lkml.org 
[lkml]   [2008]   [Jul]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86: fdiv bug detection fix
On Thu, 31 Jul 2008 23:43:44 +0200
Krzysztof Helt <krzysztof.h1@wp.pl> wrote:

> From: Krzysztof Helt <krzysztof.h1@wp.pl>
>
> 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.
>
> Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
> ---
>
> 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).
>
> diff -urp linux-alsa/arch/x86/kernel/cpu/bugs.c linux-new/arch/x86/kernel/cpu/bugs.c
> --- linux-alsa/arch/x86/kernel/cpu/bugs.c 2008-07-31 12:40:31.000000000 +0200
> +++ linux-new/arch/x86/kernel/cpu/bugs.c 2008-07-31 23:24:07.722657435 +0200
> @@ -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");
> }

hm, the code seems to have been that way for quite some time. I wonder
why nobody noticed this before.


\
 
 \ /
  Last update: 2008-07-31 23:53    [W:0.126 / U:0.140 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site