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From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andi Kleen <andi@firstfloor.org>
Subject: Re: [RFC PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used
Date: Wed, 08 Aug 2012 08:49:08 -0400	[thread overview]
Message-ID: <1344430148.6935.17.camel@gandalf.stny.rr.com> (raw)
In-Reply-To: <5021EC6B.7020605@hitachi.com>

On Wed, 2012-08-08 at 13:34 +0900, Masami Hiramatsu wrote:
>  
> > -#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
> > +#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)
> 
> I think CONFIG_HAVE_FENTRY would better unselect
> CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST in arch/x86/Kconfig explicitly.

No, CONFIG_HAVE_FENTRY just means fentry is supported, it does not mean
that it is being used. It only gets used if CC_USING_FENTRY is set,
which is set by the Makefile at time of compile.

If CONFIG_HAVE_FENTRY is defined, a test is done to see if the gcc
compiling the kernel supports -mfentry. If it does, then it defines the
CC_USING_FENTRY macro, if not, the macro is not defined and the old way
is performed.

If the old way is performed, even if CONFIG_HAVE_FENTRY is defined, then
we still need the above test. We can not have CONFIG_HAVE_FENTRY
unselect CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST.

-- Steve



  reply	other threads:[~2012-08-08 12:49 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-07 19:38 [RFC PATCH 0/4] ftrace: Add use of -mfentry for x86_64 Steven Rostedt
2012-08-07 19:38 ` [RFC PATCH 1/4] ftrace: Make recordmcount.c handle __fentry__ Steven Rostedt
2012-08-07 23:57   ` John Reiser
2012-08-08  0:05     ` Steven Rostedt
2012-08-27 17:03   ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-08-07 19:38 ` [RFC PATCH 2/4] ftrace: Add -mfentry to Makefile on function tracer Steven Rostedt
2012-08-27 17:04   ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-08-07 19:38 ` [RFC PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used Steven Rostedt
2012-08-08  4:34   ` Masami Hiramatsu
2012-08-08 12:49     ` Steven Rostedt [this message]
2012-08-09  2:58       ` Masami Hiramatsu
2012-08-09  3:45       ` Linus Torvalds
2012-08-09  3:57         ` Steven Rostedt
2012-08-09  4:15         ` H. Peter Anvin
2012-08-09 12:37         ` Andi Kleen
2012-08-27 17:05   ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-08-07 19:38 ` [RFC PATCH 4/4] ftrace/x86: Add support for -mfentry to x86_64 Steven Rostedt
2012-08-09  8:34   ` Masami Hiramatsu
2012-08-09 13:46   ` Steven Rostedt
2012-08-09 13:48     ` Steven Rostedt
2012-08-10  7:45     ` Masami Hiramatsu
2012-08-27 17:06   ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-08-07 20:23 ` [RFC PATCH 0/4] ftrace: Add use of -mfentry for x86_64 H. Peter Anvin
2012-08-13  8:42   ` Ingo Molnar
  -- strict thread matches above, loose matches on Subject: below --
2011-02-09 20:02 [RFC][PATCH 0/4] ftrace: Use -mfentry when supported (this is for x86_64 right now) Steven Rostedt
2011-02-09 20:02 ` [RFC][PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used Steven Rostedt

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