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 ([email protected]) 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 <[email protected]>
> + *
> + * 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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