Commit bec261fe authored by Yury Norov's avatar Yury Norov Committed by Andrew Morton
Browse files

tracing: move tracing declarations from kernel.h to a dedicated header 

Tracing is a half of the kernel.h in terms of LOCs, although it's a
self-consistent part.  It is intended for quick debugging purposes and
isn't used by the normal tracing utilities.

Move it to a separate header.  If someone needs to just throw a
trace_printk() in their driver, they will not have to pull all the heavy
tracing machinery.

This is a pure move.

Link: https://lkml.kernel.org/r/20260116042510.241009-7-ynorov@nvidia.com


Signed-off-by: default avatarYury Norov <ynorov@nvidia.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 86e685ff

include/linux/kernel.h

+1 −195
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 
#include <linux/build_bug.h>

#include <linux/sprintf.h>

#include <linux/static_call_types.h>

#include <linux/instruction_pointer.h>

#include <linux/trace_printk.h>

#include <linux/util_macros.h>

#include <linux/wordpart.h>
@@ -189,200 +189,6 @@ enum system_states { 
};

extern enum system_states system_state;



/*

 * General tracing related utility functions - trace_printk(),

 * tracing_on/tracing_off and tracing_start()/tracing_stop

 *

 * Use tracing_on/tracing_off when you want to quickly turn on or off

 * tracing. It simply enables or disables the recording of the trace events.

 * This also corresponds to the user space /sys/kernel/tracing/tracing_on

 * file, which gives a means for the kernel and userspace to interact.

 * Place a tracing_off() in the kernel where you want tracing to end.

 * From user space, examine the trace, and then echo 1 > tracing_on

 * to continue tracing.

 *

 * tracing_stop/tracing_start has slightly more overhead. It is used

 * by things like suspend to ram where disabling the recording of the

 * trace is not enough, but tracing must actually stop because things

 * like calling smp_processor_id() may crash the system.

 *

 * Most likely, you want to use tracing_on/tracing_off.

 */



enum ftrace_dump_mode {

	DUMP_NONE,

	DUMP_ALL,

	DUMP_ORIG,

	DUMP_PARAM,

};



#ifdef CONFIG_TRACING

void tracing_on(void);

void tracing_off(void);

int tracing_is_on(void);

void tracing_snapshot(void);

void tracing_snapshot_alloc(void);



extern void tracing_start(void);

extern void tracing_stop(void);



static inline __printf(1, 2)

void ____trace_printk_check_format(const char *fmt, ...)

{

}

#define __trace_printk_check_format(fmt, args...)			\

do {									\

	if (0)								\

		____trace_printk_check_format(fmt, ##args);		\

} while (0)



/**

 * trace_printk - printf formatting in the ftrace buffer

 * @fmt: the printf format for printing

 *

 * Note: __trace_printk is an internal function for trace_printk() and

 *       the @ip is passed in via the trace_printk() macro.

 *

 * This function allows a kernel developer to debug fast path sections

 * that printk is not appropriate for. By scattering in various

 * printk like tracing in the code, a developer can quickly see

 * where problems are occurring.

 *

 * This is intended as a debugging tool for the developer only.

 * Please refrain from leaving trace_printks scattered around in

 * your code. (Extra memory is used for special buffers that are

 * allocated when trace_printk() is used.)

 *

 * A little optimization trick is done here. If there's only one

 * argument, there's no need to scan the string for printf formats.

 * The trace_puts() will suffice. But how can we take advantage of

 * using trace_puts() when trace_printk() has only one argument?

 * By stringifying the args and checking the size we can tell

 * whether or not there are args. __stringify((__VA_ARGS__)) will

 * turn into "()\0" with a size of 3 when there are no args, anything

 * else will be bigger. All we need to do is define a string to this,

 * and then take its size and compare to 3. If it's bigger, use

 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just

 * let gcc optimize the rest.

 */



#define trace_printk(fmt, ...)				\

do {							\

	char _______STR[] = __stringify((__VA_ARGS__));	\

	if (sizeof(_______STR) > 3)			\

		do_trace_printk(fmt, ##__VA_ARGS__);	\

	else						\

		trace_puts(fmt);			\

} while (0)



#define do_trace_printk(fmt, args...)					\

do {									\

	static const char *trace_printk_fmt __used			\

		__section("__trace_printk_fmt") =			\

		__builtin_constant_p(fmt) ? fmt : NULL;			\

									\

	__trace_printk_check_format(fmt, ##args);			\

									\

	if (__builtin_constant_p(fmt))					\

		__trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);	\

	else								\

		__trace_printk(_THIS_IP_, fmt, ##args);			\

} while (0)



extern __printf(2, 3)

int __trace_bprintk(unsigned long ip, const char *fmt, ...);



extern __printf(2, 3)

int __trace_printk(unsigned long ip, const char *fmt, ...);



/**

 * trace_puts - write a string into the ftrace buffer

 * @str: the string to record

 *

 * Note: __trace_bputs is an internal function for trace_puts and

 *       the @ip is passed in via the trace_puts macro.

 *

 * This is similar to trace_printk() but is made for those really fast

 * paths that a developer wants the least amount of "Heisenbug" effects,

 * where the processing of the print format is still too much.

 *

 * This function allows a kernel developer to debug fast path sections

 * that printk is not appropriate for. By scattering in various

 * printk like tracing in the code, a developer can quickly see

 * where problems are occurring.

 *

 * This is intended as a debugging tool for the developer only.

 * Please refrain from leaving trace_puts scattered around in

 * your code. (Extra memory is used for special buffers that are

 * allocated when trace_puts() is used.)

 *

 * Returns: 0 if nothing was written, positive # if string was.

 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)

 */



#define trace_puts(str) ({						\

	static const char *trace_printk_fmt __used			\

		__section("__trace_printk_fmt") =			\

		__builtin_constant_p(str) ? str : NULL;			\

									\

	if (__builtin_constant_p(str))					\

		__trace_bputs(_THIS_IP_, trace_printk_fmt);		\

	else								\

		__trace_puts(_THIS_IP_, str);				\

})

extern int __trace_bputs(unsigned long ip, const char *str);

extern int __trace_puts(unsigned long ip, const char *str);



extern void trace_dump_stack(int skip);



/*

 * The double __builtin_constant_p is because gcc will give us an error

 * if we try to allocate the static variable to fmt if it is not a

 * constant. Even with the outer if statement.

 */

#define ftrace_vprintk(fmt, vargs)					\

do {									\

	if (__builtin_constant_p(fmt)) {				\

		static const char *trace_printk_fmt __used		\

		  __section("__trace_printk_fmt") =			\

			__builtin_constant_p(fmt) ? fmt : NULL;		\

									\

		__ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);	\

	} else								\

		__ftrace_vprintk(_THIS_IP_, fmt, vargs);		\

} while (0)



extern __printf(2, 0) int

__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);



extern __printf(2, 0) int

__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);



extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);

#else

static inline void tracing_start(void) { }

static inline void tracing_stop(void) { }

static inline void trace_dump_stack(int skip) { }



static inline void tracing_on(void) { }

static inline void tracing_off(void) { }

static inline int tracing_is_on(void) { return 0; }

static inline void tracing_snapshot(void) { }

static inline void tracing_snapshot_alloc(void) { }



static inline __printf(1, 2)

int trace_printk(const char *fmt, ...)

{

	return 0;

}

static __printf(1, 0) inline int

ftrace_vprintk(const char *fmt, va_list ap)

{

	return 0;

}

static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }

#endif /* CONFIG_TRACING */



/* Rebuild everything on CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_DYNAMIC_FTRACE

# define REBUILD_DUE_TO_DYNAMIC_FTRACE

include/linux/trace_printk.h

0 → 100644
+204 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _LINUX_TRACE_PRINTK_H

#define _LINUX_TRACE_PRINTK_H



#include <linux/compiler_attributes.h>

#include <linux/instruction_pointer.h>

#include <linux/stddef.h>

#include <linux/stringify.h>



/*

 * General tracing related utility functions - trace_printk(),

 * tracing_on/tracing_off and tracing_start()/tracing_stop

 *

 * Use tracing_on/tracing_off when you want to quickly turn on or off

 * tracing. It simply enables or disables the recording of the trace events.

 * This also corresponds to the user space /sys/kernel/tracing/tracing_on

 * file, which gives a means for the kernel and userspace to interact.

 * Place a tracing_off() in the kernel where you want tracing to end.

 * From user space, examine the trace, and then echo 1 > tracing_on

 * to continue tracing.

 *

 * tracing_stop/tracing_start has slightly more overhead. It is used

 * by things like suspend to ram where disabling the recording of the

 * trace is not enough, but tracing must actually stop because things

 * like calling smp_processor_id() may crash the system.

 *

 * Most likely, you want to use tracing_on/tracing_off.

 */



enum ftrace_dump_mode {

	DUMP_NONE,

	DUMP_ALL,

	DUMP_ORIG,

	DUMP_PARAM,

};



#ifdef CONFIG_TRACING

void tracing_on(void);

void tracing_off(void);

int tracing_is_on(void);

void tracing_snapshot(void);

void tracing_snapshot_alloc(void);



extern void tracing_start(void);

extern void tracing_stop(void);



static inline __printf(1, 2)

void ____trace_printk_check_format(const char *fmt, ...)

{

}

#define __trace_printk_check_format(fmt, args...)			\

do {									\

	if (0)								\

		____trace_printk_check_format(fmt, ##args);		\

} while (0)



/**

 * trace_printk - printf formatting in the ftrace buffer

 * @fmt: the printf format for printing

 *

 * Note: __trace_printk is an internal function for trace_printk() and

 *       the @ip is passed in via the trace_printk() macro.

 *

 * This function allows a kernel developer to debug fast path sections

 * that printk is not appropriate for. By scattering in various

 * printk like tracing in the code, a developer can quickly see

 * where problems are occurring.

 *

 * This is intended as a debugging tool for the developer only.

 * Please refrain from leaving trace_printks scattered around in

 * your code. (Extra memory is used for special buffers that are

 * allocated when trace_printk() is used.)

 *

 * A little optimization trick is done here. If there's only one

 * argument, there's no need to scan the string for printf formats.

 * The trace_puts() will suffice. But how can we take advantage of

 * using trace_puts() when trace_printk() has only one argument?

 * By stringifying the args and checking the size we can tell

 * whether or not there are args. __stringify((__VA_ARGS__)) will

 * turn into "()\0" with a size of 3 when there are no args, anything

 * else will be bigger. All we need to do is define a string to this,

 * and then take its size and compare to 3. If it's bigger, use

 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just

 * let gcc optimize the rest.

 */



#define trace_printk(fmt, ...)				\

do {							\

	char _______STR[] = __stringify((__VA_ARGS__));	\

	if (sizeof(_______STR) > 3)			\

		do_trace_printk(fmt, ##__VA_ARGS__);	\

	else						\

		trace_puts(fmt);			\

} while (0)



#define do_trace_printk(fmt, args...)					\

do {									\

	static const char *trace_printk_fmt __used			\

		__section("__trace_printk_fmt") =			\

		__builtin_constant_p(fmt) ? fmt : NULL;			\

									\

	__trace_printk_check_format(fmt, ##args);			\

									\

	if (__builtin_constant_p(fmt))					\

		__trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);	\

	else								\

		__trace_printk(_THIS_IP_, fmt, ##args);			\

} while (0)



extern __printf(2, 3)

int __trace_bprintk(unsigned long ip, const char *fmt, ...);



extern __printf(2, 3)

int __trace_printk(unsigned long ip, const char *fmt, ...);



/**

 * trace_puts - write a string into the ftrace buffer

 * @str: the string to record

 *

 * Note: __trace_bputs is an internal function for trace_puts and

 *       the @ip is passed in via the trace_puts macro.

 *

 * This is similar to trace_printk() but is made for those really fast

 * paths that a developer wants the least amount of "Heisenbug" effects,

 * where the processing of the print format is still too much.

 *

 * This function allows a kernel developer to debug fast path sections

 * that printk is not appropriate for. By scattering in various

 * printk like tracing in the code, a developer can quickly see

 * where problems are occurring.

 *

 * This is intended as a debugging tool for the developer only.

 * Please refrain from leaving trace_puts scattered around in

 * your code. (Extra memory is used for special buffers that are

 * allocated when trace_puts() is used.)

 *

 * Returns: 0 if nothing was written, positive # if string was.

 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)

 */



#define trace_puts(str) ({						\

	static const char *trace_printk_fmt __used			\

		__section("__trace_printk_fmt") =			\

		__builtin_constant_p(str) ? str : NULL;			\

									\

	if (__builtin_constant_p(str))					\

		__trace_bputs(_THIS_IP_, trace_printk_fmt);		\

	else								\

		__trace_puts(_THIS_IP_, str);				\

})

extern int __trace_bputs(unsigned long ip, const char *str);

extern int __trace_puts(unsigned long ip, const char *str);



extern void trace_dump_stack(int skip);



/*

 * The double __builtin_constant_p is because gcc will give us an error

 * if we try to allocate the static variable to fmt if it is not a

 * constant. Even with the outer if statement.

 */

#define ftrace_vprintk(fmt, vargs)					\

do {									\

	if (__builtin_constant_p(fmt)) {				\

		static const char *trace_printk_fmt __used		\

		  __section("__trace_printk_fmt") =			\

			__builtin_constant_p(fmt) ? fmt : NULL;		\

									\

		__ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);	\

	} else								\

		__ftrace_vprintk(_THIS_IP_, fmt, vargs);		\

} while (0)



extern __printf(2, 0) int

__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);



extern __printf(2, 0) int

__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);



extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);

#else

static inline void tracing_start(void) { }

static inline void tracing_stop(void) { }

static inline void trace_dump_stack(int skip) { }



static inline void tracing_on(void) { }

static inline void tracing_off(void) { }

static inline int tracing_is_on(void) { return 0; }

static inline void tracing_snapshot(void) { }

static inline void tracing_snapshot_alloc(void) { }



static inline __printf(1, 2)

int trace_printk(const char *fmt, ...)

{

	return 0;

}

static __printf(1, 0) inline int

ftrace_vprintk(const char *fmt, va_list ap)

{

	return 0;

}

static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }

#endif /* CONFIG_TRACING */



#endif