ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP

commit 4a3d2717d140401df7501a95e454180831a0c5af upstream.

xtensa is the last user of the PT_SINGLESTEP flag.  Changing tsk->ptrace in
user_enable_single_step and user_disable_single_step without locking could
potentiallly cause problems.

So use a thread info flag instead of a flag in tsk->ptrace.  Use TIF_SINGLESTEP
that xtensa already had defined but unused.

Remove the definitions of PT_SINGLESTEP and PT_BLOCKSTEP as they have no more users.

Cc: stable@vger.kernel.org
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-4-ebiederm@xmission.com


Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>