x86: fdiv bug detection fix
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>
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index c9b58a8..c8e315f 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -50,6 +50,8 @@
*/
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 @@
"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");
}