On Thu, Aug 27, 2020 at 7:07 AM H.J. Lu <hjl.tools@xxxxxxxxx> wrote: > > On Thu, Aug 27, 2020 at 6:36 AM Florian Weimer <fweimer@xxxxxxxxxx> wrote: > > > > * H. J. Lu: > > > > > On Thu, Aug 27, 2020 at 6:19 AM Florian Weimer <fweimer@xxxxxxxxxx> wrote: > > >> > > >> * Dave Martin: > > >> > > >> > You're right that this has implications: for i386, libc probably pulls > > >> > more arguments off the stack than are really there in some situations. > > >> > This isn't a new problem though. There are already generic prctls with > > >> > fewer than 4 args that are used on x86. > > >> > > >> As originally posted, glibc prctl would have to know that it has to pull > > >> an u64 argument off the argument list for ARCH_X86_CET_DISABLE. But > > >> then the u64 argument is a problem for arch_prctl as well. > > >> > > > > > > Argument of ARCH_X86_CET_DISABLE is int and passed in register. > > > > The commit message and the C source say otherwise, I think (not sure > > about the C source, not a kernel hacker). > > It should read: > > arch_prctl(ARCH_X86_CET_DISABLE, unsigned long features) > Or arch_prctl(ARCH_X86_CET_DISABLE, unsigned int features) -- H.J.
