static int linux_core_of_thread (ptid_t ptid);
static void proceed_all_lwps (void);
static void unstop_all_lwps (struct lwp_info *except);
-static void cancel_finished_single_steps (struct lwp_info *except);
static int finish_step_over (struct lwp_info *lwp);
static CORE_ADDR get_stop_pc (struct lwp_info *lwp);
static int kill_lwp (unsigned long lwpid, int signo);
return 0;
}
-/* Return 1 if this lwp has an interesting status pending. This
- function may silently resume an inferior lwp. */
+/* Return 1 if this lwp has an interesting status pending. */
static int
status_pending_p_callback (struct inferior_list_entry *entry, void *arg)
{
static int
linux_wait_for_event_1 (ptid_t ptid, int *wstat, int options)
{
- CORE_ADDR stop_pc;
struct lwp_info *event_child, *requested_child;
- again:
event_child = NULL;
requested_child = NULL;
events. */
while (1)
{
- int step_over_finished = 0;
- int bp_explains_trap = 0;
- int cancel_sigtrap;
-
- if (ptid_equal (step_over_bkpt, null_ptid))
- event_child = linux_wait_for_lwp (ptid, wstat, options);
- else
- {
- if (debug_threads)
- fprintf (stderr, "step_over_bkpt set [%s], doing a blocking wait\n",
- target_pid_to_str (step_over_bkpt));
- event_child = linux_wait_for_lwp (step_over_bkpt,
- wstat, options & ~WNOHANG);
- }
+ event_child = linux_wait_for_lwp (ptid, wstat, options);
if ((options & WNOHANG) && event_child == NULL)
{
}
}
- cancel_sigtrap = (stopping_threads
- || event_child->last_resume_kind == resume_stop);
-
- /* Do not allow nested internal breakpoint handling, or leave
- the unadjusted PCs visible to GDB. Simply cancel the
- breakpoint now, and eventually when the thread is resumed, it
- will trap again, if the breakpoint is still there by
- then. */
- if (WIFSTOPPED (*wstat)
- && WSTOPSIG (*wstat) == SIGTRAP
- && cancel_sigtrap)
- {
- if (debug_threads)
- fprintf (stderr, "Got a nested SIGTRAP while stopping threads\n");
-
- if (cancel_breakpoint (event_child))
- {
- if (debug_threads)
- fprintf (stderr, " bkpt canceled\n");
-
- /* We don't resume immediately to collect the SIGSTOP,
- due to other reasons we may care for this SIGTRAP
- below. Care must be taken to not process anything
- breakpoint related though from this point on. */
- }
- }
-
- /* If this event was not handled above, and is not a SIGTRAP, we
- report it. SIGILL and SIGSEGV are also treated as traps in
- case a breakpoint is inserted at the current PC. If this
- target does not support breakpoints, we also report the
- SIGTRAP without further processing; it's of no concern to
- us. */
- if (!WIFSTOPPED (*wstat)
- || !supports_breakpoints ()
- || (WSTOPSIG (*wstat) != SIGTRAP
- && WSTOPSIG (*wstat) != SIGILL
- && WSTOPSIG (*wstat) != SIGSEGV)
- /* Only handle SIGILL or SIGSEGV if we've hit a recognized
- breakpoint. */
- || (WSTOPSIG (*wstat) != SIGTRAP
- && !(*the_low_target.breakpoint_at) (event_child->stop_pc)))
- {
- if (debug_threads && WIFSTOPPED (*wstat))
- fprintf (stderr, "Reporting signal %d for LWP %ld.\n",
- WSTOPSIG (*wstat), lwpid_of (event_child));
-
- /* If we were stepping over a breakpoint, this signal
- arriving means we didn't manage to move past the
- breakpoint location. Cancel the operation for now --- it
- will be handled again on the next resume, if required
- (the breakpoint may be removed meanwhile, for
- example). */
- if (finish_step_over (event_child))
- {
- event_child->need_step_over = 1;
- unstop_all_lwps (event_child);
- }
- return lwpid_of (event_child);
- }
-
- stop_pc = event_child->stop_pc;
-
- /* Handle anything that requires bookkeeping before deciding to
- report the event or continue waiting. */
-
- /* First check if we can explain the SIGTRAP with an internal
- breakpoint, or if we should possibly report the event to GDB.
- Do this before anything that may remove or insert a
- breakpoint. */
- bp_explains_trap = breakpoint_inserted_here (stop_pc);
-
- /* We have a SIGTRAP, possibly a step-over dance has just
- finished. If so, tweak the state machine accordingly,
- reinsert breakpoints and delete any reinsert (software
- single-step) breakpoints. */
- step_over_finished = finish_step_over (event_child);
-
- /* Now invoke the callbacks of any breakpoints there. */
- if (!cancel_sigtrap)
- check_breakpoints (stop_pc);
-
- /* If we're stopping threads, resume once more to collect the
- SIGSTOP, and do nothing else. Note that we don't set
- need_step_over. If this predicate matches, then we've
- cancelled the SIGTRAP before reaching here, and we do want
- any breakpoint at STOP_PC to be re-hit on resume. */
- if (stopping_threads
- || event_child->last_resume_kind == resume_stop)
- {
- gdb_assert (cancel_sigtrap);
-
- if (step_over_finished)
- unstop_all_lwps (event_child);
-
- if (debug_threads)
- {
- if (event_child->last_resume_kind == resume_stop)
- fprintf (stderr, "Bailing out; GDB wanted the LWP to stop.\n");
- else if (stopping_threads)
- fprintf (stderr, "Bailing out; stopping threads.\n");
-
- if (bp_explains_trap)
- fprintf (stderr, " Hit a breakpoint.\n");
- if (step_over_finished)
- fprintf (stderr, " Step-over finished.\n");
- if (event_child->stopped_by_watchpoint)
- fprintf (stderr, " Stopped by watchpoint.\n");
- }
-
- /* Leave these pending. */
- if (event_child->stopped_by_watchpoint)
- return lwpid_of (event_child);
-
- /* Otherwise, there may or not be a pending SIGSTOP. If
- there isn't one, queue one up. In any case, go back to
- the event loop to collect it. Don't return yet, as we
- don't want this SIGTRAP to be left pending. Note that
- since we cancelled the breakpoint above, the PC is
- already adjusted, and hence get_stop_pc returns the
- correct PC when we collect the SIGSTOP. */
-
- if (!event_child->stop_expected)
- {
- event_child->stop_expected = 1;
- kill_lwp (lwpid_of (event_child), SIGSTOP);
- }
-
- /* Clear the single-stepping flag and SIGTRAP as we resume. */
- linux_resume_one_lwp (event_child, 0, 0, NULL);
- continue;
- }
-
- /* We have all the data we need. Either report the event to
- GDB, or resume threads and keep waiting for more. */
-
- /* Check If GDB would be interested in this event. If GDB
- wanted this thread to single step, we always want to report
- the SIGTRAP, and let GDB handle it. */
- if ((event_child->last_resume_kind == resume_step)
- || event_child->stopped_by_watchpoint)
- {
- if (step_over_finished)
- unstop_all_lwps (event_child);
-
- if (debug_threads)
- {
- if (event_child->last_resume_kind == resume_step)
- fprintf (stderr, "GDB wanted to single-step, reporting event.\n");
- if (event_child->stopped_by_watchpoint)
- fprintf (stderr, "Stopped by watchpoint.\n");
- }
- }
- /* We found no reason GDB would want us to stop. We either hit
- one of our own breakpoints, or finished an internal step GDB
- shouldn't know about. */
- else if (step_over_finished || bp_explains_trap)
- {
- if (debug_threads)
- {
- if (bp_explains_trap)
- fprintf (stderr, "Hit a gdbserver breakpoint.\n");
- if (step_over_finished)
- fprintf (stderr, "Step-over finished.\n");
- }
-
- /* If we stepped or ran into an internal breakpoint, we've
- already handled it. So next time we resume (from this
- PC), we should step over it. */
- if (breakpoint_here (stop_pc))
- event_child->need_step_over = 1;
-
- /* We're not reporting this breakpoint to GDB, so apply the
- decr_pc_after_break adjustment to the inferior's regcache
- ourselves. */
-
- if (the_low_target.set_pc != NULL)
- {
- struct regcache *regcache
- = get_thread_regcache (get_lwp_thread (event_child), 1);
- (*the_low_target.set_pc) (regcache, stop_pc);
- }
-
- /* We've finished stepping over a breakpoint. We've stopped
- all LWPs momentarily except the stepping one. This is
- where we resume them all again. We're going to keep
- waiting, so use proceed, which handles stepping over the
- next breakpoint. */
- if (debug_threads)
- fprintf (stderr, "proceeding all threads.\n");
- proceed_all_lwps ();
-
- /* If we stopped threads momentarily, we may have threads
- with pending statuses now (except when we're going to
- force the next event out of a specific LWP, in which case
- don't want to handle the pending events of other LWPs
- yet. */
- if (ptid_equal (step_over_bkpt, null_ptid))
- goto again;
- else
- continue;
- }
- else
- {
- /* GDB breakpoint or program trap, perhaps. */
- if (step_over_finished)
- unstop_all_lwps (event_child);
- }
-
- if (debug_threads)
- fprintf (stderr, "Hit a non-gdbserver trap event.\n");
-
return lwpid_of (event_child);
}
}
}
+
+/* Count the LWP's that have had events. */
+
+static int
+count_events_callback (struct inferior_list_entry *entry, void *data)
+{
+ struct lwp_info *lp = (struct lwp_info *) entry;
+ int *count = data;
+
+ gdb_assert (count != NULL);
+
+ /* Count only resumed LWPs that have a SIGTRAP event pending that
+ should be reported to GDB. */
+ if (get_lwp_thread (lp)->last_status.kind == TARGET_WAITKIND_IGNORE
+ && lp->last_resume_kind != resume_stop
+ && lp->status_pending_p
+ && WIFSTOPPED (lp->status_pending)
+ && WSTOPSIG (lp->status_pending) == SIGTRAP
+ && !breakpoint_inserted_here (lp->stop_pc))
+ (*count)++;
+
+ return 0;
+}
+
+/* Select the LWP (if any) that is currently being single-stepped. */
+
+static int
+select_singlestep_lwp_callback (struct inferior_list_entry *entry, void *data)
+{
+ struct lwp_info *lp = (struct lwp_info *) entry;
+
+ if (get_lwp_thread (lp)->last_status.kind == TARGET_WAITKIND_IGNORE
+ && lp->last_resume_kind == resume_step
+ && lp->status_pending_p)
+ return 1;
+ else
+ return 0;
+}
+
+/* Select the Nth LWP that has had a SIGTRAP event that should be
+ reported to GDB. */
+
+static int
+select_event_lwp_callback (struct inferior_list_entry *entry, void *data)
+{
+ struct lwp_info *lp = (struct lwp_info *) entry;
+ int *selector = data;
+
+ gdb_assert (selector != NULL);
+
+ /* Select only resumed LWPs that have a SIGTRAP event pending. */
+ if (lp->last_resume_kind != resume_stop
+ && get_lwp_thread (lp)->last_status.kind == TARGET_WAITKIND_IGNORE
+ && lp->status_pending_p
+ && WIFSTOPPED (lp->status_pending)
+ && WSTOPSIG (lp->status_pending) == SIGTRAP
+ && !breakpoint_inserted_here (lp->stop_pc))
+ if ((*selector)-- == 0)
+ return 1;
+
+ return 0;
+}
+
+static int
+cancel_breakpoints_callback (struct inferior_list_entry *entry, void *data)
+{
+ struct lwp_info *lp = (struct lwp_info *) entry;
+ 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->last_resume_kind != resume_stop
+ && get_lwp_thread (lp)->last_status.kind == TARGET_WAITKIND_IGNORE
+ && lp->status_pending_p
+ && WIFSTOPPED (lp->status_pending)
+ && WSTOPSIG (lp->status_pending) == SIGTRAP
+ && cancel_breakpoint (lp))
+ /* Throw away the SIGTRAP. */
+ lp->status_pending_p = 0;
+
+ return 0;
+}
+
+/* Select one LWP out of those that have events pending. */
+
+static void
+select_event_lwp (struct lwp_info **orig_lp)
+{
+ int num_events = 0;
+ int random_selector;
+ struct lwp_info *event_lp;
+
+ /* Give preference to any LWP that is being single-stepped. */
+ event_lp
+ = (struct lwp_info *) find_inferior (&all_lwps,
+ select_singlestep_lwp_callback, NULL);
+ if (event_lp != NULL)
+ {
+ if (debug_threads)
+ fprintf (stderr,
+ "SEL: Select single-step %s\n",
+ target_pid_to_str (ptid_of (event_lp)));
+ }
+ 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. */
+ find_inferior (&all_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_threads && num_events > 1)
+ fprintf (stderr,
+ "SEL: Found %d SIGTRAP events, selecting #%d\n",
+ num_events, random_selector);
+
+ event_lp = (struct lwp_info *) find_inferior (&all_lwps,
+ select_event_lwp_callback,
+ &random_selector);
+ }
+
+ if (event_lp != NULL)
+ {
+ /* Switch the event LWP. */
+ *orig_lp = event_lp;
+ }
+}
+
/* Set this inferior LWP's state as "want-stopped". We won't resume
this LWP until the client gives us another action for it. */
{
int w;
struct thread_info *thread = NULL;
- struct lwp_info *lwp = NULL;
+ struct lwp_info *event_child = NULL;
int options;
int pid;
+ int step_over_finished;
+ int bp_explains_trap;
+ int maybe_internal_trap;
+ int report_to_gdb;
/* Translate generic target options into linux options. */
options = __WALL;
ptid = cont_thread;
}
- pid = linux_wait_for_event (ptid, &w, options);
+ if (ptid_equal (step_over_bkpt, null_ptid))
+ pid = linux_wait_for_event (ptid, &w, options);
+ else
+ {
+ if (debug_threads)
+ fprintf (stderr, "step_over_bkpt set [%s], doing a blocking wait\n",
+ target_pid_to_str (step_over_bkpt));
+ pid = linux_wait_for_event (step_over_bkpt, &w, options & ~WNOHANG);
+ }
+
if (pid == 0) /* only if TARGET_WNOHANG */
return null_ptid;
- lwp = get_thread_lwp (current_inferior);
+ 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
{
if (WIFEXITED (w) || WIFSIGNALED (w))
{
- int pid = pid_of (lwp);
+ int pid = pid_of (event_child);
struct process_info *process = find_process_pid (pid);
#ifdef USE_THREAD_DB
thread_db_free (process, 0);
#endif
- delete_lwp (lwp);
+ delete_lwp (event_child);
linux_remove_process (process);
current_inferior = NULL;
goto retry;
}
+ /* If this event was not handled before, and is not a SIGTRAP, we
+ report it. SIGILL and SIGSEGV are also treated as traps in case
+ a breakpoint is inserted at the current PC. If this target does
+ not support internal breakpoints at all, we also report the
+ SIGTRAP without further processing; it's of no concern to us. */
+ maybe_internal_trap
+ = (supports_breakpoints ()
+ && (WSTOPSIG (w) == SIGTRAP
+ || ((WSTOPSIG (w) == SIGILL
+ || WSTOPSIG (w) == SIGSEGV)
+ && (*the_low_target.breakpoint_at) (event_child->stop_pc))));
+
+ if (maybe_internal_trap)
+ {
+ /* Handle anything that requires bookkeeping before deciding to
+ report the event or continue waiting. */
+
+ /* First check if we can explain the SIGTRAP with an internal
+ breakpoint, or if we should possibly report the event to GDB.
+ Do this before anything that may remove or insert a
+ breakpoint. */
+ bp_explains_trap = breakpoint_inserted_here (event_child->stop_pc);
+
+ /* We have a SIGTRAP, possibly a step-over dance has just
+ finished. If so, tweak the state machine accordingly,
+ reinsert breakpoints and delete any reinsert (software
+ single-step) breakpoints. */
+ step_over_finished = finish_step_over (event_child);
+
+ /* Now invoke the callbacks of any internal breakpoints there. */
+ check_breakpoints (event_child->stop_pc);
+
+ if (bp_explains_trap)
+ {
+ /* If we stepped or ran into an internal breakpoint, we've
+ already handled it. So next time we resume (from this
+ PC), we should step over it. */
+ if (debug_threads)
+ fprintf (stderr, "Hit a gdbserver breakpoint.\n");
+
+ event_child->need_step_over = 1;
+ }
+ }
+ else
+ {
+ /* We have some other signal, possibly a step-over dance was in
+ progress, and it should be cancelled too. */
+ step_over_finished = finish_step_over (event_child);
+ }
+
+ /* We have all the data we need. Either report the event to GDB, or
+ resume threads and keep waiting for more. */
+
+ /* Check If GDB would be interested in this event. If GDB wanted
+ this thread to single step, we always want to report the SIGTRAP,
+ and let GDB handle it. */
+ report_to_gdb = (!maybe_internal_trap
+ || event_child->last_resume_kind == resume_step
+ || event_child->stopped_by_watchpoint
+ || (!step_over_finished && !bp_explains_trap));
+
+ /* We found no reason GDB would want us to stop. We either hit one
+ of our own breakpoints, or finished an internal step GDB
+ shouldn't know about. */
+ if (!report_to_gdb)
+ {
+ if (debug_threads)
+ {
+ if (bp_explains_trap)
+ fprintf (stderr, "Hit a gdbserver breakpoint.\n");
+ if (step_over_finished)
+ fprintf (stderr, "Step-over finished.\n");
+ }
+
+ /* We're not reporting this breakpoint to GDB, so apply the
+ decr_pc_after_break adjustment to the inferior's regcache
+ ourselves. */
+
+ if (the_low_target.set_pc != NULL)
+ {
+ struct regcache *regcache
+ = get_thread_regcache (get_lwp_thread (event_child), 1);
+ (*the_low_target.set_pc) (regcache, event_child->stop_pc);
+ }
+
+ /* We've finished stepping over a breakpoint. We've stopped all
+ LWPs momentarily except the stepping one. This is where we
+ resume them all again. We're going to keep waiting, so use
+ proceed, which handles stepping over the next breakpoint. */
+ if (debug_threads)
+ fprintf (stderr, "proceeding all threads.\n");
+ proceed_all_lwps ();
+ goto retry;
+ }
+
+ if (debug_threads)
+ {
+ if (event_child->last_resume_kind == resume_step)
+ fprintf (stderr, "GDB wanted to single-step, reporting event.\n");
+ if (event_child->stopped_by_watchpoint)
+ fprintf (stderr, "Stopped by watchpoint.\n");
+ if (debug_threads)
+ fprintf (stderr, "Hit a non-gdbserver trap event.\n");
+ }
+
+ /* Alright, we're going to report a stop. */
+
+ if (!non_stop)
+ {
+ /* In all-stop, stop all threads. */
+ stop_all_lwps ();
+
+ /* If we're not waiting for a specific LWP, choose an event LWP
+ from among those that have had events. Giving equal priority
+ to all LWPs that have had events helps prevent
+ starvation. */
+ if (ptid_equal (ptid, minus_one_ptid))
+ {
+ event_child->status_pending_p = 1;
+ event_child->status_pending = w;
+
+ select_event_lwp (&event_child);
+
+ event_child->status_pending_p = 0;
+ w = event_child->status_pending;
+ }
+
+ /* 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. */
+ find_inferior (&all_lwps, cancel_breakpoints_callback, event_child);
+ }
+ else
+ {
+ /* If we just finished a step-over, then all threads had been
+ momentarily paused. In all-stop, that's fine, we want
+ threads stopped by now anyway. In non-stop, we need to
+ re-resume threads that GDB wanted to be running. */
+ if (step_over_finished)
+ unstop_all_lwps (event_child);
+ }
+
ourstatus->kind = TARGET_WAITKIND_STOPPED;
/* Do this before the gdb_wants_all_stopped calls below, since they
always set last_resume_kind to resume_stop. */
- if (lwp->last_resume_kind == resume_stop && WSTOPSIG (w) == SIGSTOP)
+ if (event_child->last_resume_kind == resume_stop && WSTOPSIG (w) == SIGSTOP)
{
/* A thread that has been requested to stop by GDB with vCont;t,
and it stopped cleanly, so report as SIG0. The use of
SIGSTOP is an implementation detail. */
ourstatus->value.sig = TARGET_SIGNAL_0;
}
- else if (lwp->last_resume_kind == resume_stop && WSTOPSIG (w) != SIGSTOP)
+ else if (event_child->last_resume_kind == resume_stop && WSTOPSIG (w) != SIGSTOP)
{
/* A thread that has been requested to stop by GDB with vCont;t,
but, it stopped for other reasons. */
if (!non_stop)
{
- /* In all-stop, stop all threads, we're about to report an event
- to GDB. */
- stop_all_lwps ();
-
- /* Do not leave a pending single-step finish to be reported to
- the client. The client will give us a new action for this
- thread, possibly a continue request --- otherwise, the client
- would consider this pending SIGTRAP reported later a spurious
- signal. */
- cancel_finished_single_steps (lwp);
-
/* From GDB's perspective, all-stop mode always stops all
threads implicitly. Tag all threads as "want-stopped". */
gdb_wants_all_stopped ();
/* We're reporting this LWP as stopped. Update it's
"want-stopped" state to what the client wants, until it gets
a new resume action. */
- gdb_wants_lwp_stopped (&lwp->head);
+ gdb_wants_lwp_stopped (&event_child->head);
}
if (debug_threads)
fprintf (stderr, "linux_wait ret = %s, %d, %d\n",
- target_pid_to_str (lwp->head.id),
+ target_pid_to_str (ptid_of (event_child)),
ourstatus->kind,
ourstatus->value.sig);
- get_lwp_thread (lwp)->last_status = *ourstatus;
- return lwp->head.id;
+ get_lwp_thread (event_child)->last_status = *ourstatus;
+ return ptid_of (event_child);
}
/* Get rid of any pending event in the pipe. */
lwp->stop_expected = 0;
}
-static int
-cancel_finished_single_step (struct inferior_list_entry *entry, void *except)
-{
- struct lwp_info *lwp = (struct lwp_info *) entry;
- struct thread_info *saved_inferior;
-
- if (lwp == except)
- return 0;
-
- saved_inferior = current_inferior;
- current_inferior = get_lwp_thread (lwp);
-
- /* Do not leave a pending single-step finish to be reported to the
- client. The client will give us a new action for this thread,
- possibly a continue request --- otherwise, the client would
- consider this pending SIGTRAP reported later a spurious
- signal. */
- if (lwp->status_pending_p
- && WSTOPSIG (lwp->status_pending) == SIGTRAP
- && lwp->stepping
- && !lwp->stopped_by_watchpoint)
- {
- if (debug_threads)
- fprintf (stderr, " single-step SIGTRAP cancelled\n");
-
- lwp->status_pending_p = 0;
- lwp->status_pending = 0;
- }
-
- current_inferior = saved_inferior;
- return 0;
-}
-
-static void
-cancel_finished_single_steps (struct lwp_info *except)
-{
- find_inferior (&all_lwps, cancel_finished_single_step, except);
-}
-
static void
wait_for_sigstop (struct inferior_list_entry *entry)
{
projects / deliverable / binutils-gdb.git / commitdiff
