1 /* 2 * arch/arm/kernel/return_address.c 3 * 4 * Copyright (C) 2009 Uwe Kleine-Koenig <[email protected]> 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 13 #if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) 14 #include <linux/sched.h> 15 16 #include <asm/stacktrace.h> 17 18 struct return_address_data { 19 unsigned int level; 20 void *addr; 21 }; 22 23 static int save_return_addr(struct stackframe *frame, void *d) 24 { 25 struct return_address_data *data = d; 26 27 if (!data->level) { 28 data->addr = (void *)frame->lr; 29 30 return 1; 31 } else { 32 --data->level; 33 return 0; 34 } 35 } 36 37 void *return_address(unsigned int level) 38 { 39 struct return_address_data data; 40 struct stackframe frame; 41 register unsigned long current_sp asm ("sp"); 42 43 data.level = level + 1; 44 45 frame.fp = (unsigned long)__builtin_frame_address(0); 46 frame.sp = current_sp; 47 frame.lr = (unsigned long)__builtin_return_address(0); 48 frame.pc = (unsigned long)return_address; 49 50 walk_stackframe(&frame, save_return_addr, &data); 51 52 if (!data.level) 53 return data.addr; 54 else 55 return NULL; 56 } 57 58 #else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */ 59 60 #if defined(CONFIG_ARM_UNWIND) 61 #warning "TODO: return_address should use unwind tables" 62 #endif 63 64 void *return_address(unsigned int level) 65 { 66 return NULL; 67 } 68 69 #endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */ 70 71 EXPORT_SYMBOL_GPL(return_address); 72