On Fri, Nov 30, 2018 at 3:41 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > siginfo_t as it is now still has a number of other downsides, and Andy in > particular didn't like the idea of having three new variants on x86 > (depending on how you count). His alternative suggestion of having > a single syscall entry point that takes a 'signfo_t __user *' but interprets > it as compat_siginfo depending on in_compat_syscall()/in_x32_syscall() > should work correctly, but feels wrong to me, or at least inconsistent > with how we do this elsewhere. If everyone else is okay with it, I can get on board with three variants on x86. What I can't get on board with is *five* variants on x86, which would be: procfd_signal via int80 / the 32-bit vDSO: the ia32 structure syscall64 with nr == 335 (presumably): 64-bit syscall64 with nr == 548 | 0x40000000: x32 syscall64 with nr == 548: 64-bit entry but in_compat_syscall() == true, behavior is arbitrary syscall64 with nr == 335 | 0x40000000: x32 entry, but in_compat_syscall() == false, behavior is arbitrary This mess isn't really Christian's fault -- it's been there for a while, but it's awful and I don't think we want to perpetuate it. Obviously, I'd prefer a variant where the structure that's passed in is always the same. BTW, do we consider siginfo_t to be extensible? If so, and if we pass in a pointer, presumably we should pass a length as well.
