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