linux-kernel - Re: [PATCH] x86: fix 32-bit *_cpu

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Message-ID: <20130302234623.GB15498@pd.tnic>
Date:	Sun, 3 Mar 2013 00:46:23 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Krzysztof Mazur <krzysiek@...lesie.net>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, len.brown@...el.com
Subject: Re: [PATCH] x86: fix 32-bit *_cpu_data initializers

On Sun, Mar 03, 2013 at 12:14:42AM +0100, Krzysztof Mazur wrote:
> The commit 27be457000211a6903968dfce06d5f73f051a217
> (x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag)
> removed the hlt_works_ok flag from struct cpuinfo_x86, but
> boot_cpu_data and new_cpu_data initializers were not changed causing
> setting f00f_bug flag, instead of fdiv_bug. If CONFIG_X86_F00F_BUG
> is not set the f00f_bug flag is never cleared.
> 
> To avoid such problems in future C99-style initialization is now used.
> 
> Signed-off-by: Krzysztof Mazur <krzysiek@...lesie.net>

Good catch.

Acked-by: Borislav Petkov <bp@...e.de>

> ---
> $ cat < /proc/cpuinfo
> processor	: 0
> vendor_id	: GenuineIntel
> cpu family	: 6
> model		: 13
> model name	: Intel(R) Pentium(R) M processor 1.73GHz
> stepping	: 8
> microcode	: 0x20
> cpu MHz		: 800.000
> cache size	: 2048 KB
> fdiv_bug	: no
> f00f_bug	: yes
> ...
>
> By the way now in struct cpuinfo_x86 for 32-bit systems pad0
> should be extended to 2 bytes or removed, because now 32-bit
> specific bugs area have now 6 bytes + pad0.

It's good that you bring this up - I have a patchset which removes all
those *_bug fields in cpuinfo_x86 which means the padding goes away too.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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