LXR linux/arch/x86/kernel/check.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/init.h>
   3#include <linux/sched.h>
   4#include <linux/kthread.h>
   5#include <linux/workqueue.h>
   6#include <linux/memblock.h>
   7
   8#include <asm/proto.h>
   9
  10/*
  11 * Some BIOSes seem to corrupt the low 64k of memory during events
  12 * like suspend/resume and unplugging an HDMI cable.  Reserve all
  13 * remaining free memory in that area and fill it with a distinct
  14 * pattern.
  15 */
  16#define MAX_SCAN_AREAS  8
  17
  18static int __read_mostly memory_corruption_check = -1;
  19
  20static unsigned __read_mostly corruption_check_size = 64*1024;
  21static unsigned __read_mostly corruption_check_period = 60; /* seconds */
  22
  23static struct scan_area {
  24        u64 addr;
  25        u64 size;
  26} scan_areas[MAX_SCAN_AREAS];
  27static int num_scan_areas;
  28
  29static __init int set_corruption_check(char *arg)
  30{
  31        ssize_t ret;
  32        unsigned long val;
  33
  34        ret = kstrtoul(arg, 10, &val);
  35        if (ret)
  36                return ret;
  37
  38        memory_corruption_check = val;
  39        return 0;
  40}
  41early_param("memory_corruption_check", set_corruption_check);
  42
  43static __init int set_corruption_check_period(char *arg)
  44{
  45        ssize_t ret;
  46        unsigned long val;
  47
  48        ret = kstrtoul(arg, 10, &val);
  49        if (ret)
  50                return ret;
  51
  52        corruption_check_period = val;
  53        return 0;
  54}
  55early_param("memory_corruption_check_period", set_corruption_check_period);
  56
  57static __init int set_corruption_check_size(char *arg)
  58{
  59        char *end;
  60        unsigned size;
  61
  62        size = memparse(arg, &end);
  63
  64        if (*end == '\0')
  65                corruption_check_size = size;
  66
  67        return (size == corruption_check_size) ? 0 : -EINVAL;
  68}
  69early_param("memory_corruption_check_size", set_corruption_check_size);
  70
  71
  72void __init setup_bios_corruption_check(void)
  73{
  74        phys_addr_t start, end;
  75        u64 i;
  76
  77        if (memory_corruption_check == -1) {
  78                memory_corruption_check =
  79#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
  80                        1
  81#else
  82                        0
  83#endif
  84                        ;
  85        }
  86
  87        if (corruption_check_size == 0)
  88                memory_corruption_check = 0;
  89
  90        if (!memory_corruption_check)
  91                return;
  92
  93        corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
  94
  95        for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
  96                                NULL) {
  97                start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
  98                                PAGE_SIZE, corruption_check_size);
  99                end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
 100                              PAGE_SIZE, corruption_check_size);
 101                if (start >= end)
 102                        continue;
 103
 104                memblock_reserve(start, end - start);
 105                scan_areas[num_scan_areas].addr = start;
 106                scan_areas[num_scan_areas].size = end - start;
 107
 108                /* Assume we've already mapped this early memory */
 109                memset(__va(start), 0, end - start);
 110
 111                if (++num_scan_areas >= MAX_SCAN_AREAS)
 112                        break;
 113        }
 114
 115        if (num_scan_areas)
 116                printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
 117}
 118
 119
 120void check_for_bios_corruption(void)
 121{
 122        int i;
 123        int corruption = 0;
 124
 125        if (!memory_corruption_check)
 126                return;
 127
 128        for (i = 0; i < num_scan_areas; i++) {
 129                unsigned long *addr = __va(scan_areas[i].addr);
 130                unsigned long size = scan_areas[i].size;
 131
 132                for (; size; addr++, size -= sizeof(unsigned long)) {
 133                        if (!*addr)
 134                                continue;
 135                        printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
 136                               addr, __pa(addr), *addr);
 137                        corruption = 1;
 138                        *addr = 0;
 139                }
 140        }
 141
 142        WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 143}
 144
 145static void check_corruption(struct work_struct *dummy);
 146static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
 147
 148static void check_corruption(struct work_struct *dummy)
 149{
 150        check_for_bios_corruption();
 151        schedule_delayed_work(&bios_check_work,
 152                round_jiffies_relative(corruption_check_period*HZ));
 153}
 154
 155static int start_periodic_check_for_corruption(void)
 156{
 157        if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
 158                return 0;
 159
 160        printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
 161               corruption_check_period);
 162
 163        /* First time we run the checks right away */
 164        schedule_delayed_work(&bios_check_work, 0);
 165        return 0;
 166}
 167device_initcall(start_periodic_check_for_corruption);
 168
 169