x86: early memtest to find bad ram

do simple memtest after init_memory_mapping

use find_e820_area_size to find all ram range that is not reserved.

and do some simple bits test to find some bad ram.

if find some bad ram, use reserve_early to exclude that range.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 105 insertions, 1 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 255e51f..52f54ee 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -427,6 +427,106 @@ static void __init init_gbpages(void)
 		direct_gbpages = 0;
 }
 
+static void __init memtest(unsigned long start_phys, unsigned long size, unsigned pattern)
+{
+	unsigned long i;
+	unsigned long *start;
+	unsigned long start_bad;
+	unsigned long last_bad;
+	unsigned long val;
+	unsigned long start_phys_aligned;
+	unsigned long count;
+	unsigned long incr;
+
+	switch (pattern) {
+	case 0:
+		val = 0UL;
+		break;
+	case 1:
+		val = -1UL;
+		break;
+	case 2:
+		val = 0x5555555555555555UL;
+		break;
+	case 3:
+		val = 0xaaaaaaaaaaaaaaaaUL;
+		break;
+	default:
+		return;
+	}
+
+	incr = sizeof(unsigned long);
+	start_phys_aligned = ALIGN(start_phys, incr);
+	count = (size - (start_phys_aligned - start_phys))/incr;
+	start = __va(start_phys_aligned);
+	start_bad = 0;
+	last_bad = 0;
+
+	for (i = 0; i < count; i++)
+		start[i] = val;
+	for (i = 0; i < count; i++, start++, start_phys_aligned += incr) {
+		if (*start != val) {
+			if (start_phys_aligned == last_bad + incr) {
+				last_bad += incr;
+			} else {
+				if (start_bad) {
+					printk(KERN_INFO "  %016lxx bad mem addr %016lx - %016lx reserved\n",
+						val, start_bad, last_bad + incr);
+					reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+				}
+				start_bad = last_bad = start_phys_aligned;
+			}
+		}
+	}
+	if (start_bad) {
+		printk(KERN_INFO "  %016lx bad mem addr %016lx - %016lx reserved\n",
+			val, start_bad, last_bad + incr);
+		reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+	}
+
+}
+
+static int __initdata memtest_pattern;
+static int __init parse_memtest(char *arg)
+{
+	if (arg)
+		memtest_pattern = simple_strtoul(arg, NULL, 0) + 1;
+	return 0;
+}
+
+early_param("memtest", parse_memtest);
+
+static void __init early_memtest(unsigned long start, unsigned long end)
+{
+	unsigned long t_start, t_size;
+	unsigned pattern;
+
+	if (memtest_pattern)
+		printk(KERN_INFO "early_memtest: pattern num %d", memtest_pattern);
+	for (pattern = 0; pattern < memtest_pattern; pattern++) {
+		t_start = start;
+		t_size = 0;
+		while (t_start < end) {
+			t_start = find_e820_area_size(t_start, &t_size, 1);
+
+			/* done ? */
+			if (t_start >= end)
+				break;
+			if (t_start + t_size > end)
+				t_size = end - t_start;
+
+			printk(KERN_CONT "\n  %016lx - %016lx pattern %d",
+				t_start, t_start + t_size, pattern);
+
+			memtest(t_start, t_size, pattern);
+
+			t_start += t_size;
+		}
+	}
+	if (memtest_pattern)
+		printk(KERN_CONT "\n");
+}
+
 /*
  * Setup the direct mapping of the physical memory at PAGE_OFFSET.
  * This runs before bootmem is initialized and gets pages directly from
@@ -435,8 +535,9 @@ static void __init init_gbpages(void)
 void __init_refok init_memory_mapping(unsigned long start, unsigned long end)
 {
 	unsigned long next;
+	unsigned long start_phys = start, end_phys = end;
 
-	pr_debug("init_memory_mapping\n");
+	printk(KERN_INFO "init_memory_mapping\n");
 
 	/*
 	 * Find space for the kernel direct mapping tables.
@@ -479,6 +580,9 @@ void __init_refok init_memory_mapping(unsigned long start, unsigned long end)
 	if (!after_bootmem)
 		reserve_early(table_start << PAGE_SHIFT,
 				 table_end << PAGE_SHIFT, "PGTABLE");
+
+	if (!after_bootmem)
+		early_memtest(start_phys, end_phys);
 }
 
 #ifndef CONFIG_NUMA