On Mon, Dec 23, 2019 at 6:31 AM Christophe Leroy <christophe.le...@c-s.fr> wrote: > > On powerpc, __arch_get_vdso_data() clobbers the link register, > requiring the caller to set a stack frame in order to save it. > > As the parent function already has to set a stack frame and save > the link register to call the C vdso function, retriving the > vdso data pointer there is lighter.
I'm confused. Can't you inline __arch_get_vdso_data()? Or is the issue that you can't retrieve the program counter on power without clobbering the link register? I would imagine that this patch generates worse code on any architecture with PC-relative addressing modes (which includes at least x86_64, and I would guess includes most modern architectures). --Andy
