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