x86: Constify a few items
[linux-3.10.git] / 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, 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
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