1 files changed, 51 insertions, 1 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 5424cb0006bc..99fa8ff06fd9 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -688,6 +688,48 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *in
 }
 EXPORT_SYMBOL_GPL(dequeue_signal);
 
+static int dequeue_synchronous_signal(kernel_siginfo_t *info)
+{
+        struct task_struct *tsk = current;
+        struct sigpending *pending = &tsk->pending;
+        struct sigqueue *q, *sync = NULL;
+
+        /*
+         * Might a synchronous signal be in the queue?
+         */
+        if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
+                return 0;
+
+        /*
+         * Return the first synchronous signal in the queue.
+         */
+        list_for_each_entry(q, &pending->list, list) {
+                /* Synchronous signals have a postive si_code */
+                if ((q->info.si_code > SI_USER) &&
+                    (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
+                        sync = q;
+                        goto next;
+                }
+        }
+        return 0;
+next:
+        /*
+         * Check if there is another siginfo for the same signal.
+         */
+        list_for_each_entry_continue(q, &pending->list, list) {
+                if (q->info.si_signo == sync->info.si_signo)
+                        goto still_pending;
+        }
+
+        sigdelset(&pending->signal, sync->info.si_signo);
+        recalc_sigpending();
+still_pending:
+        list_del_init(&sync->list);
+        copy_siginfo(info, &sync->info);
+        __sigqueue_free(sync);
+        return info->si_signo;
+}
+
 /*
  * Tell a process that it has a new active signal..
  *
@@ -2411,7 +2453,15 @@ relock:
                         goto relock;
                 }
 
-                signr = dequeue_signal(current, &current->blocked, &ksig->info);
+                /*
+                 * Signals generated by the execution of an instruction
+                 * need to be delivered before any other pending signals
+                 * so that the instruction pointer in the signal stack
+                 * frame points to the faulting instruction.
+                 */
+                signr = dequeue_synchronous_signal(&ksig->info);
+                if (!signr)
+                        signr = dequeue_signal(current, &current->blocked, &ksig->info);
 
                 if (!signr)
                         break; /* will return 0 */