Re: [PATCH, libmpx, i386, PR driver/65444] Pass '-z bndplt' when building dynamic objects with MPX

[Ilya Enkovich <enkovich.gnu@gmail.com>]

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.

Ilya

>1
>
> --
> H.J.