kernel/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         ssize_t ret;
  31         unsigned long val;
  32
  33         ret = kstrtoul(arg, 10, &val);
  34         if (ret)
  35                 return ret;
  36
  37         memory_corruption_check = val;
  38         return 0;
  39 }
  40 early_param("memory_corruption_check", set_corruption_check);
  41
  42 static __init int set_corruption_check_period(char *arg)
  43 {
  44         ssize_t ret;
  45         unsigned long val;
  46
  47         ret = kstrtoul(arg, 10, &val);
  48         if (ret)
  49                 return ret;
  50
  51         corruption_check_period = val;
  52         return 0;
  53 }
  54 early_param("memory_corruption_check_period", set_corruption_check_period);
  55
  56 static __init int set_corruption_check_size(char *arg)
  57 {
  58         char *end;
  59         unsigned size;
  60
  61         size = memparse(arg, &end);
  62
  63         if (*end == '\0')
  64                 corruption_check_size = size;
  65
  66         return (size == corruption_check_size) ? 0 : -EINVAL;
  67 }
  68 early_param("memory_corruption_check_size", set_corruption_check_size);
  69
  70
  71 void __init setup_bios_corruption_check(void)
  72 {
  73         phys_addr_t start, end;
  74         u64 i;
  75
  76         if (memory_corruption_check == -1) {
  77                 memory_corruption_check =
  78 #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
  79                         1
  80 #else
  81                         0
  82 #endif
  83                         ;
  84         }
  85
  86         if (corruption_check_size == 0)
  87                 memory_corruption_check = 0;
  88
  89         if (!memory_corruption_check)
  90                 return;
  91
  92         corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
  93
  94         for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL) {
  95                 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
  96                                 PAGE_SIZE, corruption_check_size);
  97                 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
  98                               PAGE_SIZE, corruption_check_size);
  99                 if (start >= end)
 100                         continue;
 101
 102                 memblock_reserve(start, end - start);
 103                 scan_areas[num_scan_areas].addr = start;
 104                 scan_areas[num_scan_areas].size = end - start;
 105
 106                 /* Assume we've already mapped this early memory */
 107                 memset(__va(start), 0, end - start);
 108
 109                 if (++num_scan_areas >= MAX_SCAN_AREAS)
 110                         break;
 111         }
 112
 113         if (num_scan_areas)
 114                 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
 115 }
 116
 117
 118 void check_for_bios_corruption(void)
 119 {
 120         int i;
 121         int corruption = 0;
 122
 123         if (!memory_corruption_check)
 124                 return;
 125
 126         for (i = 0; i < num_scan_areas; i++) {
 127                 unsigned long *addr = __va(scan_areas[i].addr);
 128                 unsigned long size = scan_areas[i].size;
 129
 130                 for (; size; addr++, size -= sizeof(unsigned long)) {
 131                         if (!*addr)
 132                                 continue;
 133                         printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
 134                                addr, __pa(addr), *addr);
 135                         corruption = 1;
 136                         *addr = 0;
 137                 }
 138         }
 139
 140         WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 141 }
 142
 143 static void check_corruption(struct work_struct *dummy);
 144 static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
 145
 146 static void check_corruption(struct work_struct *dummy)
 147 {
 148         check_for_bios_corruption();
 149         schedule_delayed_work(&bios_check_work,
 150                 round_jiffies_relative(corruption_check_period*HZ));
 151 }
 152
 153 static int start_periodic_check_for_corruption(void)
 154 {
 155         if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
 156                 return 0;
 157
 158         printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
 159                corruption_check_period);
 160
 161         /* First time we run the checks right away */
 162         schedule_delayed_work(&bios_check_work, 0);
 163         return 0;
 164 }
 165
 166 module_init(start_periodic_check_for_corruption);
 167