// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sh/kernel/return_address.c
 *
 * Copyright (C) 2009  Matt Fleming
 * Copyright (C) 2009  Paul Mundt
 */
#include <linux/kernel.h>
#include <linux/module.h>

#include <asm/dwarf.h>
#include <asm/ftrace.h>

#ifdef CONFIG_DWARF_UNWINDER

void *return_address(unsigned int depth)
{
        struct dwarf_frame *frame;
        unsigned long ra;
        int i;

        for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
                struct dwarf_frame *tmp;

                tmp = dwarf_unwind_stack(ra, frame);
                if (!tmp)
                        return NULL;

                if (frame)
                        dwarf_free_frame(frame);

                frame = tmp;

                if (!frame || !frame->return_addr)
                        break;

                ra = frame->return_addr;
        }

        /* Failed to unwind the stack to the specified depth. */
        WARN_ON(i != depth + 1);

        if (frame)
                dwarf_free_frame(frame);

        return (void *)ra;
}

#else

void *return_address(unsigned int depth)
{
        return NULL;
}

#endif

EXPORT_SYMBOL_GPL(return_address);