From: Robert Dewar <dewar@adacore.com>
To: Ilya Enkovich <enkovich.gnu@gmail.com>, "H.J. Lu" <hjl.tools@gmail.com>
Cc: Richard Biener <richard.guenther@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Uros Bizjak <ubizjak@gmail.com>
Subject: Re: [PATCH, libmpx, i386, PR driver/65444] Pass '-z bndplt' when building dynamic objects with MPX
Date: Wed, 18 Mar 2015 14:03:00 -0000 [thread overview]
Message-ID: <550985AE.4040904@adacore.com> (raw)
In-Reply-To: <CAMbmDYaNDDc6d_K61_kzzaZnfaieWvvyRLvy3kUvf=Eb6C8CXw@mail.gmail.com>
Do we really want to quote to this level? This message has 11 levels of
quotes, the most I have ever seen. If everyone does this, the whole
thread is in every message and that seems unnecessary. I don't know if
there are gcc guidelines on this???
On 3/18/2015 9:59 AM, Ilya Enkovich wrote:
> 2015-03-18 16:52 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
>> On Wed, Mar 18, 2015 at 6:41 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>> 2015-03-18 16:31 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
>>>> On Wed, Mar 18, 2015 at 6:24 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>> 2015-03-18 15:42 GMT+03:00 Richard Biener <richard.guenther@gmail.com>:
>>>>>> On Wed, Mar 18, 2015 at 1:25 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>>>> On Wed, Mar 18, 2015 at 5:13 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>>>>> 2015-03-18 15:08 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
>>>>>>>>> On Wed, Mar 18, 2015 at 5:05 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>>>>>>> 2015-03-18 15:02 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
>>>>>>>>>>> On Wed, Mar 18, 2015 at 4:56 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> This patch fixes PR target/65444 by passing '-z bndplt' to linker when appropriate. Bootstrapped and tested on x86_64-unknown-linux-gnu. Will commit it to trunk in a couple of days if no objections arise.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Ilya
>>>>>>>>>>>> --
>>>>>>>>>>>> gcc/
>>>>>>>>>>>>
>>>>>>>>>>>> 2015-03-18 Ilya Enkovich <ilya.enkovich@intel.com>
>>>>>>>>>>>>
>>>>>>>>>>>> PR driver/65444
>>>>>>>>>>>> * config/i386/linux-common.h (MPX_SPEC): New.
>>>>>>>>>>>> (CHKP_SPEC): Add MPX_SPEC.
>>>>>>>>>>>>
>>>>>>>>>>>> libmpx/
>>>>>>>>>>>>
>>>>>>>>>>>> 2015-03-18 Ilya Enkovich <ilya.enkovich@intel.com>
>>>>>>>>>>>>
>>>>>>>>>>>> PR driver/65444
>>>>>>>>>>>> * configure.ac: Add check for '-z bndplt' support
>>>>>>>>>>>> by linker. Add link_mpx output variable.
>>>>>>>>>>>> * libmpx.spec.in (link_mpx): New.
>>>>>>>>>>>> * configure: Regenerate.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> diff --git a/gcc/config/i386/linux-common.h b/gcc/config/i386/linux-common.h
>>>>>>>>>>>> index 9c6560b..dd79ec6 100644
>>>>>>>>>>>> --- a/gcc/config/i386/linux-common.h
>>>>>>>>>>>> +++ b/gcc/config/i386/linux-common.h
>>>>>>>>>>>> @@ -59,6 +59,11 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>>>>> %:include(libmpx.spec)%(link_libmpx)"
>>>>>>>>>>>> #endif
>>>>>>>>>>>>
>>>>>>>>>>>> +#ifndef MPX_SPEC
>>>>>>>>>>>> +#define MPX_SPEC "\
>>>>>>>>>>>> + %{mmpx:%{fcheck-pointer-bounds:%{!static:%:include(libmpx.spec)%(link_mpx)}}}"
>>>>>>>>>>>> +#endif
>>>>>>>>>>>> +
>>>>>>>>>>>> #ifndef LIBMPX_SPEC
>>>>>>>>>>>> #if defined(HAVE_LD_STATIC_DYNAMIC)
>>>>>>>>>>>> #define LIBMPX_SPEC "\
>>>>>>>>>>>> @@ -89,5 +94,5 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>>>>>
>>>>>>>>>>>> #ifndef CHKP_SPEC
>>>>>>>>>>>> #define CHKP_SPEC "\
>>>>>>>>>>>> -%{!nostdlib:%{!nodefaultlibs:" LIBMPX_SPEC LIBMPXWRAPPERS_SPEC "}}"
>>>>>>>>>>>> +%{!nostdlib:%{!nodefaultlibs:" LIBMPX_SPEC LIBMPXWRAPPERS_SPEC "}}" MPX_SPEC
>>>>>>>>>>>> #endif
>>>>>>>>>>>> diff --git a/libmpx/configure.ac b/libmpx/configure.ac
>>>>>>>>>>>> index fe0d3f2..3f8b50f 100644
>>>>>>>>>>>> --- a/libmpx/configure.ac
>>>>>>>>>>>> +++ b/libmpx/configure.ac
>>>>>>>>>>>> @@ -40,7 +40,18 @@ AC_MSG_RESULT($LIBMPX_SUPPORTED)
>>>>>>>>>>>> AM_CONDITIONAL(LIBMPX_SUPPORTED, [test "x$LIBMPX_SUPPORTED" = "xyes"])
>>>>>>>>>>>>
>>>>>>>>>>>> link_libmpx="-lpthread"
>>>>>>>>>>>> +link_mpx=""
>>>>>>>>>>>> +AC_MSG_CHECKING([whether ld accepts -z bndplt])
>>>>>>>>>>>> +echo "int main() {};" > conftest.c
>>>>>>>>>>>> +if AC_TRY_COMMAND([${CC} ${CFLAGS} -Wl,-z,bndplt -o conftest conftest.c 1>&AS_MESSAGE_LOG_FD])
>>>>>>>>>>>> +then
>>>>>>>>>>>> + AC_MSG_RESULT([yes])
>>>>>>>>>>>> + link_mpx="$link_mpx -z bndplt"
>>>>>>>>>>>> +else
>>>>>>>>>>>> + AC_MSG_RESULT([no])
>>>>>>>>>>>> +fi
>>>>>>>>>>>> AC_SUBST(link_libmpx)
>>>>>>>>>>>> +AC_SUBST(link_mpx)
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Without -z bndplt, MPX won't work correctly. We should always pass -z bndplt
>>>>>>>>>>> to linker. If linker doesn't support it, ld will issue a warning, not
>>>>>>>>>>> error and users
>>>>>>>>>>> will know their linker is too old. When they update linker, they don't have to
>>>>>>>>>>> rebuild GCC.
>>>>>>>>>>
>>>>>>>>>> If ld issues a warning instead of an error, then configure test passes
>>>>>>>>>> and we pass '-z bndplt' to linker.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Can you verify it with an older linker? The unknown XXX in -z XXX is always
>>>>>>>>> warned and ignored in Linux linker. If testing it on Linux always passes,
>>>>>>>>> it is useless.
>>>>>>>>
>>>>>>>> Old ld issues a warning:
>>>>>>>>
>>>>>>>> ld: warning: -z bndplt ignored.
>>>>>>>
>>>>>>> Does configure test pass?
>>>>>>>
>>>>>>>> But gold issues an error:
>>>>>>>>
>>>>>>>> ld.gold: bndplt: unknown -z option
>>>>>>>> ld.gold: use the --help option for usage information
>>>>>>>
>>>>>>> If gold is used, MPX won't work. What should we do here?
>>>>>>> Should we hardcode -fuse-ld=bfd for MPX?
>>>>>>
>>>>>> Is MPX disabled when the host linker is gold and gld isn't available?
>>>>>
>>>>> No. You may use MPX with gold and old ld but you would loose passed
>>>>> bounds when make a call via plt.
>>>>>
>>>>
>>>> If gold is default linker, the configure test will fail and we never pass
>>>> -z bndplt to linker even if ld.bfd is available and ld.gold is fixed later.
>>>> I'd rather always pass -z bndplt to ld.
>>>
>>> If gold is used and it doesn't support '-z bndplt' then it doesn't
>>> mean user can't use MPX.
>>
>> They can use -fuse-ld=bfd to select bfd linker if gold fails to generate
>> proper MPX binary.
>
> Which is a weird thing to do just to have a warning instead of an
> error. You don't guarantee MPX PLT generation by always passing '-z
> bndplt' but remove an opportunity to use gold at all. With current
> check you may use any linker and manually provide additional options
> if you want to.
>
> Ilya
>
>>
>>
>> --
>> H.J.
next prev parent reply other threads:[~2015-03-18 14:03 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-18 11:56 Ilya Enkovich
2015-03-18 12:03 ` H.J. Lu
2015-03-18 12:05 ` Ilya Enkovich
2015-03-18 12:08 ` H.J. Lu
2015-03-18 12:13 ` Ilya Enkovich
2015-03-18 12:25 ` H.J. Lu
2015-03-18 12:42 ` Richard Biener
2015-03-18 13:24 ` Ilya Enkovich
2015-03-18 13:32 ` H.J. Lu
2015-03-18 13:41 ` Ilya Enkovich
2015-03-18 13:52 ` H.J. Lu
2015-03-18 13:59 ` Ilya Enkovich
2015-03-18 14:02 ` Jakub Jelinek
2015-03-18 14:31 ` H.J. Lu
2015-03-18 14:42 ` H.J. Lu
2015-03-18 16:14 ` Ilya Enkovich
2015-03-18 16:45 ` H.J. Lu
2015-03-18 17:13 ` Ilya Enkovich
2015-03-18 17:14 ` H.J. Lu
2015-03-18 17:34 ` Ilya Enkovich
2015-03-18 17:39 ` H.J. Lu
2015-03-18 18:13 ` Ilya Enkovich
2015-03-18 14:03 ` Robert Dewar [this message]
2015-03-18 14:33 ` Markus Trippelsdorf
2015-03-23 10:19 ` Ilya Enkovich
2015-03-31 9:47 ` Ilya Enkovich
2015-04-02 4:34 ` Jeff Law
2015-04-02 11:01 ` H.J. Lu
2015-04-03 19:34 ` Joseph Myers
2015-04-06 1:45 ` Sandra Loosemore
2015-04-06 2:35 ` H.J. Lu
2015-04-06 3:08 ` Sandra Loosemore
2015-04-06 15:18 ` Ilya Enkovich
2015-04-06 15:28 ` Jeff Law
2015-04-06 15:54 ` Ilya Enkovich
2015-05-26 9:26 ` Ilya Enkovich
2015-05-27 15:35 ` Jeff Law
2015-06-03 9:04 ` Ilya Enkovich
2015-06-03 15:29 ` Joseph Myers
2015-06-03 15:59 ` Ilya Enkovich
2015-06-03 16:03 ` Joseph Myers
2015-06-04 14:14 ` Ilya Enkovich
2015-06-04 15:55 ` Joseph Myers
2015-06-05 14:44 ` Ilya Enkovich
2015-06-25 19:00 ` Jeff Law
2015-04-06 17:15 ` Sandra Loosemore
2015-04-07 19:01 ` Jeff Law
2015-04-07 19:29 ` H.J. Lu
2015-04-07 20:12 ` Markus Trippelsdorf
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