1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/sh/kernel/return_address.c 4 * 5 * Copyright (C) 2009 Matt Fleming 6 * Copyright (C) 2009 Paul Mundt 7 */ 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 11 #include <asm/dwarf.h> 12 #include <asm/ftrace.h> 13 14 #ifdef CONFIG_DWARF_UNWINDER 15 return_address(unsigned int depth)16void *return_address(unsigned int depth) 17 { 18 struct dwarf_frame *frame; 19 unsigned long ra; 20 int i; 21 22 for (i = 0, frame = NULL, ra = 0; i <= depth; i++) { 23 struct dwarf_frame *tmp; 24 25 tmp = dwarf_unwind_stack(ra, frame); 26 if (!tmp) 27 return NULL; 28 29 if (frame) 30 dwarf_free_frame(frame); 31 32 frame = tmp; 33 34 if (!frame || !frame->return_addr) 35 break; 36 37 ra = frame->return_addr; 38 } 39 40 /* Failed to unwind the stack to the specified depth. */ 41 WARN_ON(i != depth + 1); 42 43 if (frame) 44 dwarf_free_frame(frame); 45 46 return (void *)ra; 47 } 48 49 #else 50 return_address(unsigned int depth)51void *return_address(unsigned int depth) 52 { 53 return NULL; 54 } 55 56 #endif 57 58 EXPORT_SYMBOL_GPL(return_address); 59