On Sun, Nov 25, 2018 at 05:10:59AM +0300, Dmitry V. Levin wrote:
> Given that without this patch the value returned by PTRACE_GETEVENTMSG
> during syscall stop is undefined, we need two different ptrace_message
> values that cannot be set by other ptrace events to enable reliable
> identification of syscall-enter-stop and syscall-exit-stop in userspace:
> if we make PTRACE_GETEVENTMSG return 0 or any other value routinely set by
> other ptrace events, it would be hard for userspace to find out whether
> the kernel implements new semantics or not.

Ah, I see, I agree that definitely makes sense.

-- 
Cheers,
Joey Pabalinas