Make sure that both variants of the nasty TF-in-compat-syscall are
exercised regardless of what vendor's CPU is running the tests.

Also change the intentional signal after SYSCALL to use ud2, which
is a lot more comprehensible.

This crashes the kernel due to an FSGSBASE bug right now.

This test *also* detects a bug in KVM when run on an Intel host.  KVM
people, feel free to use it to help debug.  There's a bunch of code in this
test to warn instead of going into an infinite looping when the bug gets
triggered.
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc:  "BaeChang Seok" <chang.seok.bae@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: "Bae, Chang Seok" <chang.seok.bae@intel.com>
Link: https://lkml.kernel.org/r/5f5de10441ab2e3005538b4c33be9b1965d1bb63.1562035429.git.luto@kernel.org