1 files changed, 35 insertions, 8 deletions

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ad20981dfda4..de07147a7926 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -32,6 +32,30 @@
  *	add	sp, sp, #0x10
  */
 
+
+void start_backtrace(struct stackframe *frame, unsigned long fp,
+		     unsigned long pc)
+{
+	frame->fp = fp;
+	frame->pc = pc;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	frame->graph = 0;
+#endif
+
+	/*
+	 * Prime the first unwind.
+	 *
+	 * In unwind_frame() we'll check that the FP points to a valid stack,
+	 * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
+	 * treated as a transition to whichever stack that happens to be. The
+	 * prev_fp value won't be used, but we set it to 0 such that it is
+	 * definitely not an accessible stack address.
+	 */
+	bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
+	frame->prev_fp = 0;
+	frame->prev_type = STACK_TYPE_UNKNOWN;
+}
+
 /*
  * Unwind from one frame record (A) to the next frame record (B).
  *
@@ -44,10 +68,6 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 	unsigned long fp = frame->fp;
 	struct stack_info info;
 
-	/* Terminal record; nothing to unwind */
-	if (!fp)
-		return -ENOENT;
-
 	if (fp & 0xf)
 		return -EINVAL;
 
@@ -108,6 +128,12 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 
 	frame->pc = ptrauth_strip_insn_pac(frame->pc);
 
+	/*
+	 * This is a terminal record, so we have finished unwinding.
+	 */
+	if (!frame->fp && !frame->pc)
+		return -ENOENT;
+
 	return 0;
 }
 NOKPROBE_SYMBOL(unwind_frame);
@@ -194,8 +220,9 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
 
 #ifdef CONFIG_STACKTRACE
 
-void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
-		     struct task_struct *task, struct pt_regs *regs)
+noinline void arch_stack_walk(stack_trace_consume_fn consume_entry,
+			      void *cookie, struct task_struct *task,
+			      struct pt_regs *regs)
 {
 	struct stackframe frame;
 
@@ -203,8 +230,8 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 		start_backtrace(&frame, regs->regs[29], regs->pc);
 	else if (task == current)
 		start_backtrace(&frame,
-				(unsigned long)__builtin_frame_address(0),
-				(unsigned long)arch_stack_walk);
+				(unsigned long)__builtin_frame_address(1),
+				(unsigned long)__builtin_return_address(0));
 	else
 		start_backtrace(&frame, thread_saved_fp(task),
 				thread_saved_pc(task));