xref: /openbmc/linux/arch/x86/kernel/check.c (revision c4f7ac64)
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(arg, 10, &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(arg, 10, &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(arg, &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(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 
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(&bios_check_work,
171 		round_jiffies_relative(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(&bios_check_work, 0);
183 
184 	return 0;
185 }
186 device_initcall(start_periodic_check_for_corruption);
187 
188