Re: [PATCH] Linux Kernel Markers 0.13 for 2.6.17

[Mathieu Desnoyers]

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@xxxxxxxxxxxxxxxxxx) 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@xxxxxxxxxx>
> + *
> + * 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)
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