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From: Ingo Molnar <mingo@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	Alexander Potapenko <glider@google.com>,
	Dmitriy Vyukov <dvyukov@google.com>,
	Matthias Kaehlcke <mka@chromium.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent
Date: Sat, 2 Sep 2017 12:32:21 +0200	[thread overview]
Message-ID: <20170902103221.5gw5vtxxknprzgdr@gmail.com> (raw)
In-Reply-To: <20170831173132.i5y5p4gdmm4iv3h3@treble>


* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> On Thu, Aug 31, 2017 at 12:25:42PM -0500, Josh Poimboeuf wrote:
> > 2) Put "sp" in the clobbers list instead of as an i/o constraint.  This
> >    mostly works for GCC, and doesn't break clang.  However, it causes
> >    GCC to insert a "lea -0x10(%rbp),%rsp" in the epilogue of every
> >    affected function.
> 
> And maybe this extra instruction is negligible for performance and not a
> big deal?  I might look at this one after the holiday too.

Please do statistics of how many functions are affected, on a defconfig-ish 
kernel.

Thanks,

	Ingo

  reply	other threads:[~2017-09-02 10:32 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-31 14:11 [RFC PATCH 0/4] x86/asm: Add ASM_CALL() macro for inline asms with call instructions Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 1/4] x86/paravirt: Fix output constraint macro names Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 2/4] x86/asm: Convert some inline asm positional operands to named operands Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent Josh Poimboeuf
2017-08-31 16:11   ` Linus Torvalds
2017-08-31 17:25     ` Josh Poimboeuf
2017-08-31 17:31       ` Josh Poimboeuf
2017-09-02 10:32         ` Ingo Molnar [this message]
2017-09-14 14:48           ` Josh Poimboeuf
2017-09-14 17:16             ` Linus Torvalds
2017-09-14 17:26               ` Josh Poimboeuf
2017-09-14 17:33                 ` Josh Poimboeuf
2017-09-14 18:28                   ` Linus Torvalds
2017-09-14 18:45                     ` Josh Poimboeuf
2017-09-15 16:10                       ` Josh Poimboeuf
2017-09-15 16:53       ` Andrey Ryabinin
2017-09-15 17:20         ` Josh Poimboeuf
2017-09-15 18:01         ` Linus Torvalds
2017-09-15 23:29           ` Josh Poimboeuf
2017-09-16 22:22             ` Andrey Ryabinin
2017-09-18 17:40               ` Josh Poimboeuf
2017-09-19 16:02           ` Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 4/4] x86/asm: Use ASM_CALL() macro for inline asm statements with call instructions Josh Poimboeuf
2017-08-31 14:50   ` Peter Zijlstra
2017-08-31 15:21     ` Josh Poimboeuf
2017-08-31 15:36       ` Dmitry Vyukov

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