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

[Magnus Granberg <zorry at gentoo dot org>]

fredag 08 maj 2015 10.35.44 skrev  H.J. Lu:
> On Thu, May 7, 2015 at 2:17 PM, Joseph Myers <joseph@codesourcery.com> 
wrote:
> > On Fri, 6 Mar 2015, H.J. Lu wrote:
> >> +# We don't want to compile the compiler with -fPIE, it make PCH fail.
> >> +COMPILER += @NO_PIE_CFLAGS@
> >> +
> >> +# Link with -no-pie since we compile the compiler with -fno-PIE.
> >> +LINKER += @NO_PIE_FLAG@
> > 
> > As I understand it, what we don't want is the compiler to be a PIE.  That
> > is, it must be linked -no-pie (and given that the compiler is not a PIE,
> > compiling -fPIE would be pointless, although it wouldn't actually break
> > things to have PIE objects in the compiler as long as it's linked for a
> > fixed address).
> > 
> >> +#if defined ENABLE_DEFAULT_PIE
> >> +#define GNU_USER_TARGET_STARTFILE_SPEC \
> >> +  "%{!shared: %{pg|p|profile:gcrt1.o%s;: \
> >> +    %{" PIE_SPEC ":Scrt1.o%s} %{" NO_PIE_SPEC ":crt1.o%s}}} \
> >> +   crti.o%s %{static:crtbeginT.o%s;: %{shared:crtbeginS.o%s} \
> >> +           %{" PIE_SPEC ":crtbeginS.o%s} \
> >> +           %{" NO_PIE_SPEC ":crtbegin.o%s}}" \
> >> +   FVTABLE_VERIFY_SPEC
> >> +#else
> >> +#define GNU_USER_TARGET_STARTFILE_SPEC \
> >> +  "%{!shared: %{pg|p|profile:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}} \
> >> +   crti.o%s
> >> %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}" \ +  
> >> FVTABLE_VERIFY_SPEC
> >> +#endif
> > 
> > With appropriate definitions of PIE_SPEC and NO_PIE_SPEC, shouldn't a
> > single definition of GNU_USER_TARGET_STARTFILE_SPEC be able to work for
> > both ENABLE_DEFAULT_PIE and !ENABLE_DEFAULT_PIE?
> 
> Yes.
> 
> > <https://gcc.gnu.org/ml/gcc-patches/2015-03/msg00393.html> noted a
> > possible issue with MIPS.  Actually, rather more config/*.h and
> > config/*/*.h headers contain specs testing for (-fpie, -fPIE, -fno-pie,
> > -fno-PIE, -pie) options, which would be affected by these changes.  I'd
> > say this patch should include an initial attempt at adjusting those config
> > headers, which should be an essentially mechanical change not requiring
> > understanding anything target-specific.  For link-time specs, that may
> > mean using PIE_SPEC and NO_PIE_SPEC.  For compile-time specs, similar new
> > macros would be added.  Given such adjustments included in the patch and
> > the relevant target maintainers CC:ed, I might then be inclined to approve
> > the patch on the basis of allowing a week for target maintainers to test
> > the changes for their targets before commit, as I don't see any major
> > problems with it beyond the need to update the target-specific specs.
> 
> Here is the updated patch.  I will post patches for cris, mips, powerpc
> and sparc separately.  The target maintainers should be able to adjust
> backend ASM_SPEC with FPIE_OR_FPIC_SPEC and
> NO_FPIE_AND_FPIC_SPEC.
> 
> OK for trunk?
> 
> Thanks.
PIng

Any progress on this?

/Magnus G.