Re: PTRACE_SYSEMU behavior difference on arm64

[Keno Fischer]

On Fri, May 15, 2020 at 8:13 AM Will Deacon <will@xxxxxxxxxx> wrote:
> But it also
> means that nobody is using this on arm64, so we could also consider removing
> it entirely. Did you spot this because you are trying to use it for
> something or just by inspection/unit-testing?

No, I was trying to port a tool from x86 and nothing made sense for
many hours :). (it was quite a bit of debugging, because the
syscall that it was supposed to skip installed a seccomp filter,
which then later veto'd random syscalls making the
symptoms quite confusing). Having PTRACE_SYSEMU isn't
critical, but we might as well support it.
It makes things a bit more efficient and is probably safer
(if it works correctly ;). The patch is fairly small. Will validate
and then send it here for review.


Keno