1/* 2 * arch/arm/kernel/return_address.c 3 * 4 * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de> 5 * for Pengutronix 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License version 2 as published by 9 * the Free Software Foundation. 10 */ 11#include <linux/module.h> 12#include <linux/ftrace.h> 13 14#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) 15#include <linux/sched.h> 16 17#include <asm/stacktrace.h> 18 19struct return_address_data { 20 unsigned int level; 21 void *addr; 22}; 23 24static int save_return_addr(struct stackframe *frame, void *d) 25{ 26 struct return_address_data *data = d; 27 28 if (!data->level) { 29 data->addr = (void *)frame->lr; 30 31 return 1; 32 } else { 33 --data->level; 34 return 0; 35 } 36} 37 38void *return_address(unsigned int level) 39{ 40 struct return_address_data data; 41 struct stackframe frame; 42 register unsigned long current_sp asm ("sp"); 43 44 data.level = level + 1; 45 46 frame.fp = (unsigned long)__builtin_frame_address(0); 47 frame.sp = current_sp; 48 frame.lr = (unsigned long)__builtin_return_address(0); 49 frame.pc = (unsigned long)return_address; 50 51 walk_stackframe(&frame, save_return_addr, &data); 52 53 if (!data.level) 54 return data.addr; 55 else 56 return NULL; 57} 58 59#else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */ 60 61#if defined(CONFIG_ARM_UNWIND) 62#warning "TODO: return_address should use unwind tables" 63#endif 64 65void *return_address(unsigned int level) 66{ 67 return NULL; 68} 69 70#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */ 71 72EXPORT_SYMBOL_GPL(return_address); 73