x86: memtest: remove 64-bit division

Using gcc 3.3.5 a "make allmodconfig" + "CONFIG_KVM=n"
triggers a build error:

 arch/x86/mm/built-in.o(.init.text+0x43f7): In function `__change_page_attr':
 arch/x86/mm/pageattr.c:114: undefined reference to `__udivdi3'
 make: *** [.tmp_vmlinux1] Error 1

The culprit turned out to be a division in arch/x86/mm/memtest.c
For more info see this thread:

  http://marc.info/?l=linux-kernel&m=124416232620683

The patch entirely removes the division that caused the build
error.

[ Impact: build fix with certain GCC versions ]

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: xiyou.wangcong@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <20090608170939.GB12431@alberich.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 605c8be06217b0da36344abd5f23d06326bcd87a..c0bedcd10f9733a3a9a21873b9043ead3a87546e 100644 (file)
--- a/arch/x86/mm/memtest.c
+++ b/arch/x86/mm/memtest.c
@@ -40,23 +40,23 @@ static void __init reserve_bad_mem(u64 pattern, u64 start_bad, u64 end_bad)
 
 static void __init memtest(u64 pattern, u64 start_phys, u64 size)
 {
-       u64 i, count;
-       u64 *start;
+       u64 *p;
+       void *start, *end;
        u64 start_bad, last_bad;
        u64 start_phys_aligned;
        size_t incr;
 
        incr = sizeof(pattern);
        start_phys_aligned = ALIGN(start_phys, incr);
-       count = (size - (start_phys_aligned - start_phys))/incr;
        start = __va(start_phys_aligned);
+       end = start + size - (start_phys_aligned - start_phys);
        start_bad = 0;
        last_bad = 0;
 
-       for (i = 0; i < count; i++)
-               start[i] = pattern;
-       for (i = 0; i < count; i++, start++, start_phys_aligned += incr) {
-               if (*start == pattern)
+       for (p = start; p < end; p++)
+               *p = pattern;
+       for (p = start; p < end; p++, start_phys_aligned += incr) {
+               if (*p == pattern)
                        continue;
                if (start_phys_aligned == last_bad + incr) {
                        last_bad += incr;