100 lines · plain
1# SPDX-License-Identifier: GPL-2.0-only2 3config HAVE_ARCH_KFENCE4 bool5 6menuconfig KFENCE7 bool "KFENCE: low-overhead sampling-based memory safety error detector"8 depends on HAVE_ARCH_KFENCE9 select STACKTRACE10 select IRQ_WORK11 help12 KFENCE is a low-overhead sampling-based detector of heap out-of-bounds13 access, use-after-free, and invalid-free errors. KFENCE is designed14 to have negligible cost to permit enabling it in production15 environments.16 17 See <file:Documentation/dev-tools/kfence.rst> for more details.18 19 Note that, KFENCE is not a substitute for explicit testing with tools20 such as KASAN. KFENCE can detect a subset of bugs that KASAN can21 detect, albeit at very different performance profiles. If you can22 afford to use KASAN, continue using KASAN, for example in test23 environments. If your kernel targets production use, and cannot24 enable KASAN due to its cost, consider using KFENCE.25 26if KFENCE27 28config KFENCE_SAMPLE_INTERVAL29 int "Default sample interval in milliseconds"30 default 10031 help32 The KFENCE sample interval determines the frequency with which heap33 allocations will be guarded by KFENCE. May be overridden via boot34 parameter "kfence.sample_interval".35 36 Set this to 0 to disable KFENCE by default, in which case only37 setting "kfence.sample_interval" to a non-zero value enables KFENCE.38 39config KFENCE_NUM_OBJECTS40 int "Number of guarded objects available"41 range 1 6553542 default 25543 help44 The number of guarded objects available. For each KFENCE object, 245 pages are required; with one containing the object and two adjacent46 ones used as guard pages.47 48config KFENCE_DEFERRABLE49 bool "Use a deferrable timer to trigger allocations"50 help51 Use a deferrable timer to trigger allocations. This avoids forcing52 CPU wake-ups if the system is idle, at the risk of a less predictable53 sample interval.54 55 Warning: The KUnit test suite fails with this option enabled - due to56 the unpredictability of the sample interval!57 58 Say N if you are unsure.59 60config KFENCE_STATIC_KEYS61 bool "Use static keys to set up allocations" if EXPERT62 depends on JUMP_LABEL63 help64 Use static keys (static branches) to set up KFENCE allocations. This65 option is only recommended when using very large sample intervals, or66 performance has carefully been evaluated with this option.67 68 Using static keys comes with trade-offs that need to be carefully69 evaluated given target workloads and system architectures. Notably,70 enabling and disabling static keys invoke IPI broadcasts, the latency71 and impact of which is much harder to predict than a dynamic branch.72 73 Say N if you are unsure.74 75config KFENCE_STRESS_TEST_FAULTS76 int "Stress testing of fault handling and error reporting" if EXPERT77 default 078 help79 The inverse probability with which to randomly protect KFENCE object80 pages, resulting in spurious use-after-frees. The main purpose of81 this option is to stress test KFENCE with concurrent error reports82 and allocations/frees. A value of 0 disables stress testing logic.83 84 Only for KFENCE testing; set to 0 if you are not a KFENCE developer.85 86config KFENCE_KUNIT_TEST87 tristate "KFENCE integration test suite" if !KUNIT_ALL_TESTS88 default KUNIT_ALL_TESTS89 depends on TRACEPOINTS && KUNIT90 help91 Test suite for KFENCE, testing various error detection scenarios with92 various allocation types, and checking that reports are correctly93 output to console.94 95 Say Y here if you want the test to be built into the kernel and run96 during boot; say M if you want the test to build as a module; say N97 if you are unsure.98 99endif # KFENCE100