/*
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* arch/arm64/kernel/return_address.c
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*
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* Copyright (C) 2013 Linaro Limited
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* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <linux/ftrace.h>
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#include <linux/kprobes.h>
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#include <asm/stack_pointer.h>
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#include <asm/stacktrace.h>
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struct return_address_data {
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unsigned int level;
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void *addr;
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};
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static int save_return_addr(struct stackframe *frame, void *d)
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{
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struct return_address_data *data = d;
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if (!data->level) {
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data->addr = (void *)frame->pc;
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return 1;
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} else {
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--data->level;
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return 0;
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}
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}
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NOKPROBE_SYMBOL(save_return_addr);
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void *return_address(unsigned int level)
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{
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struct return_address_data data;
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struct stackframe frame;
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data.level = level + 2;
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data.addr = NULL;
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frame.fp = (unsigned long)__builtin_frame_address(0);
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frame.pc = (unsigned long)return_address; /* dummy */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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frame.graph = current->curr_ret_stack;
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#endif
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walk_stackframe(current, &frame, save_return_addr, &data);
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if (!data.level)
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return data.addr;
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else
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return NULL;
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}
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EXPORT_SYMBOL_GPL(return_address);
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NOKPROBE_SYMBOL(return_address);
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