linux-kernel - Re: [patch] Fix crash due to missing debugctlmsr on AMD K6-3

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Message-ID: <20080722121749.GC5806@elte.hu>
Date:	Tue, 22 Jul 2008 14:17:49 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jan Kratochvil <jan.kratochvil@...hat.com>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Roland McGrath <roland@...hat.com>,
	Mikulas Patocka <mpatocka@...hat.com>,
	Chuck Ebbert <cebbert@...hat.com>
Subject: Re: [patch] Fix crash due to missing debugctlmsr on AMD K6-3


* Jan Kratochvil <jan.kratochvil@...hat.com> wrote:

> Hi,
> 
> currently if you use PTRACE_SINGLEBLOCK on AMD K6-3 (i586) it will 
> crash. Kernel now wrongly assumes existing DEBUGCTLMSR MSR register 
> there.
> 
> Removed the assumption also for some other non-K6 CPUs but I am not 
> sure there (but it can only bring small inefficiency there if my 
> assumption is wrong).
> 
> Based on info from Roland McGrath, Chuck Ebbert and Mikulas Patocka. 
> More info at:
> 	https://bugzilla.redhat.com/show_bug.cgi?id=456175
> 
> Please Cc me in a reply.

applied to tip/x86/urgent, thanks Jan! The commit below is also for 
-stable.

	Ingo

----------------->
commit d536b1f86591fb081c7a56eab04e711eb4dab951
Author: Jan Kratochvil <jan.kratochvil@...hat.com>
Date:   Tue Jul 22 14:00:47 2008 +0200

    x86: fix crash due to missing debugctlmsr on AMD K6-3
    
    currently if you use PTRACE_SINGLEBLOCK on AMD K6-3 (i586) it will crash.
    Kernel now wrongly assumes existing DEBUGCTLMSR MSR register there.
    
    Removed the assumption also for some other non-K6 CPUs but I am not sure there
    (but it can only bring small inefficiency there if my assumption is wrong).
    
    Based on info from Roland McGrath, Chuck Ebbert and Mikulas Patocka.
    More info at:
    	https://bugzilla.redhat.com/show_bug.cgi?id=456175
    
    Signed-off-by: Jan Kratochvil <jan.kratochvil@...hat.com>
    Cc: <stable@...nel.org>
    Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/Kconfig.cpu |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 54b8c02..2c518fb 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -414,4 +414,4 @@ config X86_MINIMUM_CPU_FAMILY
 
 config X86_DEBUGCTLMSR
 	def_bool y
-	depends on !(M586MMX || M586TSC || M586 || M486 || M386)
+	depends on !(MK6 || MWINCHIPC6 || MWINCHIP2 || MWINCHIP3D || MCYRIXIII || M586MMX || M586TSC || M586 || M486 || M386)
--
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