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-rw-r--r--arch/x86/kernel/check.c161
1 files changed, 161 insertions, 0 deletions
diff --git a/arch/x86/kernel/check.c b/arch/x86/kernel/check.c
new file mode 100644
index 000000000000..2ac0ab71412a
--- /dev/null
+++ b/arch/x86/kernel/check.c
@@ -0,0 +1,161 @@
1#include <linux/module.h>
2#include <linux/sched.h>
3#include <linux/kthread.h>
4#include <linux/workqueue.h>
5#include <asm/e820.h>
6#include <asm/proto.h>
7
8/*
9 * Some BIOSes seem to corrupt the low 64k of memory during events
10 * like suspend/resume and unplugging an HDMI cable. Reserve all
11 * remaining free memory in that area and fill it with a distinct
12 * pattern.
13 */
14#define MAX_SCAN_AREAS 8
15
16static int __read_mostly memory_corruption_check = -1;
17
18static unsigned __read_mostly corruption_check_size = 64*1024;
19static unsigned __read_mostly corruption_check_period = 60; /* seconds */
20
21static struct e820entry scan_areas[MAX_SCAN_AREAS];
22static int num_scan_areas;
23
24
25static __init int set_corruption_check(char *arg)
26{
27 char *end;
28
29 memory_corruption_check = simple_strtol(arg, &end, 10);
30
31 return (*end == 0) ? 0 : -EINVAL;
32}
33early_param("memory_corruption_check", set_corruption_check);
34
35static __init int set_corruption_check_period(char *arg)
36{
37 char *end;
38
39 corruption_check_period = simple_strtoul(arg, &end, 10);
40
41 return (*end == 0) ? 0 : -EINVAL;
42}
43early_param("memory_corruption_check_period", set_corruption_check_period);
44
45static __init int set_corruption_check_size(char *arg)
46{
47 char *end;
48 unsigned size;
49
50 size = memparse(arg, &end);
51
52 if (*end == '\0')
53 corruption_check_size = size;
54
55 return (size == corruption_check_size) ? 0 : -EINVAL;
56}
57early_param("memory_corruption_check_size", set_corruption_check_size);
58
59
60void __init setup_bios_corruption_check(void)
61{
62 u64 addr = PAGE_SIZE; /* assume first page is reserved anyway */
63
64 if (memory_corruption_check == -1) {
65 memory_corruption_check =
66#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
67 1
68#else
69 0
70#endif
71 ;
72 }
73
74 if (corruption_check_size == 0)
75 memory_corruption_check = 0;
76
77 if (!memory_corruption_check)
78 return;
79
80 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
81
82 while (addr < corruption_check_size && num_scan_areas < MAX_SCAN_AREAS) {
83 u64 size;
84 addr = find_e820_area_size(addr, &size, PAGE_SIZE);
85
86 if (addr == 0)
87 break;
88
89 if ((addr + size) > corruption_check_size)
90 size = corruption_check_size - addr;
91
92 if (size == 0)
93 break;
94
95 e820_update_range(addr, size, E820_RAM, E820_RESERVED);
96 scan_areas[num_scan_areas].addr = addr;
97 scan_areas[num_scan_areas].size = size;
98 num_scan_areas++;
99
100 /* Assume we've already mapped this early memory */
101 memset(__va(addr), 0, size);
102
103 addr += size;
104 }
105
106 printk(KERN_INFO "Scanning %d areas for low memory corruption\n",
107 num_scan_areas);
108 update_e820();
109}
110
111
112void check_for_bios_corruption(void)
113{
114 int i;
115 int corruption = 0;
116
117 if (!memory_corruption_check)
118 return;
119
120 for (i = 0; i < num_scan_areas; i++) {
121 unsigned long *addr = __va(scan_areas[i].addr);
122 unsigned long size = scan_areas[i].size;
123
124 for (; size; addr++, size -= sizeof(unsigned long)) {
125 if (!*addr)
126 continue;
127 printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
128 addr, __pa(addr), *addr);
129 corruption = 1;
130 *addr = 0;
131 }
132 }
133
134 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
135}
136
137static void check_corruption(struct work_struct *dummy);
138static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
139
140static void check_corruption(struct work_struct *dummy)
141{
142 check_for_bios_corruption();
143 schedule_delayed_work(&bios_check_work,
144 round_jiffies_relative(corruption_check_period*HZ));
145}
146
147static int start_periodic_check_for_corruption(void)
148{
149 if (!memory_corruption_check || corruption_check_period == 0)
150 return 0;
151
152 printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
153 corruption_check_period);
154
155 /* First time we run the checks right away */
156 schedule_delayed_work(&bios_check_work, 0);
157 return 0;
158}
159
160module_init(start_periodic_check_for_corruption);
161