| # SPDX-License-Identifier: GPL-2.0-only |
| |
| config HAVE_ARCH_KCSAN |
| bool |
| |
| menuconfig KCSAN |
| bool "KCSAN: watchpoint-based dynamic data race detector" |
| depends on HAVE_ARCH_KCSAN && !KASAN && STACKTRACE |
| default n |
| help |
| Kernel Concurrency Sanitizer is a dynamic data race detector, which |
| uses a watchpoint-based sampling approach to detect races. See |
| <file:Documentation/dev-tools/kcsan.rst> for more details. |
| |
| if KCSAN |
| |
| config KCSAN_DEBUG |
| bool "Debugging of KCSAN internals" |
| default n |
| |
| config KCSAN_SELFTEST |
| bool "Perform short selftests on boot" |
| default y |
| help |
| Run KCSAN selftests on boot. On test failure, causes kernel to panic. |
| |
| config KCSAN_EARLY_ENABLE |
| bool "Early enable during boot" |
| default y |
| help |
| If KCSAN should be enabled globally as soon as possible. KCSAN can |
| later be enabled/disabled via debugfs. |
| |
| config KCSAN_NUM_WATCHPOINTS |
| int "Number of available watchpoints" |
| default 64 |
| help |
| Total number of available watchpoints. An address range maps into a |
| specific watchpoint slot as specified in kernel/kcsan/encoding.h. |
| Although larger number of watchpoints may not be usable due to |
| limited number of CPUs, a larger value helps to improve performance |
| due to reducing cache-line contention. The chosen default is a |
| conservative value; we should almost never observe "no_capacity" |
| events (see /sys/kernel/debug/kcsan). |
| |
| config KCSAN_UDELAY_TASK |
| int "Delay in microseconds (for tasks)" |
| default 80 |
| help |
| For tasks, the microsecond delay after setting up a watchpoint. |
| |
| config KCSAN_UDELAY_INTERRUPT |
| int "Delay in microseconds (for interrupts)" |
| default 20 |
| help |
| For interrupts, the microsecond delay after setting up a watchpoint. |
| Interrupts have tighter latency requirements, and their delay should |
| be lower than for tasks. |
| |
| config KCSAN_DELAY_RANDOMIZE |
| bool "Randomize above delays" |
| default y |
| help |
| If delays should be randomized, where the maximum is KCSAN_UDELAY_*. |
| If false, the chosen delays are always KCSAN_UDELAY_* defined above. |
| |
| config KCSAN_SKIP_WATCH |
| int "Skip instructions before setting up watchpoint" |
| default 4000 |
| help |
| The number of per-CPU memory operations to skip, before another |
| watchpoint is set up, i.e. one in KCSAN_WATCH_SKIP per-CPU |
| memory operations are used to set up a watchpoint. A smaller value |
| results in more aggressive race detection, whereas a larger value |
| improves system performance at the cost of missing some races. |
| |
| config KCSAN_SKIP_WATCH_RANDOMIZE |
| bool "Randomize watchpoint instruction skip count" |
| default y |
| help |
| If instruction skip count should be randomized, where the maximum is |
| KCSAN_WATCH_SKIP. If false, the chosen value is always |
| KCSAN_WATCH_SKIP. |
| |
| # Note that, while some of the below options could be turned into boot |
| # parameters, to optimize for the common use-case, we avoid this because: (a) |
| # it would impact performance (and we want to avoid static branch for all |
| # {READ,WRITE}_ONCE, atomic_*, bitops, etc.), and (b) complicate the design |
| # without real benefit. The main purpose of the below options are for use in |
| # fuzzer configs to control reported data races, and are not expected to be |
| # switched frequently by a user. |
| |
| config KCSAN_REPORT_RACE_UNKNOWN_ORIGIN |
| bool "Report races of unknown origin" |
| default y |
| help |
| If KCSAN should report races where only one access is known, and the |
| conflicting access is of unknown origin. This type of race is |
| reported if it was only possible to infer a race due to a data value |
| change while an access is being delayed on a watchpoint. |
| |
| config KCSAN_REPORT_VALUE_CHANGE_ONLY |
| bool "Only report races where watcher observed a data value change" |
| default y |
| help |
| If enabled and a conflicting write is observed via watchpoint, but |
| the data value of the memory location was observed to remain |
| unchanged, do not report the data race. |
| |
| config KCSAN_IGNORE_ATOMICS |
| bool "Do not instrument marked atomic accesses" |
| default n |
| help |
| If enabled, never instruments marked atomic accesses. This results in |
| not reporting data races where one access is atomic and the other is |
| a plain access. |
| |
| endif # KCSAN |
