---

yaml
---
r: 106218
b: refs/heads/master
c: 7bcf6a2
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 283d7559e7712f95a05331eb0a85394c6368101b
+refs/heads/master: 7bcf6a2ca5f639b038c48711ebe6c4eca2036641

trunk/include/linux/tracehook.h

@@ -422,4 +422,33 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task,
 	return (task_ptrace(task) & PT_PTRACED) != 0;
 }
 
+/**
+ * tracehook_get_signal - deliver synthetic signal to traced task
+ * @task:		@current
+ * @regs:		task_pt_regs(@current)
+ * @info:		details of synthetic signal
+ * @return_ka:		sigaction for synthetic signal
+ *
+ * Return zero to check for a real pending signal normally.
+ * Return -1 after releasing the siglock to repeat the check.
+ * Return a signal number to induce an artifical signal delivery,
+ * setting *@info and *@return_ka to specify its details and behavior.
+ *
+ * The @return_ka->sa_handler value controls the disposition of the
+ * signal, no matter the signal number.  For %SIG_DFL, the return value
+ * is a representative signal to indicate the behavior (e.g. %SIGTERM
+ * for death, %SIGQUIT for core dump, %SIGSTOP for job control stop,
+ * %SIGTSTP for stop unless in an orphaned pgrp), but the signal number
+ * reported will be @info->si_signo instead.
+ *
+ * Called with @task->sighand->siglock held, before dequeuing pending signals.
+ */
+static inline int tracehook_get_signal(struct task_struct *task,
+				       struct pt_regs *regs,
+				       siginfo_t *info,
+				       struct k_sigaction *return_ka)
+{
+	return 0;
+}
+
 #endif	/* <linux/tracehook.h> */

trunk/kernel/signal.c

@@ -1754,17 +1754,33 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 		    do_signal_stop(0))
 			goto relock;
 
-		signr = dequeue_signal(current, &current->blocked, info);
-		if (!signr)
-			break; /* will return 0 */
+		/*
+		 * Tracing can induce an artifical signal and choose sigaction.
+		 * The return value in @signr determines the default action,
+		 * but @info->si_signo is the signal number we will report.
+		 */
+		signr = tracehook_get_signal(current, regs, info, return_ka);
+		if (unlikely(signr < 0))
+			goto relock;
+		if (unlikely(signr != 0))
+			ka = return_ka;
+		else {
+			signr = dequeue_signal(current, &current->blocked,
+					       info);
 
-		if (signr != SIGKILL) {
-			signr = ptrace_signal(signr, info, regs, cookie);
 			if (!signr)
-				continue;
+				break; /* will return 0 */
+
+			if (signr != SIGKILL) {
+				signr = ptrace_signal(signr, info,
+						      regs, cookie);
+				if (!signr)
+					continue;
+			}
+
+			ka = &sighand->action[signr-1];
 		}
 
-		ka = &sighand->action[signr-1];
 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
 			continue;
 		if (ka->sa.sa_handler != SIG_DFL) {
@@ -1812,7 +1828,7 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 				spin_lock_irq(&sighand->siglock);
 			}
 
-			if (likely(do_signal_stop(signr))) {
+			if (likely(do_signal_stop(info->si_signo))) {
 				/* It released the siglock.  */
 				goto relock;
 			}
@@ -1833,7 +1849,7 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
-				print_fatal_signal(regs, signr);
+				print_fatal_signal(regs, info->si_signo);
 			/*
 			 * If it was able to dump core, this kills all
 			 * other threads in the group and synchronizes with
@@ -1842,13 +1858,13 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 			 * first and our do_group_exit call below will use
 			 * that value and ignore the one we pass it.
 			 */
-			do_coredump((long)signr, signr, regs);
+			do_coredump(info->si_signo, info->si_signo, regs);
 		}
 
 		/*
 		 * Death signals, no core dump.
 		 */
-		do_group_exit(signr);
+		do_group_exit(info->si_signo);
 		/* NOTREACHED */
 	}
 	spin_unlock_irq(&sighand->siglock);