Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field

From	"H. Peter Anvin" <hpa@zytor.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field
Date	2016-02-27 20:40 +0100
Message-ID	<r6SSC-7LP-11@gated-at.bofh.it> (permalink)
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On February 27, 2016 11:16:44 AM PST, Dave Hansen <dave@sr71.net> wrote:
>On 02/27/2016 03:41 AM, Ingo Molnar wrote:
>> * Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>>> > On Fri, 26 Feb 2016 09:44:00 -0800 "H. Peter Anvin"
><hpa@zytor.com> wrote:
>>>> > > __u64 is okay, "unsigned long" is really messy in the presence
>of 32-on-64 bit ABIs...
>>> > 
>>> > Yeah, but unfortunately, any 64 bit scalar type here will change
>the
>>> > alignment of the enclosing unions on (some) 32 bit platforms and
>thus
>>> > break the ABI.
>> Then a different solution has to be found.
>
>I've acked Stephen's initial patch changing the 'u64' to an 'int'.  x86
>only needs 4 bits, and in the remote chance that a future
>implementation
>needed more space, we could easily add a second 32-bit field "_pkey_hi"
>or something that wouldn't have the alignment issues of a true 64-bit
>type.
>
>How should we get Stephen's patch in to the tip tree?

u32?
-- 
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Thread

[PATCH] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen <dave@sr71.net> - 2016-02-26 18:40 +0100
  Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field "H. Peter Anvin" <hpa@zytor.com> - 2016-02-26 18:50 +0100
    Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-26 23:20 +0100
      Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Ingo Molnar <mingo@kernel.org> - 2016-02-27 12:50 +0100
        Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen <dave@sr71.net> - 2016-02-27 20:20 +0100
          Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 20:40 +0100
            Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-28 00:30 +0100
              [PATCH v2] signals, pkeys: make si_pkey 32 bits Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-28 00:50 +0100
                Re: [PATCH v2] signals, pkeys: make si_pkey 32 bits Ingo Molnar <mingo@kernel.org> - 2016-02-29 09:00 +0100
              Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Ingo Molnar <mingo@kernel.org> - 2016-02-29 09:10 +0100
                Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-03-01 00:00 +0100

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