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 deafult, 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 to support module tracing, we need to enable -mlong-calls for the long call from modules space to kernel space. -mlong-calls load the address of _mcount to a register and then jump to it, so, the address is allowed to be 32bit long, but without -mlong-calls, for the instruction "jal _mcount" only left 26bit for the address of _mcount, which is not enough for jumping from the module space to kernel space. Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Wu Zhangjin <wuzhangjin@xxxxxxxxx> --- arch/mips/Kconfig | 1 + arch/mips/Makefile | 4 ++ arch/mips/include/asm/ftrace.h | 25 +++++++++++- arch/mips/kernel/Makefile | 2 + arch/mips/kernel/mcount.S | 89 ++++++++++++++++++++++++++++++++++++++++ arch/mips/kernel/mips_ksyms.c | 5 ++ 6 files changed, 125 insertions(+), 1 deletions(-) create mode 100644 arch/mips/kernel/mcount.S diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 03bd56a..6b33e88 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -4,6 +4,7 @@ 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 !LEMOTE_FULOONG2E diff --git a/arch/mips/Makefile b/arch/mips/Makefile index 77f5021..041deca 100644 --- a/arch/mips/Makefile +++ b/arch/mips/Makefile @@ -48,7 +48,11 @@ ifneq ($(SUBARCH),$(ARCH)) endif endif +ifndef CONFIG_FUNCTION_TRACER cflags-y := -ffunction-sections +else +cflags-y := -mlong-calls +endif cflags-y += $(call cc-option, -mno-check-zero-division) ifdef CONFIG_32BIT diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrace.h index 40a8c17..5f8ebcf 100644 --- a/arch/mips/include/asm/ftrace.h +++ b/arch/mips/include/asm/ftrace.h @@ -1 +1,24 @@ -/* empty */ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive for + * more details. + * + * Copyright (C) 2009 DSLab, Lanzhou University, China + * Author: Wu Zhangjin <wuzj@xxxxxxxxxx> + */ + +#ifndef _ASM_MIPS_FTRACE_H +#define _ASM_MIPS_FTRACE_H + +#ifdef CONFIG_FUNCTION_TRACER + +#define MCOUNT_ADDR ((unsigned long)(_mcount)) +#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ + +#ifndef __ASSEMBLY__ +extern void _mcount(void); +#define mcount _mcount + +#endif /* __ASSEMBLY__ */ +#endif /* CONFIG_FUNCTION_TRACER */ +#endif /* _ASM_MIPS_FTRACE_H */ diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile index f228868..38e704a 100644 --- a/arch/mips/kernel/Makefile +++ b/arch/mips/kernel/Makefile @@ -10,6 +10,7 @@ obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \ ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_trace_clock.o = -pg +CFLAGS_REMOVE_early_printk.o = -pg endif obj-$(CONFIG_CEVT_BCM1480) += cevt-bcm1480.o @@ -29,6 +30,7 @@ obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-$(CONFIG_MODULES) += mips_ksyms.o module.o obj-$(CONFIG_FTRACE) += trace_clock.o +obj-$(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 diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S new file mode 100644 index 0000000..0c39bc8 --- /dev/null +++ b/arch/mips/kernel/mcount.S @@ -0,0 +1,89 @@ +/* + * 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@xxxxxxxxxx> + */ + +#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 + PTR_ADDIU sp, PT_SIZE +.endm + + .macro MCOUNT_SET_ARGS + move a0, ra /* arg1: next ip, selfaddr */ + move a1, AT /* arg2: the caller's next ip, parent */ + PTR_SUBU a0, MCOUNT_INSN_SIZE + .endm + + .macro RETURN_BACK +#ifdef CONFIG_32BIT + PTR_ADDIU sp, 8 +#endif + 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 + + j ftrace_stub + nop + +static_trace: + MCOUNT_SAVE_REGS + + MCOUNT_SET_ARGS /* call *ftrace_trace_function */ + jalr t1 /* (1) */ + nop + + MCOUNT_RESTORE_REGS + .globl ftrace_stub +ftrace_stub: + RETURN_BACK + END(_mcount) + + .set at + .set reorder diff --git a/arch/mips/kernel/mips_ksyms.c b/arch/mips/kernel/mips_ksyms.c index 225755d..1d04807 100644 --- a/arch/mips/kernel/mips_ksyms.c +++ b/arch/mips/kernel/mips_ksyms.c @@ -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 -- 1.6.2.1
