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Re: [PATCH 1/2] x86-64/setcontext: Pop the pointer into %rdx after syscall

From: "H.J. Lu" <hjl dot tools at gmail dot com>
To: Florian Weimer <fweimer at redhat dot com>
Cc: GNU C Library <libc-alpha at sourceware dot org>
Date: Sun, 29 Apr 2018 15:07:43 -0700
Subject: Re: [PATCH 1/2] x86-64/setcontext: Pop the pointer into %rdx after syscall
References: <20180426121700.GA30766@intel.com> <8b0e9b44-d231-ef32-05a7-5fad5c7352b1@redhat.com>

On Sun, Apr 29, 2018 at 2:03 PM, Florian Weimer <fweimer@redhat.com> wrote:
> On 04/26/2018 02:17 PM, H.J. Lu wrote:
>>
>> +       /* Pop the pointer into RDX which is preserved by the syscall.  */
>> +       popq    %rdx
>
>
> Sorry, the comment is a bit unclear.  Why do you need to restore %rdx if it
> is preserved by the system call?  Maybe it becomes clearer with a future
> change?
>

Here is the patch to use it:

https://github.com/hjl-tools/glibc/commit/182ce0987aada98b2d606276d4aa4fbd2527031b


-- 
H.J.

References:
- [PATCH 1/2] x86-64/setcontext: Pop the pointer into %rdx after syscall
  - From: H.J. Lu
- Re: [PATCH 1/2] x86-64/setcontext: Pop the pointer into %rdx after syscall
  - From: Florian Weimer

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