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Diffstat (limited to 'gdb/lin-lwp.c')
| -rw-r--r-- | gdb/lin-lwp.c | 1048 |
1 files changed, 1048 insertions, 0 deletions
diff --git a/gdb/lin-lwp.c b/gdb/lin-lwp.c new file mode 100644 index 0000000..3b0812e --- /dev/null +++ b/gdb/lin-lwp.c @@ -0,0 +1,1048 @@ +/* Multi-threaded debugging support for Linux (LWP layer). + Copyright 2000 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 2 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, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include "defs.h" + +#include "gdb_assert.h" +#include <errno.h> +#include <signal.h> +#include <sys/ptrace.h> +#include "gdb_wait.h" + +#include "gdbthread.h" +#include "inferior.h" +#include "target.h" + +#define DEBUG 1 + +#if DEBUG +extern const char *strsignal (int sig); +#endif + +/* On Linux there are no real LWP's. The closest thing to LWP's are + processes sharing the same VM space. A multi-threaded process is + basically a group of such processes. However, such a grouping is + almost entirely a user-space issue; the kernel doesn't enforce such + a grouping at all (this might change in the future). In general, + we'll rely on the threads library (i.e. the LinuxThreads library) + to provide such a grouping. + + It is perfectly well possible to write a multi-threaded application + without the assistance of a threads library, by using the clone + system call directly. This module should be able to give some + rudimentary support for debugging such applications if developers + specify the CLONE_PTRACE flag in the clone system call, and are + using Linux 2.4 or above. + + Note that there are some peculiarities in Linux that affect this + code: + + - In general one should specify the __WCLONE flag to waitpid in + order to make it report events for any of the cloned processes. + However, if a cloned process has exited the exit status is only + reported if the __WCLONE flag is absent. + + - When a traced, cloned process exits and is waited for by the + debugger, the kernel reassigns it to the origional parent and + keeps it around as a "zombie". Somehow, the LinuxThreads library + doesn't notice this, which leads to the "zombie problem": When + debugged a multi-threaded process that spawns a lot of threads + will run out of processes, even if the threads exit, because the + "zombies" stay around. */ + +/* Structure describing a LWP. */ +struct lwp_info +{ + /* The process id of the LWP. This is a combination of the LWP id + and overall process id. */ + int pid; + + /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report + it back yet). */ + int signalled; + + /* Non-zero if this LWP is stopped. */ + int stopped; + + /* If non-zero, a pending wait status. */ + int status; + + /* Non-zero if we were stepping this LWP. */ + int step; + + /* Next LWP in list. */ + struct lwp_info *next; +}; + +/* List of known LWPs. */ +static struct lwp_info *lwp_list; + +/* Number of LWPs in the list. */ +static int num_lwps; + +/* Non-zero if we're running in "threaded" mode. */ +static int threaded; + + +#ifndef TIDGET +#define TIDGET(PID) (((PID) & 0x7fffffff) >> 16) +#define PIDGET(PID) (((PID) & 0xffff)) +#define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16)) +#endif + +#define THREAD_FLAG 0x80000000 +#define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid)) +#define GET_LWP(pid) TIDGET (pid) +#define GET_PID(pid) PIDGET (pid) +#define BUILD_LWP(tid, pid) MERGEPID (pid, tid) + +#define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid)) + +/* If the last reported event was a SIGTRAP, this variable is set to + the process id of the LWP/thread that got it. */ +int trap_pid; + + +/* This module's target-specific operations. */ +static struct target_ops lin_lwp_ops; + +/* The standard child operations. */ +extern struct target_ops child_ops; + +/* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in + _initialize_lin_lwp. */ +static sigset_t suspend_mask; + + +/* Prototypes for local functions. */ +static void lin_lwp_mourn_inferior (void); + + +/* Initialize the list of LWPs. */ + +static void +init_lwp_list (void) +{ + struct lwp_info *lp, *lpnext; + + for (lp = lwp_list; lp; lp = lpnext) + { + lpnext = lp->next; + free (lp); + } + + lwp_list = NULL; + num_lwps = 0; + threaded = 0; +} + +/* Add the LWP specified by PID to the list. If this causes the + number of LWPs to become larger than one, go into "threaded" mode. + Return a pointer to the structure describing the new LWP. */ + +static struct lwp_info * +add_lwp (int pid) +{ + struct lwp_info *lp; + + gdb_assert (is_lwp (pid)); + + lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info)); + + memset (lp, 0, sizeof (struct lwp_info)); + + lp->pid = pid; + + lp->next = lwp_list; + lwp_list = lp; + if (++num_lwps > 1) + threaded = 1; + + return lp; +} + +/* Remove the LWP specified by PID from the list. */ + +static void +delete_lwp (int pid) +{ + struct lwp_info *lp, *lpprev; + + lpprev = NULL; + + for (lp = lwp_list; lp; lpprev = lp, lp = lp->next) + if (lp->pid == pid) + break; + + if (!lp) + return; + + /* We don't go back to "non-threaded" mode if the number of threads + becomes less than two. */ + num_lwps--; + + if (lpprev) + lpprev->next = lp->next; + else + lwp_list = lp->next; + + free (lp); +} + +/* Return a pointer to the structure describing the LWP corresponding + to PID. If no corresponding LWP could be found, return NULL. */ + +static struct lwp_info * +find_lwp_pid (int pid) +{ + struct lwp_info *lp; + + if (is_lwp (pid)) + pid = GET_LWP (pid); + + for (lp = lwp_list; lp; lp = lp->next) + if (pid == GET_LWP (lp->pid)) + return lp; + + return NULL; +} + +/* Call CALLBACK with its second argument set to DATA for every LWP in + the list. If CALLBACK returns 1 for a particular LWP, return a + pointer to the structure describing that LWP immediately. + Otherwise return NULL. */ + +struct lwp_info * +iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data) +{ + struct lwp_info *lp; + + for (lp = lwp_list; lp; lp = lp->next) + if ((*callback) (lp, data)) + return lp; + + return NULL; +} + + +/* Helper functions. */ + +static void +restore_inferior_pid (void *arg) +{ + int *saved_pid_ptr = arg; + inferior_pid = *saved_pid_ptr; + free (arg); +} + +static struct cleanup * +save_inferior_pid (void) +{ + int *saved_pid_ptr; + + saved_pid_ptr = xmalloc (sizeof (int)); + *saved_pid_ptr = inferior_pid; + return make_cleanup (restore_inferior_pid, saved_pid_ptr); +} + + +/* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP layer. */ + +int +lin_lwp_prepare_to_proceed (void) +{ + if (trap_pid && inferior_pid != trap_pid) + { + /* Switched over from TRAP_PID. */ + CORE_ADDR stop_pc = read_pc (); + CORE_ADDR trap_pc; + + /* Avoid switching where it wouldn't do any good, i.e. if both + threads are at the same breakpoint. */ + trap_pc = read_pc_pid (trap_pid); + if (trap_pc != stop_pc && breakpoint_here_p (trap_pc)) + { + /* User hasn't deleted the breakpoint. Return non-zero, and + switch back to TRAP_PID. */ + inferior_pid = trap_pid; + + /* FIXME: Is this stuff really necessary? */ + flush_cached_frames (); + registers_changed (); + + return 1; + } + } + + return 0; +} + + +#if 0 +static void +lin_lwp_open (char *args, int from_tty) +{ + push_target (&lin_lwp_ops); +} +#endif + +/* Attach to the LWP specified by PID. If VERBOSE is non-zero, print + a message telling the user that a new LWP has been added to the + process. */ + +void +lin_lwp_attach_lwp (int pid, int verbose) +{ + struct lwp_info *lp; + + gdb_assert (is_lwp (pid)); + + if (verbose) + printf_filtered ("[New %s]\n", target_pid_to_str (pid)); + + if (ptrace (PTRACE_ATTACH, GET_LWP (pid), 0, 0) < 0) + error ("Can't attach %s: %s", target_pid_to_str (pid), strerror (errno)); + + lp = add_lwp (pid); + lp->signalled = 1; +} + +static void +lin_lwp_attach (char *args, int from_tty) +{ + /* FIXME: We should probably accept a list of process id's, and + attach all of them. */ + error("Not implemented yet"); +} + +static void +lin_lwp_detach (char *args, int from_tty) +{ + /* FIXME: Provide implementation when we implement lin_lwp_attach. */ + error ("Not implemented yet"); +} + + +struct private_thread_info +{ + int lwpid; +}; + +/* Return non-zero if TP corresponds to the LWP specified by DATA + (which is assumed to be a pointer to a `struct lwp_info'. */ + +static int +find_lwp_callback (struct thread_info *tp, void *data) +{ + struct lwp_info *lp = data; + + if (tp->private->lwpid == GET_LWP (lp->pid)) + return 1; + + return 0; +} + +/* Resume LP. */ + +static int +resume_callback (struct lwp_info *lp, void *data) +{ + if (lp->stopped && lp->status == 0) + { + struct thread_info *tp; + +#if 1 + /* FIXME: kettenis/2000-08-26: This should really be handled + properly by core GDB. */ + + tp = find_thread_pid (lp->pid); + if (tp == NULL) + tp = iterate_over_threads (find_lwp_callback, lp); + gdb_assert (tp); + + /* If we were previously stepping the thread, and now continue + the thread we must invalidate the stepping range. However, + if there is a step_resume breakpoint for this thread, we must + preserve the stepping range to make it possible to continue + stepping once we hit it. */ + if (tp->step_range_end && tp->step_resume_breakpoint == NULL) + { + gdb_assert (lp->step); + tp->step_range_start = tp->step_range_end = 0; + } +#endif + + child_resume (GET_LWP (lp->pid), 0, TARGET_SIGNAL_0); + lp->stopped = 0; + lp->step = 0; + } + + return 0; +} + +static void +lin_lwp_resume (int pid, int step, enum target_signal signo) +{ + struct lwp_info *lp; + int resume_all; + + /* Apparently the interpretation of PID is dependent on STEP: If + STEP is non-zero, a specific PID means `step only this process + id'. But if STEP is zero, then PID means `continue *all* + processes, but give the signal only to this one'. */ + resume_all = (pid == -1) || !step; + + /* If PID is -1, it's the current inferior that should be + handled special. */ + if (pid == -1) + pid = inferior_pid; + + lp = find_lwp_pid (pid); + if (lp) + { + pid = GET_LWP (lp->pid); + + /* Mark LWP as not stopped to prevent it from being continued by + resume_callback. */ + lp->stopped = 0; + + /* Remember if we're stepping. */ + lp->step = step; + + /* If we have a pending wait status for this thread, there is no + point in resuming the process. */ + if (lp->status) + { + /* FIXME: What should we do if we are supposed to continue + this thread with a signal? */ + gdb_assert (signo == TARGET_SIGNAL_0); + return; + } + } + + if (resume_all) + iterate_over_lwps (resume_callback, NULL); + + child_resume (pid, step, signo); +} + + +/* Send a SIGSTOP to LP. */ + +static int +stop_callback (struct lwp_info *lp, void *data) +{ + if (! lp->stopped && ! lp->signalled) + { + int ret; + + ret = kill (GET_LWP (lp->pid), SIGSTOP); + gdb_assert (ret == 0); + + lp->signalled = 1; + gdb_assert (lp->status == 0); + } + + return 0; +} + +/* Wait until LP is stopped. */ + +static int +stop_wait_callback (struct lwp_info *lp, void *data) +{ + if (! lp->stopped && lp->signalled) + { + pid_t pid; + int status; + + gdb_assert (lp->status == 0); + + pid = waitpid (GET_LWP (lp->pid), &status, + is_cloned (lp->pid) ? __WCLONE : 0); + if (pid == -1 && errno == ECHILD) + /* OK, the proccess has disappeared. We'll catch the actual + exit event in lin_lwp_wait. */ + return 0; + + gdb_assert (pid == GET_LWP (lp->pid)); + + if (WIFEXITED (status) || WIFSIGNALED (status)) + { + gdb_assert (num_lwps > 1); + gdb_assert (! is_cloned (lp->pid)); + + gdb_assert (in_thread_list (lp->pid)); + if (lp->pid != inferior_pid) + delete_thread (lp->pid); + printf_unfiltered ("[%s exited]\n", + target_pid_to_str (lp->pid)); + + delete_lwp (lp->pid); + return 0; + } + + gdb_assert (WIFSTOPPED (status)); + lp->stopped = 1; + + if (WSTOPSIG (status) != SIGSTOP) + { + if (WSTOPSIG (status) == SIGTRAP + && breakpoint_inserted_here_p (read_pc_pid (pid) + - DECR_PC_AFTER_BREAK)) + { + /* If a LWP other than the LWP that we're reporting an + event for has hit a GDB breakpoint (as opposed to + some random trap signal), then just arrange for it to + hit it again later. We don't keep the SIGTRAP status + and don't forward the SIGTRAP signal to the LWP. We + will handle the current event, eventually we will + resume all LWPs, and this one will get its breakpoint + trap again. + + If we do not do this, then we run the risk that the + user will delete or disable the breakpoint, but the + thread will have already tripped on it. */ +#if DEBUG + printf ("Tripped breakpoint at %lx in LWP %d" + " while waiting for SIGSTOP.\n", + (long) read_pc_pid (lp->pid), pid); +#endif + /* Set the PC to before the trap. */ + if (DECR_PC_AFTER_BREAK) + write_pc_pid (read_pc_pid (pid) - DECR_PC_AFTER_BREAK, pid); + } + else + { +#if DEBUG + printf ("Received %s in LWP %d while waiting for SIGSTOP.\n", + strsignal (WSTOPSIG (status)), pid); +#endif + /* The thread was stopped with a signal other than + SIGSTOP, and didn't accidentiliy trip a breakpoint. + Record the wait status. */ + lp->status = status; + } + } + else + { + /* We caught the SIGSTOP that we intended to catch, so + there's no SIGSTOP pending. */ + lp->signalled = 0; + } + } + + return 0; +} + +/* Return non-zero if LP has a wait status pending. */ + +static int +status_callback (struct lwp_info *lp, void *data) +{ + return (lp->status != 0); +} + +/* Return non-zero if LP isn't stopped. */ + +static int +running_callback (struct lwp_info *lp, void *data) +{ + return (lp->stopped == 0); +} + +static int +lin_lwp_wait (int pid, struct target_waitstatus *ourstatus) +{ + struct lwp_info *lp = NULL; + int options = 0; + int status = 0; + + retry: + + /* First check if there is a LWP with a wait status pending. */ + if (pid == -1) + { + /* Any LWP will do. */ + lp = iterate_over_lwps (status_callback, NULL); + if (lp) + { +#if DEBUG + printf ("Using pending wait status for LWP %d.\n", + GET_LWP (lp->pid)); +#endif + status = lp->status; + lp->status = 0; + } + + /* But if we don't fine one, we'll have to wait, and check both + cloned and uncloned processes. We start with the cloned + processes. */ + options = __WCLONE | WNOHANG; + } + else if (is_lwp (pid)) + { +#if DEBUG + printf ("Waiting for specific LWP %d.\n", GET_LWP (pid)); +#endif + /* We have a specific LWP to check. */ + lp = find_lwp_pid (GET_LWP (pid)); + gdb_assert (lp); + status = lp->status; + lp->status = 0; +#if DEBUG + if (status) + printf ("Using pending wait status for LWP %d.\n", + GET_LWP (lp->pid)); +#endif + + /* If we have to wait, take into account whether PID is a cloned + process or not. And we have to convert it to something that + the layer beneath us can understand. */ + options = is_cloned (lp->pid) ? __WCLONE : 0; + pid = GET_LWP (pid); + } + + if (status && lp->signalled) + { + /* A pending SIGSTOP may interfere with the normal stream of + events. In a typical case where interference is a problem, + we have a SIGSTOP signal pending for LWP A while + single-stepping it, encounter an event in LWP B, and take the + pending SIGSTOP while trying to stop LWP A. After processing + the event in LWP B, LWP A is continued, and we'll never see + the SIGTRAP associated with the last time we were + single-stepping LWP A. */ + + /* Resume the thread. It should halt immediately returning the + pending SIGSTOP. */ + child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); + lp->stopped = 0; + + /* This should catch the pending SIGSTOP. */ + stop_wait_callback (lp, NULL); + } + + set_sigint_trap (); /* Causes SIGINT to be passed on to the + attached process. */ + set_sigio_trap (); + + while (status == 0) + { + pid_t lwpid; + + lwpid = waitpid (pid, &status, options); + if (lwpid > 0) + { + gdb_assert (pid == -1 || lwpid == pid); + + lp = find_lwp_pid (lwpid); + if (! lp) + { + lp = add_lwp (BUILD_LWP (lwpid, inferior_pid)); + if (threaded) + { + gdb_assert (WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP); + lp->signalled = 1; + + if (! in_thread_list (inferior_pid)) + { + inferior_pid = BUILD_LWP (inferior_pid, inferior_pid); + add_thread (inferior_pid); + } + + add_thread (lp->pid); + printf_unfiltered ("[New %s]\n", + target_pid_to_str (lp->pid)); + } + } + + /* Make sure we don't report a TARGET_WAITKIND_EXITED or + TARGET_WAITKIND_SIGNALLED event if there are still LWP's + left in the process. */ + if ((WIFEXITED (status) || WIFSIGNALED (status)) && num_lwps > 1) + { + if (in_thread_list (lp->pid)) + { + /* Core GDB cannot deal with us deeting the current + thread. */ + if (lp->pid != inferior_pid) + delete_thread (lp->pid); + printf_unfiltered ("[%s exited]\n", + target_pid_to_str (lp->pid)); + } +#if DEBUG + printf ("%s exited.\n", target_pid_to_str (lp->pid)); +#endif + delete_lwp (lp->pid); + + /* Make sure there is at least one thread running. */ + gdb_assert (iterate_over_lwps (running_callback, NULL)); + + /* Discard the event. */ + status = 0; + continue; + } + + /* Make sure we don't report a SIGSTOP that we sent + ourselves in an attempt to stop an LWP. */ + if (lp->signalled && WIFSTOPPED (status) + && WSTOPSIG (status) == SIGSTOP) + { +#if DEBUG + printf ("Delayed SIGSTOP caught for %s.\n", + target_pid_to_str (lp->pid)); +#endif + /* This is a delayed SIGSTOP. */ + lp->signalled = 0; + + child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); + lp->stopped = 0; + + /* Discard the event. */ + status = 0; + continue; + } + + break; + } + + if (pid == -1) + { + /* Alternate between checking cloned and uncloned processes. */ + options ^= __WCLONE; + + /* And suspend every time we have checked both. */ + if (options & __WCLONE) + sigsuspend (&suspend_mask); + } + + /* We shouldn't end up here unless we want to try again. */ + gdb_assert (status == 0); + } + + clear_sigio_trap (); + clear_sigint_trap (); + + gdb_assert (lp); + + /* Don't report signals that GDB isn't interested in, such as + signals that are neither printed nor stopped upon. Stopping all + threads can be a bit time-consuming so if we want decent + performance with heavily multi-threaded programs, especially when + they're using a high frequency timer, we'd better avoid it if we + can. */ + + if (WIFSTOPPED (status)) + { + int signo = target_signal_from_host (WSTOPSIG (status)); + + if (signal_stop_state (signo) == 0 + && signal_print_state (signo) == 0 + && signal_pass_state (signo) == 1) + { + child_resume (GET_LWP (lp->pid), lp->step, signo); + lp->stopped = 0; + status = 0; + goto retry; + } + } + + /* This LWP is stopped now. */ + lp->stopped = 1; + + /* Now stop all other LWP's ... */ + iterate_over_lwps (stop_callback, NULL); + + /* ... and wait until all of them have reported back that they're no + longer running. */ + iterate_over_lwps (stop_wait_callback, NULL); + + /* If we're not running in "threaded" mode, we'll report the bare + process id. */ + + if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP) + trap_pid = (threaded ? lp->pid : GET_LWP (lp->pid)); + else + trap_pid = 0; + + store_waitstatus (ourstatus, status); + return (threaded ? lp->pid : GET_LWP (lp->pid)); +} + +static int +kill_callback (struct lwp_info *lp, void *data) +{ + ptrace (PTRACE_KILL, GET_LWP (lp->pid), 0, 0); + return 0; +} + +static int +kill_wait_callback (struct lwp_info *lp, void *data) +{ + pid_t pid; + + /* We must make sure that there are no pending events (delayed + SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current + program doesn't interfere with any following debugging session. */ + + /* For cloned processes we must check both with __WCLONE and + without, since the exit status of a cloned process isn't reported + with __WCLONE. */ + if (is_cloned (lp->pid)) + { + do + { + pid = waitpid (GET_LWP (lp->pid), NULL, __WCLONE); + } + while (pid == GET_LWP (lp->pid)); + + gdb_assert (pid == -1 && errno == ECHILD); + } + + do + { + pid = waitpid (GET_LWP (lp->pid), NULL, 0); + } + while (pid == GET_LWP (lp->pid)); + + gdb_assert (pid == -1 && errno == ECHILD); + return 0; +} + +static void +lin_lwp_kill (void) +{ + /* Kill all LWP's ... */ + iterate_over_lwps (kill_callback, NULL); + + /* ... and wait until we've flushed all events. */ + iterate_over_lwps (kill_wait_callback, NULL); + + target_mourn_inferior (); +} + +static void +lin_lwp_create_inferior (char *exec_file, char *allargs, char **env) +{ + struct target_ops *target_beneath; + + init_lwp_list (); + +#if 0 + target_beneath = find_target_beneath (&lin_lwp_ops); +#else + target_beneath = &child_ops; +#endif + target_beneath->to_create_inferior (exec_file, allargs, env); +} + +static void +lin_lwp_mourn_inferior (void) +{ + struct target_ops *target_beneath; + + init_lwp_list (); + + trap_pid = 0; + +#if 0 + target_beneath = find_target_beneath (&lin_lwp_ops); +#else + target_beneath = &child_ops; +#endif + target_beneath->to_mourn_inferior (); +} + +static void +lin_lwp_fetch_registers (int regno) +{ + struct cleanup *old_chain = save_inferior_pid (); + + if (is_lwp (inferior_pid)) + inferior_pid = GET_LWP (inferior_pid); + + fetch_inferior_registers (regno); + + do_cleanups (old_chain); +} + +static void +lin_lwp_store_registers (int regno) +{ + struct cleanup *old_chain = save_inferior_pid (); + + if (is_lwp (inferior_pid)) + inferior_pid = GET_LWP (inferior_pid); + + store_inferior_registers (regno); + + do_cleanups (old_chain); +} + +static int +lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write, + struct target_ops *target) +{ + struct cleanup *old_chain = save_inferior_pid (); + int xfer; + + if (is_lwp (inferior_pid)) + inferior_pid = GET_LWP (inferior_pid); + + xfer = child_xfer_memory (memaddr, myaddr, len, write, target); + + do_cleanups (old_chain); + return xfer; +} + +static int +lin_lwp_thread_alive (int pid) +{ + gdb_assert (is_lwp (pid)); + + errno = 0; + ptrace (PTRACE_PEEKUSER, GET_LWP (pid), 0, 0); + if (errno) + return 0; + + return 1; +} + +static char * +lin_lwp_pid_to_str (int pid) +{ + static char buf[64]; + + if (is_lwp (pid)) + { + snprintf (buf, sizeof (buf), "LWP %d", GET_LWP (pid)); + return buf; + } + + return normal_pid_to_str (pid); +} + +static void +init_lin_lwp_ops (void) +{ +#if 0 + lin_lwp_ops.to_open = lin_lwp_open; +#endif + lin_lwp_ops.to_shortname = "lwp-layer"; + lin_lwp_ops.to_longname = "lwp-layer"; + lin_lwp_ops.to_doc = "Low level threads support (LWP layer)"; + lin_lwp_ops.to_attach = lin_lwp_attach; + lin_lwp_ops.to_detach = lin_lwp_detach; + lin_lwp_ops.to_resume = lin_lwp_resume; + lin_lwp_ops.to_wait = lin_lwp_wait; + lin_lwp_ops.to_fetch_registers = lin_lwp_fetch_registers; + lin_lwp_ops.to_store_registers = lin_lwp_store_registers; + lin_lwp_ops.to_xfer_memory = lin_lwp_xfer_memory; + lin_lwp_ops.to_kill = lin_lwp_kill; + lin_lwp_ops.to_create_inferior = lin_lwp_create_inferior; + lin_lwp_ops.to_mourn_inferior = lin_lwp_mourn_inferior; + lin_lwp_ops.to_thread_alive = lin_lwp_thread_alive; + lin_lwp_ops.to_pid_to_str = lin_lwp_pid_to_str; + lin_lwp_ops.to_stratum = thread_stratum; + lin_lwp_ops.to_has_thread_control = tc_schedlock; + lin_lwp_ops.to_magic = OPS_MAGIC; +} + +static void +sigchld_handler (int signo) +{ + /* Do nothing. The only reason for this handler is that it allows + us to use sigsuspend in lin_lwp_wait above to wait for the + arrival of a SIGCHLD. */ +} + +void +_initialize_lin_lwp (void) +{ + struct sigaction action; + sigset_t mask; + + extern void thread_db_init (struct target_ops *); + + init_lin_lwp_ops (); + add_target (&lin_lwp_ops); + thread_db_init (&lin_lwp_ops); + + action.sa_handler = sigchld_handler; + sigemptyset (&action.sa_mask); + action.sa_flags = 0; + sigaction (SIGCHLD, &action, NULL); + + /* We block SIGCHLD throughout this code ... */ + sigemptyset (&mask); + sigaddset (&mask, SIGCHLD); + sigprocmask (SIG_BLOCK, &mask, &suspend_mask); + + /* ... except during a sigsuspend. */ + sigdelset (&suspend_mask, SIGCHLD); +} + + +/* FIXME: kettenis/2000-08-26: The stuff on this page is specific to + the LinuxThreads library and therefore doesn't really belong here. */ + +/* Read variable NAME in the target and return its value if found. + Otherwise return zero. It is assumed that the type of the variable + is `int'. */ + +static int +get_signo (const char *name) +{ + struct minimal_symbol *ms; + int signo; + + ms = lookup_minimal_symbol (name, NULL, NULL); + if (ms == NULL) + return 0; + + if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms), (char *) &signo, + sizeof (signo)) != 0) + return 0; + + return signo; +} + +/* Return the set of signals used by the threads library in *SET. */ + +void +lin_thread_get_thread_signals (sigset_t *set) +{ + int restart; + int cancel; + + sigemptyset (set); + + restart = get_signo ("__pthread_sig_restart"); + if (restart == 0) + return; + + cancel = get_signo ("__pthread_sig_cancel"); + if (cancel == 0) + return; + + sigaddset (set, restart); + sigaddset (set, cancel); +} |