Re: [PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1

From: Andy Lutomirski
Date: Tue Aug 25 2015 - 03:19:34 EST

On Mon, Jul 27, 2015 at 12:26 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Mon, Jul 27, 2015 at 12:19 PM, Denys Vlasenko <dvlasenk@xxxxxxxxxx> wrote:
>> On 07/24/2015 07:50 PM, Andy Lutomirski wrote:
>>> On Fri, Jul 24, 2015 at 6:47 AM, Denys Vlasenko <dvlasenk@xxxxxxxxxx> wrote:
>>>> SYSCALL32 code is nearly identical to SYSCALL32, except for initial
>>>> section. Merge them.
>>>> The removal is split into two parts, to make review eaiser. This is part 1.
>>>> auditsys_entry_common and auditsys_exit macros are indented one more tab without
>>>> any changes. This prevents diff from becoming unreadable.
>>>> They will be removed in part 2.
>>> I need to read these more closely, which is, at present, exceeding my
>>> ability to look at asm. (See the big NMI thread.) I'll look soon.
>>> Meanwhile, this code is incredibly fragile wrt syscall restart.
>>> (Syscall restart on compat is really weird.) Do we have a decent test
>>> for it?
>> How about this? (Feel free to expand, this is a first cut only).
> On a very brief glance, it looks reasonable, but I'd try it with
> recvfrom instead of recv because it's a six-argument syscall.

I was wondering how syscall restart works on compat syscalls on AMD
(i.e. SYSCALL32). I think the answer is that it doesn't. Sigh.
(Tested with ptrace instead of actual syscall restart.)

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