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x86: fdiv bug detection fix

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The fdiv detection code writes s32 integer into
the boot_cpu_data.fdiv_bug.
However, the boot_cpu_data.fdiv_bug is only char (s8)
field so the detection overwrites already set fields for
other bugs, e.g. the f00f bug field.

Use local s32 variable to receive result.

This is a partial fix to Bugzilla #9928  - fixes wrong
information about the f00f bug (tested) and probably
for coma bug (I have no cpu to test this).

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Krzysztof Helt 2008-07-31 23:43:44 +02:00 committed by Ingo Molnar
parent 8978b74253
commit e0d22d03c0
1 changed files with 5 additions and 1 deletions
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6
arch/x86/kernel/cpu/bugs.c
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@ -50,6 +50,8 @@ static double __initdata y = 3145727.0;
*/
static void __init check_fpu(void)
{
s32 fdiv_bug;
if (!boot_cpu_data.hard_math) {
#ifndef CONFIG_MATH_EMULATION
printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
@ -74,8 +76,10 @@ static void __init check_fpu(void)
"fistpl %0\n\t"
"fwait\n\t"
"fninit"
: "=m" (*&boot_cpu_data.fdiv_bug)
: "=m" (*&fdiv_bug)
: "m" (*&x), "m" (*&y));
boot_cpu_data.fdiv_bug = fdiv_bug;
if (boot_cpu_data.fdiv_bug)
printk("Hmm, FPU with FDIV bug.\n");
}