x86: memtest: reuse test patterns when memtest parameter exceeds number of available patterns
Impact: fix unexpected behaviour when pattern number is out of range
Current implementation provides 4 patterns for memtest. The code doesn't
check whether the memtest parameter value exceeds the maximum pattern number.
Instead the memtest code pretends to test with non-existing patterns, e.g.
when booting with memtest=10 I've observed the following
...
early_memtest: pattern num 10
0000001000 - 0000006000 pattern 0
...
0000001000 - 0000006000 pattern 1
...
0000001000 - 0000006000 pattern 2
...
0000001000 - 0000006000 pattern 3
...
0000001000 - 0000006000 pattern 4
...
0000001000 - 0000006000 pattern 5
...
0000001000 - 0000006000 pattern 6
...
0000001000 - 0000006000 pattern 7
...
0000001000 - 0000006000 pattern 8
...
0000001000 - 0000006000 pattern 9
...
But in fact Linux didn't test anything for patterns > 4 as the default
case in memtest() is to leave the function.
I suggest to use the memtest parameter as the number of tests to be
performed and to re-iterate over all existing patterns.
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/memtest.c b/arch/x86/mm/memtest.c
index 9cab18b..00b8bdc 100644
--- a/arch/x86/mm/memtest.c
+++ b/arch/x86/mm/memtest.c
@@ -9,6 +9,8 @@
#include <asm/e820.h>
+#define _MAX_MEM_PATTERNS 4
+
static void __init memtest(unsigned long start_phys, unsigned long size,
unsigned pattern)
{
@@ -21,6 +23,8 @@
unsigned long count;
unsigned long incr;
+ pattern = pattern % _MAX_MEM_PATTERNS;
+
switch (pattern) {
case 0:
val = 0UL;
@@ -110,8 +114,9 @@
t_size = end - t_start;
printk(KERN_CONT "\n %010llx - %010llx pattern %d",
- (unsigned long long)t_start,
- (unsigned long long)t_start + t_size, pattern);
+ (unsigned long long)t_start,
+ (unsigned long long)t_start + t_size,
+ pattern % _MAX_MEM_PATTERNS);
memtest(t_start, t_size, pattern);
