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Re: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
- From: Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- To: Martin Bligh <mbligh at google dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, prasanna at in dot ibm dot com, Andrew Morton <akpm at osdl dot org>, Ingo Molnar <mingo at elte dot hu>, Paul Mundt <lethal at linux-sh dot org>, linux-kernel <linux-kernel at vger dot kernel dot org>, Jes Sorensen <jes at sgi dot com>, Tom Zanussi <zanussi at us dot ibm dot com>, Richard J Moore <richardj_moore at uk dot ibm dot com>, Michel Dagenais <michel dot dagenais at polymtl dot ca>, Christoph Hellwig <hch at infradead dot org>, Greg Kroah-Hartman <gregkh at suse dot de>, Thomas Gleixner <tglx at linutronix dot de>, William Cohen <wcohen at redhat dot com>, ltt-dev at shafik dot org, systemtap at sources dot redhat dot com, Alan Cox <alan at lxorguk dot ukuu dot org dot uk>, Jeremy Fitzhardinge <jeremy at goop dot org>, Karim Yaghmour <karim at opersys dot com>, Pavel Machek <pavel at suse dot cz>, Joe Perches <joe at perches dot com>, "Randy.Dunlap" <rdunlap at xenotime dot net>, "Jose R. Santos" <jrs at us dot ibm dot com>
- Date: Mon, 25 Sep 2006 19:56:17 -0400
- Subject: Re: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
- References: <20060925233349.GA2352@Krystal>
Just as a precision :
The following sequence (please refer to the code below for local symbols
1 and 2) :
1:
preempt_disable()
call (*__mark_call_##name)(format, ## args);
preempt_enable_no_resched()
2:
is insured because :
1 is part of an inline assembly with rw dependency on __marker_sequencer
the call is surrounded by memory barriers.
2 is part of an inline assembly with rw dependency on __marker_sequencer
Mathieu
* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
> +++ b/include/asm-generic/marker.h
> @@ -0,0 +1,22 @@
> +/*
> + * marker.h
> + *
> + * Code markup for dynamic and static tracing. Generic header.
> + *
> + * This file is released under the GPLv2.
> + * See the file COPYING for more details.
> + */
> +
> +#define MARK_CALL(name, format, args...) \
> + do { \
> + static marker_probe_func *__mark_call_##name = \
> + __mark_empty_function; \
> + asm volatile( ".section .markers, \"a\";\n\t" \
> + ".long %1, %2;\n\t" \
> + ".previous;\n\t" : "+m" (__marker_sequencer) : \
> + "m" (__mark_call_##name), \
> + "m" (*format)); \
> + preempt_disable(); \
> + (*__mark_call_##name)(format, ## args); \
> + preempt_enable_no_resched(); \
> + } while(0)
> --- /dev/null
> +++ b/include/asm-i386/marker.h
> @@ -0,0 +1,30 @@
> +/*
> + * marker.h
> + *
> + * Code markup for dynamic and static tracing. i386 architecture optimisations.
> + *
> + * (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> + *
> + * This file is released under the GPLv2.
> + * See the file COPYING for more details.
> + */
> +
> +#include <asm-generic/marker.h>
> +
> +#define ARCH_HAS_MARK_JUMP
> +
> +/* Note : max 256 bytes between over_label and near_jump */
> +#define MARK_JUMP(name, format, args...) \
> + do { \
> + asm volatile( ".section .markers, \"a\";\n\t" \
> + ".long 0f, 1f, 2f;\n\t" \
> + ".previous;\n\t" \
> + ".align 16;\n\t" \
> + ".byte 0xeb;\n\t" \
> + "0:\n\t" \
> + ".byte 2f-1f;\n\t" \
> + "1:\n\t" \
> + : "+m" (__marker_sequencer) : ); \
> + MARK_CALL(name, format, ## args); \
> + asm volatile ( "2:\n\t" : "+m" (__marker_sequencer) : ); \
> + } while(0)
OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg
Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68