Commit 52159d98 authored by Jason Baron's avatar Jason Baron Committed by Steven Rostedt
Browse files

jump label: Convert dynamic debug to use jump labels 



Convert the 'dynamic debug' infrastructure to use jump labels.

Signed-off-by: default avatarJason Baron <jbaron@redhat.com>
LKML-Reference: <b77627358cea3e27d7be4386f45f66219afb8452.1284733808.git.jbaron@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 8f7b50c5

include/linux/dynamic_debug.h

+21 −18
Original line number Diff line number Diff line 
#ifndef _DYNAMIC_DEBUG_H

#define _DYNAMIC_DEBUG_H



#include <linux/jump_label.h>



/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which

 * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They

 * use independent hash functions, to reduce the chance of false positives.
@@ -22,8 +24,6 @@ struct _ddebug { 
	const char *function;

	const char *filename;

	const char *format;

	char primary_hash;

	char secondary_hash;

	unsigned int lineno:24;

	/*

 	 * The flags field controls the behaviour at the callsite.
@@ -33,6 +33,7 @@ struct _ddebug { 
#define _DPRINTK_FLAGS_PRINT   (1<<0)  /* printk() a message using the format */

#define _DPRINTK_FLAGS_DEFAULT 0

	unsigned int flags:8;

	char enabled;

} __attribute__((aligned(8)));
@@ -42,33 +43,35 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n, 
#if defined(CONFIG_DYNAMIC_DEBUG)

extern int ddebug_remove_module(const char *mod_name);



#define __dynamic_dbg_enabled(dd)  ({	     \

	int __ret = 0;							     \

	if (unlikely((dynamic_debug_enabled & (1LL << DEBUG_HASH)) &&	     \

			(dynamic_debug_enabled2 & (1LL << DEBUG_HASH2))))   \

				if (unlikely(dd.flags))			     \

					__ret = 1;			     \

	__ret; })



#define dynamic_pr_debug(fmt, ...) do {					\

	__label__ do_printk;						\

	__label__ out;							\

	static struct _ddebug descriptor				\

	__used								\

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

	{ KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH,	\

		DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT };	\

	if (__dynamic_dbg_enabled(descriptor))				\

	{ KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__,		\

		_DPRINTK_FLAGS_DEFAULT };				\

	JUMP_LABEL(&descriptor.enabled, do_printk);			\

	goto out;							\

do_printk:								\

	printk(KERN_DEBUG pr_fmt(fmt),	##__VA_ARGS__);			\

out:	;								\

	} while (0)





#define dynamic_dev_dbg(dev, fmt, ...) do {				\

	__label__ do_printk;						\

	__label__ out;							\

	static struct _ddebug descriptor				\

	__used								\

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

	{ KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH,	\

		DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT };	\

	if (__dynamic_dbg_enabled(descriptor))				\

	{ KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__,		\

		_DPRINTK_FLAGS_DEFAULT };				\

	JUMP_LABEL(&descriptor.enabled, do_printk);			\

	goto out;							\

do_printk:								\

	dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);		\

out:	;								\

	} while (0)



#else

lib/dynamic_debug.c

+3 −39
Original line number Diff line number Diff line
@@ -26,19 +26,11 @@ 
#include <linux/dynamic_debug.h>

#include <linux/debugfs.h>

#include <linux/slab.h>

#include <linux/jump_label.h>



extern struct _ddebug __start___verbose[];

extern struct _ddebug __stop___verbose[];



/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which

 * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They

 * use independent hash functions, to reduce the chance of false positives.

 */

long long dynamic_debug_enabled;

EXPORT_SYMBOL_GPL(dynamic_debug_enabled);

long long dynamic_debug_enabled2;

EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);



struct ddebug_table {

	struct list_head link;

	char *mod_name;
@@ -87,26 +79,6 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf, 
	return buf;

}



/*

 * must be called with ddebug_lock held

 */



static int disabled_hash(char hash, bool first_table)

{

	struct ddebug_table *dt;

	char table_hash_value;



	list_for_each_entry(dt, &ddebug_tables, link) {

		if (first_table)

			table_hash_value = dt->ddebugs->primary_hash;

		else

			table_hash_value = dt->ddebugs->secondary_hash;

		if (dt->num_enabled && (hash == table_hash_value))

			return 0;

	}

	return 1;

}



/*

 * Search the tables for _ddebug's which match the given

 * `query' and apply the `flags' and `mask' to them.  Tells
@@ -170,17 +142,9 @@ static void ddebug_change(const struct ddebug_query *query, 
				dt->num_enabled++;

			dp->flags = newflags;

			if (newflags) {

				dynamic_debug_enabled |=

						(1LL << dp->primary_hash);

				dynamic_debug_enabled2 |=

						(1LL << dp->secondary_hash);

				enable_jump_label(&dp->enabled);

			} else {

				if (disabled_hash(dp->primary_hash, true))

					dynamic_debug_enabled &=

						~(1LL << dp->primary_hash);

				if (disabled_hash(dp->secondary_hash, false))

					dynamic_debug_enabled2 &=

						~(1LL << dp->secondary_hash);

				disable_jump_label(&dp->enabled);

			}

			if (verbose)

				printk(KERN_INFO

scripts/Makefile.lib

+1 −10
Original line number Diff line number Diff line
@@ -101,14 +101,6 @@ basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))" 
modname_flags  = $(if $(filter 1,$(words $(modname))),\

                 -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")



#hash values

ifdef CONFIG_DYNAMIC_DEBUG

debug_flags = -D"DEBUG_HASH=$(shell ./scripts/basic/hash djb2 $(@D)$(modname))"\

              -D"DEBUG_HASH2=$(shell ./scripts/basic/hash r5 $(@D)$(modname))"

else

debug_flags =

endif



orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \

                 $(ccflags-y) $(CFLAGS_$(basetarget).o)

_c_flags       = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(orig_c_flags))
@@ -152,8 +144,7 @@ endif 


c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \

		 $(__c_flags) $(modkern_cflags)                           \

		 -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags) \

		  $(debug_flags)

		 -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)



a_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \

		 $(__a_flags) $(modkern_aflags)

scripts/basic/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ 
# fixdep: 	 Used to generate dependency information during build process

# docproc:	 Used in Documentation/DocBook



hostprogs-y	:= fixdep docproc hash

hostprogs-y	:= fixdep docproc

always		:= $(hostprogs-y)



# fixdep is needed to compile other host programs

scripts/basic/hash.c

deleted100644 → 0
+0 −64
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>

 *

 */



#include <stdio.h>

#include <stdlib.h>

#include <string.h>



#define DYNAMIC_DEBUG_HASH_BITS 6



static const char *program;



static void usage(void)

{

	printf("Usage: %s <djb2|r5> <modname>\n", program);

	exit(1);

}



/* djb2 hashing algorithm by Dan Bernstein. From:

 * http://www.cse.yorku.ca/~oz/hash.html

 */



static unsigned int djb2_hash(char *str)

{

	unsigned long hash = 5381;

	int c;



	c = *str;

	while (c) {

		hash = ((hash << 5) + hash) + c;

		c = *++str;

	}

	return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));

}



static unsigned int r5_hash(char *str)

{

	unsigned long hash = 0;

	int c;



	c = *str;

	while (c) {

		hash = (hash + (c << 4) + (c >> 4)) * 11;

		c = *++str;

	}

	return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));

}



int main(int argc, char *argv[])

{

	program = argv[0];



	if (argc != 3)

		usage();

	if (!strcmp(argv[1], "djb2"))

		printf("%d\n", djb2_hash(argv[2]));

	else if (!strcmp(argv[1], "r5"))

		printf("%d\n", r5_hash(argv[2]));

	else

		usage();

	exit(0);

}

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