// SPDX-License-Identifier: GPL-2.0
/*
 * This file contains hardware tag-based KASAN specific error reporting code.
 *
 * Copyright (c) 2020 Google, Inc.
 * Author: Andrey Konovalov <andreyknvl@google.com>
 */

#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/types.h>

#include "kasan.h"

const void *kasan_find_first_bad_addr(const void *addr, size_t size)
{
        /*
         * Hardware Tag-Based KASAN only calls this function for normal memory
         * accesses, and thus addr points precisely to the first bad address
         * with an invalid (and present) memory tag. Therefore:
         * 1. Return the address as is without walking memory tags.
         * 2. Skip the addr_has_metadata check.
         */
        return kasan_reset_tag(addr);
}

size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache)
{
        size_t size = 0;
        int i = 0;
        u8 memory_tag;

        /*
         * Skip the addr_has_metadata check, as this function only operates on
         * slab memory, which must have metadata.
         */

        /*
         * The loop below returns 0 for freed objects, for which KASAN cannot
         * calculate the allocation size based on the metadata.
         */
        while (size < cache->object_size) {
                memory_tag = hw_get_mem_tag(object + i * KASAN_GRANULE_SIZE);
                if (memory_tag != KASAN_TAG_INVALID)
                        size += KASAN_GRANULE_SIZE;
                else
                        return size;
                i++;
        }

        return cache->object_size;
}

void kasan_metadata_fetch_row(char *buffer, void *row)
{
        int i;

        for (i = 0; i < META_BYTES_PER_ROW; i++)
                buffer[i] = hw_get_mem_tag(row + i * KASAN_GRANULE_SIZE);
}

void kasan_print_tags(u8 addr_tag, const void *addr)
{
        u8 memory_tag = hw_get_mem_tag((void *)addr);

        pr_err("Pointer tag: [%02x], memory tag: [%02x]\n",
                addr_tag, memory_tag);
}