From 197165d44925bd0fa892990851dee4d312a44b39 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Fri, 24 Apr 2015 14:24:44 +0530 Subject: [PATCH] powerpc/ftrace: add powerpc timebase as a trace clock source Add a new powerpc-specific trace clock using the timebase register, similar to x86-tsc. This gives us - a fast, monotonic, hardware clock source for trace entries, and - a clock that can be used to correlate events across cpus as well as across hypervisor and guests. Signed-off-by: Naveen N. Rao Acked-by: Steven Rostedt Signed-off-by: Michael Ellerman --- Documentation/trace/ftrace.txt | 5 +++++ arch/powerpc/include/asm/Kbuild | 1 - arch/powerpc/include/asm/trace_clock.h | 19 +++++++++++++++++++ arch/powerpc/kernel/Makefile | 1 + arch/powerpc/kernel/trace_clock.c | 15 +++++++++++++++ 5 files changed, 40 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/include/asm/trace_clock.h create mode 100644 arch/powerpc/kernel/trace_clock.c diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 7ddb1e3..87bb4aa 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -346,6 +346,11 @@ of ftrace. Here is a list of some of the key files: x86-tsc: Architectures may define their own clocks. For example, x86 uses its own TSC cycle clock here. + ppc-tb: This uses the powerpc timebase register value. + This is in sync across CPUs and can also be used + to correlate events across hypervisor/guest if + tb_offset is known. + To set a clock, simply echo the clock name into this file. echo global > trace_clock diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild index 050712e..ab9f4e0 100644 --- a/arch/powerpc/include/asm/Kbuild +++ b/arch/powerpc/include/asm/Kbuild @@ -6,5 +6,4 @@ generic-y += local64.h generic-y += mcs_spinlock.h generic-y += preempt.h generic-y += rwsem.h -generic-y += trace_clock.h generic-y += vtime.h diff --git a/arch/powerpc/include/asm/trace_clock.h b/arch/powerpc/include/asm/trace_clock.h new file mode 100644 index 0000000..cf1ee75 --- /dev/null +++ b/arch/powerpc/include/asm/trace_clock.h @@ -0,0 +1,19 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License, version 2, as + * published by the Free Software Foundation. + * + * Copyright (C) 2015 Naveen N. Rao, IBM Corporation + */ + +#ifndef _ASM_PPC_TRACE_CLOCK_H +#define _ASM_PPC_TRACE_CLOCK_H + +#include +#include + +extern u64 notrace trace_clock_ppc_tb(void); + +#define ARCH_TRACE_CLOCKS { trace_clock_ppc_tb, "ppc-tb", 0 }, + +#endif /* _ASM_PPC_TRACE_CLOCK_H */ diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 12868b1..ba33693 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -118,6 +118,7 @@ obj-$(CONFIG_PPC_IO_WORKAROUNDS) += io-workarounds.o obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o +obj-$(CONFIG_TRACING) += trace_clock.o ifneq ($(CONFIG_PPC_INDIRECT_PIO),y) obj-y += iomap.o diff --git a/arch/powerpc/kernel/trace_clock.c b/arch/powerpc/kernel/trace_clock.c new file mode 100644 index 0000000..4917069 --- /dev/null +++ b/arch/powerpc/kernel/trace_clock.c @@ -0,0 +1,15 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License, version 2, as + * published by the Free Software Foundation. + * + * Copyright (C) 2015 Naveen N. Rao, IBM Corporation + */ + +#include +#include + +u64 notrace trace_clock_ppc_tb(void) +{ + return get_tb(); +} -- 2.7.4