Commit e0d22d03 authored Jul 31, 2008 by Krzysztof Helt Committed by Ingo Molnar Jul 31, 2008

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>

parent 8978b742

arch/x86/kernel/cpu/bugs.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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");
		}