linux-imx

// SPDX-License-Identifier: GPL-2.0

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/mm.h>

#include <linux/highmem.h>

#include <linux/page_ext.h>

#include <linux/poison.h>

#include <linux/ratelimit.h>

#include <linux/kasan.h>

​

static bool want_page_poisoning __read_mostly;

​

static int __init early_page_poison_param(char *buf)

{

    if (!buf)

        return -EINVAL;

    return strtobool(buf, &want_page_poisoning);

}

early_param("page_poison", early_page_poison_param);

​

/**

 * page_poisoning_enabled - check if page poisoning is enabled

 *

 * Return true if page poisoning is enabled, or false if not.

 */

bool page_poisoning_enabled(void)

{

    /*

     * Assumes that debug_pagealloc_enabled is set before

     * memblock_free_all.

     * Page poisoning is debug page alloc for some arches. If

     * either of those options are enabled, enable poisoning.

     */

    return (want_page_poisoning ||

        (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&

        debug_pagealloc_enabled()));

}

EXPORT_SYMBOL_GPL(page_poisoning_enabled);

​

static void poison_page(struct page *page)

{

    void *addr = kmap_atomic(page);

​

    /* KASAN still think the page is in-use, so skip it. */

    kasan_disable_current();

    memset(addr, PAGE_POISON, PAGE_SIZE);

    kasan_enable_current();

    kunmap_atomic(addr);

}

​

static void poison_pages(struct page *page, int n)

{

    int i;

​

    for (i = 0; i < n; i++)

        poison_page(page + i);

}

​

static bool single_bit_flip(unsigned char a, unsigned char b)

{

    unsigned char error = a ^ b;

​

    return error && !(error & (error - 1));