1 files changed, 90 insertions, 0 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 9fa60ee48499..ce190ee18a20 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -67,6 +67,96 @@ static inline void unwind_init_from_task(struct unwind_state *state,
 	state->pc = thread_saved_pc(task);
 }
 
+/*
+ * We can only safely access per-cpu stacks from current in a non-preemptible
+ * context.
+ */
+static bool on_accessible_stack(const struct task_struct *tsk,
+				unsigned long sp, unsigned long size,
+				struct stack_info *info)
+{
+	if (info)
+		info->type = STACK_TYPE_UNKNOWN;
+
+	if (on_task_stack(tsk, sp, size, info))
+		return true;
+	if (tsk != current || preemptible())
+		return false;
+	if (on_irq_stack(sp, size, info))
+		return true;
+	if (on_overflow_stack(sp, size, info))
+		return true;
+	if (on_sdei_stack(sp, size, info))
+		return true;
+
+	return false;
+}
+
+/*
+ * Unwind from one frame record (A) to the next frame record (B).
+ *
+ * We terminate early if the location of B indicates a malformed chain of frame
+ * records (e.g. a cycle), determined based on the location and fp value of A
+ * and the location (but not the fp value) of B.
+ */
+static int notrace unwind_next(struct unwind_state *state)
+{
+	struct task_struct *tsk = state->task;
+	unsigned long fp = state->fp;
+	struct stack_info info;
+	int err;
+
+	/* Final frame; nothing to unwind */
+	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
+		return -ENOENT;
+
+	err = unwind_next_common(state, &info, on_accessible_stack, NULL);
+	if (err)
+		return err;
+
+	state->pc = ptrauth_strip_insn_pac(state->pc);
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	if (tsk->ret_stack &&
+		(state->pc == (unsigned long)return_to_handler)) {
+		unsigned long orig_pc;
+		/*
+		 * This is a case where function graph tracer has
+		 * modified a return address (LR) in a stack frame
+		 * to hook a function return.
+		 * So replace it to an original value.
+		 */
+		orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,
+						(void *)state->fp);
+		if (WARN_ON_ONCE(state->pc == orig_pc))
+			return -EINVAL;
+		state->pc = orig_pc;
+	}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+#ifdef CONFIG_KRETPROBES
+	if (is_kretprobe_trampoline(state->pc))
+		state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);
+#endif
+
+	return 0;
+}
+NOKPROBE_SYMBOL(unwind_next);
+
+static void notrace unwind(struct unwind_state *state,
+			   stack_trace_consume_fn consume_entry, void *cookie)
+{
+	while (1) {
+		int ret;
+
+		if (!consume_entry(cookie, state->pc))
+			break;
+		ret = unwind_next(state);
+		if (ret < 0)
+			break;
+	}
+}
+NOKPROBE_SYMBOL(unwind);
+
 static bool dump_backtrace_entry(void *arg, unsigned long where)
 {
 	char *loglvl = arg;