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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
17static int __read_mostly memory_corruption_check = -1;
18
19static unsigned __read_mostly corruption_check_size = 64*1024;
20static unsigned __read_mostly corruption_check_period = 60; /* seconds */
21
22static struct scan_area {
23 u64 addr;
24 u64 size;
25} scan_areas[MAX_SCAN_AREAS];
26static int num_scan_areas;
27
28static __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}
40early_param("memory_corruption_check", set_corruption_check);
41
42static __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}
54early_param("memory_corruption_check_period", set_corruption_check_period);
55
56static __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}
68early_param("memory_corruption_check_size", set_corruption_check_size);
69
70
71void __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, MAX_NUMNODES, &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
118void 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
143static void check_corruption(struct work_struct *dummy);
144static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
145
146static 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
153static 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
166module_init(start_periodic_check_for_corruption);
167
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
17static int __read_mostly memory_corruption_check = -1;
18
19static unsigned __read_mostly corruption_check_size = 64*1024;
20static unsigned __read_mostly corruption_check_period = 60; /* seconds */
21
22static struct scan_area {
23 u64 addr;
24 u64 size;
25} scan_areas[MAX_SCAN_AREAS];
26static int num_scan_areas;
27
28static __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}
36early_param("memory_corruption_check", set_corruption_check);
37
38static __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}
46early_param("memory_corruption_check_period", set_corruption_check_period);
47
48static __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}
60early_param("memory_corruption_check_size", set_corruption_check_size);
61
62
63void __init setup_bios_corruption_check(void)
64{
65 u64 addr = PAGE_SIZE; /* assume first page is reserved anyway */
66
67 if (memory_corruption_check == -1) {
68 memory_corruption_check =
69#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
70 1
71#else
72 0
73#endif
74 ;
75 }
76
77 if (corruption_check_size == 0)
78 memory_corruption_check = 0;
79
80 if (!memory_corruption_check)
81 return;
82
83 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
84
85 while (addr < corruption_check_size && num_scan_areas < MAX_SCAN_AREAS) {
86 u64 size;
87 addr = memblock_x86_find_in_range_size(addr, &size, PAGE_SIZE);
88
89 if (addr == MEMBLOCK_ERROR)
90 break;
91
92 if (addr >= corruption_check_size)
93 break;
94
95 if ((addr + size) > corruption_check_size)
96 size = corruption_check_size - addr;
97
98 memblock_x86_reserve_range(addr, addr + size, "SCAN RAM");
99 scan_areas[num_scan_areas].addr = addr;
100 scan_areas[num_scan_areas].size = size;
101 num_scan_areas++;
102
103 /* Assume we've already mapped this early memory */
104 memset(__va(addr), 0, size);
105
106 addr += size;
107 }
108
109 if (num_scan_areas)
110 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
111}
112
113
114void check_for_bios_corruption(void)
115{
116 int i;
117 int corruption = 0;
118
119 if (!memory_corruption_check)
120 return;
121
122 for (i = 0; i < num_scan_areas; i++) {
123 unsigned long *addr = __va(scan_areas[i].addr);
124 unsigned long size = scan_areas[i].size;
125
126 for (; size; addr++, size -= sizeof(unsigned long)) {
127 if (!*addr)
128 continue;
129 printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
130 addr, __pa(addr), *addr);
131 corruption = 1;
132 *addr = 0;
133 }
134 }
135
136 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
137}
138
139static void check_corruption(struct work_struct *dummy);
140static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
141
142static void check_corruption(struct work_struct *dummy)
143{
144 check_for_bios_corruption();
145 schedule_delayed_work(&bios_check_work,
146 round_jiffies_relative(corruption_check_period*HZ));
147}
148
149static int start_periodic_check_for_corruption(void)
150{
151 if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
152 return 0;
153
154 printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
155 corruption_check_period);
156
157 /* First time we run the checks right away */
158 schedule_delayed_work(&bios_check_work, 0);
159 return 0;
160}
161
162module_init(start_periodic_check_for_corruption);
163