Merge branch 'for-5.3/core' into for-linus

2 files changed, 8 insertions, 11 deletions

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index c53370d596be..3c764e73b032 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -259,7 +259,6 @@ 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",
@@ -293,11 +292,11 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
  */
 static bool klp_try_switch_task(struct task_struct *task)
 {
+	static char err_buf[STACK_ERR_BUF_SIZE];
 	struct rq *rq;
 	struct rq_flags flags;
 	int ret;
 	bool success = false;
-	char err_buf[STACK_ERR_BUF_SIZE];
 
 	err_buf[0] = '\0';
 
@@ -306,6 +305,13 @@ static bool klp_try_switch_task(struct task_struct *task)
 		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
 	 * state.
@@ -340,7 +346,6 @@ done:
 		pr_debug("%s", err_buf);
 
 	return success;
-
 }
 
 /*
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 27bafc1e271e..319e7fcf3083 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -254,14 +254,6 @@ 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