# SPDX-License-Identifier: GPL-2.0-only config HAVE_ARCH_KFENCE	bool menuconfig KFENCE	bool "KFENCE: low-overhead sampling-based memory safety error detector"	depends on HAVE_ARCH_KFENCE	select STACKTRACE	select IRQ_WORK	help	  KFENCE is a low-overhead sampling-based detector of heap out-of-bounds	  access, use-after-free, and invalid-free errors. KFENCE is designed	  to have negligible cost to permit enabling it in production	  environments. 	  See <file:Documentation/dev-tools/kfence.rst> for more details. 	  Note that, KFENCE is not a substitute for explicit testing with tools	  such as KASAN. KFENCE can detect a subset of bugs that KASAN can	  detect, albeit at very different performance profiles. If you can	  afford to use KASAN, continue using KASAN, for example in test	  environments. If your kernel targets production use, and cannot	  enable KASAN due to its cost, consider using KFENCE. if KFENCE config KFENCE_SAMPLE_INTERVAL	int "Default sample interval in milliseconds"	default 100	help	  The KFENCE sample interval determines the frequency with which heap	  allocations will be guarded by KFENCE. May be overridden via boot	  parameter "kfence.sample_interval". 	  Set this to 0 to disable KFENCE by default, in which case only	  setting "kfence.sample_interval" to a non-zero value enables KFENCE. config KFENCE_NUM_OBJECTS	int "Number of guarded objects available"	range 1 65535	default 255	help	  The number of guarded objects available. For each KFENCE object, 2	  pages are required; with one containing the object and two adjacent	  ones used as guard pages. config KFENCE_DEFERRABLE	bool "Use a deferrable timer to trigger allocations"	help	  Use a deferrable timer to trigger allocations. This avoids forcing	  CPU wake-ups if the system is idle, at the risk of a less predictable	  sample interval. 	  Warning: The KUnit test suite fails with this option enabled - due to	  the unpredictability of the sample interval! 	  Say N if you are unsure. config KFENCE_STATIC_KEYS	bool "Use static keys to set up allocations" if EXPERT	depends on JUMP_LABEL	help	  Use static keys (static branches) to set up KFENCE allocations. This	  option is only recommended when using very large sample intervals, or	  performance has carefully been evaluated with this option. 	  Using static keys comes with trade-offs that need to be carefully	  evaluated given target workloads and system architectures. Notably,	  enabling and disabling static keys invoke IPI broadcasts, the latency	  and impact of which is much harder to predict than a dynamic branch. 	  Say N if you are unsure. config KFENCE_STRESS_TEST_FAULTS	int "Stress testing of fault handling and error reporting" if EXPERT	default 0	help	  The inverse probability with which to randomly protect KFENCE object	  pages, resulting in spurious use-after-frees. The main purpose of	  this option is to stress test KFENCE with concurrent error reports	  and allocations/frees. A value of 0 disables stress testing logic. 	  Only for KFENCE testing; set to 0 if you are not a KFENCE developer. config KFENCE_KUNIT_TEST	tristate "KFENCE integration test suite" if !KUNIT_ALL_TESTS	default KUNIT_ALL_TESTS	depends on TRACEPOINTS && KUNIT	help	  Test suite for KFENCE, testing various error detection scenarios with	  various allocation types, 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 # KFENCE