Re: [uclibc-ng-devel] [Powerpc] HAVE_ASM_PPC_REL16 and BR2_PIC_PIE

Hi Romain, can you confirm that attached patch works for you? I tested with non-PIE and PIE and both seems to work.

best regards Waldemar Romain Naour wrote, > Hi Waldemar, > > Le 19/05/2021 à 00:09, Waldemar Brodkorb a écrit : >> Hi Romain, >> Romain Naour wrote, >> >>> Hello, >>> >>> Recently in Buildroot the option BR2_PIC_PIE has been enabled by default along >>> with other hardening features [1]. Since then some ppc defconfig such >>> qemu_ppc_e500mc_defconfig are failing to boot due to a segfault in init program. >>> >>> The segfault appear very early in __uClibc_main while starting any binaries, >>> an issue located in crt1.S (powerpc)[2]. >>> >>> After some trial and error, removing HAVE_ASM_PPC_REL16 from CFLAGS [3] >>> allow to generate a working system again. But this is actually wrong since >>> instead we should consider HAVE_ASM_PPC_REL16 always true nowadays. >> >> What if the assembly inside HAVE_ASM_PPC_REL16 isn't pie safe? > > Good question. > > I guess it should work with pie (see PIEFLAG_NAME:=-fpie) > https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/Rules.mak?h=v1.0.38#… > > I did a try with Glibc without any problem with BR2_PIC_PIE enabled. > > Best regards, > Romain > >> >>> Indeed, Glibc removed HAVE_ASM_PPC_REL16 since version 2.22 [4] since "the >>> minimum binutils supports rel16 relocs". Binutils 2.22 supports R_PPC_REL16 as >>> default. >>> >>> uClibc-ng should remove HAVE_ASM_PPC_REL16 but keep the code as it was defined. >>> But this doesn't fix the initial issue. >>> >>> Any idea ? >>> >>> [1] >>> https://git.buildroot.net/buildroot/commit/?id=810ba387bec3c5b6904e8893fb4c… >>> [2] >>> https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/libc/sysdeps/linux/p… >>> [3] >>> https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/Rules.mak?id=2bf4991… >>> [4] >>> https://sourceware.org/git/?p=glibc.git;a=commit;h=59261ad3eb345e0d7b9f5c73… >> >> best regards >> Waldemar >> >