On 11/07, Andy Lutomirski wrote: > > On Wed, Nov 4, 2015 at 4:50 PM, Amanieu d'Antras <amanieu@xxxxxxxxx> wrote: > > One issue that isn't resolved in this series is sending signals between a 32-bit > > process and 64-bit process. Sending a si_int will work correctly, but a si_ptr > > value will likely get corrupted due to the different layouts of the 32-bit and > > 64-bit siginfo_t structures. > > This is so screwed up it's not even funny. Agreed, > A 64-bit big-endian compat calls rt_sigqueueinfo. It passes in (among > other things) a sigval_t. The kernel can choose to interpret it I always thought that the kernel should not interpret it at all. And indeed, copy_siginfo_to_user() does if (from->si_code < 0) return __copy_to_user(to, from, sizeof(siginfo_t)) probably copy_siginfo_to_user32() should do something similar, at least it should not truncate ->si_code it it is less than zero. Not sure what signalfd_copyinfo() should do. But perhaps I was wrong, I failed to find man sigqueueinfo, and man sigqueue() documents that it passes sigval_t. > BTW, x86 has its own set of screwups here. Somehow cr2 and error_code > ended up as part of ucontext instead of siginfo, which makes > absolutely no sense to me and bloats task_struct. Yes, and probably ->ip should have been the part of siginfo too. Say, if you get SIGBUS you can't trust sc->ip if another signal was dequeued before SIGBUS, in this case sc->ip will point to the handler of that another signal. That is why we have SYNCHRONOUS_MASK and it helps, but still this doesn't look nice. Oleg.
