Anton Blanchard <an...@samba.org> wrote on 25.03.2014 12:44:06: > There are two known outstanding issues: > > - If a kernel module calls into an exported assembly function > which in turns calls out to C, r2 is going to be wrong. One example > is __copy_tofrom_user_power7. > > The reason is _GLOBAL() doesn't have a global entry point setup > with the associated addis/addi used to create r2. I tried adding > it and quickly realised that _GLOBAL is used places that will not > tolerate the addi/addis (eg __start()).
You probably should have two different macros _GLOBAL_TOC vs. _GLOBAL (or _GLOBAL vs. _GLOBAL_NOTOC), and use the variant that provides a global entry point setting up the TOC only with those functions that actually require a TOC. > - arch/powerpc/platforms/pseries/hvCall.S assumes we always have a > parameter save area, which is incorrect for ABIv2. I tried to be > intelligent and use the toc save area to store some information > but that failed as soon as we started using modules. It would be > nice to avoid a stack frame in the common (tracepoints disabled) > case, but we may end up having to allocate one. When I looked at this last time, I remarked: >./platforms/pseries/hvCall.S: >./platforms/cell/beat_hvCall.S: >Looks safe since all functions are called via varargs prototypes >(or > 8 integer arguments). Checking again, this still seems true. These are the prototypes for all the functions in hvCall.S: long plpar_hcall_norets(unsigned long opcode, ...); long plpar_hcall(unsigned long opcode, unsigned long *retbuf, ...); long plpar_hcall_raw(unsigned long opcode, unsigned long *retbuf, ...); long plpar_hcall9(unsigned long opcode, unsigned long *retbuf, ...); long plpar_hcall9_raw(unsigned long opcode, unsigned long *retbuf, ...); Functions like that *will* always have a save area allocated by the caller, even in the ELFv2 ABI. Am I missing something here? Bye, Ulrich _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
