8 @@ static void linux_resume_one_lwp (struct lwp_info *lwp, static void linux_resume (struct thread_resume *resume_info, size_t n); static void stop_all_lwps (int suspend, struct lwp_info *except); static void unstop_all_lwps (int unsuspend, struct lwp_info *except); +static int linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, + int *wstat, int options); static int linux_wait_for_event (ptid_t ptid, int *wstat, int options); static struct lwp_info *add_lwp (ptid_t ptid); static int linux_stopped_by_watchpoint (void); @@ -276,7 +278,7 @@ static int linux_event_pipe[2] = { -1, -1 }; #define target_is_async_p() (linux_event_pipe[0] != -1) static void send_sigstop (struct lwp_info *lwp); -static void wait_for_sigstop (struct inferior_list_entry *entry); +static void wait_for_sigstop (void); /* Return non-zero if HEADER is a 64-bit ELF file. */ @@ -335,7 +337,12 @@ linux_pid_exe_is_elf_64_file (int pid, unsigned int *machine) static void delete_lwp (struct lwp_info *lwp) { - remove_thread (get_lwp_thread (lwp)); + struct thread_info *thr = get_lwp_thread (lwp); + + if (debug_threads) + debug_printf ("deleting %ld\n", lwpid_of (thr)); + + remove_thread (thr); free (lwp->arch_private); free (lwp); } @@ -396,6 +403,11 @@ handle_extended_wait (struct lwp_info *event_child, int wstat) warning ("wait returned unexpected status 0x%x", status); } + 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_build (pid_of (event_thr), new_pid, 0); new_lwp = add_lwp (ptid); @@ -847,10 +859,8 @@ second_thread_of_pid_p (struct inferior_list_entry *entry, void *args) } static int -last_thread_of_process_p (struct thread_info *thread) +last_thread_of_process_p (int pid) { - ptid_t ptid = thread->entry.id; - int pid = ptid_get_pid (ptid); struct counter counter = { pid , 0 }; return (find_inferior (&all_threads, @@ -1252,152 +1262,107 @@ find_lwp_pid (ptid_t ptid) return get_thread_lwp ((struct thread_info *) thread); } -static struct lwp_info * -linux_wait_for_lwp (ptid_t ptid, int *wstatp, int options) -{ - int ret; - int to_wait_for = -1; - struct lwp_info *child; - struct thread_info *thread; - - if (debug_threads) - debug_printf ("linux_wait_for_lwp: %s\n", target_pid_to_str (ptid)); - - if (ptid_equal (ptid, minus_one_ptid)) - to_wait_for = -1; /* any child */ - else - to_wait_for = ptid_get_lwp (ptid); /* this lwp only */ - - options |= __WALL; - -retry: +/* Return the number of known LWPs in the tgid given by PID. */ - ret = my_waitpid (to_wait_for, wstatp, options); - if (ret == 0 || (ret == -1 && errno == ECHILD && (options & WNOHANG))) - return NULL; - else if (ret == -1) - perror_with_name ("waitpid"); - - if (debug_threads - && (!WIFSTOPPED (*wstatp) - || (WSTOPSIG (*wstatp) != 32 - && WSTOPSIG (*wstatp) != 33))) - debug_printf ("Got an event from %d (%x)\n", ret, *wstatp); - - child = find_lwp_pid (pid_to_ptid (ret)); - if (child != NULL) - thread = get_lwp_thread (child); - else - thread = NULL; +static int +num_lwps (int pid) +{ + struct inferior_list_entry *inf, *tmp; + int count = 0; - /* 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 (*wstatp)) + ALL_INFERIORS (&all_threads, inf, tmp) { - add_to_pid_list (&stopped_pids, ret, *wstatp); - goto retry; + if (ptid_get_pid (inf->id) == pid) + count++; } - else if (child == NULL) - goto retry; - - child->stopped = 1; - - child->last_status = *wstatp; - - if (WIFSTOPPED (*wstatp)) - { - struct process_info *proc; - - /* Architecture-specific setup after inferior is running. 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. */ - proc = find_process_pid (pid_of (thread)); - if (proc->private->new_inferior) - { - struct thread_info *saved_inferior; - - saved_inferior = current_inferior; - current_inferior = thread; - - the_low_target.arch_setup (); - current_inferior = saved_inferior; - - proc->private->new_inferior = 0; - } - } + return count; +} - /* Fetch the possibly triggered data watchpoint info and store it in - CHILD. +/* Detect zombie thread group leaders, and "exit" them. We can't reap + their exits until all other threads in the group have exited. */ - On some archs, like x86, that use debug registers to set - watchpoints, it's possible that the way to know which watched - address trapped, is to check the register that is used to select - which address to watch. Problem is, between setting the - watchpoint and reading back which data address trapped, the user - may change the set of watchpoints, and, as a consequence, GDB - changes the debug registers in the inferior. To avoid reading - back a stale stopped-data-address when that happens, we cache in - LP the fact that a watchpoint trapped, and the corresponding data - address, as soon as we see CHILD stop with a SIGTRAP. If GDB - changes the debug registers meanwhile, we have the cached data we - can rely on. */ +static void +check_zombie_leaders (void) +{ + struct process_info *proc, *tmp; - if (WIFSTOPPED (*wstatp) && WSTOPSIG (*wstatp) == SIGTRAP) + ALL_PROCESSES (proc, tmp) { - if (the_low_target.stopped_by_watchpoint == NULL) - { - child->stopped_by_watchpoint = 0; - } - else - { - struct thread_info *saved_inferior; + pid_t leader_pid = pid_of (proc); + struct lwp_info *leader_lp; - saved_inferior = current_inferior; - current_inferior = get_lwp_thread (child); + leader_lp = find_lwp_pid (pid_to_ptid (leader_pid)); - child->stopped_by_watchpoint - = the_low_target.stopped_by_watchpoint (); + 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 + /* 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 (child->stopped_by_watchpoint) - { - if (the_low_target.stopped_data_address != NULL) - child->stopped_data_address - = the_low_target.stopped_data_address (); - else - child->stopped_data_address = 0; - } + if (debug_threads) + fprintf (stderr, + "CZL: Thread group leader %d zombie " + "(it exited, or another thread execd).\n", + leader_pid); - current_inferior = saved_inferior; + delete_lwp (leader_lp); } } +} - /* Store the STOP_PC, with adjustment applied. This depends on the - architecture being defined already (so that CHILD has a valid - regcache), and on LAST_STATUS being set (to check for SIGTRAP or - not). */ - if (WIFSTOPPED (*wstatp)) - child->stop_pc = get_stop_pc (child); +/* Callback for `find_inferior'. Returns the first LWP that is not + stopped. ARG is a PTID filter. */ - if (debug_threads - && WIFSTOPPED (*wstatp) - && the_low_target.get_pc != NULL) - { - struct thread_info *saved_inferior = current_inferior; - struct regcache *regcache; - CORE_ADDR pc; +static int +not_stopped_callback (struct inferior_list_entry *entry, void *arg) +{ + struct thread_info *thr = (struct thread_info *) entry; + struct lwp_info *lwp; + ptid_t filter = *(ptid_t *) arg; - current_inferior = get_lwp_thread (child); - regcache = get_thread_regcache (current_inferior, 1); - pc = (*the_low_target.get_pc) (regcache); - debug_printf ("linux_wait_for_lwp: pc is 0x%lx\n", (long) pc); - current_inferior = saved_inferior; - } + if (!ptid_match (ptid_of (thr), filter)) + return 0; - return child; + lwp = get_thread_lwp (thr); + if (!lwp->stopped) + return 1; + + return 0; } /* This function should only be called if the LWP got a SIGTRAP. @@ -1749,23 +1714,259 @@ cancel_breakpoint (struct lwp_info *lwp) return 0; } +/* Do low-level handling of the event, and check if we should go on + and pass it to caller code. Return the affected lwp if we are, or + NULL otherwise. */ + +static struct lwp_info * +linux_low_filter_event (ptid_t filter_ptid, int lwpid, int wstat) +{ + struct lwp_info *child; + struct thread_info *thread; + + child = find_lwp_pid (pid_to_ptid (lwpid)); + + /* 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 NULL; + } + else if (child == NULL) + return NULL; + + thread = get_lwp_thread (child); + + child->stopped = 1; + + child->last_status = wstat; + + if (WIFSTOPPED (wstat)) + { + struct process_info *proc; + + /* Architecture-specific setup after inferior is running. 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. */ + proc = find_process_pid (pid_of (thread)); + if (proc->private->new_inferior) + { + struct thread_info *saved_inferior; + + saved_inferior = current_inferior; + current_inferior = thread; + + the_low_target.arch_setup (); + + current_inferior = saved_inferior; + + proc->private->new_inferior = 0; + } + } + + /* Store the STOP_PC, with adjustment applied. This depends on the + architecture being defined already (so that CHILD has a valid + regcache), and on LAST_STATUS being set (to check for SIGTRAP or + not). */ + if (WIFSTOPPED (wstat)) + { + if (debug_threads + && the_low_target.get_pc != NULL) + { + struct thread_info *saved_inferior; + struct regcache *regcache; + CORE_ADDR pc; + + saved_inferior = current_inferior; + current_inferior = thread; + regcache = get_thread_regcache (current_inferior, 1); + pc = (*the_low_target.get_pc) (regcache); + debug_printf ("linux_low_filter_event: pc is 0x%lx\n", (long) pc); + current_inferior = saved_inferior; + } + + child->stop_pc = get_stop_pc (child); + } + + /* Fetch the possibly triggered data watchpoint info and store it in + CHILD. + + On some archs, like x86, that use debug registers to set + watchpoints, it's possible that the way to know which watched + address trapped, is to check the register that is used to select + which address to watch. Problem is, between setting the + watchpoint and reading back which data address trapped, the user + may change the set of watchpoints, and, as a consequence, GDB + changes the debug registers in the inferior. To avoid reading + back a stale stopped-data-address when that happens, we cache in + LP the fact that a watchpoint trapped, and the corresponding data + address, as soon as we see CHILD stop with a SIGTRAP. If GDB + changes the debug registers meanwhile, we have the cached data we + can rely on. */ + + if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP) + { + if (the_low_target.stopped_by_watchpoint == NULL) + { + child->stopped_by_watchpoint = 0; + } + else + { + struct thread_info *saved_inferior; + + saved_inferior = current_inferior; + current_inferior = thread; + + child->stopped_by_watchpoint + = the_low_target.stopped_by_watchpoint (); + + if (child->stopped_by_watchpoint) + { + if (the_low_target.stopped_data_address != NULL) + child->stopped_data_address + = the_low_target.stopped_data_address (); + else + child->stopped_data_address = 0; + } + + current_inferior = saved_inferior; + } + } + + if (WIFSTOPPED (wstat) && child->must_set_ptrace_flags) + { + linux_enable_event_reporting (lwpid); + child->must_set_ptrace_flags = 0; + } + + if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP + && wstat >> 16 != 0) + { + handle_extended_wait (child, wstat); + return NULL; + } + + 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. */ + } + else if (stopping_threads != NOT_STOPPING_THREADS) + { + /* Stopping threads. We don't want this SIGSTOP to end up + pending in the FILTER_PTID handling below. */ + return NULL; + } + else + { + /* Filter out the event. */ + linux_resume_one_lwp (child, child->stepping, 0, NULL); + return NULL; + } + } + + /* Check if the thread has exited. */ + if ((WIFEXITED (wstat) || WIFSIGNALED (wstat)) + && num_lwps (pid_of (thread)) > 1) + { + if (debug_threads) + debug_printf ("LLW: %d exited.\n", lwpid); + + /* If there is at least one more LWP, then the exit signal + was not the end of the debugged application and should be + ignored. */ + delete_lwp (child); + return NULL; + } + + if (!ptid_match (ptid_of (thread), filter_ptid)) + { + if (debug_threads) + debug_printf ("LWP %d got an event %06x, leaving pending.\n", + lwpid, wstat); + + if (WIFSTOPPED (wstat)) + { + child->status_pending_p = 1; + child->status_pending = wstat; + + if (WSTOPSIG (wstat) != SIGSTOP) + { + /* Cancel breakpoint hits. The breakpoint may be + removed before we fetch events from this process to + report to the core. It is best not to assume the + moribund breakpoints heuristic always handles these + cases --- it could be too many events go through to + the core before this one is handled. All-stop always + cancels breakpoint hits in all threads. */ + if (non_stop + && WSTOPSIG (wstat) == SIGTRAP + && cancel_breakpoint (child)) + { + /* Throw away the SIGTRAP. */ + child->status_pending_p = 0; + + if (debug_threads) + debug_printf ("LLW: LWP %d hit a breakpoint while" + " waiting for another process;" + " cancelled it\n", lwpid); + } + } + } + else if (WIFEXITED (wstat) || WIFSIGNALED (wstat)) + { + if (debug_threads) + debug_printf ("LLWE: process %d exited while fetching " + "event from another LWP\n", lwpid); + + /* This was the last lwp in the process. Since events are + serialized to GDB core, and we can't report this one + right now, but GDB core and the other target layers will + want to be notified about the exit code/signal, leave the + status pending for the next time we're able to report + it. */ + mark_lwp_dead (child, wstat); + } + + return NULL; + } + + return child; +} + /* When the event-loop is doing a step-over, this points at the thread being stepped. */ ptid_t step_over_bkpt; -/* Wait for an event from child PID. If PID is -1, wait for any - child. Store the stop status through the status pointer WSTAT. - OPTIONS is passed to the waitpid call. Return 0 if no child stop - event was found and OPTIONS contains WNOHANG. Return the PID of - the stopped child and update current_inferior otherwise. */ +/* Wait for an event from child(ren) WAIT_PTID, and return any that + match FILTER_PTID (leaving others pending). The PTIDs can be: + minus_one_ptid, to specify any child; a pid PTID, specifying all + lwps of a thread group; or a PTID representing a single lwp. Store + the stop status through the status pointer WSTAT. OPTIONS is + passed to the waitpid call. Return 0 if no event was found and + OPTIONS contains WNOHANG. Return -1 if no unwaited-for children + was found. Return the PID of the stopped child otherwise. */ static int -linux_wait_for_event (ptid_t ptid, int *wstat, int options) +linux_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; - ptid_t wait_ptid; + 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; @@ -1774,18 +1975,18 @@ linux_wait_for_event (ptid_t ptid, int *wstat, int options) /* Check for a lwp with a pending status. */ - if (ptid_equal (ptid, minus_one_ptid) || ptid_is_pid (ptid)) + if (ptid_equal (filter_ptid, minus_one_ptid) || ptid_is_pid (filter_ptid)) { event_thread = (struct thread_info *) - find_inferior (&all_threads, status_pending_p_callback, &ptid); + find_inferior (&all_threads, status_pending_p_callback, &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 + else if (!ptid_equal (filter_ptid, null_ptid)) { - requested_child = find_lwp_pid (ptid); + requested_child = find_lwp_pid (filter_ptid); if (stopping_threads == NOT_STOPPING_THREADS && requested_child->status_pending_p @@ -1814,146 +2015,142 @@ linux_wait_for_event (ptid_t ptid, int *wstat, int options) if (debug_threads) debug_printf ("Got an event from pending child %ld (%04x)\n", lwpid_of (event_thread), event_child->status_pending); - *wstat = event_child->status_pending; + *wstatp = event_child->status_pending; event_child->status_pending_p = 0; event_child->status_pending = 0; current_inferior = event_thread; return lwpid_of (event_thread); } - if (ptid_is_pid (ptid)) - { - /* A request to wait for a specific tgid. This is not possible - with waitpid, so instead, we wait for any child, and leave - children we're not interested in right now with a pending - status to report later. */ - wait_ptid = minus_one_ptid; - } - else - wait_ptid = ptid; + /* 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); + sigprocmask (SIG_BLOCK, &block_mask, &prev_mask); - /* 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. */ - while (1) + while (event_child == NULL) { - event_child = linux_wait_for_lwp (wait_ptid, wstat, options); + pid_t ret = 0; - if ((options & WNOHANG) && event_child == NULL) - { - if (debug_threads) - debug_printf ("WNOHANG set, no event found\n"); - return 0; - } + /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace + quirks: - if (event_child == NULL) - error ("event from unknown child"); + - 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. - event_thread = get_lwp_thread (event_child); - if (ptid_is_pid (ptid) - && ptid_get_pid (ptid) != ptid_get_pid (ptid_of (event_thread))) - { - if (! WIFSTOPPED (*wstat)) - mark_lwp_dead (event_child, *wstat); - else - { - event_child->status_pending_p = 1; - event_child->status_pending = *wstat; - } - continue; - } + - 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 (although we don't currently enable exec + events). */ + errno = 0; + ret = my_waitpid (-1, wstatp, options | WNOHANG); - current_inferior = event_thread; + if (debug_threads) + debug_printf ("LWFE: waitpid(-1, ...) returned %d, %s\n", + ret, errno ? strerror (errno) : "ERRNO-OK"); - /* Check for thread exit. */ - if (! WIFSTOPPED (*wstat)) + if (ret > 0) { if (debug_threads) - debug_printf ("LWP %ld exiting\n", lwpid_of (event_thread)); - - /* If the last thread is exiting, just return. */ - if (last_thread_of_process_p (current_inferior)) - { - if (debug_threads) - debug_printf ("LWP %ld is last lwp of process\n", - lwpid_of (event_thread)); - return lwpid_of (event_thread); - } - - if (!non_stop) - { - current_inferior = get_first_thread (); - if (debug_threads) - debug_printf ("Current inferior is now %ld\n", - lwpid_of (current_inferior)); - } - else { - current_inferior = NULL; - if (debug_threads) - debug_printf ("Current inferior is now <NULL>\n"); + debug_printf ("LLW: waitpid %ld received %s\n", + (long) ret, status_to_str (*wstatp)); } - /* If we were waiting for this particular child to do something... - well, it did something. */ - if (requested_child != NULL) + event_child = linux_low_filter_event (filter_ptid, + ret, *wstatp); + if (event_child != NULL) { - int lwpid = lwpid_of (event_thread); - - /* Cancel the step-over operation --- the thread that - started it is gone. */ - if (finish_step_over (event_child)) - unstop_all_lwps (1, event_child); - delete_lwp (event_child); - return lwpid; + /* We got an event to report to the core. */ + event_thread = get_lwp_thread (event_child); + break; } - delete_lwp (event_child); - - /* Wait for a more interesting event. */ + /* Retry until nothing comes out of waitpid. A single + SIGCHLD can indicate more than one child stopped. */ continue; } - if (event_child->must_set_ptrace_flags) + /* Check for zombie thread group leaders. Those can't be reaped + until all other threads in the thread group are. */ + check_zombie_leaders (); + + /* 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_inferior (&all_threads, + not_stopped_callback, + &wait_ptid) == NULL)) { - linux_enable_event_reporting (lwpid_of (event_thread)); - event_child->must_set_ptrace_flags = 0; + if (debug_threads) + debug_printf ("LLW: exit (no unwaited-for LWP)\n"); + sigprocmask (SIG_SETMASK, &prev_mask, NULL); + return -1; } - if (WIFSTOPPED (*wstat) && WSTOPSIG (*wstat) == SIGTRAP - && *wstat >> 16 != 0) + /* No interesting event to report to the caller. */ + if ((options & WNOHANG)) { - handle_extended_wait (event_child, *wstat); - continue; + if (debug_threads) + debug_printf ("WNOHANG set, no event found\n"); + + sigprocmask (SIG_SETMASK, &prev_mask, NULL); + return 0; } - if (WIFSTOPPED (*wstat) - && WSTOPSIG (*wstat) == SIGSTOP - && event_child->stop_expected) - { - int should_stop; + /* Block until we get an event reported with SIGCHLD. */ + if (debug_threads) + debug_printf ("sigsuspend'ing\n"); - if (debug_threads) - debug_printf ("Expected stop.\n"); - event_child->stop_expected = 0; + sigsuspend (&prev_mask); + sigprocmask (SIG_SETMASK, &prev_mask, NULL); + goto retry; + } - should_stop = (current_inferior->last_resume_kind == resume_stop - || stopping_threads != NOT_STOPPING_THREADS); + sigprocmask (SIG_SETMASK, &prev_mask, NULL); - if (!should_stop) - { - linux_resume_one_lwp (event_child, - event_child->stepping, 0, NULL); - continue; - } - } + current_inferior = event_thread; + + /* Check for thread exit. */ + if (! WIFSTOPPED (*wstatp)) + { + gdb_assert (last_thread_of_process_p (pid_of (event_thread))); + if (debug_threads) + debug_printf ("LWP %d is the last lwp of process. " + "Process %ld exiting.\n", + pid_of (event_thread), lwpid_of (event_thread)); return lwpid_of (event_thread); } - /* NOTREACHED */ - return 0; + return lwpid_of (event_thread); +} + +/* Wait for an event from child(ren) PTID. PTIDs can be: + minus_one_ptid, to specify any child; a pid PTID, specifying all + lwps of a thread group; or a PTID representing a single lwp. Store + the stop status through the status pointer WSTAT. OPTIONS is + passed to the waitpid call. Return 0 if no event was found and + OPTIONS contains WNOHANG. Return -1 if no unwaited-for children + was found. Return the PID of the stopped child otherwise. */ + +static int +linux_wait_for_event (ptid_t ptid, int *wstatp, int options) +{ + return linux_wait_for_event_filtered (ptid, ptid, wstatp, options); } /* Count the LWP's that have had events. */ @@ -2322,70 +2519,69 @@ retry: pid = linux_wait_for_event (step_over_bkpt, &w, options & ~WNOHANG); } - if (pid == 0) /* only if TARGET_WNOHANG */ + if (pid == 0) { + gdb_assert (target_options & TARGET_WNOHANG); + if (debug_threads) { - debug_printf ("linux_wait_1 ret = null_ptid\n"); + debug_printf ("linux_wait_1 ret = null_ptid, " + "TARGET_WAITKIND_IGNORE\n"); debug_exit (); } + + ourstatus->kind = TARGET_WAITKIND_IGNORE; return null_ptid; } + else if (pid == -1) + { + if (debug_threads) + { + debug_printf ("linux_wait_1 ret = null_ptid, " + "TARGET_WAITKIND_NO_RESUMED\n"); + debug_exit (); + } - event_child = get_thread_lwp (current_inferior); - - /* If we are waiting for a particular child, and it exited, - linux_wait_for_event will return its exit status. Similarly if - the last child exited. If this is not the last child, however, - do not report it as exited until there is a 'thread exited' response - available in the remote protocol. Instead, just wait for another event. - This should be safe, because if the thread crashed we will already - have reported the termination signal to GDB; that should stop any - in-progress stepping operations, etc. + ourstatus->kind = TARGET_WAITKIND_NO_RESUMED; + return null_ptid; + } - Report the exit status of the last thread to exit. This matches - LinuxThreads' behavior. */ + event_child = get_thread_lwp (current_inferior); - if (last_thread_of_process_p (current_inferior)) + /* linux_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) || WIFSIGNALED (w)) + if (WIFEXITED (w)) { - if (WIFEXITED (w)) - { - ourstatus->kind = TARGET_WAITKIND_EXITED; - ourstatus->value.integer = WEXITSTATUS (w); + ourstatus->kind = TARGET_WAITKIND_EXITED; + ourstatus->value.integer = WEXITSTATUS (w); - if (debug_threads) - { - debug_printf ("linux_wait_1 ret = %s, exited with " - "retcode %d\n", - target_pid_to_str (ptid_of (current_inferior)), - WEXITSTATUS (w)); - debug_exit (); - } - } - else + if (debug_threads) { - ourstatus->kind = TARGET_WAITKIND_SIGNALLED; - ourstatus->value.sig = gdb_signal_from_host (WTERMSIG (w)); - - if (debug_threads) - { - debug_printf ("linux_wait_1 ret = %s, terminated with " - "signal %d\n", - target_pid_to_str (ptid_of (current_inferior)), - WTERMSIG (w)); - debug_exit (); - } + debug_printf ("linux_wait_1 ret = %s, exited with " + "retcode %d\n", + target_pid_to_str (ptid_of (current_inferior)), + WEXITSTATUS (w)); + debug_exit (); } + } + else + { + ourstatus->kind = TARGET_WAITKIND_SIGNALLED; + ourstatus->value.sig = gdb_signal_from_host (WTERMSIG (w)); - return ptid_of (current_inferior); + if (debug_threads) + { + debug_printf ("linux_wait_1 ret = %s, terminated with " + "signal %d\n", + target_pid_to_str (ptid_of (current_inferior)), + WTERMSIG (w)); + debug_exit (); + } } - } - else - { - if (!WIFSTOPPED (w)) - goto retry; + + return ptid_of (current_inferior); } /* If this event was not handled before, and is not a SIGTRAP, we @@ -2929,24 +3125,15 @@ mark_lwp_dead (struct lwp_info *lwp, int wstat) lwp->stop_expected = 0; } +/* Wait for all children to stop for the SIGSTOPs we just queued. */ + static void -wait_for_sigstop (struct inferior_list_entry *entry) +wait_for_sigstop (void) { - struct thread_info *thread = (struct thread_info *) entry; - struct lwp_info *lwp = get_thread_lwp (thread); struct thread_info *saved_inferior; - int wstat; ptid_t saved_tid; - ptid_t ptid; - int pid; - - if (lwp->stopped) - { - if (debug_threads) - debug_printf ("wait_for_sigstop: LWP %ld already stopped\n", - lwpid_of (thread)); - return; - } + int wstat; + int ret; saved_inferior = current_inferior; if (saved_inferior != NULL) @@ -2954,50 +3141,15 @@ wait_for_sigstop (struct inferior_list_entry *entry) else saved_tid = null_ptid; /* avoid bogus unused warning */ - ptid = thread->entry.id; - if (debug_threads) - debug_printf ("wait_for_sigstop: pulling one event\n"); + debug_printf ("wait_for_sigstop: pulling events\n"); - pid = linux_wait_for_event (ptid, &wstat, __WALL); - - /* If we stopped with a non-SIGSTOP signal, save it for later - and record the pending SIGSTOP. If the process exited, just - return. */ - if (WIFSTOPPED (wstat)) - { - if (debug_threads) - debug_printf ("LWP %ld stopped with signal %d\n", - lwpid_of (thread), WSTOPSIG (wstat)); - - if (WSTOPSIG (wstat) != SIGSTOP) - { - if (debug_threads) - debug_printf ("LWP %ld stopped with non-sigstop status %06x\n", - lwpid_of (thread), wstat); - - lwp->status_pending_p = 1; - lwp->status_pending = wstat; - } - } - else - { - if (debug_threads) - debug_printf ("Process %d exited while stopping LWPs\n", pid); - - lwp = find_lwp_pid (pid_to_ptid (pid)); - if (lwp) - { - /* Leave this status pending for the next time we're able to - report it. In the mean time, we'll report this lwp as - dead to GDB, so GDB doesn't try to read registers and - memory from it. This can only happen if this was the - last thread of the process; otherwise, PID is removed - from the thread tables before linux_wait_for_event - returns. */ - mark_lwp_dead (lwp, wstat); - } - } + /* 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 = linux_wait_for_event_filtered (minus_one_ptid, null_ptid, + &wstat, __WALL); + gdb_assert (ret == -1); if (saved_inferior == NULL || linux_thread_alive (saved_tid)) current_inferior = saved_inferior; @@ -3124,7 +3276,7 @@ stop_all_lwps (int suspend, struct lwp_info *except) find_inferior (&all_threads, suspend_and_send_sigstop_callback, except); else find_inferior (&all_threads, send_sigstop_callback, except); - for_each_inferior (&all_threads, wait_for_sigstop); + wait_for_sigstop (); stopping_threads = NOT_STOPPING_THREADS; if (debug_threads) diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c index 115aca4..9868af6 100644 --- a/gdb/gdbserver/server.c +++ b/gdb/gdbserver/server.c @@ -2367,8 +2367,18 @@ resume (struct thread_resume *actions, size_t num_actions) { last_ptid = mywait (minus_one_ptid, &last_status, 0, 1); + if (last_status.kind == TARGET_WAITKIND_NO_RESUMED) + { + /* No proper RSP support for this yet. At least return + error. */ + sprintf (own_buf, "E.No unwaited-for children left."); + disable_async_io (); + return; + } + if (last_status.kind != TARGET_WAITKIND_EXITED - && last_status.kind != TARGET_WAITKIND_SIGNALLED) + && last_status.kind != TARGET_WAITKIND_SIGNALLED + && last_status.kind != TARGET_WAITKIND_NO_RESUMED) current_inferior->last_status = last_status; /* From the client's perspective, all-stop mode always stops all @@ -3897,7 +3907,11 @@ handle_target_event (int err, gdb_client_data client_data) last_ptid = mywait (minus_one_ptid, &last_status, TARGET_WNOHANG, 1); - if (last_status.kind != TARGET_WAITKIND_IGNORE) + if (last_status.kind == TARGET_WAITKIND_NO_RESUMED) + { + /* No RSP support for this yet. */ + } + else if (last_status.kind != TARGET_WAITKIND_IGNORE) { int pid = ptid_get_pid (last_ptid); struct process_info *process = find_process_pid (pid); |