arch/x86/kernel/check.c

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