kselftest/arm64: Remove spurious comment from MTE test Makefile

There's a stray comment in the MTE test Makefile which documents
something that's since been removed, delete it.

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-v1-6-89c69d377727@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Support build of MTE tests with clang

The assembly portions of the MTE selftests need to be built with a
toolchain supporting MTE. Since we support GCC versions that lack MTE
support we have logic to suppress build of these tests when using such a
toolchain but that logic is broken for LLVM=1 builds, it uses CC but CC
is only set for LLVM builds in libs.mk which needs to be included after
we have selected which test programs to build.

Since all supported LLVM versions support MTE we can simply assume MTE
support when LLVM is set. This is not a thing of beauty but it does the
job.

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-v1-5-89c69d377727@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Don't enable v8.5 for MTE selftest builds

Currently we set -march=armv8.5+memtag when building the MTE selftests,
allowing the compiler to emit v8.5 and MTE instructions for anything it
generates. This means that we may get code that will generate SIGILLs when
run on older systems rather than skipping on non-MTE systems as should be
the case. Most toolchains don't select any incompatible instructions but
I have seen some reports which suggest that some may be appearing which do
so. This is also potentially problematic in that if the compiler chooses to
emit any MTE instructions for the C code it may interfere with the MTE
usage we are trying to test.

Since the only reason we are specifying this option is to allow us to
assemble MTE instructions in mte_helper.S we can avoid these issues by
moving to using a .arch directive there and adding the -march explicitly to
the toolchain support check instead of the generic CFLAGS.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220928154517.173108-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

selftests: stop using KSFT_KHDR_INSTALL

Stop using the KSFT_KHDR_INSTALL flag as installing the kernel headers
from the kselftest Makefile is causing some issues. Instead, rely on
the headers to be installed directly by the top-level Makefile
"headers_install" make target prior to building kselftest.

Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

kselftest/arm64: mte: Makefile: Fix clang compilation

When clang finds a header file on the command line, it wants to
precompile that, which would end up in a separate output file.
Specifying -o on that same command line collides with that effort, so
the compiler complains:

clang: error: cannot specify -o when generating multiple output files

Since we are not really after a precompiled header, just drop the header
file from the command line, by removing it from the list of source
files in the Makefile.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-10-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: mte: Output warning about failing compiler

At the moment we check the compiler's ability to compile MTE enabled
code, but guard all the Makefile rules by it. As a consequence a broken
or not capable compiler just doesn't do anything, and make happily
returns without any error message, but with no programs created.

Since the MTE feature is only supported by recent aarch64 compilers (not
all stable distro compilers support it), having an explicit message
seems like a good idea. To not break building multiple targets, we let
make proceed without errors.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-9-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: mte: Use cross-compiler if specified

At the moment we either need to provide CC explicitly, or use a native
machine to get the ARM64 MTE selftest compiled.

It seems useful to use the same (cross-)compiler as we use for the
kernel, so copy the recipe we use in the pauth selftest.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-8-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: mte: Fix pthread linking

The GCC manual suggests to use -pthread, when linking with the PThread
library, also to add this switch to both the compilation and linking
stages.

Do as the manual says, to fix compilation with Ubuntu's 20.04 toolchain,
which was getting -lpthread too early on the command line:
------------
/usr/bin/ld: /tmp/cc5zbo2A.o: in function `execute_test':
tools/testing/selftests/arm64/mte/check_gcr_el1_cswitch.c:86:
undefined reference to `pthread_create'
/usr/bin/ld: tools/testing/selftests/arm64/mte/check_gcr_el1_cswitch.c:90:
undefined reference to `pthread_join'
------------

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-3-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: mte: Fix compilation with native compiler

The mte selftest Makefile contains a check for GCC, to add the memtag
-march flag to the compiler options. This check fails if the compiler
is not explicitly specified, so reverts to the standard "cc", in which
case --version doesn't mention the "gcc" string we match against:
$ cc --version | head -n 1
cc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0

This will not add the -march switch to the command line, so compilation
fails:
mte_helper.S: Assembler messages:
mte_helper.S:25: Error: selected processor does not support `irg x0,x0,xzr'
mte_helper.S:38: Error: selected processor does not support `gmi x1,x0,xzr'
...

Actually clang accepts the same -march option as well, so we can just
drop this check and add this unconditionally to the command line, to avoid
any future issues with this check altogether (gcc actually prints
basename(argv[0]) when called with --version).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-2-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: check GCR_EL1 after context switch

This test is specific to MTE and verifies that the GCR_EL1 register is
context switched correctly.

It spawns 1024 processes and each process spawns 5 threads. Each thread
writes a random setting of GCR_EL1 through the prctl() system call and
reads it back verifying that it is the same. If the values are not the
same it reports a failure.

Note: The test has been extended to verify that even SYNC and ASYNC mode
setting is preserved correctly over context switching.

Link: https://lkml.kernel.org/r/b51a165426e906e7ec8a68d806ef3f8cd92581a6.1606161801.git.andreyknvl@google.com
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kselftest/arm64: Add utilities and a test to validate mte memory

This test checks that the memory tag is present after mte allocation and
the memory is accessible with those tags. This testcase verifies all
sync, async and none mte error reporting mode. The allocated mte buffers
are verified for Allocated range (no error expected while accessing
buffer), Underflow range, and Overflow range.

Different test scenarios covered here are,
* Verify that mte memory are accessible at byte/block level.
* Force underflow and overflow to occur and check the data consistency.
* Check to/from between tagged and untagged memory.
* Check that initial allocated memory to have 0 tag.

This change also creates the necessary infrastructure to add mte test
cases. MTE kselftests can use the several utility functions provided here
to add wide variety of mte test scenarios.

GCC compiler need flag '-march=armv8.5-a+memtag' so those flags are
verified before compilation.

The mte testcases can be launched with kselftest framework as,

make TARGETS=arm64 ARM64_SUBTARGETS=mte kselftest

or compiled as,

make -C tools/testing/selftests TARGETS=arm64 ARM64_SUBTARGETS=mte CC='compiler'

Co-developed-by: Gabor Kertesz <gabor.kertesz@arm.com>
Signed-off-by: Gabor Kertesz <gabor.kertesz@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201002115630.24683-2-amit.kachhap@arm.com
Signed-off-by: Will Deacon <will@kernel.org>