kselftest/arm64: Add test coverage for NT_ARM_TLS

In preparation for extending support for NT_ARM_TLS to cover additional
TPIDRs add some tests for the existing interface. Do this in a generic
ptrace test program to provide a place to collect additional tests in
the future.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154921.837871-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Add simple hwcap validation

Add some trivial hwcap validation which checks that /proc/cpuinfo and
AT_HWCAP agree with each other and can verify that for extensions that can
generate a SIGILL due to adding new instructions one appears or doesn't
appear as expected. I've added SVE and SME, other capabilities can be
added later if this gets merged.

This isn't super exciting but on the other hand took very little time to
write and should be handy when verifying that you wired up AT_HWCAP
properly.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154602.827275-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Add tests for TPIDR2

The Scalable Matrix Extension adds a new system register TPIDR2 intended to
be used by libc for its own thread specific use, add some kselftests which
exercise the ABI for it.

Since this test should with some adjustment work for TPIDR and any other
similar registers added in future add tests for it in a separate
directory rather than placing it with the other floating point tests,
nothing existing looked suitable so I created a new test directory
called "abi".

Since this feature is intended to be used by libc the test is built as
freestanding code using nolibc so we don't end up with the test program
and libc both trying to manage the register simultaneously and
distrupting each other. As a result of being written using nolibc rather
than using hwcaps to identify if SME is available in the system we check
for the default SME vector length configuration in proc, adding hwcap
support to nolibc seems like disproportionate effort and didn't feel
entirely idiomatic for what nolibc is trying to do.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-31-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Add a test program to exercise the syscall ABI

Currently we don't have any coverage of the syscall ABI so let's add a very
dumb test program which sets up register patterns, does a sysscall and then
checks that the register state after the syscall matches what we expect.
The program is written in an extremely simplistic fashion with the goal of
making it easy to verify that it's doing what it thinks it's doing, it is
not a model of how one should write actual code.

Currently we validate the general purpose, FPSIMD and SVE registers. There
are other thing things that could be covered like FPCR and flags registers,
these can be covered incrementally - my main focus at the minute is
covering the ABI for the SVE registers.

The program repeats the tests for all possible SVE vector lengths in case
some vector length specific optimisation causes issues, as well as testing
FPSIMD only. It tries two syscalls, getpid() and sched_yield(), in an
effort to cover both immediate return to userspace and scheduling another
task though there are no guarantees which cases will be hit.

A new test directory "abi" is added to hold the test, it doesn't seem to
fit well into any of the existing directories.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211210184133.320748-7-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>