| /* Multi-threaded debugging support for GNU/Linux (LWP layer). |
| Copyright 2000, 2001 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 "gdb_string.h" |
| #include <errno.h> |
| #include <signal.h> |
| #include <sys/ptrace.h> |
| #include "gdb_wait.h" |
| |
| #include "gdbthread.h" |
| #include "inferior.h" |
| #include "target.h" |
| #include "regcache.h" |
| #include "gdbcmd.h" |
| |
| static int debug_lin_lwp; |
| extern const char *strsignal (int sig); |
| |
| /* On GNU/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 GNU/Linux |
| Threads 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 the Linux kernel 2.4 or above. |
| |
| Note that there are some peculiarities in GNU/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 |
| (and leave it out for the initial process). However, if a cloned |
| process has exited the exit status is only reported if the |
| __WCLONE flag is absent. Linux kernel 2.4 has a __WALL flag, but |
| we cannot use it since GDB must work on older systems too. |
| |
| - When a traced, cloned process exits and is waited for by the |
| debugger, the kernel reassigns it to the original parent and |
| keeps it around as a "zombie". Somehow, the GNU/Linux Threads |
| 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. */ |
| ptid_t ptid; |
| |
| /* Non-zero if this LWP is cloned. In this context "cloned" means |
| that the LWP is reporting to its parent using a signal other than |
| SIGCHLD. */ |
| int cloned; |
| |
| /* 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; |
| |
| /* Non-zero if this LWP will be/has been resumed. Note that an LWP |
| can be marked both as stopped and resumed at the same time. This |
| happens if we try to resume an LWP that has a wait status |
| pending. We shouldn't let the LWP run until that wait status has |
| been processed, but we should not report that wait status if GDB |
| didn't try to let the LWP run. */ |
| int resumed; |
| |
| /* 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; |
| |
| |
| #define GET_LWP(ptid) ptid_get_lwp (ptid) |
| #define GET_PID(ptid) ptid_get_pid (ptid) |
| #define is_lwp(ptid) (GET_LWP (ptid) != 0) |
| #define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0) |
| |
| /* If the last reported event was a SIGTRAP, this variable is set to |
| the process id of the LWP/thread that got it. */ |
| ptid_t trap_ptid; |
| |
| |
| /* This module's target-specific operations. */ |
| static struct target_ops lin_lwp_ops; |
| |
| /* The standard child operations. */ |
| extern struct target_ops child_ops; |
| |
| /* Since we cannot wait (in lin_lwp_wait) for the initial process and |
| any cloned processes with a single call to waitpid, we have to use |
| the WNOHANG flag and call waitpid in a loop. To optimize |
| things a bit we use `sigsuspend' to wake us up when a process has |
| something to report (it will send us a SIGCHLD if it has). To make |
| this work we have to juggle with the signal mask. We save the |
| original signal mask such that we can restore it before creating a |
| new process in order to avoid blocking certain signals in the |
| inferior. We then block SIGCHLD during the waitpid/sigsuspend |
| loop. */ |
| |
| /* Original signal mask. */ |
| static sigset_t normal_mask; |
| |
| /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in |
| _initialize_lin_lwp. */ |
| static sigset_t suspend_mask; |
| |
| /* Signals to block to make that sigsuspend work. */ |
| static sigset_t blocked_mask; |
| |
| |
| /* Prototypes for local functions. */ |
| static int stop_wait_callback (struct lwp_info *lp, void *data); |
| |
| /* Convert wait status STATUS to a string. Used for printing debug |
| messages only. */ |
| |
| static char * |
| status_to_str (int status) |
| { |
| static char buf[64]; |
| |
| if (WIFSTOPPED (status)) |
| snprintf (buf, sizeof (buf), "%s (stopped)", |
| strsignal (WSTOPSIG (status))); |
| else if (WIFSIGNALED (status)) |
| snprintf (buf, sizeof (buf), "%s (terminated)", |
| strsignal (WSTOPSIG (status))); |
| else |
| snprintf (buf, sizeof (buf), "%d (exited)", |
| WEXITSTATUS (status)); |
| |
| return buf; |
| } |
| |
| /* Initialize the list of LWPs. Note that this module, contrary to |
| what GDB's generic threads layer does for its thread list, |
| re-initializes the LWP lists whenever we mourn or detach (which |
| doesn't involve mourning) the inferior. */ |
| |
| static void |
| init_lwp_list (void) |
| { |
| struct lwp_info *lp, *lpnext; |
| |
| for (lp = lwp_list; lp; lp = lpnext) |
| { |
| lpnext = lp->next; |
| xfree (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 (ptid_t ptid) |
| { |
| struct lwp_info *lp; |
| |
| gdb_assert (is_lwp (ptid)); |
| |
| lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info)); |
| |
| memset (lp, 0, sizeof (struct lwp_info)); |
| |
| lp->ptid = ptid; |
| |
| 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 (ptid_t ptid) |
| { |
| struct lwp_info *lp, *lpprev; |
| |
| lpprev = NULL; |
| |
| for (lp = lwp_list; lp; lpprev = lp, lp = lp->next) |
| if (ptid_equal (lp->ptid, ptid)) |
| 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; |
| |
| xfree (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 (ptid_t ptid) |
| { |
| struct lwp_info *lp; |
| int lwp; |
| |
| if (is_lwp (ptid)) |
| lwp = GET_LWP (ptid); |
| else |
| lwp = GET_PID (ptid); |
| |
| for (lp = lwp_list; lp; lp = lp->next) |
| if (lwp == GET_LWP (lp->ptid)) |
| 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, *lpnext; |
| |
| for (lp = lwp_list; lp; lp = lpnext) |
| { |
| lpnext = lp->next; |
| if ((*callback) (lp, data)) |
| return lp; |
| } |
| |
| return NULL; |
| } |
| |
| |
| /* Implementation of the PREPARE_TO_PROCEED hook for the GNU/Linux LWP |
| layer. |
| |
| Note that this implementation is potentially redundant now that |
| default_prepare_to_proceed() has been added. |
| |
| FIXME This may not support switching threads after Ctrl-C |
| correctly. The default implementation does support this. */ |
| |
| int |
| lin_lwp_prepare_to_proceed (void) |
| { |
| if (! ptid_equal (trap_ptid, null_ptid) |
| && ! ptid_equal (inferior_ptid, trap_ptid)) |
| { |
| /* 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_ptid); |
| 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_ptid = trap_ptid; |
| |
| /* 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 (ptid_t ptid, int verbose) |
| { |
| struct lwp_info *lp; |
| |
| gdb_assert (is_lwp (ptid)); |
| |
| /* Make sure SIGCHLD is blocked. We don't want SIGCHLD events |
| to interrupt either the ptrace() or waitpid() calls below. */ |
| if (! sigismember (&blocked_mask, SIGCHLD)) |
| { |
| sigaddset (&blocked_mask, SIGCHLD); |
| sigprocmask (SIG_BLOCK, &blocked_mask, NULL); |
| } |
| |
| if (verbose) |
| printf_filtered ("[New %s]\n", target_pid_to_str (ptid)); |
| |
| lp = find_lwp_pid (ptid); |
| if (lp == NULL) |
| lp = add_lwp (ptid); |
| |
| /* We assume that we're already attached to any LWP that has an |
| id equal to the overall process id. */ |
| if (GET_LWP (ptid) != GET_PID (ptid)) |
| { |
| pid_t pid; |
| int status; |
| |
| if (ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0) |
| error ("Can't attach %s: %s", target_pid_to_str (ptid), |
| safe_strerror (errno)); |
| |
| pid = waitpid (GET_LWP (ptid), &status, 0); |
| if (pid == -1 && errno == ECHILD) |
| { |
| /* Try again with __WCLONE to check cloned processes. */ |
| pid = waitpid (GET_LWP (ptid), &status, __WCLONE); |
| lp->cloned = 1; |
| } |
| |
| gdb_assert (pid == GET_LWP (ptid) |
| && WIFSTOPPED (status) && WSTOPSIG (status)); |
| |
| lp->stopped = 1; |
| } |
| else |
| { |
| /* We assume that the LWP representing the original process |
| is already stopped. Mark it as stopped in the data structure |
| that the lin-lwp layer uses to keep track of threads. Note |
| that this won't have already been done since the main thread |
| will have, we assume, been stopped by an attach from a |
| different layer. */ |
| lp->stopped = 1; |
| } |
| } |
| |
| static void |
| lin_lwp_attach (char *args, int from_tty) |
| { |
| struct lwp_info *lp; |
| pid_t pid; |
| int status; |
| |
| /* FIXME: We should probably accept a list of process id's, and |
| attach all of them. */ |
| child_ops.to_attach (args, from_tty); |
| |
| /* Add the initial process as the first LWP to the list. */ |
| lp = add_lwp (BUILD_LWP (GET_PID (inferior_ptid), GET_PID (inferior_ptid))); |
| |
| /* Make sure the initial process is stopped. The user-level threads |
| layer might want to poke around in the inferior, and that won't |
| work if things haven't stabilized yet. */ |
| pid = waitpid (GET_PID (inferior_ptid), &status, 0); |
| if (pid == -1 && errno == ECHILD) |
| { |
| warning ("%s is a cloned process", target_pid_to_str (inferior_ptid)); |
| |
| /* Try again with __WCLONE to check cloned processes. */ |
| pid = waitpid (GET_PID (inferior_ptid), &status, __WCLONE); |
| lp->cloned = 1; |
| } |
| |
| gdb_assert (pid == GET_PID (inferior_ptid) |
| && WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP); |
| |
| lp->stopped = 1; |
| |
| /* Fake the SIGSTOP that core GDB expects. */ |
| lp->status = W_STOPCODE (SIGSTOP); |
| lp->resumed = 1; |
| } |
| |
| static int |
| detach_callback (struct lwp_info *lp, void *data) |
| { |
| gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status)); |
| |
| if (debug_lin_lwp && lp->status) |
| fprintf_unfiltered (gdb_stdlog, "Pending %s for LWP %ld on detach.\n", |
| strsignal (WSTOPSIG (lp->status)), GET_LWP (lp->ptid)); |
| |
| while (lp->signalled && lp->stopped) |
| { |
| if (ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, |
| WSTOPSIG (lp->status)) < 0) |
| error ("Can't continue %s: %s", target_pid_to_str (lp->ptid), |
| safe_strerror (errno)); |
| |
| lp->stopped = 0; |
| lp->signalled = 0; |
| lp->status = 0; |
| stop_wait_callback (lp, NULL); |
| |
| gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status)); |
| } |
| |
| /* We don't actually detach from the LWP that has an id equal to the |
| overall process id just yet. */ |
| if (GET_LWP (lp->ptid) != GET_PID (lp->ptid)) |
| { |
| if (ptrace (PTRACE_DETACH, GET_LWP (lp->ptid), 0, |
| WSTOPSIG (lp->status)) < 0) |
| error ("Can't detach %s: %s", target_pid_to_str (lp->ptid), |
| safe_strerror (errno)); |
| |
| delete_lwp (lp->ptid); |
| } |
| |
| return 0; |
| } |
| |
| static void |
| lin_lwp_detach (char *args, int from_tty) |
| { |
| iterate_over_lwps (detach_callback, NULL); |
| |
| /* Only the initial process should be left right now. */ |
| gdb_assert (num_lwps == 1); |
| |
| trap_ptid = null_ptid; |
| |
| /* Destroy LWP info; it's no longer valid. */ |
| init_lwp_list (); |
| |
| /* Restore the original signal mask. */ |
| sigprocmask (SIG_SETMASK, &normal_mask, NULL); |
| sigemptyset (&blocked_mask); |
| |
| inferior_ptid = pid_to_ptid (GET_PID (inferior_ptid)); |
| child_ops.to_detach (args, from_tty); |
| } |
| |
| |
| 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->ptid)) |
| 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 0 |
| /* FIXME: kettenis/2000-08-26: This should really be handled |
| properly by core GDB. */ |
| |
| tp = find_thread_pid (lp->ptid); |
| 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 (pid_to_ptid (GET_LWP (lp->ptid)), 0, TARGET_SIGNAL_0); |
| lp->stopped = 0; |
| lp->step = 0; |
| } |
| |
| return 0; |
| } |
| |
| static int |
| resume_clear_callback (struct lwp_info *lp, void *data) |
| { |
| lp->resumed = 0; |
| return 0; |
| } |
| |
| static int |
| resume_set_callback (struct lwp_info *lp, void *data) |
| { |
| lp->resumed = 1; |
| return 0; |
| } |
| |
| static void |
| lin_lwp_resume (ptid_t ptid, 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 = (PIDGET (ptid) == -1) || !step; |
| |
| if (resume_all) |
| iterate_over_lwps (resume_set_callback, NULL); |
| else |
| iterate_over_lwps (resume_clear_callback, NULL); |
| |
| /* If PID is -1, it's the current inferior that should be |
| handled specially. */ |
| if (PIDGET (ptid) == -1) |
| ptid = inferior_ptid; |
| |
| lp = find_lwp_pid (ptid); |
| if (lp) |
| { |
| ptid = pid_to_ptid (GET_LWP (lp->ptid)); |
| |
| /* Remember if we're stepping. */ |
| lp->step = step; |
| |
| /* Mark this LWP as resumed. */ |
| lp->resumed = 1; |
| |
| /* 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; |
| } |
| |
| /* Mark LWP as not stopped to prevent it from being continued by |
| resume_callback. */ |
| lp->stopped = 0; |
| } |
| |
| if (resume_all) |
| iterate_over_lwps (resume_callback, NULL); |
| |
| child_resume (ptid, 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->ptid), SIGSTOP); |
| gdb_assert (ret == 0); |
| |
| lp->signalled = 1; |
| gdb_assert (lp->status == 0); |
| } |
| |
| return 0; |
| } |
| |
| /* Wait until LP is stopped. If DATA is non-null it is interpreted as |
| a pointer to a set of signals to be flushed immediately. */ |
| |
| static int |
| stop_wait_callback (struct lwp_info *lp, void *data) |
| { |
| sigset_t *flush_mask = data; |
| |
| if (! lp->stopped && lp->signalled) |
| { |
| pid_t pid; |
| int status; |
| |
| gdb_assert (lp->status == 0); |
| |
| pid = waitpid (GET_LWP (lp->ptid), &status, lp->cloned ? __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->ptid)); |
| |
| if (WIFEXITED (status) || WIFSIGNALED (status)) |
| { |
| gdb_assert (num_lwps > 1); |
| |
| if (in_thread_list (lp->ptid)) |
| { |
| /* Core GDB cannot deal with us deleting the current |
| thread. */ |
| if (!ptid_equal (lp->ptid, inferior_ptid)) |
| delete_thread (lp->ptid); |
| printf_unfiltered ("[%s exited]\n", |
| target_pid_to_str (lp->ptid)); |
| } |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "%s exited.\n", target_pid_to_str (lp->ptid)); |
| |
| delete_lwp (lp->ptid); |
| return 0; |
| } |
| |
| gdb_assert (WIFSTOPPED (status)); |
| |
| /* Ignore any signals in FLUSH_MASK. */ |
| if (flush_mask && sigismember (flush_mask, WSTOPSIG (status))) |
| { |
| ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0); |
| return stop_wait_callback (lp, flush_mask); |
| } |
| |
| if (WSTOPSIG (status) != SIGSTOP) |
| { |
| if (WSTOPSIG (status) == SIGTRAP) |
| { |
| /* 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. */ |
| |
| /* Now resume this LWP and get the SIGSTOP event. */ |
| ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0); |
| if (debug_lin_lwp) |
| { |
| fprintf_unfiltered (gdb_stderr, |
| "SWC: Candidate SIGTRAP event in %ld\n", |
| GET_LWP (lp->ptid)); |
| } |
| /* Hold the SIGTRAP for handling by lin_lwp_wait. */ |
| stop_wait_callback (lp, data); |
| /* If there's another event, throw it back into the queue. */ |
| if (lp->status) |
| kill (GET_LWP (lp->ptid), WSTOPSIG (lp->status)); |
| /* Save the sigtrap event. */ |
| lp->status = status; |
| return 0; |
| } |
| else |
| { |
| /* The thread was stopped with a signal other than |
| SIGSTOP, and didn't accidentally trip a breakpoint. */ |
| |
| if (debug_lin_lwp) |
| { |
| fprintf_unfiltered (gdb_stderr, |
| "SWC: Pending event %d in %ld\n", |
| WSTOPSIG (status), GET_LWP (lp->ptid)); |
| } |
| /* Now resume this LWP and get the SIGSTOP event. */ |
| ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0); |
| |
| /* Hold this event/waitstatus while we check to see if |
| there are any more (we still want to get that SIGSTOP). */ |
| stop_wait_callback (lp, data); |
| /* If the lp->status field is still empty, use it to hold |
| this event. If not, then this event must be returned |
| to the event queue of the LWP. */ |
| if (lp->status == 0) |
| lp->status = status; |
| else |
| kill (GET_LWP (lp->ptid), WSTOPSIG (status)); |
| return 0; |
| } |
| } |
| else |
| { |
| /* We caught the SIGSTOP that we intended to catch, so |
| there's no SIGSTOP pending. */ |
| lp->stopped = 1; |
| 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) |
| { |
| /* Only report a pending wait status if we pretend that this has |
| indeed been resumed. */ |
| return (lp->status != 0 && lp->resumed); |
| } |
| |
| /* Return non-zero if LP isn't stopped. */ |
| |
| static int |
| running_callback (struct lwp_info *lp, void *data) |
| { |
| return (lp->stopped == 0); |
| } |
| |
| /* Count the LWP's that have had events. */ |
| |
| static int |
| count_events_callback (struct lwp_info *lp, void *data) |
| { |
| int *count = data; |
| |
| gdb_assert (count != NULL); |
| |
| /* Count only LWPs that have a SIGTRAP event pending. */ |
| if (lp->status != 0 |
| && WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP) |
| (*count)++; |
| |
| return 0; |
| } |
| |
| /* Select the LWP (if any) that is currently being single-stepped. */ |
| |
| static int |
| select_singlestep_lwp_callback (struct lwp_info *lp, void *data) |
| { |
| if (lp->step && lp->status != 0) |
| return 1; |
| else |
| return 0; |
| } |
| |
| /* Select the Nth LWP that has had a SIGTRAP event. */ |
| |
| static int |
| select_event_lwp_callback (struct lwp_info *lp, void *data) |
| { |
| int *selector = data; |
| |
| gdb_assert (selector != NULL); |
| |
| /* Select only LWPs that have a SIGTRAP event pending. */ |
| if (lp->status != 0 |
| && WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP) |
| if ((*selector)-- == 0) |
| return 1; |
| |
| return 0; |
| } |
| |
| static int |
| cancel_breakpoints_callback (struct lwp_info *lp, void *data) |
| { |
| struct lwp_info *event_lp = data; |
| |
| /* Leave the LWP that has been elected to receive a SIGTRAP alone. */ |
| if (lp == event_lp) |
| return 0; |
| |
| /* 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 LWP will have already |
| tripped on it. */ |
| |
| if (lp->status != 0 |
| && WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP |
| && breakpoint_inserted_here_p (read_pc_pid (lp->ptid) - |
| DECR_PC_AFTER_BREAK)) |
| { |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "Push back breakpoint for LWP %ld\n", |
| GET_LWP (lp->ptid)); |
| |
| /* Back up the PC if necessary. */ |
| if (DECR_PC_AFTER_BREAK) |
| write_pc_pid (read_pc_pid (lp->ptid) - DECR_PC_AFTER_BREAK, lp->ptid); |
| |
| /* Throw away the SIGTRAP. */ |
| lp->status = 0; |
| } |
| |
| return 0; |
| } |
| |
| /* Select one LWP out of those that have events pending. */ |
| |
| static void |
| select_event_lwp (struct lwp_info **orig_lp, int *status) |
| { |
| int num_events = 0; |
| int random_selector; |
| struct lwp_info *event_lp; |
| |
| /* Record the wait status for the origional LWP. */ |
| (*orig_lp)->status = *status; |
| |
| /* Give preference to any LWP that is being single-stepped. */ |
| event_lp = iterate_over_lwps (select_singlestep_lwp_callback, NULL); |
| if (event_lp != NULL) |
| { |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "Select single-step LWP %ld\n", |
| GET_LWP (event_lp->ptid)); |
| } |
| else |
| { |
| /* No single-stepping LWP. Select one at random, out of those |
| which have had SIGTRAP events. */ |
| |
| /* First see how many SIGTRAP events we have. */ |
| iterate_over_lwps (count_events_callback, &num_events); |
| |
| /* Now randomly pick a LWP out of those that have had a SIGTRAP. */ |
| random_selector = (int) |
| ((num_events * (double) rand ()) / (RAND_MAX + 1.0)); |
| |
| if (debug_lin_lwp && num_events > 1) |
| fprintf_unfiltered (gdb_stdlog, |
| "Found %d SIGTRAP events, selecting #%d\n", |
| num_events, random_selector); |
| |
| event_lp = iterate_over_lwps (select_event_lwp_callback, |
| &random_selector); |
| } |
| |
| if (event_lp != NULL) |
| { |
| /* Switch the event LWP. */ |
| *orig_lp = event_lp; |
| *status = event_lp->status; |
| } |
| |
| /* Flush the wait status for the event LWP. */ |
| (*orig_lp)->status = 0; |
| } |
| |
| /* Return non-zero if LP has been resumed. */ |
| |
| static int |
| resumed_callback (struct lwp_info *lp, void *data) |
| { |
| return lp->resumed; |
| } |
| |
| #ifdef CHILD_WAIT |
| |
| /* We need to override child_wait to support attaching to cloned |
| processes, since a normal wait (as done by the default version) |
| ignores those processes. */ |
| |
| /* Wait for child PTID to do something. Return id of the child, |
| minus_one_ptid in case of error; store status into *OURSTATUS. */ |
| |
| ptid_t |
| child_wait (ptid_t ptid, struct target_waitstatus *ourstatus) |
| { |
| int save_errno; |
| int status; |
| pid_t pid; |
| |
| do |
| { |
| set_sigint_trap (); /* Causes SIGINT to be passed on to the |
| attached process. */ |
| set_sigio_trap (); |
| |
| pid = waitpid (GET_PID (ptid), &status, 0); |
| if (pid == -1 && errno == ECHILD) |
| /* Try again with __WCLONE to check cloned processes. */ |
| pid = waitpid (GET_PID (ptid), &status, __WCLONE); |
| save_errno = errno; |
| |
| clear_sigio_trap (); |
| clear_sigint_trap (); |
| } |
| while (pid == -1 && save_errno == EINTR); |
| |
| if (pid == -1) |
| { |
| warning ("Child process unexpectedly missing: %s", safe_strerror (errno)); |
| |
| /* Claim it exited with unknown signal. */ |
| ourstatus->kind = TARGET_WAITKIND_SIGNALLED; |
| ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN; |
| return minus_one_ptid; |
| } |
| |
| store_waitstatus (ourstatus, status); |
| return pid_to_ptid (pid); |
| } |
| |
| #endif |
| |
| static ptid_t |
| lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus) |
| { |
| struct lwp_info *lp = NULL; |
| int options = 0; |
| int status = 0; |
| pid_t pid = PIDGET (ptid); |
| sigset_t flush_mask; |
| |
| sigemptyset (&flush_mask); |
| |
| /* Make sure SIGCHLD is blocked. */ |
| if (! sigismember (&blocked_mask, SIGCHLD)) |
| { |
| sigaddset (&blocked_mask, SIGCHLD); |
| sigprocmask (SIG_BLOCK, &blocked_mask, NULL); |
| } |
| |
| retry: |
| |
| /* Make sure there is at least one LWP that has been resumed, at |
| least if there are any LWPs at all. */ |
| gdb_assert (num_lwps == 0 || iterate_over_lwps (resumed_callback, NULL)); |
| |
| /* First check if there is a LWP with a wait status pending. */ |
| if (pid == -1) |
| { |
| /* Any LWP that's been resumed will do. */ |
| lp = iterate_over_lwps (status_callback, NULL); |
| if (lp) |
| { |
| status = lp->status; |
| lp->status = 0; |
| |
| if (debug_lin_lwp && status) |
| fprintf_unfiltered (gdb_stdlog, |
| "Using pending wait status %s for LWP %ld.\n", |
| status_to_str (status), GET_LWP (lp->ptid)); |
| } |
| |
| /* 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 (ptid)) |
| { |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "Waiting for specific LWP %ld.\n", |
| GET_LWP (ptid)); |
| |
| /* We have a specific LWP to check. */ |
| lp = find_lwp_pid (ptid); |
| gdb_assert (lp); |
| status = lp->status; |
| lp->status = 0; |
| |
| if (debug_lin_lwp && status) |
| fprintf_unfiltered (gdb_stdlog, |
| "Using pending wait status %s for LWP %ld.\n", |
| status_to_str (status), GET_LWP (lp->ptid)); |
| |
| /* 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 = lp->cloned ? __WCLONE : 0; |
| pid = GET_LWP (ptid); |
| } |
| |
| 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 (pid_to_ptid (GET_LWP (lp->ptid)), lp->step, |
| TARGET_SIGNAL_0); |
| lp->stopped = 0; |
| gdb_assert (lp->resumed); |
| |
| /* 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 (pid_to_ptid (lwpid)); |
| if (! lp) |
| { |
| lp = add_lwp (BUILD_LWP (lwpid, GET_PID (inferior_ptid))); |
| if (options & __WCLONE) |
| lp->cloned = 1; |
| |
| if (threaded) |
| { |
| gdb_assert (WIFSTOPPED (status) |
| && WSTOPSIG (status) == SIGSTOP); |
| lp->signalled = 1; |
| |
| if (! in_thread_list (inferior_ptid)) |
| { |
| inferior_ptid = BUILD_LWP (GET_PID (inferior_ptid), |
| GET_PID (inferior_ptid)); |
| add_thread (inferior_ptid); |
| } |
| |
| add_thread (lp->ptid); |
| printf_unfiltered ("[New %s]\n", |
| target_pid_to_str (lp->ptid)); |
| } |
| } |
| |
| /* 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->ptid)) |
| { |
| /* Core GDB cannot deal with us deleting the current |
| thread. */ |
| if (! ptid_equal (lp->ptid, inferior_ptid)) |
| delete_thread (lp->ptid); |
| printf_unfiltered ("[%s exited]\n", |
| target_pid_to_str (lp->ptid)); |
| } |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "%s exited.\n", |
| target_pid_to_str (lp->ptid)); |
| |
| delete_lwp (lp->ptid); |
| |
| /* 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_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "Delayed SIGSTOP caught for %s.\n", |
| target_pid_to_str (lp->ptid)); |
| |
| /* This is a delayed SIGSTOP. */ |
| lp->signalled = 0; |
| |
| child_resume (pid_to_ptid (GET_LWP (lp->ptid)), lp->step, |
| TARGET_SIGNAL_0); |
| lp->stopped = 0; |
| gdb_assert (lp->resumed); |
| |
| /* 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) |
| { |
| /* FIMXE: kettenis/2001-06-06: Should we resume all threads |
| here? It is not clear we should. GDB may not expect |
| other threads to run. On the other hand, not resuming |
| newly attached threads may cause an unwanted delay in |
| getting them running. */ |
| child_resume (pid_to_ptid (GET_LWP (lp->ptid)), lp->step, signo); |
| lp->stopped = 0; |
| status = 0; |
| goto retry; |
| } |
| |
| if (signo == TARGET_SIGNAL_INT |
| && signal_pass_state (signo) == 0) |
| { |
| /* If ^C/BREAK is typed at the tty/console, SIGINT gets |
| forwarded to the entire process group, that is, all LWP's |
| will receive it. Since we only want to report it once, |
| we try to flush it from all LWPs except this one. */ |
| sigaddset (&flush_mask, SIGINT); |
| } |
| } |
| |
| /* This LWP is stopped now. */ |
| lp->stopped = 1; |
| |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, "Candidate event %s in LWP %ld.\n", |
| status_to_str (status), GET_LWP (lp->ptid)); |
| |
| /* 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, &flush_mask); |
| |
| /* 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 (pid == -1) |
| select_event_lwp (&lp, &status); |
| |
| /* Now that we've selected our final event LWP, cancel any |
| breakpoints in other LWPs that have hit a GDB breakpoint. See |
| the comment in cancel_breakpoints_callback to find out why. */ |
| iterate_over_lwps (cancel_breakpoints_callback, lp); |
| |
| /* If we're not running in "threaded" mode, we'll report the bare |
| process id. */ |
| |
| if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP) |
| { |
| trap_ptid = (threaded ? lp->ptid : pid_to_ptid (GET_LWP (lp->ptid))); |
| if (debug_lin_lwp) |
| fprintf_unfiltered (gdb_stdlog, |
| "LLW: trap_ptid is %ld\n", |
| GET_LWP (trap_ptid)); |
| } |
| else |
| trap_ptid = null_ptid; |
| |
| store_waitstatus (ourstatus, status); |
| return (threaded ? lp->ptid : pid_to_ptid (GET_LWP (lp->ptid))); |
| } |
| |
| static int |
| kill_callback (struct lwp_info *lp, void *data) |
| { |
| ptrace (PTRACE_KILL, GET_LWP (lp->ptid), 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 (lp->cloned) |
| { |
| do |
| { |
| pid = waitpid (GET_LWP (lp->ptid), NULL, __WCLONE); |
| } |
| while (pid == GET_LWP (lp->ptid)); |
| |
| gdb_assert (pid == -1 && errno == ECHILD); |
| } |
| |
| do |
| { |
| pid = waitpid (GET_LWP (lp->ptid), NULL, 0); |
| } |
| while (pid == GET_LWP (lp->ptid)); |
| |
| 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) |
| { |
| child_ops.to_create_inferior (exec_file, allargs, env); |
| } |
| |
| static void |
| lin_lwp_mourn_inferior (void) |
| { |
| trap_ptid = null_ptid; |
| |
| /* Destroy LWP info; it's no longer valid. */ |
| init_lwp_list (); |
| |
| /* Restore the original signal mask. */ |
| sigprocmask (SIG_SETMASK, &normal_mask, NULL); |
| sigemptyset (&blocked_mask); |
| |
| child_ops.to_mourn_inferior (); |
| } |
| |
| static void |
| lin_lwp_fetch_registers (int regno) |
| { |
| struct cleanup *old_chain = save_inferior_ptid (); |
| |
| if (is_lwp (inferior_ptid)) |
| inferior_ptid = pid_to_ptid (GET_LWP (inferior_ptid)); |
| |
| fetch_inferior_registers (regno); |
| |
| do_cleanups (old_chain); |
| } |
| |
| static void |
| lin_lwp_store_registers (int regno) |
| { |
| struct cleanup *old_chain = save_inferior_ptid (); |
| |
| if (is_lwp (inferior_ptid)) |
| inferior_ptid = pid_to_ptid (GET_LWP (inferior_ptid)); |
| |
| store_inferior_registers (regno); |
| |
| do_cleanups (old_chain); |
| } |
| |
| static int |
| lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write, |
| struct mem_attrib *attrib, |
| struct target_ops *target) |
| { |
| struct cleanup *old_chain = save_inferior_ptid (); |
| int xfer; |
| |
| if (is_lwp (inferior_ptid)) |
| inferior_ptid = pid_to_ptid (GET_LWP (inferior_ptid)); |
| |
| xfer = child_xfer_memory (memaddr, myaddr, len, write, attrib, target); |
| |
| do_cleanups (old_chain); |
| return xfer; |
| } |
| |
| static int |
| lin_lwp_thread_alive (ptid_t ptid) |
| { |
| gdb_assert (is_lwp (ptid)); |
| |
| errno = 0; |
| ptrace (PTRACE_PEEKUSER, GET_LWP (ptid), 0, 0); |
| if (errno) |
| return 0; |
| |
| return 1; |
| } |
| |
| static char * |
| lin_lwp_pid_to_str (ptid_t ptid) |
| { |
| static char buf[64]; |
| |
| if (is_lwp (ptid)) |
| { |
| snprintf (buf, sizeof (buf), "LWP %ld", GET_LWP (ptid)); |
| return buf; |
| } |
| |
| return normal_pid_to_str (ptid); |
| } |
| |
| 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; |
| |
| extern void thread_db_init (struct target_ops *); |
| |
| init_lin_lwp_ops (); |
| add_target (&lin_lwp_ops); |
| thread_db_init (&lin_lwp_ops); |
| |
| /* Save the original signal mask. */ |
| sigprocmask (SIG_SETMASK, NULL, &normal_mask); |
| |
| action.sa_handler = sigchld_handler; |
| sigemptyset (&action.sa_mask); |
| action.sa_flags = 0; |
| sigaction (SIGCHLD, &action, NULL); |
| |
| /* Make sure we don't block SIGCHLD during a sigsuspend. */ |
| sigprocmask (SIG_SETMASK, NULL, &suspend_mask); |
| sigdelset (&suspend_mask, SIGCHLD); |
| |
| sigemptyset (&blocked_mask); |
| |
| add_show_from_set (add_set_cmd ("lin-lwp", no_class, var_zinteger, |
| (char *) &debug_lin_lwp, |
| "Set debugging of GNU/Linux lwp module.\n\ |
| Enables printf debugging output.\n", |
| &setdebuglist), |
| &showdebuglist); |
| } |
| |
| |
| /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to |
| the GNU/Linux Threads 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) |
| { |
| struct sigaction action; |
| int restart, 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); |
| |
| /* The GNU/Linux Threads library makes terminating threads send a |
| special "cancel" signal instead of SIGCHLD. Make sure we catch |
| those (to prevent them from terminating GDB itself, which is |
| likely to be their default action) and treat them the same way as |
| SIGCHLD. */ |
| |
| action.sa_handler = sigchld_handler; |
| sigemptyset (&action.sa_mask); |
| action.sa_flags = 0; |
| sigaction (cancel, &action, NULL); |
| |
| /* We block the "cancel" signal throughout this code ... */ |
| sigaddset (&blocked_mask, cancel); |
| sigprocmask (SIG_BLOCK, &blocked_mask, NULL); |
| |
| /* ... except during a sigsuspend. */ |
| sigdelset (&suspend_mask, cancel); |
| } |