On Thu, Dec 11, 2014 at 07:51:44PM +1030, Alan Modra wrote: > On Thu, Dec 11, 2014 at 10:06:23AM +0100, Dominik Vogt wrote: > > On s390x, the static chain register cannot be used for passing the > > Go closure pointer to a function: According to the Abi, the > > dynamic linker is allowed to destroy the contents of r0 (static > > chain register) eventually causing a crash if libgo is linked > > dynamically. The assumption that the static chain register can be > > used to pass information to a function is wrong for s390x. > > I was worried about exactly the same "problem" on powerpc with r11 > being used for the static chain and also destroyed in linkage stubs. > It turns out we don't traverse any linkage stubs.
Just to make this clear: It's not something that *might* happen. It *does* happen on s390[x] which does not use libffi but the hand written code in makefunc_s390.S and makefuncgo_s390[x].go. The same may not happen when calling functions through libffi (which may be dynamically linked) because ffi_call_go() is passed the closure pointer as an argument and not in the static chain register. > See https://gcc.gnu.org/ml/gcc-patches/2014-11/msg00446.html. Thanks for the link. Ciao Dominik ^_^ ^_^ -- Dominik Vogt IBM Germany
