From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andi Kleen <ak@linux.intel.com>,
Stefani Seibold <stefani@seibold.net>, X86 ML <x86@kernel.org>,
Greg KH <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
John Stultz <john.stultz@linaro.org>,
Pavel Emelyanov <xemul@parallels.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
andriy.shevchenko@linux.intel.com,
Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com
Subject: Re: [PATCH 1/2] x86: Mark __vdso entries as asmlinkage
Date: Wed, 26 Feb 2014 21:22:57 -0800 [thread overview]
Message-ID: <530ECBB1.40806@zytor.com> (raw)
In-Reply-To: <CALCETrWbS3B_63Q76E5RL0Y6B=1=1ObmECR3HTMk1HQ-4OwN8A@mail.gmail.com>
On 02/26/2014 09:19 PM, Andy Lutomirski wrote:
>>
>> The normal ABI almost certainly makes more sense; as such -mregparm=3 is
>> probably not what we want, and I suspect it makes more sense to just
>> drop that from the CFLAGS line?
>
> Hmm. What happens on a native 32-bit build? IIRC the whole kernel is
> build with regparm(3).
>
Well, the vdso is still built separately, so we can use different CFLAGS
if we want to.
> If we want to save a cycle or two, then regparm(3) is probably faster.
> But I think that these functions should either be asmlinkage or (on
> 32 bit builds) explicitly regparm(3) to avoid confusion.
I suggest using the standard ABI, but I suggest doing it via CFLAGS.
It isn't any faster if the C library has to provide a wrapper just to
marshal parameters.
-hpa
next prev parent reply other threads:[~2014-02-27 5:31 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-26 19:34 Final: Add 32 bit VDSO time function support Stefani Seibold
2014-02-26 20:10 ` Andy Lutomirski
2014-02-26 20:45 ` Greg KH
2014-02-26 20:54 ` Andy Lutomirski
2014-02-27 0:55 ` Andy Lutomirski
2014-02-27 1:02 ` [PATCH 0/2] Improvements/fixes to 32-bit vdso timing Andy Lutomirski
2014-02-27 1:02 ` [PATCH 1/2] x86: Mark __vdso entries as asmlinkage Andy Lutomirski
2014-02-27 3:25 ` H. Peter Anvin
2014-02-27 3:39 ` Andi Kleen
2014-02-27 5:06 ` H. Peter Anvin
2014-02-27 5:19 ` Andy Lutomirski
2014-02-27 5:22 ` H. Peter Anvin [this message]
2014-02-27 20:11 ` Andy Lutomirski
2014-02-27 23:12 ` H. Peter Anvin
2014-02-27 5:07 ` H. Peter Anvin
2014-02-27 1:02 ` [PATCH 2/2] x86: Inline the CLOCK_MONOTONIC vdso code Andy Lutomirski
2014-02-28 0:18 ` [PATCH v2 0/4] vDSO fixes, on top of tip/x86/vdso Andy Lutomirski
2014-02-28 0:18 ` [PATCH v2 1/4] x86: Use the default ABI for the 32-bit vDSO Andy Lutomirski
2014-02-28 7:28 ` Stefani Seibold
2014-02-28 15:06 ` H. Peter Anvin
2014-02-28 20:19 ` Andy Lutomirski
2014-03-01 13:43 ` Stefani Seibold
2014-02-28 0:18 ` [PATCH v2 2/4] x86: Inline the CLOCK_MONOTONIC vdso code Andy Lutomirski
2014-02-28 0:18 ` [PATCH v2 3/4] x86: Patch alternatives in the 32-bit vDSO Andy Lutomirski
2014-02-28 7:22 ` Stefani Seibold
2014-03-01 14:04 ` Stefani Seibold
2014-02-28 0:18 ` [PATCH v2 4/4] x86: Zero-pad the VVAR page Andy Lutomirski
2014-02-28 7:33 ` [PATCH v2 0/4] vDSO fixes, on top of tip/x86/vdso Stefani Seibold
2014-02-28 20:15 ` Andy Lutomirski
2014-03-01 14:02 ` Stefani Seibold
2014-02-28 7:22 ` Final: Add 32 bit VDSO time function support Stefani Seibold
2014-03-01 2:00 ` Andy Lutomirski
2014-03-01 22:56 ` H. Peter Anvin
2014-03-02 8:01 ` Stefani Seibold
2014-02-27 5:07 ` H. Peter Anvin
2014-02-27 12:14 ` Ingo Molnar
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