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Unverified Commit 10626c32 authored by Alan Kao's avatar Alan Kao Committed by Palmer Dabbelt
Browse files

riscv/ftrace: Add basic support 



This patch contains basic ftrace support for RV64I platform.
Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph
tracer (HAVE_FUNCTION_GRAPH_TRACER), and a frame pointer test
(HAVE_FUNCTION_GRAPH_FP_TEST) are implemented following the
instructions in Documentation/trace/ftrace-design.txt.

Note that the functions in both ftrace.c and setup.c should not be
hooked with the compiler's -pg option: to prevent infinite self-
referencing for the former, and to ignore early setup stuff for the
latter.

Signed-off-by: default avatarAlan Kao <alankao@andestech.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent 5d44bf20

arch/riscv/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -55,6 +55,9 @@ config PAGE_OFFSET 
config STACKTRACE_SUPPORT

	def_bool y



config TRACE_IRQFLAGS_SUPPORT

	def_bool y



config RWSEM_GENERIC_SPINLOCK

	def_bool y
@@ -107,6 +110,8 @@ config ARCH_RV64I 
	bool "RV64I"

	select CPU_SUPPORTS_64BIT_KERNEL

	select 64BIT

	select HAVE_FUNCTION_TRACER

	select HAVE_FUNCTION_GRAPH_TRACER



endchoice

arch/riscv/include/asm/Kbuild

+0 −1
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ generic-y += errno.h 
generic-y += exec.h

generic-y += fb.h

generic-y += fcntl.h

generic-y += ftrace.h

generic-y += futex.h

generic-y += hardirq.h

generic-y += hash.h

arch/riscv/include/asm/ftrace.h

0 → 100644
+10 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (C) 2017 Andes Technology Corporation */



/*

 * The graph frame test is not possible if CONFIG_FRAME_POINTER is not enabled.

 * Check arch/riscv/kernel/mcount.S for detail.

 */

#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)

#define HAVE_FUNCTION_GRAPH_FP_TEST

#endif

arch/riscv/kernel/Makefile

+7 −0
Original line number Diff line number Diff line
@@ -2,6 +2,11 @@ 
# Makefile for the RISC-V Linux kernel

#



ifdef CONFIG_FTRACE

CFLAGS_REMOVE_ftrace.o = -pg

CFLAGS_REMOVE_setup.o = -pg

endif



extra-y += head.o

extra-y += vmlinux.lds
@@ -29,5 +34,7 @@ CFLAGS_setup.o := -mcmodel=medany 
obj-$(CONFIG_SMP)		+= smpboot.o

obj-$(CONFIG_SMP)		+= smp.o

obj-$(CONFIG_MODULES)		+= module.o

obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o



clean:

arch/riscv/kernel/ftrace.c

0 → 100644
+41 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2013 Linaro Limited

 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>

 * Copyright (C) 2017 Andes Technology Corporation

 */



#include <linux/ftrace.h>



/*

 * Most of this file is copied from arm64.

 */

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

			   unsigned long frame_pointer)

{

	unsigned long return_hooker = (unsigned long)&return_to_handler;

	unsigned long old;

	struct ftrace_graph_ent trace;

	int err;



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

		return;



	/*

	 * We don't suffer access faults, so no extra fault-recovery assembly

	 * is needed here.

	 */

	old = *parent;



	trace.func = self_addr;

	trace.depth = current->curr_ret_stack + 1;



	if (!ftrace_graph_entry(&trace))

		return;



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

				       frame_pointer, NULL);

	if (err == -EBUSY)

		return;

	*parent = return_hooker;

}