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Commit 8256e47c authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Linus Torvalds
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Linux Kernel Markers 



The marker activation functions sits in kernel/marker.c.  A hash table is used
to keep track of the registered probes and armed markers, so the markers
within a newly loaded module that should be active can be activated at module
load time.

marker_query has been removed. marker_get_first, marker_get_next and
marker_release should be used as iterators on the markers.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: default avatar"Frank Ch. Eigler" <fche@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Mike Mason <mmlnx@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 09cadedb

include/asm-generic/vmlinux.lds.h

+6 −1
Original line number Diff line number Diff line
@@ -12,7 +12,11 @@ 
/* .data section */

#define DATA_DATA							\

	*(.data)							\

	*(.data.init.refok)

	*(.data.init.refok)						\

	. = ALIGN(8);							\

	VMLINUX_SYMBOL(__start___markers) = .;				\

	*(__markers)							\

	VMLINUX_SYMBOL(__stop___markers) = .;



#define RO_DATA(align)							\

	. = ALIGN((align));						\
@@ -20,6 +24,7 @@ 
		VMLINUX_SYMBOL(__start_rodata) = .;			\

		*(.rodata) *(.rodata.*)					\

		*(__vermagic)		/* Kernel version magic */	\

		*(__markers_strings)	/* Markers: strings */		\

	}								\

									\

	.rodata1          : AT(ADDR(.rodata1) - LOAD_OFFSET) {		\

include/linux/marker.h

0 → 100644
+130 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_MARKER_H

#define _LINUX_MARKER_H



/*

 * Code markup for dynamic and static tracing.

 *

 * See Documentation/marker.txt.

 *

 * (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

 *

 * This file is released under the GPLv2.

 * See the file COPYING for more details.

 */



#include <linux/types.h>



struct module;

struct marker;



/**

 * marker_probe_func - Type of a marker probe function

 * @mdata: pointer of type struct marker

 * @private_data: caller site private data

 * @fmt: format string

 * @...: variable argument list

 *

 * Type of marker probe functions. They receive the mdata and need to parse the

 * format string to recover the variable argument list.

 */

typedef void marker_probe_func(const struct marker *mdata,

	void *private_data, const char *fmt, ...);



struct marker {

	const char *name;	/* Marker name */

	const char *format;	/* Marker format string, describing the

				 * variable argument list.

				 */

	char state;		/* Marker state. */

	marker_probe_func *call;/* Probe handler function pointer */

	void *private;		/* Private probe data */

} __attribute__((aligned(8)));



#ifdef CONFIG_MARKERS



/*

 * Note : the empty asm volatile with read constraint is used here instead of a

 * "used" attribute to fix a gcc 4.1.x bug.

 * Make sure the alignment of the structure in the __markers section will

 * not add unwanted padding between the beginning of the section and the

 * structure. Force alignment to the same alignment as the section start.

 */

#define __trace_mark(name, call_data, format, args...)			\

	do {								\

		static const char __mstrtab_name_##name[]		\

		__attribute__((section("__markers_strings")))		\

		= #name;						\

		static const char __mstrtab_format_##name[]		\

		__attribute__((section("__markers_strings")))		\

		= format;						\

		static struct marker __mark_##name			\

		__attribute__((section("__markers"), aligned(8))) =	\

		{ __mstrtab_name_##name, __mstrtab_format_##name,	\

		0, __mark_empty_function, NULL };			\

		asm volatile("" : : "i" (&__mark_##name));		\

		__mark_check_format(format, ## args);			\

		if (unlikely(__mark_##name.state)) {			\

			preempt_disable();				\

			(*__mark_##name.call)				\

				(&__mark_##name, call_data,		\

				format, ## args);			\

			preempt_enable();				\

		}							\

	} while (0)



extern void marker_update_probe_range(struct marker *begin,

	struct marker *end, struct module *probe_module, int *refcount);

#else /* !CONFIG_MARKERS */

#define __trace_mark(name, call_data, format, args...) \

		__mark_check_format(format, ## args)

static inline void marker_update_probe_range(struct marker *begin,

	struct marker *end, struct module *probe_module, int *refcount)

{ }

#endif /* CONFIG_MARKERS */



/**

 * trace_mark - Marker

 * @name: marker name, not quoted.

 * @format: format string

 * @args...: variable argument list

 *

 * Places a marker.

 */

#define trace_mark(name, format, args...) \

	__trace_mark(name, NULL, format, ## args)



#define MARK_MAX_FORMAT_LEN	1024



/**

 * MARK_NOARGS - Format string for a marker with no argument.

 */

#define MARK_NOARGS " "



/* To be used for string format validity checking with gcc */

static inline void __printf(1, 2) __mark_check_format(const char *fmt, ...)

{

}



extern marker_probe_func __mark_empty_function;



/*

 * Connect a probe to a marker.

 * private data pointer must be a valid allocated memory address, or NULL.

 */

extern int marker_probe_register(const char *name, const char *format,

				marker_probe_func *probe, void *private);



/*

 * Returns the private data given to marker_probe_register.

 */

extern void *marker_probe_unregister(const char *name);

/*

 * Unregister a marker by providing the registered private data.

 */

extern void *marker_probe_unregister_private_data(void *private);



extern int marker_arm(const char *name);

extern int marker_disarm(const char *name);

extern void *marker_get_private_data(const char *name);



#endif

include/linux/module.h

+12 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/stringify.h>

#include <linux/kobject.h>

#include <linux/moduleparam.h>

#include <linux/marker.h>

#include <asm/local.h>



#include <asm/module.h>
@@ -354,6 +355,10 @@ struct module 
	/* The command line arguments (may be mangled).  People like

	   keeping pointers to this stuff */

	char *args;

#ifdef CONFIG_MARKERS

	struct marker *markers;

	unsigned int num_markers;

#endif

};

#ifndef MODULE_ARCH_INIT

#define MODULE_ARCH_INIT {}
@@ -457,6 +462,8 @@ int unregister_module_notifier(struct notifier_block * nb); 


extern void print_modules(void);



extern void module_update_markers(struct module *probe_module, int *refcount);



#else /* !CONFIG_MODULES... */

#define EXPORT_SYMBOL(sym)

#define EXPORT_SYMBOL_GPL(sym)
@@ -556,6 +563,11 @@ static inline void print_modules(void) 
{

}



static inline void module_update_markers(struct module *probe_module,

		int *refcount)

{

}



#endif /* CONFIG_MODULES */



struct device_driver;

kernel/Kconfig.instrumentation

+6 −0
Original line number Diff line number Diff line
@@ -40,4 +40,10 @@ config KPROBES 
	  for kernel debugging, non-intrusive instrumentation and testing.

	  If in doubt, say "N".



config MARKERS

	bool "Activate markers"

	help

	  Place an empty function call at each marker site. Can be

	  dynamically changed for a probe function.



endif # INSTRUMENTATION

kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ obj-$(CONFIG_RELAY) += relay.o 
obj-$(CONFIG_SYSCTL) += utsname_sysctl.o

obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o

obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o

obj-$(CONFIG_MARKERS) += marker.o



ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)

# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is