On Wed, Mar 18, 2015 at 6:41 AM, Ilya Enkovich <enkovich....@gmail.com> wrote:
> 2015-03-18 16:31 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>> On Wed, Mar 18, 2015 at 6:24 AM, Ilya Enkovich <enkovich....@gmail.com>
>> wrote:
>>> 2015-03-18 15:42 GMT+03:00 Richard Biener <richard.guent...@gmail.com>:
>>>> On Wed, Mar 18, 2015 at 1:25 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>>> On Wed, Mar 18, 2015 at 5:13 AM, Ilya Enkovich <enkovich....@gmail.com>
>>>>> wrote:
>>>>>> 2015-03-18 15:08 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>>>>>> On Wed, Mar 18, 2015 at 5:05 AM, Ilya Enkovich <enkovich....@gmail.com>
>>>>>>> wrote:
>>>>>>>> 2015-03-18 15:02 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>>>>>>>> On Wed, Mar 18, 2015 at 4:56 AM, Ilya Enkovich
>>>>>>>>> <enkovich....@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.enkov...@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.enkov...@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.
--
H.J.
