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

   1// SPDX-License-Identifier: GPL-2.0
   2
   3#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   4
   5#include <linux/init.h>
   6#include <linux/sched.h>
   7#include <linux/kthread.h>
   8#include <linux/workqueue.h>
   9#include <linux/memblock.h>
  10
  11#include <asm/proto.h>
  12#include <asm/setup.h>
  13
  14/*
  15 * Some BIOSes seem to corrupt the low 64k of memory during events
  16 * like suspend/resume and unplugging an HDMI cable.  Reserve all
  17 * remaining free memory in that area and fill it with a distinct
  18 * pattern.
  19 */
  20#define MAX_SCAN_AREAS  8
  21
  22static int __read_mostly memory_corruption_check = -1;
  23
  24static unsigned __read_mostly corruption_check_size = 64*1024;
  25static unsigned __read_mostly corruption_check_period = 60; /* seconds */
  26
  27static struct scan_area {
  28        u64 addr;
  29        u64 size;
  30} scan_areas[MAX_SCAN_AREAS];
  31static int num_scan_areas;
  32
  33static __init int set_corruption_check(char *arg)
  34{
  35        ssize_t ret;
  36        unsigned long val;
  37
  38        if (!arg) {
  39                pr_err("memory_corruption_check config string not provided\n");
  40                return -EINVAL;
  41        }
  42
  43        ret = kstrtoul(arg, 10, &val);
  44        if (ret)
  45                return ret;
  46
  47        memory_corruption_check = val;
  48
  49        return 0;
  50}
  51early_param("memory_corruption_check", set_corruption_check);
  52
  53static __init int set_corruption_check_period(char *arg)
  54{
  55        ssize_t ret;
  56        unsigned long val;
  57
  58        if (!arg) {
  59                pr_err("memory_corruption_check_period config string not provided\n");
  60                return -EINVAL;
  61        }
  62
  63        ret = kstrtoul(arg, 10, &val);
  64        if (ret)
  65                return ret;
  66
  67        corruption_check_period = val;
  68        return 0;
  69}
  70early_param("memory_corruption_check_period", set_corruption_check_period);
  71
  72static __init int set_corruption_check_size(char *arg)
  73{
  74        char *end;
  75        unsigned size;
  76
  77        if (!arg) {
  78                pr_err("memory_corruption_check_size config string not provided\n");
  79                return -EINVAL;
  80        }
  81
  82        size = memparse(arg, &end);
  83
  84        if (*end == '\0')
  85                corruption_check_size = size;
  86
  87        return (size == corruption_check_size) ? 0 : -EINVAL;
  88}
  89early_param("memory_corruption_check_size", set_corruption_check_size);
  90
  91
  92void __init setup_bios_corruption_check(void)
  93{
  94        phys_addr_t start, end;
  95        u64 i;
  96
  97        if (memory_corruption_check == -1) {
  98                memory_corruption_check =
  99#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
 100                        1
 101#else
 102                        0
 103#endif
 104                        ;
 105        }
 106
 107        if (corruption_check_size == 0)
 108                memory_corruption_check = 0;
 109
 110        if (!memory_corruption_check)
 111                return;
 112
 113        corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
 114
 115        for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
 116                                NULL) {
 117                start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
 118                                PAGE_SIZE, corruption_check_size);
 119                end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
 120                              PAGE_SIZE, corruption_check_size);
 121                if (start >= end)
 122                        continue;
 123
 124                memblock_reserve(start, end - start);
 125                scan_areas[num_scan_areas].addr = start;
 126                scan_areas[num_scan_areas].size = end - start;
 127
 128                /* Assume we've already mapped this early memory */
 129                memset(__va(start), 0, end - start);
 130
 131                if (++num_scan_areas >= MAX_SCAN_AREAS)
 132                        break;
 133        }
 134
 135        if (num_scan_areas)
 136                pr_info("Scanning %d areas for low memory corruption\n", num_scan_areas);
 137}
 138
 139
 140static void check_for_bios_corruption(void)
 141{
 142        int i;
 143        int corruption = 0;
 144
 145        if (!memory_corruption_check)
 146                return;
 147
 148        for (i = 0; i < num_scan_areas; i++) {
 149                unsigned long *addr = __va(scan_areas[i].addr);
 150                unsigned long size = scan_areas[i].size;
 151
 152                for (; size; addr++, size -= sizeof(unsigned long)) {
 153                        if (!*addr)
 154                                continue;
 155                        pr_err("Corrupted low memory at %p (%lx phys) = %08lx\n", addr, __pa(addr), *addr);
 156                        corruption = 1;
 157                        *addr = 0;
 158                }
 159        }
 160
 161        WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 162}
 163
 164static void check_corruption(struct work_struct *dummy);
 165static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
 166
 167static void check_corruption(struct work_struct *dummy)
 168{
 169        check_for_bios_corruption();
 170        schedule_delayed_work(&bios_check_work,
 171                round_jiffies_relative(corruption_check_period*HZ));
 172}
 173
 174static int start_periodic_check_for_corruption(void)
 175{
 176        if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
 177                return 0;
 178
 179        pr_info("Scanning for low memory corruption every %d seconds\n", corruption_check_period);
 180
 181        /* First time we run the checks right away */
 182        schedule_delayed_work(&bios_check_work, 0);
 183
 184        return 0;
 185}
 186device_initcall(start_periodic_check_for_corruption);
 187
 188