Re: [PATCH -v2] x86/hweight: Get rid of the special calling convention

From	Brian Gerst <brgerst@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH -v2] x86/hweight: Get rid of the special calling convention
Date	2016-05-11 13:20 +0200
Message-ID	<rxAlk-7bN-27@gated-at.bofh.it> (permalink)
References	(6 earlier) <rxjDP-75T-1@gated-at.bofh.it> <rxlcD-uF-29@gated-at.bofh.it> <rxlmh-zy-13@gated-at.bofh.it> <rxotQ-3v7-13@gated-at.bofh.it> <rxtMR-Fp-1@gated-at.bofh.it>
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On Wed, May 11, 2016 at 12:11 AM, Borislav Petkov <bp@suse.de> wrote:
> On Tue, May 10, 2016 at 03:30:48PM -0700, H. Peter Anvin wrote:
>> I didn't mean inline assembly.
>
> How does that matter?
>
> The problem is having as less insn bytes as possible and the minimal
> size we can do is issuing POPCNT everywhere which is 4 or 5 bytes. The
> alternatives then replace that with a CALL which is also 5 bytes.
>
> The way I did it now, it adds 22K more to allyesconfig vmlinux due to
> the static_cpu_has doubled alternatives sections and the JMPs. The
> thunks will keep those 5 bytes *and* get rid of the calling convention
> without the growth.
>
> Or?

I think he meant the out of line version would be asm, so you could
control what registers were clobbered.

--
Brian Gerst

Thread

[RFC PATCH] x86/hweight: Get rid of the special calling convention Borislav Petkov <bp@suse.de> - 2016-05-04 20:50 +0200
  Re: [RFC PATCH] x86/hweight: Get rid of the special calling convention Brian Gerst <brgerst@gmail.com> - 2016-05-04 21:40 +0200
    Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 21:40 +0200
      Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-04 21:50 +0200
        Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 22:00 +0200
          Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-04 22:30 +0200
            Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 23:00 +0200
            Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention Andi Kleen <andi@firstfloor.org> - 2016-05-04 23:20 +0200
            Re: [RFC PATCH] x86/hweight: Get rid of the special calling convention Denys Vlasenko <dvlasenk@redhat.com> - 2016-05-05 15:10 +0200
              Re: [RFC PATCH] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-05 16:10 +0200
                [PATCH -v2] x86/hweight: Get rid of the special calling convention Borislav Petkov <bp@suse.de> - 2016-05-10 19:00 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Peter Zijlstra <peterz@infradead.org> - 2016-05-10 19:30 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-10 21:10 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-10 21:20 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-11 00:40 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-11 06:20 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling convention Brian Gerst <brgerst@gmail.com> - 2016-05-11 13:20 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Peter Zijlstra <peterz@infradead.org> - 2016-05-11 13:30 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-11 14:50 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling convention "H. Peter Anvin" <hpa@zytor.com> - 2016-05-12 07:00 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-12 14:00 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Peter Zijlstra <peterz@infradead.org> - 2016-05-12 14:20 +0200
                Re: [PATCH -v2] x86/hweight: Get rid of the special calling  convention Borislav Petkov <bp@suse.de> - 2016-05-10 21:10 +0200

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