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1// SPDX-License-Identifier: GPL-2.0
2
3#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
4
5#include <linux/init.h>
6#include <linux/sched.h>
7#include <linux/kthread.h>
8#include <linux/workqueue.h>
9#include <linux/memblock.h>
10
11#include <asm/proto.h>
12#include <asm/setup.h>
13
14/*
15 * Some BIOSes seem to corrupt the low 64k of memory during events
16 * like suspend/resume and unplugging an HDMI cable. Reserve all
17 * remaining free memory in that area and fill it with a distinct
18 * pattern.
19 */
20#define MAX_SCAN_AREAS 8
21
22static int __read_mostly memory_corruption_check = -1;
23
24static unsigned __read_mostly corruption_check_size = 64*1024;
25static unsigned __read_mostly corruption_check_period = 60; /* seconds */
26
27static struct scan_area {
28 u64 addr;
29 u64 size;
30} scan_areas[MAX_SCAN_AREAS];
31static int num_scan_areas;
32
33static __init int set_corruption_check(char *arg)
34{
35 ssize_t ret;
36 unsigned long val;
37
38 if (!arg) {
39 pr_err("memory_corruption_check config string not provided\n");
40 return -EINVAL;
41 }
42
43 ret = kstrtoul(arg, 10, &val);
44 if (ret)
45 return ret;
46
47 memory_corruption_check = val;
48
49 return 0;
50}
51early_param("memory_corruption_check", set_corruption_check);
52
53static __init int set_corruption_check_period(char *arg)
54{
55 ssize_t ret;
56 unsigned long val;
57
58 if (!arg) {
59 pr_err("memory_corruption_check_period config string not provided\n");
60 return -EINVAL;
61 }
62
63 ret = kstrtoul(arg, 10, &val);
64 if (ret)
65 return ret;
66
67 corruption_check_period = val;
68 return 0;
69}
70early_param("memory_corruption_check_period", set_corruption_check_period);
71
72static __init int set_corruption_check_size(char *arg)
73{
74 char *end;
75 unsigned size;
76
77 if (!arg) {
78 pr_err("memory_corruption_check_size config string not provided\n");
79 return -EINVAL;
80 }
81
82 size = memparse(arg, &end);
83
84 if (*end == '\0')
85 corruption_check_size = size;
86
87 return (size == corruption_check_size) ? 0 : -EINVAL;
88}
89early_param("memory_corruption_check_size", set_corruption_check_size);
90
91
92void __init setup_bios_corruption_check(void)
93{
94 phys_addr_t start, end;
95 u64 i;
96
97 if (memory_corruption_check == -1) {
98 memory_corruption_check =
99#ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
100 1
101#else
102 0
103#endif
104 ;
105 }
106
107 if (corruption_check_size == 0)
108 memory_corruption_check = 0;
109
110 if (!memory_corruption_check)
111 return;
112
113 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
114
115 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
116 NULL) {
117 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
118 PAGE_SIZE, corruption_check_size);
119 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
120 PAGE_SIZE, corruption_check_size);
121 if (start >= end)
122 continue;
123
124 memblock_reserve(start, end - start);
125 scan_areas[num_scan_areas].addr = start;
126 scan_areas[num_scan_areas].size = end - start;
127
128 /* Assume we've already mapped this early memory */
129 memset(__va(start), 0, end - start);
130
131 if (++num_scan_areas >= MAX_SCAN_AREAS)
132 break;
133 }
134
135 if (num_scan_areas)
136 pr_info("Scanning %d areas for low memory corruption\n", num_scan_areas);
137}
138
139
140static void check_for_bios_corruption(void)
141{
142 int i;
143 int corruption = 0;
144
145 if (!memory_corruption_check)
146 return;
147
148 for (i = 0; i < num_scan_areas; i++) {
149 unsigned long *addr = __va(scan_areas[i].addr);
150 unsigned long size = scan_areas[i].size;
151
152 for (; size; addr++, size -= sizeof(unsigned long)) {
153 if (!*addr)
154 continue;
155 pr_err("Corrupted low memory at %p (%lx phys) = %08lx\n", addr, __pa(addr), *addr);
156 corruption = 1;
157 *addr = 0;
158 }
159 }
160
161 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
162}
163
164static void check_corruption(struct work_struct *dummy);
165static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
166
167static void check_corruption(struct work_struct *dummy)
168{
169 check_for_bios_corruption();
170 schedule_delayed_work(&bios_check_work,
171 round_jiffies_relative(corruption_check_period*HZ));
172}
173
174static int start_periodic_check_for_corruption(void)
175{
176 if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
177 return 0;
178
179 pr_info("Scanning for low memory corruption every %d seconds\n", corruption_check_period);
180
181 /* First time we run the checks right away */
182 schedule_delayed_work(&bios_check_work, 0);
183
184 return 0;
185}
186device_initcall(start_periodic_check_for_corruption);
187
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