1 #include <linux/init.h>
2 #include <linux/sched.h>
3 #include <linux/kthread.h>
4 #include <linux/workqueue.h>
5 #include <linux/memblock.h>
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
15 #define MAX_SCAN_AREAS 8
17 static int __read_mostly memory_corruption_check = -1;
19 static unsigned __read_mostly corruption_check_size = 64*1024;
20 static unsigned __read_mostly corruption_check_period = 60; /* seconds */
22 static struct scan_area {
25 } scan_areas[MAX_SCAN_AREAS];
26 static int num_scan_areas;
28 static __init int set_corruption_check(char *arg)
34 pr_err("memory_corruption_check config string not provided\n");
38 ret = kstrtoul(arg, 10, &val);
42 memory_corruption_check = val;
45 early_param("memory_corruption_check", set_corruption_check);
47 static __init int set_corruption_check_period(char *arg)
53 pr_err("memory_corruption_check_period config string not provided\n");
57 ret = kstrtoul(arg, 10, &val);
61 corruption_check_period = val;
64 early_param("memory_corruption_check_period", set_corruption_check_period);
66 static __init int set_corruption_check_size(char *arg)
72 pr_err("memory_corruption_check_size config string not provided\n");
76 size = memparse(arg, &end);
79 corruption_check_size = size;
81 return (size == corruption_check_size) ? 0 : -EINVAL;
83 early_param("memory_corruption_check_size", set_corruption_check_size);
86 void __init setup_bios_corruption_check(void)
88 phys_addr_t start, end;
91 if (memory_corruption_check == -1) {
92 memory_corruption_check =
93 #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
101 if (corruption_check_size == 0)
102 memory_corruption_check = 0;
104 if (!memory_corruption_check)
107 corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
109 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end,
111 start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE),
112 PAGE_SIZE, corruption_check_size);
113 end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE),
114 PAGE_SIZE, corruption_check_size);
118 memblock_reserve(start, end - start);
119 scan_areas[num_scan_areas].addr = start;
120 scan_areas[num_scan_areas].size = end - start;
122 /* Assume we've already mapped this early memory */
123 memset(__va(start), 0, end - start);
125 if (++num_scan_areas >= MAX_SCAN_AREAS)
130 printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
134 void check_for_bios_corruption(void)
139 if (!memory_corruption_check)
142 for (i = 0; i < num_scan_areas; i++) {
143 unsigned long *addr = __va(scan_areas[i].addr);
144 unsigned long size = scan_areas[i].size;
146 for (; size; addr++, size -= sizeof(unsigned long)) {
149 printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
150 addr, __pa(addr), *addr);
156 WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n");
159 static void check_corruption(struct work_struct *dummy);
160 static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
162 static void check_corruption(struct work_struct *dummy)
164 check_for_bios_corruption();
165 schedule_delayed_work(&bios_check_work,
166 round_jiffies_relative(corruption_check_period*HZ));
169 static int start_periodic_check_for_corruption(void)
171 if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
174 printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
175 corruption_check_period);
177 /* First time we run the checks right away */
178 schedule_delayed_work(&bios_check_work, 0);
181 device_initcall(start_periodic_check_for_corruption);