gcc: specify LDFLAGS_FOR_TARGET and --with-boot-ldflags, disable dynamicbase for compiler #6907
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jeremyd2019
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Well, it builds. I'm going to try building python with this, since it is known to use lto, but hopefully others (especially with x86_64) will put these through their paces a bit too. |
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I was able to build python both on my i686 tablet, and I also fired up a 64-bit windows virtual machine and built python on x86_64. Both completed without issue. |
msys2#6932 and msys2#6907 show packages have issues with the new default base addresses, so add an option to change back to the old defaults during the transition.
and --with-boot-ldflags. Allows these flags to affect binaries produced post-stage1. Add LDFLAGS to linking of shared libgcc.
GCC's precompiled header mechanism is not compatible with ASLR, so GCC itself needs dynamicbase to be disabled, but the runtime libraries would still benefit from having it set, so only disable dynamicbase for GCC itself.
Works around segfaults while compiling libgcc (and probably other, hard to diagnose creashes). But don't set image-base on lto-plugin. In fact, go ahead and let it use the target ldflags instead, while replicating the other flags it was getting before.
…lags_for_target_disable_dynamicbase
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From discussion on #6932 (comment), I added a command line option to binutils to switch default image bases back to their original 'low' values, and changed my gcc flags to use that instead of specifying the 'magic value' 0x400000. The binutils patch might reasonably be its own pull request, but I merged it into this one for CI's benefit. |
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* The new release includes https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=2e4e16f75e637d6486d0fdbb8c6ab13701238a55 which looks like it should disable dynamicbase where required * All the flags we wanted to inject via LDFLAGS are the default in binutils for some time now Ideally this cleanup should not change anything. For context where this was introduced: msys2#6907
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Related to #6899 (sharing the first commit with it), but with a less-hacky solution to disabling dynamicbase for the compiler itself while leaving it enabled for the runtime libraries. Note that this depends on the binutils from #6906 for the --disable-dynamicbase flag (draft until that's live so CI can build successfully).
Results can be divided into 3 sets:
Binaries that respect LDFLAGS or --with-boot-ldflags (LDFLAGS applies to stage1, --with-boot-ldflags to later stages):
./mingw-w64-i686-gcc/mingw32/bin/c++.exe
./mingw-w64-i686-gcc/mingw32/bin/cc.exe
./mingw-w64-i686-gcc/mingw32/bin/cpp.exe
./mingw-w64-i686-gcc/mingw32/bin/g++.exe
./mingw-w64-i686-gcc/mingw32/bin/gcc-ar.exe
./mingw-w64-i686-gcc/mingw32/bin/gcc-nm.exe
./mingw-w64-i686-gcc/mingw32/bin/gcc-ranlib.exe
./mingw-w64-i686-gcc/mingw32/bin/gcc.exe
./mingw-w64-i686-gcc/mingw32/bin/gcov-tool.exe
./mingw-w64-i686-gcc/mingw32/bin/gcov.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-c++.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-g++.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-gcc-10.2.0.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-gcc-ar.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-gcc-nm.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-gcc-ranlib.exe
./mingw-w64-i686-gcc/mingw32/bin/i686-w64-mingw32-gcc.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/cc1.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/cc1plus.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/collect2.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/lto-wrapper.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/lto1.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatbind.exe
./mingw-w64-i686-gcc-ada/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/gnat1.exe
./mingw-w64-i686-gcc-fortran/mingw32/bin/gfortran.exe
./mingw-w64-i686-gcc-fortran/mingw32/bin/i686-w64-mingw32-gfortran.exe
./mingw-w64-i686-gcc-fortran/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/f951.exe
./mingw-w64-i686-gcc-objc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/cc1obj.exe
./mingw-w64-i686-gcc-objc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/cc1objplus.exe
Binaries that respect LDFLAGS_FOR_TARGET:
./mingw-w64-i686-gcc/mingw32/lib/bfd-plugins/liblto_plugin-0.dll (with 1c41e8e)
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/install-tools/fixincl.exe
./mingw-w64-i686-gcc/mingw32/lib/gcc/i686-w64-mingw32/10.2.0/liblto_plugin-0.dll (with 1c41e8e)
./mingw-w64-i686-gcc-ada/mingw32/bin/gnat.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatchop.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatclean.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatdll.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatfind.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatkr.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatlink.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatls.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatmake.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatname.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatprep.exe
./mingw-w64-i686-gcc-ada/mingw32/bin/gnatxref.exe
./mingw-w64-i686-gcc-libgfortran/mingw32/bin/libgfortran-5.dll
./mingw-w64-i686-gcc-libs/mingw32/bin/libatomic-1.dll
./mingw-w64-i686-gcc-libs/mingw32/bin/libgcc_s_dw2-1.dll (due to new patch)
./mingw-w64-i686-gcc-libs/mingw32/bin/libgomp-1.dll
./mingw-w64-i686-gcc-libs/mingw32/bin/libquadmath-0.dll
./mingw-w64-i686-gcc-libs/mingw32/bin/libssp-0.dll
./mingw-w64-i686-gcc-libs/mingw32/bin/libstdc++-6.dll
./mingw-w64-i686-gcc-objc/mingw32/bin/libobjc-4.dll
Binaries that don't respect either, and use binutils defaults☹️ :
./mingw-w64-i686-gcc-ada/mingw32/bin/libgnarl-10.dll
./mingw-w64-i686-gcc-ada/mingw32/bin/libgnat-10.dll