// 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);