1 #include <linux/init.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
set_corruption_check(char * arg)28 static __init int set_corruption_check(char *arg)
29 {
30 ssize_t ret;
31 unsigned long val;
32
33 if (!arg) {
34 pr_err("memory_corruption_check config string not provided\n");
35 return -EINVAL;
36 }
37
38 ret = kstrtoul(arg, 10, &val);
39 if (ret)
40 return ret;
41
42 memory_corruption_check = val;
43 return 0;
44 }
45 early_param("memory_corruption_check", set_corruption_check);
46
set_corruption_check_period(char * arg)47 static __init int set_corruption_check_period(char *arg)
48 {
49 ssize_t ret;
50 unsigned long val;
51
52 if (!arg) {
53 pr_err("memory_corruption_check_period config string not provided\n");
54 return -EINVAL;
55 }
56
57 ret = kstrtoul(arg, 10, &val);
58 if (ret)
59 return ret;
60
61 corruption_check_period = val;
62 return 0;
63 }
64 early_param("memory_corruption_check_period", set_corruption_check_period);
65
set_corruption_check_size(char * arg)66 static __init int set_corruption_check_size(char *arg)
67 {
68 char *end;
69 unsigned size;
70
71 if (!arg) {
72 pr_err("memory_corruption_check_size config string not provided\n");
73 return -EINVAL;
74 }
75
76 size = memparse(arg, &end);
77
78 if (*end == '\0')
79 corruption_check_size = size;
80
81 return (size == corruption_check_size) ? 0 : -EINVAL;
82 }
83 early_param("memory_corruption_check_size", set_corruption_check_size);
84
85
setup_bios_corruption_check(void)86 void __init setup_bios_corruption_check(void)
87 {
88 phys_addr_t start, end;
89 u64 i;
90
91 if (memory_corruption_check == -1) {
92 memory_corruption_check =
93 #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
94 1
95 #else
96 0
97 #endif
98 ;
99 }
100
101 if (corruption_check_size == 0)
102 memory_corruption_check = 0;
103
104 if (!memory_corruption_check)
105 return;
106
107 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
108
109 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
110 NULL) {
111 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
112 PAGE_SIZE, corruption_check_size);
113 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
114 PAGE_SIZE, corruption_check_size);
115 if (start >= end)
116 continue;
117
118 memblock_reserve(start, end - start);
119 scan_areas[num_scan_areas].addr = start;
120 scan_areas[num_scan_areas].size = end - start;
121
122 /* Assume we've already mapped this early memory */
123 memset(__va(start), 0, end - start);
124
125 if (++num_scan_areas >= MAX_SCAN_AREAS)
126 break;
127 }
128
129 if (num_scan_areas)
130 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
131 }
132
133
check_for_bios_corruption(void)134 void check_for_bios_corruption(void)
135 {
136 int i;
137 int corruption = 0;
138
139 if (!memory_corruption_check)
140 return;
141
142 for (i = 0; i < num_scan_areas; i++) {
143 unsigned long *addr = __va(scan_areas[i].addr);
144 unsigned long size = scan_areas[i].size;
145
146 for (; size; addr++, size -= sizeof(unsigned long)) {
147 if (!*addr)
148 continue;
149 printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
150 addr, __pa(addr), *addr);
151 corruption = 1;
152 *addr = 0;
153 }
154 }
155
156 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
157 }
158
159 static void check_corruption(struct work_struct *dummy);
160 static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
161
check_corruption(struct work_struct * dummy)162 static void check_corruption(struct work_struct *dummy)
163 {
164 check_for_bios_corruption();
165 schedule_delayed_work(&bios_check_work,
166 round_jiffies_relative(corruption_check_period*HZ));
167 }
168
start_periodic_check_for_corruption(void)169 static int start_periodic_check_for_corruption(void)
170 {
171 if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
172 return 0;
173
174 printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
175 corruption_check_period);
176
177 /* First time we run the checks right away */
178 schedule_delayed_work(&bios_check_work, 0);
179 return 0;
180 }
181 device_initcall(start_periodic_check_for_corruption);
182
183