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Date:   Thu, 13 May 2021 20:23:17 -0700
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Subject: Re: [RFC v2 PATCH 7/7] x86/entry: use int for syscall number; handle all invalid syscall nrs
To:     Andy Lutomirski <andy@linux.luto.us>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>
CC:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
From:   "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <486B4C98-FFD1-40B9-B7AF-5323DE07A0FE@zytor.com>
Precedence: bulk

Yeah=2E Also, x32 long is 32 bits=2E=2E=2E

On May 13, 2021 8:18:37 PM PDT, Andy Lutomirski <andy@linux=2Eluto=2Eus> w=
rote:
>On 5/13/21 5:38 PM, H=2E Peter Anvin wrote:
>> On 5/12/21 3:22 PM, Thomas Gleixner wrote:
>>>>
>>>> As far as this being a user ABI change, this is actually a revert
>to the
>>>> original x86-64 ABI; see my message to Ingo=2E
>>>
>>> I'm not against that change, but it has to be well justified and the
>>> reasoning wants to be in the changelog=2E You know the drill :)
>>>
>>=20
>> FYI:
>>=20
>> So in the process of breaking up and better document this patch, I
>have
>> looked at the syscall_numbering_64 (and have rewritten it to be more
>> complete=2E)
>>=20
>> I found that running it under strace fails, as strace (possibly
>ptrace,
>> possibly the strace binary) causes %rax =3D 2^32 to be clobbered to
>zero
>> already=2E=2E=2E
>>=20
>> More motivation, I guess=2E
>>=20
>
>Indeed=2E
>
>I would love to go back in time and switch to long, but there are
>plenty
>of things that use int now=2E  I suppose we could try to make it long for
>real, but seccomp has u32 baked into its ABI=2E

--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E