/* * arch/arm64/kernel/return_address.c * * Copyright (C) 2013 Linaro Limited * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> * * 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> #include <asm/stack_pointer.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; data.level = level + 2; data.addr = NULL; frame.fp = (unsigned long)__builtin_frame_address(0); frame.pc = (unsigned long)return_address; /* dummy */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER frame.graph = 0; #endif walk_stackframe(current, &frame, save_return_addr, &data); if (!data.level) return data.addr; else return NULL; } EXPORT_SYMBOL_GPL(return_address);