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Commit 376cfa87 authored by Tim Bird's avatar Tim Bird Committed by Rabin Vincent
Browse files

ARM: ftrace: function graph tracer support 



Cc: Tim Bird <tim.bird@am.sony.com>
[rabin@rab.in: rebase on top of latest code,
	       keep code in ftrace.c instead of separate file,
	       check for ftrace_graph_entry also]
Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
parent d3b9dc9d

arch/arm/kernel/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$(TEXT_OFFSET)

AFLAGS_head.o        := -DTEXT_OFFSET=$(TEXT_OFFSET)



ifdef CONFIG_DYNAMIC_FTRACE

ifdef CONFIG_FUNCTION_TRACER

CFLAGS_REMOVE_ftrace.o = -pg

endif
@@ -33,6 +33,7 @@ obj-$(CONFIG_SMP) += smp.o 
obj-$(CONFIG_HAVE_ARM_SCU)	+= smp_scu.o

obj-$(CONFIG_HAVE_ARM_TWD)	+= smp_twd.o

obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o

obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o

obj-$(CONFIG_KPROBES)		+= kprobes.o kprobes-decode.o

obj-$(CONFIG_ATAGS_PROC)	+= atags.o

arch/arm/kernel/entry-common.S

+46 −0
Original line number Diff line number Diff line
@@ -148,6 +148,20 @@ ENDPROC(ret_from_fork) 
	adr	r0, .Lftrace_stub

	cmp	r0, r2

	bne	1f



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	ldr     r1, =ftrace_graph_return

	ldr     r2, [r1]

	cmp     r0, r2

	bne     ftrace_graph_caller\suffix



	ldr     r1, =ftrace_graph_entry

	ldr     r2, [r1]

	ldr     r0, =ftrace_graph_entry_stub

	cmp     r0, r2

	bne     ftrace_graph_caller\suffix

#endif



	mcount_exit



1: 	mcount_get_lr	r1			@ lr of instrumented func
@@ -172,6 +186,15 @@ ftrace_call\suffix: 
	mcount_exit

.endm



.macro __ftrace_graph_caller

	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)

	mov	r1, lr			@ instrumented routine (func)

	sub	r1, r1, #MCOUNT_INSN_SIZE

	mov	r2, fp			@ frame pointer

	bl	prepare_ftrace_return

	mcount_exit

.endm



#ifdef CONFIG_OLD_MCOUNT

/*

 * mcount
@@ -206,6 +229,12 @@ ENTRY(ftrace_caller_old) 
ENDPROC(ftrace_caller_old)

#endif



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ENTRY(ftrace_graph_caller_old)

	__ftrace_graph_caller

ENDPROC(ftrace_graph_caller_old)

#endif



.purgem mcount_enter

.purgem mcount_get_lr

.purgem mcount_exit
@@ -244,10 +273,27 @@ ENTRY(ftrace_caller) 
ENDPROC(ftrace_caller)

#endif



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ENTRY(ftrace_graph_caller)

	__ftrace_graph_caller

ENDPROC(ftrace_graph_caller)

#endif



.purgem mcount_enter

.purgem mcount_get_lr

.purgem mcount_exit



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	.globl return_to_handler

return_to_handler:

	stmdb	sp!, {r0-r3}

	mov	r0, fp			@ frame pointer

	bl	ftrace_return_to_handler

	mov	lr, r0			@ r0 has real ret addr

	ldmia	sp!, {r0-r3}

	mov	pc, lr

#endif



ENTRY(ftrace_stub)

.Lftrace_stub:

	mov	pc, lr

arch/arm/kernel/ftrace.c

+34 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#define	NOP		0xe8bd4000	/* pop {lr} */

#endif



#ifdef CONFIG_DYNAMIC_FTRACE

#ifdef CONFIG_OLD_MCOUNT

#define OLD_MCOUNT_ADDR	((unsigned long) mcount)

#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
@@ -193,3 +194,36 @@ int __init ftrace_dyn_arch_init(void *data) 


	return 0;

}

#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,

			   unsigned long frame_pointer)

{

	unsigned long return_hooker = (unsigned long) &return_to_handler;

	struct ftrace_graph_ent trace;

	unsigned long old;

	int err;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;



	old = *parent;

	*parent = return_hooker;



	err = ftrace_push_return_trace(old, self_addr, &trace.depth,

				       frame_pointer);

	if (err == -EBUSY) {

		*parent = old;

		return;

	}



	trace.func = self_addr;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		*parent = old;

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */