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x86: memtest: reuse test patterns when memtest parameter exceeds number of available patterns

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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>
This commit is contained in:
Andreas Herrmann 2009-02-25 11:26:18 +01:00 committed by Ingo Molnar
parent a852cbfaaf
commit 40823f737e
1 changed files with 7 additions and 2 deletions
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9
arch/x86/mm/memtest.c
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@ -9,6 +9,8 @@
#include <asm/e820.h> #include <asm/e820.h>
#define _MAX_MEM_PATTERNS 4
static void __init memtest(unsigned long start_phys, unsigned long size, static void __init memtest(unsigned long start_phys, unsigned long size,
unsigned pattern) unsigned pattern)
{ {
@ -21,6 +23,8 @@ static void __init memtest(unsigned long start_phys, unsigned long size,
unsigned long count; unsigned long count;
unsigned long incr; unsigned long incr;
pattern = pattern % _MAX_MEM_PATTERNS;
switch (pattern) { switch (pattern) {
case 0: case 0:
val = 0UL; val = 0UL;
@ -110,8 +114,9 @@ void __init early_memtest(unsigned long start, unsigned long end)
t_size = end - t_start; t_size = end - t_start;
printk(KERN_CONT "\n %010llx - %010llx pattern %d", printk(KERN_CONT "\n %010llx - %010llx pattern %d",
(unsigned long long)t_start, (unsigned long long)t_start,
(unsigned long long)t_start + t_size, pattern); (unsigned long long)t_start + t_size,
pattern % _MAX_MEM_PATTERNS);
memtest(t_start, t_size, pattern); memtest(t_start, t_size, pattern);