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