linux-kernel - Re: [ltt-dev] LTTng 0.11

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Date:	Wed, 16 Jul 2008 23:10:10 -0400
From:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
To:	ltt-dev@...ts.casi.polymtl.ca, linux-kernel@...r.kernel.org,
	Takashi Nishiie <t-nishiie@...css.fujitsu.com>
Subject: Re: [ltt-dev] LTTng 0.11

LTTng 0.11 is released, which contains this bugfix.

http://ltt.polymtl.ca/lttng/patch-2.6.26-0.11.tar.bz2

Mathieu

* Mathieu Desnoyers (compudj@...stal.dyndns.org) wrote:
> I rarely emit a single patch for a fix wrt LTTng (I usually just release
> a new version), but this one is worth it. It will be in 0.11 pretty
> soon, but if you want to apply it to 0.10 meanwhile, it's highly
> recommended.
> 
> Caused a kernel OOPS when loading the tracepoint probes once in a while
> on a 8-way x86_64.
> 
> 
> Immedate Values Optimized Jump Fix
> 
> Fix the immediate values optimized jump fallback, which parameters were wrong
> following the last changes. It should be a 5 bytes instruction (not 2) with a 4
> bytes operand.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
> ---
>  arch/x86/kernel/immediate.c |    2 +-
>  include/asm-x86/immediate.h |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6-lttng/arch/x86/kernel/immediate.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/x86/kernel/immediate.c	2008-07-16 22:50:35.000000000 -0400
> +++ linux-2.6-lttng/arch/x86/kernel/immediate.c	2008-07-16 22:51:07.000000000 -0400
> @@ -500,7 +500,7 @@ __kprobes int arch_imv_update(struct __i
>  				"Jump target fallback at %lX, nr fail %d\n",
>  				imv->imv, ++nr_fail);
>  #endif
> -			imv->size = 1;
> +			imv->size = 4;	/* Fallback on movl */
>  		} else {
>  #ifdef DEBUG_IMMEDIATE
>  			static int nr_success;
> Index: linux-2.6-lttng/include/asm-x86/immediate.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-x86/immediate.h	2008-07-16 22:49:19.000000000 -0400
> +++ linux-2.6-lttng/include/asm-x86/immediate.h	2008-07-16 22:51:07.000000000 -0400
> @@ -132,7 +132,7 @@ struct __imv {
>  		BUILD_BUG_ON(sizeof(__typeof__(name##__imv)) > 1);	\
>  		asm (".section __imv,\"aw\",@progbits\n\t"		\
>  			_ASM_PTR "%c1, (3f)-4\n\t"			\
> -			".byte 0, 2\n\t"				\
> +			".byte 0, 5\n\t"				\
>  			".previous\n\t"					\
>  			"mov $0,%0\n\t"					\
>  			"3:\n\t"					\
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
> _______________________________________________
> ltt-dev mailing list
> ltt-dev@...ts.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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