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torvalds-linux/lib/Kconfig.kmsan
Nathan Chancellor 5ff8c11775
KMSAN: Remove tautological checks
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, two KMSAN checks can be cleaned up.

CONFIG_HAVE_KMSAN_COMPILER will always be true when using clang so
remove the cc-option test and use a simple check for CONFIG_CC_IS_CLANG.

CONFIG_HAVE_KMSAN_PARAM_RETVAL will always be true so it can be removed
outright.

Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20250821-bump-min-llvm-ver-15-v2-12-635f3294e5f0@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-08-28 16:58:46 -07:00

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# SPDX-License-Identifier: GPL-2.0-only
config HAVE_ARCH_KMSAN
bool
config HAVE_KMSAN_COMPILER
def_bool CC_IS_CLANG
config KMSAN
bool "KMSAN: detector of uninitialized values use"
depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER
depends on DEBUG_KERNEL && !KASAN && !KCSAN
depends on !PREEMPT_RT
select STACKDEPOT
select STACKDEPOT_ALWAYS_INIT
help
KernelMemorySanitizer (KMSAN) is a dynamic detector of uses of
uninitialized values in the kernel. It is based on compiler
instrumentation provided by Clang and thus requires Clang to build.
An important note is that KMSAN is not intended for production use,
because it drastically increases kernel memory footprint and slows
the whole system down.
See <file:Documentation/dev-tools/kmsan.rst> for more details.
if KMSAN
config KMSAN_CHECK_PARAM_RETVAL
bool "Check for uninitialized values passed to and returned from functions"
default y
help
If the compiler supports -fsanitize-memory-param-retval, KMSAN will
eagerly check every function parameter passed by value and every
function return value.
Disabling KMSAN_CHECK_PARAM_RETVAL will result in tracking shadow for
function parameters and return values across function borders. This
is a more relaxed mode, but it generates more instrumentation code and
may potentially report errors in corner cases when non-instrumented
functions call instrumented ones.
config KMSAN_KUNIT_TEST
tristate "KMSAN integration test suite" if !KUNIT_ALL_TESTS
default KUNIT_ALL_TESTS
depends on TRACEPOINTS && KUNIT
help
Test suite for KMSAN, testing various error detection scenarios,
and checking that reports are correctly output to console.
Say Y here if you want the test to be built into the kernel and run
during boot; say M if you want the test to build as a module; say N
if you are unsure.
endif