arch/x86/kernel/check.c

   1 #include <linux/module.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         char *end;
  31
  32         memory_corruption_check = simple_strtol(arg, &end, 10);
  33
  34         return (*end == 0) ? 0 : -EINVAL;
  35 }
  36 early_param("memory_corruption_check", set_corruption_check);
  37
  38 static __init int set_corruption_check_period(char *arg)
  39 {
  40         char *end;
  41
  42         corruption_check_period = simple_strtoul(arg, &end, 10);
  43
  44         return (*end == 0) ? 0 : -EINVAL;
  45 }
  46 early_param("memory_corruption_check_period", set_corruption_check_period);
  47
  48 static __init int set_corruption_check_size(char *arg)
  49 {
  50         char *end;
  51         unsigned size;
  52
  53         size = memparse(arg, &end);
  54
  55         if (*end == '\0')
  56                 corruption_check_size = size;
  57
  58         return (size == corruption_check_size) ? 0 : -EINVAL;
  59 }
  60 early_param("memory_corruption_check_size", set_corruption_check_size);
  61
  62
  63 void __init setup_bios_corruption_check(void)
  64 {
  65         phys_addr_t start, end;
  66         u64 i;
  67
  68         if (memory_corruption_check == -1) {
  69                 memory_corruption_check =
  70 #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
  71                         1
  72 #else
  73                         0
  74 #endif
  75                         ;
  76         }
  77
  78         if (corruption_check_size == 0)
  79                 memory_corruption_check = 0;
  80
  81         if (!memory_corruption_check)
  82                 return;
  83
  84         corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
  85
  86         for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL) {
  87                 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
  88                                 PAGE_SIZE, corruption_check_size);
  89                 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
  90                               PAGE_SIZE, corruption_check_size);
  91                 if (start >= end)
  92                         continue;
  93
  94                 memblock_reserve(start, end - start);
  95                 scan_areas[num_scan_areas].addr = start;
  96                 scan_areas[num_scan_areas].size = end - start;
  97
  98                 /* Assume we've already mapped this early memory */
  99                 memset(__va(start), 0, end - start);
 100
 101                 if (++num_scan_areas >= MAX_SCAN_AREAS)
 102                         break;
 103         }
 104
 105         if (num_scan_areas)
 106                 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
 107 }
 108
 109
 110 void check_for_bios_corruption(void)
 111 {
 112         int i;
 113         int corruption = 0;
 114
 115         if (!memory_corruption_check)
 116                 return;
 117
 118         for (i = 0; i < num_scan_areas; i++) {
 119                 unsigned long *addr = __va(scan_areas[i].addr);
 120                 unsigned long size = scan_areas[i].size;
 121
 122                 for (; size; addr++, size -= sizeof(unsigned long)) {
 123                         if (!*addr)
 124                                 continue;
 125                         printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
 126                                addr, __pa(addr), *addr);
 127                         corruption = 1;
 128                         *addr = 0;
 129                 }
 130         }
 131
 132         WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 133 }
 134
 135 static void check_corruption(struct work_struct *dummy);
 136 static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
 137
 138 static void check_corruption(struct work_struct *dummy)
 139 {
 140         check_for_bios_corruption();
 141         schedule_delayed_work(&bios_check_work,
 142                 round_jiffies_relative(corruption_check_period*HZ));
 143 }
 144
 145 static int start_periodic_check_for_corruption(void)
 146 {
 147         if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
 148                 return 0;
 149
 150         printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
 151                corruption_check_period);
 152
 153         /* First time we run the checks right away */
 154         schedule_delayed_work(&bios_check_work, 0);
 155         return 0;
 156 }
 157
 158 module_init(start_periodic_check_for_corruption);
 159