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