| #include <linux/init.h> |
| #include <linux/sched.h> |
| #include <linux/kthread.h> |
| #include <linux/workqueue.h> |
| #include <linux/memblock.h> |
| |
| #include <asm/proto.h> |
| |
| /* |
| * Some BIOSes seem to corrupt the low 64k of memory during events |
| * like suspend/resume and unplugging an HDMI cable. Reserve all |
| * remaining free memory in that area and fill it with a distinct |
| * pattern. |
| */ |
| #define MAX_SCAN_AREAS 8 |
| |
| static int __read_mostly memory_corruption_check = -1; |
| |
| static unsigned __read_mostly corruption_check_size = 64*1024; |
| static unsigned __read_mostly corruption_check_period = 60; /* seconds */ |
| |
| static struct scan_area { |
| u64 addr; |
| u64 size; |
| } scan_areas[MAX_SCAN_AREAS]; |
| static int num_scan_areas; |
| |
| static __init int set_corruption_check(char *arg) |
| { |
| ssize_t ret; |
| unsigned long val; |
| |
| if (!arg) { |
| pr_err("memory_corruption_check config string not provided\n"); |
| return -EINVAL; |
| } |
| |
| ret = kstrtoul(arg, 10, &val); |
| if (ret) |
| return ret; |
| |
| memory_corruption_check = val; |
| return 0; |
| } |
| early_param("memory_corruption_check", set_corruption_check); |
| |
| static __init int set_corruption_check_period(char *arg) |
| { |
| ssize_t ret; |
| unsigned long val; |
| |
| if (!arg) { |
| pr_err("memory_corruption_check_period config string not provided\n"); |
| return -EINVAL; |
| } |
| |
| ret = kstrtoul(arg, 10, &val); |
| if (ret) |
| return ret; |
| |
| corruption_check_period = val; |
| return 0; |
| } |
| early_param("memory_corruption_check_period", set_corruption_check_period); |
| |
| static __init int set_corruption_check_size(char *arg) |
| { |
| char *end; |
| unsigned size; |
| |
| if (!arg) { |
| pr_err("memory_corruption_check_size config string not provided\n"); |
| return -EINVAL; |
| } |
| |
| size = memparse(arg, &end); |
| |
| if (*end == '\0') |
| corruption_check_size = size; |
| |
| return (size == corruption_check_size) ? 0 : -EINVAL; |
| } |
| early_param("memory_corruption_check_size", set_corruption_check_size); |
| |
| |
| void __init setup_bios_corruption_check(void) |
| { |
| phys_addr_t start, end; |
| u64 i; |
| |
| if (memory_corruption_check == -1) { |
| memory_corruption_check = |
| #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK |
| 1 |
| #else |
| 0 |
| #endif |
| ; |
| } |
| |
| if (corruption_check_size == 0) |
| memory_corruption_check = 0; |
| |
| if (!memory_corruption_check) |
| return; |
| |
| corruption_check_size = round_up(corruption_check_size, PAGE_SIZE); |
| |
| for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, |
| NULL) { |
| start = clamp_t(phys_addr_t, round_up(start, PAGE_SIZE), |
| PAGE_SIZE, corruption_check_size); |
| end = clamp_t(phys_addr_t, round_down(end, PAGE_SIZE), |
| PAGE_SIZE, corruption_check_size); |
| if (start >= end) |
| continue; |
| |
| memblock_reserve(start, end - start); |
| scan_areas[num_scan_areas].addr = start; |
| scan_areas[num_scan_areas].size = end - start; |
| |
| /* Assume we've already mapped this early memory */ |
| memset(__va(start), 0, end - start); |
| |
| if (++num_scan_areas >= MAX_SCAN_AREAS) |
| break; |
| } |
| |
| if (num_scan_areas) |
| printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas); |
| } |
| |
| |
| void check_for_bios_corruption(void) |
| { |
| int i; |
| int corruption = 0; |
| |
| if (!memory_corruption_check) |
| return; |
| |
| for (i = 0; i < num_scan_areas; i++) { |
| unsigned long *addr = __va(scan_areas[i].addr); |
| unsigned long size = scan_areas[i].size; |
| |
| for (; size; addr++, size -= sizeof(unsigned long)) { |
| if (!*addr) |
| continue; |
| printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n", |
| addr, __pa(addr), *addr); |
| corruption = 1; |
| *addr = 0; |
| } |
| } |
| |
| WARN_ONCE(corruption, KERN_ERR "Memory corruption detected in low memory\n"); |
| } |
| |
| static void check_corruption(struct work_struct *dummy); |
| static DECLARE_DELAYED_WORK(bios_check_work, check_corruption); |
| |
| static void check_corruption(struct work_struct *dummy) |
| { |
| check_for_bios_corruption(); |
| schedule_delayed_work(&bios_check_work, |
| round_jiffies_relative(corruption_check_period*HZ)); |
| } |
| |
| static int start_periodic_check_for_corruption(void) |
| { |
| if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0) |
| return 0; |
| |
| printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n", |
| corruption_check_period); |
| |
| /* First time we run the checks right away */ |
| schedule_delayed_work(&bios_check_work, 0); |
| return 0; |
| } |
| device_initcall(start_periodic_check_for_corruption); |
| |