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