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Commit ee08c6ec authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

tracing/ftrace: syscall tracing infrastructure, basics 



Provide basic callbacks to do syscall tracing.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1236401580-5758-2-git-send-email-fweisbec@gmail.com>
[ simplified it to a trace_printk() for now. ]
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 4c6ed8f4

include/linux/ftrace.h

+21 −0
Original line number Diff line number Diff line
@@ -503,4 +503,25 @@ static inline void trace_hw_branch_oops(void) {} 


#endif /* CONFIG_HW_BRANCH_TRACER */



/*

 * A syscall entry in the ftrace syscalls array.

 *

 * @syscall_nr: syscall number

 */

struct syscall_trace_entry {

	int		syscall_nr;

};



#ifdef CONFIG_FTRACE_SYSCALLS

extern void start_ftrace_syscalls(void);

extern void stop_ftrace_syscalls(void);

extern void ftrace_syscall_enter(struct pt_regs *regs);

extern void ftrace_syscall_exit(struct pt_regs *regs);

#else

static inline void start_ftrace_syscalls(void) { }

static inline void stop_ftrace_syscalls(void) { }

static inline void ftrace_syscall_enter(struct pt_regs *regs) { }

static inline void ftrace_syscall_exit(struct pt_regs *regs) { }

#endif



#endif /* _LINUX_FTRACE_H */

kernel/trace/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -34,6 +34,9 @@ config HAVE_FTRACE_MCOUNT_RECORD 
config HAVE_HW_BRANCH_TRACER

	bool



config HAVE_FTRACE_SYSCALLS

	bool



config TRACER_MAX_TRACE

	bool
@@ -175,6 +178,13 @@ config EVENT_TRACER 
	  allowing the user to pick and choose which trace point they

	  want to trace.



config FTRACE_SYSCALLS

	bool "Trace syscalls"

	depends on HAVE_FTRACE_SYSCALLS

	select TRACING

	help

	  Basic tracer to catch the syscall entry and exit events.



config BOOT_TRACER

	bool "Trace boot initcalls"

	select TRACING

kernel/trace/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -43,5 +43,6 @@ obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o 
obj-$(CONFIG_EVENT_TRACER) += trace_events.o

obj-$(CONFIG_EVENT_TRACER) += events.o

obj-$(CONFIG_EVENT_TRACER) += trace_export.o

obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o



libftrace-y := ftrace.o

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -30,6 +30,8 @@ enum trace_type { 
	TRACE_GRAPH_ENT,

	TRACE_USER_STACK,

	TRACE_HW_BRANCHES,

	TRACE_SYSCALL_ENTER,

	TRACE_SYSCALL_EXIT,

	TRACE_KMEM_ALLOC,

	TRACE_KMEM_FREE,

	TRACE_POWER,

kernel/trace/trace_syscalls.c

0 → 100644
+113 −0
Original line number Diff line number Diff line 
#include <linux/ftrace.h>

#include <linux/kernel.h>



#include <asm/syscall.h>



#include "trace_output.h"

#include "trace.h"



static atomic_t refcount;



void start_ftrace_syscalls(void)

{

	unsigned long flags;

	struct task_struct *g, *t;



	if (atomic_inc_return(&refcount) != 1)

		goto out;



	read_lock_irqsave(&tasklist_lock, flags);



	do_each_thread(g, t) {

		set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);

	} while_each_thread(g, t);



	read_unlock_irqrestore(&tasklist_lock, flags);

out:

	atomic_dec(&refcount);

}



void stop_ftrace_syscalls(void)

{

	unsigned long flags;

	struct task_struct *g, *t;



	if (atomic_dec_return(&refcount))

		goto out;



	read_lock_irqsave(&tasklist_lock, flags);



	do_each_thread(g, t) {

		clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);

	} while_each_thread(g, t);



	read_unlock_irqrestore(&tasklist_lock, flags);

out:

	atomic_inc(&refcount);

}



void ftrace_syscall_enter(struct pt_regs *regs)

{

	int syscall_nr;



	syscall_nr = syscall_get_nr(current, regs);



	trace_printk("syscall %d enter\n", syscall_nr);

}



void ftrace_syscall_exit(struct pt_regs *regs)

{

	int syscall_nr;



	syscall_nr = syscall_get_nr(current, regs);



	trace_printk("syscall %d exit\n", syscall_nr);

}



static int init_syscall_tracer(struct trace_array *tr)

{

	start_ftrace_syscalls();



	return 0;

}



static void reset_syscall_tracer(struct trace_array *tr)

{

	stop_ftrace_syscalls();

}



static struct trace_event syscall_enter_event = {

	.type		= TRACE_SYSCALL_ENTER,

};



static struct trace_event syscall_exit_event = {

	.type		= TRACE_SYSCALL_EXIT,

};



static struct tracer syscall_tracer __read_mostly = {

	.name		= "syscall",

	.init		= init_syscall_tracer,

	.reset		= reset_syscall_tracer

};



__init int register_ftrace_syscalls(void)

{

	int ret;



	ret = register_ftrace_event(&syscall_enter_event);

	if (!ret) {

		printk(KERN_WARNING "event %d failed to register\n",

		       syscall_enter_event.type);

		WARN_ON_ONCE(1);

	}



	ret = register_ftrace_event(&syscall_exit_event);

	if (!ret) {

		printk(KERN_WARNING "event %d failed to register\n",

		       syscall_exit_event.type);

		WARN_ON_ONCE(1);

	}



	return register_tracer(&syscall_tracer);

}

device_initcall(register_ftrace_syscalls);