PING^3: [PATCH]: New configure options that make the compiler use -fPIE and -pie as default option

PING.  I am enclosing the patch here for review.

On Wed, Feb 11, 2015 at 8:47 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> PING.
>
> On Wed, Jan 28, 2015 at 8:05 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> PING.
>>
>> On Tue, Jan 13, 2015 at 3:25 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Tue, Jan 13, 2015 at 5:03 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>> On Mon, Jan 12, 2015 at 11:50:41PM +0000, Joseph Myers wrote:
>>>>> On Mon, 12 Jan 2015, H.J. Lu wrote:
>>>>>
>>>>> > +if test x$enable_default_pie = xyes; then
>>>>> > +  AC_MSG_CHECKING(if $target supports default PIE)
>>>>> > +  enable_default_pie=no
>>>>> > +  case $target in
>>>>> > +    i?86*-*-linux* | x86_64*-*-linux*)
>>>>> > +      saved_LDFLAGS="$LDFLAGS"
>>>>> > +      saved_CFLAGS="$CFLAGS"
>>>>> > +      CFLAGS="$CFLAGS -fPIE"
>>>>> > +      LDFLAGS="$LDFLAGS -fPIE -pie"
>>>>> > +      AC_TRY_LINK(,,[enable_default_pie=yes],)
>>>>> > +      LDFLAGS="$saved_LDFLAGS"
>>>>> > +      CFLAGS="$saved_CFLAGS"
>>>>> > +      ;;
>>>>> > +    *)
>>>>> > +      ;;
>>>>> > +    esac
>>>>>
>>>>> There should not be any such hardcoding of targets here without concrete
>>>>> evidence that the targets for which this sets enable_default_pie=no really
>>>>> cannot support PIE.  In particular, there is no reason at all for this to
>>>>> be architecture-specific; all GNU/Linux architectures should support PIE.
>>>>>
>>>>> I believe AC_TRY_LINK here will test for the host, whereas what you want
>>>>> to know is what's supported for the target (but it's not possible to run
>>>>> link tests for the target at this point; the compiler for the target
>>>>> hasn't even been built).
>>>>>
>>>>> So: just presume that if the user passes --enable-default-pie then they
>>>>> know what they are doing, and don't try to override their choice.
>>>>>
>>>>> > diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
>>>>> > index c9e3bf1..89fc305 100644
>>>>> > --- a/gcc/doc/install.texi
>>>>> > +++ b/gcc/doc/install.texi
>>>>> > @@ -1583,6 +1583,10 @@ not be built.
>>>>> >  Specify that the run-time libraries for stack smashing protection
>>>>> >  should not be built.
>>>>> >
>>>>> > +@item --enable-default-pie
>>>>> > +Turn on @option{-fPIE} and @option{-pie} by default if supported.
>>>>> > +Currently supported targets are i?86-*-linux* and x86-64-*-linux*.
>>>>>
>>>>> The "if supported" and target list can then be removed here.
>>>>>
>>>>
>>>> Here is the updated patch.  To support --enable-default-pie, each target
>>>> must update STARTFILE_SPEC to support PIE_SPEC and NO_PIE_SPEC.  I can
>>>> provide STARTFILE_SPEC patch if needed.
>>>>
>>>> Thanks.
>>>>
>>>>
>>>> H.J.
>>>> ---
>>>> gcc/
>>>>
>>>> 2015-01-12  Magnus Granberg  <zorry@gentoo.org>
>>>>             H.J. Lu  <hongjiu.lu@intel.com>
>>>>
>>>>         * Makefile.in (COMPILER): Add @NO_PIE_CFLAGS@.
>>>>         (LINKER): Add @NO_PIE_FLAG@.
>>>>         (libgcc.mvars): Set NO_PIE_CFLAGS to -fno-PIE for
>>>>         --enable-default-pie.
>>>>         * common.opt (fPIE): Initialize to -1.
>>>>         (fpie): Likewise.
>>>>         (static): Add "RejectNegative Negative(shared)".
>>>>         (no-pie): New option.
>>>>         (pie): Replace "Negative(shared)" with "Negative(no-pie)".
>>>>         * configure.ac: Add --enable-default-pie.
>>>>         (NO_PIE_CFLAGS): New.  Check if -fno-PIE works.  AC_SUBST.
>>>>         (NO_PIE_FLAG): New.  Check if -no-pie works.  AC_SUBST.
>>>>         * defaults.h (DEFAULT_FLAG_PIE): New.  Default PIE to -fPIE.
>>>>         * gcc.c (NO_PIE_SPEC): New.
>>>>         (PIE_SPEC): Likewise.
>>>>         (LD_PIE_SPEC): Likewise.
>>>>         (LINK_PIE_SPEC): Handle -no-pie.  Use PIE_SPEC and LD_PIE_SPEC.
>>>>         * opts.c (DEFAULT_FLAG_PIE): New.  Set to 0 if ENABLE_DEFAULT_PIE
>>>>         is undefined.
>>>>         (finish_options): Update opts->x_flag_pie if it is -1.
>>>>         * config/gnu-user.h (FVTABLE_VERIFY_SPEC): New.
>>>>         (GNU_USER_TARGET_STARTFILE_SPEC): Use FVTABLE_VERIFY_SPEC.  Use
>>>>         NO_PIE_SPEC and NO_PIE_SPEC if ENABLE_DEFAULT_PIE is defined.
>>>>         (GNU_USER_TARGET_STARTFILE_SPEC): Use FVTABLE_VERIFY_SPEC.
>>>>         * doc/install.texi: Document --enable-default-pie.
>>>>         * doc/invoke.texi: Document -no-pie.
>>>>         * config.in: Regenerated.
>>>>         * configure: Likewise.
>>>>
>>>> gcc/ada/
>>>>
>>>> 2015-01-12  H.J. Lu  <hongjiu.lu@intel.com>
>>>>
>>>>         * gcc-interface/Makefile.in (TOOLS_LIBS): Add @NO_PIE_FLAG@.
>>>>
>>>> libgcc/
>>>>
>>>> 2015-01-12  H.J. Lu  <hongjiu.lu@intel.com>
>>>>
>>>>         * Makefile.in (CRTSTUFF_CFLAGS): Add $(NO_PIE_CFLAGS).
>>>>
>>>
>>> This is the updated patch.  I fixed the -r regression.   LTO tests
>>> pass now.
>>>
>>> --
>>> H.J.
>>
>>
>>
>> --
>> H.J.
>
>
>
> --
> H.J.

PING^3: [PATCH]: New configure options that make the compiler use -fPIE and -pie as default option

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