Commit d2bb0762 authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
Browse files

MIPS: Tracing: Add static function tracer support for MIPS 



If -pg of gcc is enabled with CONFIG_FUNCTION_TRACER=y. a calling to
_mcount will be inserted into each kernel function. so, there is a
possibility to trace the kernel functions in _mcount.

This patch add the MIPS specific _mcount support for static function
tracing. by default, ftrace_trace_function is initialized as
ftrace_stub(an empty function), so, the default _mcount will introduce
very little overhead. after enabling ftrace in user-space, it will jump
to a real tracing function and do static function tracing for us.

and -ffunction-sections is incompatible with -pg, so, disable it when
ftracer is enabled.

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/672/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 8922f79e

arch/mips/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ config MIPS 
	select HAVE_IDE

	select HAVE_OPROFILE

	select HAVE_ARCH_KGDB

	select HAVE_FUNCTION_TRACER

	# Horrible source of confusion.  Die, die, die ...

	select EMBEDDED

	select RTC_LIB if !MACH_LOONGSON

arch/mips/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -48,7 +48,9 @@ ifneq ($(SUBARCH),$(ARCH)) 
  endif

endif



ifndef CONFIG_FUNCTION_TRACER

cflags-y := -ffunction-sections

endif

cflags-y += $(call cc-option, -mno-check-zero-division)



ifdef CONFIG_32BIT

arch/mips/include/asm/ftrace.h

+24 −1
Original line number Diff line number Diff line 
/* empty */
 
/*

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive for

 * more details.

 *

 * Copyright (C) 2009 DSLab, Lanzhou University, China

 * Author: Wu Zhangjin <wuzj@lemote.com>

 */



#ifndef _ASM_MIPS_FTRACE_H

#define _ASM_MIPS_FTRACE_H



#ifdef CONFIG_FUNCTION_TRACER



#define MCOUNT_ADDR ((unsigned long)(_mcount))

#define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */



#ifndef __ASSEMBLY__

extern void _mcount(void);

#define mcount _mcount



#endif /* __ASSEMBLY__ */

#endif /* CONFIG_FUNCTION_TRACER */

#endif /* _ASM_MIPS_FTRACE_H */

arch/mips/kernel/Makefile

+6 −0
Original line number Diff line number Diff line
@@ -10,6 +10,10 @@ obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \ 
		   ptrace.o reset.o setup.o signal.o syscall.o \

		   time.o topology.o traps.o unaligned.o watch.o



ifdef CONFIG_FUNCTION_TRACER

CFLAGS_REMOVE_early_printk.o = -pg

endif



obj-$(CONFIG_CEVT_BCM1480)	+= cevt-bcm1480.o

obj-$(CONFIG_CEVT_R4K_LIB)	+= cevt-r4k.o

obj-$(CONFIG_MIPS_MT_SMTC)	+= cevt-smtc.o
@@ -27,6 +31,8 @@ obj-$(CONFIG_SYNC_R4K) += sync-r4k.o 
obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o



obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o



obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o

obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o

obj-$(CONFIG_CPU_MIPS64)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/mcount.S

0 → 100644
+83 −0
Original line number Diff line number Diff line 
/*

 * MIPS specific _mcount support

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive for

 * more details.

 *

 * Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University, China

 * Author: Wu Zhangjin <wuzj@lemote.com>

 */



#include <asm/regdef.h>

#include <asm/stackframe.h>

#include <asm/ftrace.h>



	.text

	.set noreorder

	.set noat



	.macro MCOUNT_SAVE_REGS

	PTR_SUBU	sp, PT_SIZE

	PTR_S	ra, PT_R31(sp)

	PTR_S	AT, PT_R1(sp)

	PTR_S	a0, PT_R4(sp)

	PTR_S	a1, PT_R5(sp)

	PTR_S	a2, PT_R6(sp)

	PTR_S	a3, PT_R7(sp)

#ifdef CONFIG_64BIT

	PTR_S	a4, PT_R8(sp)

	PTR_S	a5, PT_R9(sp)

	PTR_S	a6, PT_R10(sp)

	PTR_S	a7, PT_R11(sp)

#endif

	.endm



	.macro MCOUNT_RESTORE_REGS

	PTR_L	ra, PT_R31(sp)

	PTR_L	AT, PT_R1(sp)

	PTR_L	a0, PT_R4(sp)

	PTR_L	a1, PT_R5(sp)

	PTR_L	a2, PT_R6(sp)

	PTR_L	a3, PT_R7(sp)

#ifdef CONFIG_64BIT

	PTR_L	a4, PT_R8(sp)

	PTR_L	a5, PT_R9(sp)

	PTR_L	a6, PT_R10(sp)

	PTR_L	a7, PT_R11(sp)

#endif

#ifdef CONFIG_64BIT

	PTR_ADDIU	sp, PT_SIZE

#else

	PTR_ADDIU	sp, (PT_SIZE + 8)

#endif

.endm



	.macro RETURN_BACK

	jr ra

	 move ra, AT

	.endm



NESTED(_mcount, PT_SIZE, ra)

	PTR_LA	t0, ftrace_stub

	PTR_L	t1, ftrace_trace_function /* Prepare t1 for (1) */

	bne	t0, t1, static_trace

	 nop

	b	ftrace_stub

	 nop



static_trace:

	MCOUNT_SAVE_REGS



	move	a0, ra		/* arg1: next ip, selfaddr */

	jalr	t1	/* (1) call *ftrace_trace_function */

	 move	a1, AT		/* arg2: the caller's next ip, parent */



	MCOUNT_RESTORE_REGS

	.globl ftrace_stub

ftrace_stub:

	RETURN_BACK

	END(_mcount)



	.set at

	.set reorder

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