From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-patches-return-97512-listarch-gdb-patches=sources.redhat.com@sourceware.org>
Received: (qmail 31876 invoked by alias); 8 Jan 2013 17:50:21 -0000
Received: (qmail 31864 invoked by uid 22791); 8 Jan 2013 17:50:19 -0000
X-SWARE-Spam-Status: No, hits=-3.8 required=5.0	tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,KHOP_RCVD_TRUST,KHOP_THREADED,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE
X-Spam-Check-By: sourceware.org
Received: from mail-qc0-f174.google.com (HELO mail-qc0-f174.google.com) (209.85.216.174)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 08 Jan 2013 17:50:01 +0000
Received: by mail-qc0-f174.google.com with SMTP id o22so924185qcr.33        for <gdb-patches@sourceware.org>; Tue, 08 Jan 2013 09:50:01 -0800 (PST)
MIME-Version: 1.0
Received: by 10.224.100.130 with SMTP id y2mr5178158qan.40.1357667401121; Tue, 08 Jan 2013 09:50:01 -0800 (PST)
Received: by 10.49.12.210 with HTTP; Tue, 8 Jan 2013 09:50:00 -0800 (PST)
In-Reply-To: <201301081245.14528.vapier@gentoo.org>
References: <1357657280-24150-1-git-send-email-vapier@gentoo.org>	<201301081059.40723.vapier@gentoo.org>	<CAMe9rOqAWq6+ojohVHYa751eUOQ23Y9puDDbo1r9tbVL=V0B5w@mail.gmail.com>	<201301081245.14528.vapier@gentoo.org>
Date: Tue, 08 Jan 2013 17:50:00 -0000
Message-ID: <CAMe9rOoBgpgoaStNgoo7M3okFgQGF7R4SkDo9WVZ+5surSOo-A@mail.gmail.com>
Subject: Re: [PATCH] gdb: x86: fix x32 builds with inline asm
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Mike Frysinger <vapier@gentoo.org>
Cc: gdb-patches@sourceware.org, jan.kratochvil@redhat.com
Content-Type: text/plain; charset=ISO-8859-1
X-IsSubscribed: yes
Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb-patches.sourceware.org>
List-Subscribe: <mailto:gdb-patches-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb-patches/>
List-Post: <mailto:gdb-patches@sourceware.org>
List-Help: <mailto:gdb-patches-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-patches-owner@sourceware.org
X-SW-Source: 2013-01/txt/msg00142.txt.bz2

On Tue, Jan 8, 2013 at 9:45 AM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Tuesday 08 January 2013 11:54:32 H.J. Lu wrote:
>> On Tue, Jan 8, 2013 at 7:59 AM, Mike Frysinger <vapier@gentoo.org> wrote:
>> > On Tuesday 08 January 2013 10:01:20 Mike Frysinger wrote:
>> >> +       asm volatile ("push %0;"
>> >>                       ".globl linux_ptrace_test_ret_to_nx_instr;"
>> >>                       "linux_ptrace_test_ret_to_nx_instr:"
>> >>                       "ret"
>> >> -                     : : "r" (return_address) : "%rsp", "memory");
>> >> +                     : : "r" (return_address) : "sp", "memory");
>> >
>> > hrm, this works for -m32 and -m64, but doesn't actually help with -mx32.
>> > this doesn't seem to line up with my expectations.  can you suggest
>> > something here H.J. Lu ?
>> >
>> > $ cat test.c
>> > main() { asm volatile ("push %0; ret;" : : "r"(main) : "sp", "memory"); }
>> >
>> > $ gcc -m32 test.c
>> >    8:   50                      push   %eax
>> >    9:   c3                      ret
>> > $ gcc -m64 test.c
>> >    9:   50                      push   %rax
>> >    a:   c3                      retq
>> >
>> > $ gcc -mx32 test.c
>> > test.c: Assembler messages:
>> > test.c:2: Error: operand type mismatch for `push'
>>
>> Can you try this?
>>
>> +#ifdef __x86_64__
>> +                       : : "r" ((uint64_t) (uintptr_t) (return_address))
>
> that seems to work for me, but seems wrong.  i guess while most 32/64 bit
> issues can be handled transparently, the stack still only allows
> pushing/popping of 64bit values in x32 mode.
> -mike

I believe it is correct for x32 since "ret" will pop 64bit as return address
for x32.

-- 
H.J.