This patch modifies report_signal callback for gdbstub and
uprobe_handler.
Previously we would alert in uprobe_handler that gdb should stop the
thread. For this we expected the thread to stop before it singlestepped.
However this seems unreliable and also we werent doing a explicit
UTRACE_STOP.
With this patch, report_signal callback has enuf intelligence to know if
SIGTRAPS were occurring at the address where gdb requested for
breakpoints. Now we have a dummy uprobe_handler.
Signed-off-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
diff --git a/kernel/utrace-gdb.c b/kernel/utrace-gdb.c
index 0c84afb..f7833dc 100644
--- a/kernel/utrace-gdb.c
+++ b/kernel/utrace-gdb.c
@@ -231,51 +231,33 @@ static void push_output_packet (struct gdb_connection *p,
const char *s)
/* ------------------------------------------------------------------------ */
-
-
-#ifdef CONFIG_HAVE_UPROBES
-/* uprobe callback */
-void gdb_uprobe_handler (struct uprobe* up, struct pt_regs* regs)
+static bool can_gdb_handle_sigtrap(struct pt_regs *regs,
+ struct gdb_connection *p)
{
- struct gdb_connection *p = NULL;
- struct list_head *l;
unsigned long bkpt = ubp_get_bkpt_addr (regs);
struct task_struct *task = current;
- pr_debug ("uprobe hit for %d, pc=%p\n", task->pid, (void*)bkpt);
-
- /* Find the right gdb_connection* for this task. */
- mutex_lock (& gdb_connections_mutex);
- list_for_each(l, &gdb_connections) {
- p = list_entry (l, struct gdb_connection, link);
- if (p->target == task_tgid_nr(task)) {
- struct list_head *l;
- struct list_head *l2;
- struct gdb_uprobe *gup = NULL;
-
- mutex_unlock (& gdb_connections_mutex);
- mutex_lock (& p->output_mutex);
-
- list_for_each_safe(l, l2, & p->uprobes) {
- gup = list_entry (l, struct gdb_uprobe, link);
- pr_debug ("considering addr=%p %s\n", (void*)
gup->up.vaddr,
- gup->disarmed_p ? "disarmed" : "");
- if (gup->up.vaddr == bkpt && !gup->disarmed_p)
{
- p->at_quiesce_do = UTRACE_STOP;
- snprintf (p->stopcode, GDB_BUFMAX,
"S%02x", 5); /* SIGTRAP */
- push_output_packet (p, p->stopcode);
- /* NB: This thread will be shortly
stopped, even before
- * uprobes get a chance to singlestep,
or to complete an
- * unregister_uprobe().
- */
- }
- }
+ if (p->target == task_tgid_nr(task)) {
+ struct list_head *l;
+ struct list_head *l2;
+ struct gdb_uprobe *gup = NULL;
+
+ list_for_each_safe(l, l2, &p->uprobes) {
+ gup = list_entry(l, struct gdb_uprobe, link);
+ pr_debug("considering addr=%p %s\n",
+ (void *)gup->up.vaddr,
+ gup->disarmed_p ? "disarmed" : "");
+ if (gup->up.vaddr == bkpt && !gup->disarmed_p)
+ return true;
+ }
+ }
+ return false;
+}
- mutex_unlock (& p->output_mutex);
- return;
- }
- }
- mutex_unlock (& gdb_connections_mutex);
+#ifdef CONFIG_HAVE_UPROBES
+/* uprobe callback */
+void gdb_uprobe_handler(struct uprobe *up, struct pt_regs *regs)
+{
}
#endif /* CONFIG_HAVE_UPROBES */
@@ -405,14 +387,14 @@ u32 gdb_utrace_report_signal(u32 action,
break;
case UTRACE_SIGNAL_REPORT: /* case 3 */
- if (p->stop_signals>0) {
+ if (p->stop_signals > 0) {
p->stop_signals --;
snprintf (p->stopcode, GDB_BUFMAX, "S%02x", 2); /*
SIGINT */
push_output_packet (p, p->stopcode);
p->at_quiesce_do = UTRACE_STOP;
ret = UTRACE_STOP | UTRACE_SIGNAL_IGN;
} else {
- ret = UTRACE_RESUME | utrace_signal_action(action);
+ ret = p->at_quiesce_do | utrace_signal_action(action);
}
break;
@@ -424,14 +406,17 @@ u32 gdb_utrace_report_signal(u32 action,
case UTRACE_SIGNAL_TSTP:
#ifdef CONFIG_HAVE_UPROBES
if (info->si_signo == SIGTRAP) { /* case 2a */
- unsigned long bkpt = ubp_get_bkpt_addr (regs);
- /* XXX: search for nearby uprobes. */
- (void) bkpt;
-
- /* NB: don't set p->at_quiesce_do, since the
uprobes_handler
- might have already been called, and set UTRACE_STOP
there. */
- ret = UTRACE_RESUME; /* Let uprobes consume the
signal. */
- break;
+ if (can_gdb_handle_sigtrap(regs, p)) {
+ p->at_quiesce_do = UTRACE_STOP;
+ /* SIGTRAP */
+ snprintf(p->stopcode, GDB_BUFMAX, "S%02x", 5);
+ push_output_packet(p, p->stopcode);
+ ret = UTRACE_STOP |
+ utrace_signal_action(action);
+ } else
+ ret = UTRACE_RESUME |
+ utrace_signal_action(action);
+ break;
}
#endif /* CONFIG_HAVE_UPROBES */
if (p->pass_signals > 0 /*&& kern_p*/) { /* case 4 */
@@ -443,7 +428,7 @@ u32 gdb_utrace_report_signal(u32 action,
map_signal_kern2gdb(info->si_signo));
push_output_packet (p, p->stopcode);
p->at_quiesce_do = UTRACE_STOP;
- ret = UTRACE_STOP;
+ ret = UTRACE_STOP | utrace_signal_action(action);
}
break;
}
@@ -1327,7 +1312,6 @@ again:
mutex_unlock(&p->output_mutex);
goto again;
}
-
len = min (count, (size_t)(p->output_buf_size - p->output_buf_read));
if (copy_to_user (buf, & p->output_buf[p->output_buf_read], len)) {
rc = -EFAULT;
