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 | |
22 | static int __read_mostly memory_corruption_check = -1; |
23 | |
24 | static unsigned __read_mostly corruption_check_size = 64*1024; |
25 | static unsigned __read_mostly corruption_check_period = 60; /* seconds */ |
26 | |
27 | static struct scan_area { |
28 | u64 addr; |
29 | u64 size; |
30 | } scan_areas[MAX_SCAN_AREAS]; |
31 | static int num_scan_areas; |
32 | |
33 | static __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(s: arg, base: 10, res: &val); |
44 | if (ret) |
45 | return ret; |
46 | |
47 | memory_corruption_check = val; |
48 | |
49 | return 0; |
50 | } |
51 | early_param("memory_corruption_check" , set_corruption_check); |
52 | |
53 | static __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(s: arg, base: 10, res: &val); |
64 | if (ret) |
65 | return ret; |
66 | |
67 | corruption_check_period = val; |
68 | return 0; |
69 | } |
70 | early_param("memory_corruption_check_period" , set_corruption_check_period); |
71 | |
72 | static __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(ptr: arg, retptr: &end); |
83 | |
84 | if (*end == '\0') |
85 | corruption_check_size = size; |
86 | |
87 | return (size == corruption_check_size) ? 0 : -EINVAL; |
88 | } |
89 | early_param("memory_corruption_check_size" , set_corruption_check_size); |
90 | |
91 | |
92 | void __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(base: start, size: 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 | |
140 | static 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 | |
164 | static void check_corruption(struct work_struct *dummy); |
165 | static DECLARE_DELAYED_WORK(bios_check_work, check_corruption); |
166 | |
167 | static void check_corruption(struct work_struct *dummy) |
168 | { |
169 | check_for_bios_corruption(); |
170 | schedule_delayed_work(dwork: &bios_check_work, |
171 | delay: round_jiffies_relative(j: corruption_check_period*HZ)); |
172 | } |
173 | |
174 | static 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(dwork: &bios_check_work, delay: 0); |
183 | |
184 | return 0; |
185 | } |
186 | device_initcall(start_periodic_check_for_corruption); |
187 | |
188 | |