From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Steven Rostedt <rostedt@goodmis.org>
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>,
yrl.pp-manager.tt@hitachi.com
Subject: Re: [RFC PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used
Date: Thu, 09 Aug 2012 11:58:58 +0900 [thread overview]
Message-ID: <50232772.4070102@hitachi.com> (raw)
In-Reply-To: <1344430148.6935.17.camel@gandalf.stny.rr.com>
(2012/08/08 21:49), Steven Rostedt wrote:
> 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.
Ah, I see. OK, I don't see any other issue.
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2012-08-09 2:59 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
2012-08-09 2:58 ` Masami Hiramatsu [this message]
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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