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MIPS: Tracing: Add static function tracer support for MIPS

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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: Wu Zhangjin <wuzhangjin@gmail.com>
Reviewed-by: Steven 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: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Wu Zhangjin 2009-11-20 20:34:29 +08:00 committed by Ralf Baechle
parent 8922f79ee5
commit d2bb076299
6 changed files with 121 additions and 1 deletions
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1
arch/mips/Kconfig
View File

@ -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

2
arch/mips/Makefile
View File

@ -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

25
arch/mips/include/asm/ftrace.h
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@ -1 +1,24 @@
/* 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 */

6
arch/mips/kernel/Makefile
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@ -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

83
arch/mips/kernel/mcount.S Normal file
View File

@ -0,0 +1,83 @@
/*
* 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

5
arch/mips/kernel/mips_ksyms.c
View File

@ -13,6 +13,7 @@
#include <asm/checksum.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/ftrace.h>
extern void *__bzero(void *__s, size_t __count);
extern long __strncpy_from_user_nocheck_asm(char *__to,
@ -51,3 +52,7 @@ EXPORT_SYMBOL(csum_partial_copy_nocheck);
EXPORT_SYMBOL(__csum_partial_copy_user);
EXPORT_SYMBOL(invalid_pte_table);
#ifdef CONFIG_FUNCTION_TRACER
/* _mcount is defined in arch/mips/kernel/mcount.S */
EXPORT_SYMBOL(_mcount);
#endif