/* * arch/arm/kernel/return_address.c * * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de> * for Pengutronix * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. */#include <linux/export.h>#include <linux/ftrace.h> #if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)#include <linux/sched.h> #include <asm/stacktrace.h> struct return_address_data {	unsigned int level;	void *addr;}; static int save_return_addr(struct stackframe *frame, void *d){	struct return_address_data *data = d; 	if (!data->level) {		data->addr = (void *)frame->pc; 		return 1;	} else {		--data->level;		return 0;	}} void *return_address(unsigned int level){	struct return_address_data data;	struct stackframe frame;	register unsigned long current_sp asm ("sp"); 	data.level = level + 2;	data.addr = NULL; 	frame.fp = (unsigned long)__builtin_frame_address(0);	frame.sp = current_sp;	frame.lr = (unsigned long)__builtin_return_address(0);	frame.pc = (unsigned long)return_address; 	walk_stackframe(&frame, save_return_addr, &data); 	if (!data.level)		return data.addr;	else		return NULL;} #else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */ #if defined(CONFIG_ARM_UNWIND)#warning "TODO: return_address should use unwind tables"#endif void *return_address(unsigned int level){	return NULL;} #endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */ EXPORT_SYMBOL_GPL(return_address);