Initial import

1 files changed, 167 insertions, 0 deletions

diff --git a/arch/x86/kernel/check.c b/arch/x86/kernel/check.c
new file mode 100644
index 000000000..83a799562
--- /dev/null
+++ b/arch/x86/kernel/check.c
@@ -0,0 +1,167 @@
+#include <linux/module.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;
+
+	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;
+
+	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;
+
+	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, &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;
+}
+
+module_init(start_periodic_check_for_corruption);
+