// SPDX-License-Identifier: GPL-2.0-only/* * This code come from arch/arm64/kernel/return_address.c * * Copyright (C) 2023 SiFive. */ #include <linux/export.h>#include <linux/kprobes.h>#include <linux/stacktrace.h> struct return_address_data {	unsigned int level;	void *addr;}; static bool save_return_addr(void *d, unsigned long pc){	struct return_address_data *data = d; 	if (!data->level) {		data->addr = (void *)pc;		return false;	} 	--data->level; 	return true;}NOKPROBE_SYMBOL(save_return_addr); noinline void *return_address(unsigned int level){	struct return_address_data data; 	data.level = level + 3;	data.addr = NULL; 	arch_stack_walk(save_return_addr, &data, current, NULL); 	if (!data.level)		return data.addr;	else		return NULL; }EXPORT_SYMBOL_GPL(return_address);NOKPROBE_SYMBOL(return_address);