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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 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
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/init.h>
3#include <linux/sched.h>
4#include <linux/kthread.h>
5#include <linux/workqueue.h>
6#include <linux/memblock.h>
7
8#include <asm/proto.h>
9
10/*
11 * Some BIOSes seem to corrupt the low 64k of memory during events
12 * like suspend/resume and unplugging an HDMI cable. Reserve all
13 * remaining free memory in that area and fill it with a distinct
14 * pattern.
15 */
16#define MAX_SCAN_AREAS 8
17
18static int __read_mostly memory_corruption_check = -1;
19
20static unsigned __read_mostly corruption_check_size = 64*1024;
21static unsigned __read_mostly corruption_check_period = 60; /* seconds */
22
23static struct scan_area {
24 u64 addr;
25 u64 size;
26} scan_areas[MAX_SCAN_AREAS];
27static int num_scan_areas;
28
29static __init int set_corruption_check(char *arg)
30{
31 ssize_t ret;
32 unsigned long val;
33
34 ret = kstrtoul(arg, 10, &val);
35 if (ret)
36 return ret;
37
38 memory_corruption_check = val;
39 return 0;
40}
41early_param("memory_corruption_check", set_corruption_check);
42
43static __init int set_corruption_check_period(char *arg)
44{
45 ssize_t ret;
46 unsigned long val;
47
48 ret = kstrtoul(arg, 10, &val);
49 if (ret)
50 return ret;
51
52 corruption_check_period = val;
53 return 0;
54}
55early_param("memory_corruption_check_period", set_corruption_check_period);
56
57static __init int set_corruption_check_size(char *arg)
58{
59 char *end;
60 unsigned size;
61
62 size = memparse(arg, &end);
63
64 if (*end == '\0')
65 corruption_check_size = size;
66
67 return (size == corruption_check_size) ? 0 : -EINVAL;
68}
69early_param("memory_corruption_check_size", set_corruption_check_size);
70
71
72void __init setup_bios_corruption_check(void)
73{
74 phys_addr_t start, end;
75 u64 i;
76
77 if (memory_corruption_check == -1) {
78 memory_corruption_check =
79#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
80 1
81#else
82 0
83#endif
84 ;
85 }
86
87 if (corruption_check_size == 0)
88 memory_corruption_check = 0;
89
90 if (!memory_corruption_check)
91 return;
92
93 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
94
95 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
96 NULL) {
97 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
98 PAGE_SIZE, corruption_check_size);
99 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
100 PAGE_SIZE, corruption_check_size);
101 if (start >= end)
102 continue;
103
104 memblock_reserve(start, end - start);
105 scan_areas[num_scan_areas].addr = start;
106 scan_areas[num_scan_areas].size = end - start;
107
108 /* Assume we've already mapped this early memory */
109 memset(__va(start), 0, end - start);
110
111 if (++num_scan_areas >= MAX_SCAN_AREAS)
112 break;
113 }
114
115 if (num_scan_areas)
116 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
117}
118
119
120void check_for_bios_corruption(void)
121{
122 int i;
123 int corruption = 0;
124
125 if (!memory_corruption_check)
126 return;
127
128 for (i = 0; i < num_scan_areas; i++) {
129 unsigned long *addr = __va(scan_areas[i].addr);
130 unsigned long size = scan_areas[i].size;
131
132 for (; size; addr++, size -= sizeof(unsigned long)) {
133 if (!*addr)
134 continue;
135 printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
136 addr, __pa(addr), *addr);
137 corruption = 1;
138 *addr = 0;
139 }
140 }
141
142 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
143}
144
145static void check_corruption(struct work_struct *dummy);
146static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
147
148static void check_corruption(struct work_struct *dummy)
149{
150 check_for_bios_corruption();
151 schedule_delayed_work(&bios_check_work,
152 round_jiffies_relative(corruption_check_period*HZ));
153}
154
155static int start_periodic_check_for_corruption(void)
156{
157 if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
158 return 0;
159
160 printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
161 corruption_check_period);
162
163 /* First time we run the checks right away */
164 schedule_delayed_work(&bios_check_work, 0);
165 return 0;
166}
167device_initcall(start_periodic_check_for_corruption);
168