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/*
* 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/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.pc = (unsigned long)return_address; /* dummy */
walk_stackframe(&frame, save_return_addr, &data);
if (!data.level)
return data.addr;
else
return NULL;
}
EXPORT_SYMBOL_GPL(return_address);
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