Merge branch 'for-5.3-core' into for-next

Author: pmladek

kernel/livepatch/transition.c

@@ -247,7 +247,6 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
 	int ret, nr_entries;
 
 	ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
-	WARN_ON_ONCE(ret == -ENOSYS);
 	if (ret < 0) {
 		snprintf(err_buf, STACK_ERR_BUF_SIZE,
 			 "%s: %s:%d has an unreliable stack\n",
@@ -293,6 +292,13 @@ static bool klp_try_switch_task(struct task_struct *task)
 	if (task->patch_state == klp_target_state)
 		return true;
 
+	/*
+	 * For arches which don't have reliable stack traces, we have to rely
+	 * on other methods (e.g., switching tasks at kernel exit).
+	 */
+	if (!klp_have_reliable_stack())
+		return false;
+
 	/*
 	 * Now try to check the stack for any to-be-patched or to-be-unpatched
 	 * functions.  If all goes well, switch the task to the target patch

kernel/stacktrace.c

@@ -255,14 +255,6 @@ save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 	WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
 }
 
-__weak int
-save_stack_trace_tsk_reliable(struct task_struct *tsk,
-			      struct stack_trace *trace)
-{
-	WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
-	return -ENOSYS;
-}
-
 /**
  * stack_trace_save - Save a stack trace into a storage array
  * @store:	Pointer to storage array