// SPDX-License-Identifier: GPL-2.0-only/* * arch/arm/kernel/return_address.c * * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de> * for Pengutronix */#include <linux/export.h>#include <linux/ftrace.h>#include <linux/sched.h> #include <asm/stacktrace.h> struct return_address_data {	unsigned int level;	void *addr;}; static bool save_return_addr(void *d, unsigned long pc){	struct return_address_data *data = d; 	if (!data->level) {		data->addr = (void *)pc; 		return false;	} else {		--data->level;		return true;	}} void *return_address(unsigned int level){	struct return_address_data data;	struct stackframe frame; 	data.level = level + 2;	data.addr = NULL; 	frame.fp = (unsigned long)__builtin_frame_address(0);	frame.sp = current_stack_pointer;	frame.lr = (unsigned long)__builtin_return_address(0);here:	frame.pc = (unsigned long)&&here;#ifdef CONFIG_KRETPROBES	frame.kr_cur = NULL;	frame.tsk = current;#endif	frame.ex_frame = false; 	walk_stackframe(&frame, save_return_addr, &data); 	if (!data.level)		return data.addr;	else		return NULL;} EXPORT_SYMBOL_GPL(return_address);