kselftest/arm64: Remove redundant _start labels from FP tests

There are a number of freestanding static executables used in floating
point testing that have no runtime at all. These all define the main entry
point as:

.globl _start
function _start
_start:

but clang's integrated assembler complains that:

error: symbol '_start' is already defined

due to having both a label and function directive. Remove the label to
allow building with clang.

No functional change.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230111-arm64-kselftest-clang-v1-2-89c69d377727@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Install signal handlers before output in FP stress tests

To interface more robustly with other processes install the signal handers
in the floating point stress tests before we produce any output, this
means that a parent process can know that if it has seen any output from
the test then the test is ready to handle incoming signals.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220906220056.820295-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Count SIGUSR2 deliveries in FP stress tests

Currently the floating point stress tests mostly support testing that the
data they are checking can be disrupted from a signal handler triggered by
SIGUSR1. This is not properly implemented for all the tests and in testing
is frequently modified to just handle the signal without corrupting data in
order to ensure that signal handling does not corrupt data. Directly support
this usage by installing a SIGUSR2 handler which simply counts the signal
delivery.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154452.824870-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

selftests: arm64: Factor out utility functions for assembly FP tests

The various floating point test programs written in assembly have a bunch
of helper functions and macros which are cut'n'pasted between them. Factor
them out into a separate source file which is linked into all of them.

We don't include memcmp() since it isn't as generic as it should be and
directly branches to report an error in the programs.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211019181851.3341232-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

arm64: selftests: Fix spelling of 'Mismatch'

The SVE and FPSIMD stress tests have a spelling mistake in the output, fix
it.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210108183144.673-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

selftests: arm64: Add stress tests for FPSMID and SVE context switching

Add programs sve-test and fpsimd-test which spin reading and writing to
the SVE and FPSIMD registers, verifying the operations they perform. The
intended use is to leave them running to stress the context switch code's
handling of these registers which isn't compatible with what kselftest
does so they're not integrated into the framework but there's no other
obvious testsuite where they fit so let's store them here.

These tests were written by Dave Martin and lightly adapted by me.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>