[ Upstream commit f18aef742c8fbd68e280dff0a63ba0ca6ee8ad85 ]

On at least x86 and ARM64, and as documented in the ptrace man page
a skipped system call will still cause a syscall exit ptrace stop.

Previous to this commit 32-bit ARM did not, resulting in strace
being confused when seccomp skips system calls.

This change also impacts programs that use ptrace to skip system calls.

Fixes: ad75b514 ("ARM: 7579/1: arch/allow a scno of -1 to not cause a SIGILL")
Signed-off-by: NTimothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Signed-off-by: NEugene Syromyatnikov <evgsyr@gmail.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Tested-by: NKees Cook <keescook@chromium.org>
Tested-by: NEugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NSasha Levin <sashal@kernel.org>