/* 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;
static int threaded;
\f
-#ifndef TIDGET
-#define TIDGET(PID) (((PID) & 0x7fffffff) >> 16)
-#define PIDGET0(PID) (((PID) & 0xffff))
-#define PIDGET(PID) ((PIDGET0 (PID) == 0xffff) ? -1 : PIDGET0 (PID))
-#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 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)
#define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
\f
/* Prototypes for local functions. */
-static void lin_lwp_mourn_inferior (void);
+static int stop_wait_callback (struct lwp_info *lp, void *data);
\f
+/* Convert wait status STATUS to a string. Used for printing debug
+ messages only. */
-/* Initialize the list of LWPs. */
+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;
+}
+\f
+/* 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 *
iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data)
{
- struct lwp_info *lp;
+ struct lwp_info *lp, *lpnext;
- for (lp = lwp_list; lp; lp = lp->next)
- if ((*callback) (lp, data))
- return lp;
+ for (lp = lwp_list; lp; lp = lpnext)
+ {
+ lpnext = lp->next;
+ if ((*callback) (lp, data))
+ return lp;
+ }
return NULL;
}
\f
-/* Helper functions. */
-
-static void
-restore_inferior_ptid (void *arg)
-{
- ptid_t *saved_ptid_ptr = arg;
- inferior_ptid = *saved_ptid_ptr;
- xfree (arg);
-}
-
-static struct cleanup *
-save_inferior_ptid (void)
-{
- ptid_t *saved_ptid_ptr;
-
- saved_ptid_ptr = xmalloc (sizeof (ptid_t));
- *saved_ptid_ptr = inferior_ptid;
- return make_cleanup (restore_inferior_ptid, saved_ptid_ptr);
-}
-\f
-
/* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP
layer.
Note that this implementation is potentially redundant now that
- default_prepare_to_proceed() has been added. */
+ 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 (verbose)
printf_filtered ("[New %s]\n", target_pid_to_str (ptid));
- if (ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0)
+ /* We assume that we're already tracing the initial process. */
+ if (is_cloned (ptid) && ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0)
error ("Can't attach %s: %s", target_pid_to_str (ptid), strerror (errno));
- lp = add_lwp (ptid);
- lp->signalled = 1;
+ lp = find_lwp_pid (ptid);
+ if (lp == NULL)
+ lp = add_lwp (ptid);
+
+ if (is_cloned (ptid))
+ {
+ lp->signalled = 1;
+ stop_wait_callback (lp, NULL);
+ }
}
static void
lin_lwp_attach (char *args, int from_tty)
{
+ struct lwp_info *lp;
+
/* FIXME: We should probably accept a list of process id's, and
attach all of them. */
- error("Not implemented yet");
+ child_ops.to_attach (args, from_tty);
+
+ /* Add the initial process as the first LWP to the list. */
+ lp = add_lwp (BUILD_LWP (PIDGET (inferior_ptid), PIDGET (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. */
+ lp->signalled = 1;
+ stop_wait_callback (lp, NULL);
+ gdb_assert (lp->status == 0);
+
+ /* 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),
+ strerror (errno));
+
+ lp->stopped = 0;
+ lp->signalled = 0;
+ lp->status = 0;
+ stop_wait_callback (lp, NULL);
+
+ gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status));
+ }
+
+ if (is_cloned (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),
+ strerror (errno));
+
+ delete_lwp (lp->ptid);
+ }
+
+ return 0;
}
static void
lin_lwp_detach (char *args, int from_tty)
{
- /* FIXME: Provide implementation when we implement lin_lwp_attach. */
- error ("Not implemented yet");
+ iterate_over_lwps (detach_callback, NULL);
+
+ /* Only the initial (uncloned) 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);
}
\f
{
struct thread_info *tp;
-#if 1
+#if 0
/* FIXME: kettenis/2000-08-26: This should really be handled
properly by core GDB. */
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)
{
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 special. */
+ handled specially. */
if (PIDGET (ptid) == -1)
ptid = inferior_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)
}
gdb_assert (WIFSTOPPED (status));
- lp->stopped = 1;
if (WSTOPSIG (status) != SIGSTOP)
{
- if (WSTOPSIG (status) == SIGTRAP
- && breakpoint_inserted_here_p (read_pc_pid (pid_to_ptid (pid))
- - DECR_PC_AFTER_BREAK))
+ 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
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_stdlog,
- "Tripped breakpoint at %lx in LWP %d"
- " while waiting for SIGSTOP.\n",
- (long) read_pc_pid (lp->ptid), pid);
-
- /* Set the PC to before the trap. */
- if (DECR_PC_AFTER_BREAK)
- write_pc_pid (read_pc_pid (pid_to_ptid (pid))
- - DECR_PC_AFTER_BREAK,
- pid_to_ptid (pid));
+ {
+ 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 if (WSTOPSIG (status) == SIGINT &&
+ signal_pass_state (SIGINT) == 0)
+ {
+ /* Since SIGINT gets forwarded to the entire process group
+ (in the case where ^C/BREAK is typed at the tty/console),
+ just ignore all SIGINT events from all lwp's except for
+ the one that was caught by lin_lwp_wait. */
+
+ /* Now resume this LWP and get the SIGSTOP event. */
+ ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
+ return stop_wait_callback (lp, data);
}
else
{
- if (debug_lin_lwp)
- fprintf_unfiltered (gdb_stdlog,
- "Received %s in LWP %d while waiting for SIGSTOP.\n",
- strsignal (WSTOPSIG (status)), pid);
-
/* The thread was stopped with a signal other than
- SIGSTOP, and didn't accidentiliy trip a breakpoint.
- Record the wait status. */
- lp->status = status;
+ 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;
}
}
static int
status_callback (struct lwp_info *lp, void *data)
{
- return (lp->status != 0);
+ /* 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. */
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;
+}
+
static ptid_t
lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
retry:
+ /* Make sure there is at least one thread that has been resumed. */
+ gdb_assert (iterate_over_lwps (resumed_callback, NULL));
+
/* First check if there is a LWP with a wait status pending. */
if (pid == -1)
{
- /* Any LWP will do. */
+ /* Any LWP that's been resumed will do. */
lp = iterate_over_lwps (status_callback, NULL);
if (lp)
{
- if (debug_lin_lwp)
- fprintf_unfiltered (gdb_stdlog,
- "Using pending wait status for LWP %d.\n",
- (int) GET_LWP (lp->ptid));
-
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
{
if (debug_lin_lwp)
fprintf_unfiltered (gdb_stdlog,
- "Waiting for specific LWP %d.\n",
- (int) GET_LWP (ptid));
+ "Waiting for specific LWP %ld.\n",
+ GET_LWP (ptid));
/* We have a specific LWP to check. */
lp = find_lwp_pid (ptid);
status = lp->status;
lp->status = 0;
- if (debug_lin_lwp)
- if (status)
- fprintf_unfiltered (gdb_stdlog,
- "Using pending wait status for LWP %d.\n",
- GET_LWP (lp->ptid));
+ 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
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);
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;
&& 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;
/* 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);
longer running. */
iterate_over_lwps (stop_wait_callback, NULL);
+ /* 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)));
+ {
+ 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;
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);
+ child_ops.to_create_inferior (exec_file, allargs, env);
}
static void
lin_lwp_mourn_inferior (void)
{
- struct target_ops *target_beneath;
+ trap_ptid = null_ptid;
+ /* Destroy LWP info; it's no longer valid. */
init_lwp_list ();
- trap_ptid = null_ptid;
-
/* Restore the original signal mask. */
sigprocmask (SIG_SETMASK, &normal_mask, NULL);
sigemptyset (&blocked_mask);
-#if 0
- target_beneath = find_target_beneath (&lin_lwp_ops);
-#else
- target_beneath = &child_ops;
-#endif
- target_beneath->to_mourn_inferior ();
+ child_ops.to_mourn_inferior ();
}
static void
projects / deliverable / binutils-gdb.git / blobdiff