[PATCH] powerpc/ftrace: add powerpc timebase as a trace clock source

[Steven Rostedt]

On Thu, 23 Apr 2015 12:15:04 +0530
"Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> wrote:

> diff --git a/arch/powerpc/include/asm/trace_clock.h b/arch/powerpc/include/asm/trace_clock.h
> new file mode 100644
> index 0000000..0b0d094
> --- /dev/null
> +++ b/arch/powerpc/include/asm/trace_clock.h
> @@ -0,0 +1,27 @@
> +/*
> + * 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 <linux/compiler.h>
> +#include <linux/types.h>
> +
> +#ifdef CONFIG_TRACE_CLOCK

You don't need this #if statement. What else is using this besides
kernel/trace/trace.c, which selects TRACE_CLOCK if it is compiled.

If you were trying to match x86, where it has:

#ifdef CONFIG_X86_TSC

where you have CONFIG_TRACE_CLOCK. We needed the #ifdef because you
can compile the x86 kernel without TSC support, and we did not want to
export a tsc tracing clock if one did not exist.

And the only place that I see that even includes this header in ppc, is
also only compiled if CONFIG_TRACE_CLOCK is selected.

I'm fine with the change, just nuke the unnecessary #ifdef.

-- Steve



> +
> +extern u64 notrace trace_clock_ppc_tb(void);
> +
> +#define ARCH_TRACE_CLOCKS { trace_clock_ppc_tb, "ppc-tb", 0 },
> +
> +#else
> +
> +#define ARCH_TRACE_CLOCKS
> +
> +#endif /* CONFIG_TRACE_CLOCK */
> +
> +#endif  /* _ASM_PPC_TRACE_CLOCK_H */
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 502cf69..f9936f3 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-$(CONFIG_TRACE_CLOCK)	+= trace_clock.o
>  
>  ifneq ($(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 <asm/trace_clock.h>
> +#include <asm/time.h>
> +
> +u64 notrace trace_clock_ppc_tb(void)
> +{
> +	return get_tb();
> +}