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Diffstat (limited to 'lib/Kconfig.kcsan')
-rw-r--r-- | lib/Kconfig.kcsan | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan new file mode 100644 index 000000000000..f0b791143c6a --- /dev/null +++ b/lib/Kconfig.kcsan @@ -0,0 +1,156 @@ +# SPDX-License-Identifier: GPL-2.0-only + +config HAVE_ARCH_KCSAN + bool + +menuconfig KCSAN + bool "KCSAN: dynamic race detector" + depends on HAVE_ARCH_KCSAN && DEBUG_KERNEL && !KASAN + select STACKTRACE + help + The Kernel Concurrency Sanitizer (KCSAN) is a dynamic race detector, + which relies on compile-time instrumentation, and uses a + watchpoint-based sampling approach to detect races. + + KCSAN's primary purpose is to detect data races. KCSAN can also be + used to check properties, with the help of provided assertions, of + concurrent code where bugs do not manifest as data races. + + See <file:Documentation/dev-tools/kcsan.rst> for more details. + +if KCSAN + +config KCSAN_DEBUG + bool "Debugging of KCSAN internals" + +config KCSAN_SELFTEST + bool "Perform short selftests on boot" + default y + help + Run KCSAN selftests on boot. On test failure, causes the 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 the KCSAN_UDELAY_* values + as 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. + +config KCSAN_REPORT_ONCE_IN_MS + int "Duration in milliseconds, in which any given race is only reported once" + default 3000 + help + Any given race is only reported once in the defined time window. + Different races may still generate reports within a duration that is + smaller than the duration defined here. This allows rate limiting + reporting to avoid flooding the console with reports. Setting this + to 0 disables rate limiting. + +# The main purpose of the below options is to control reported data races (e.g. +# in fuzzer configs), and are not expected to be switched frequently by other +# users. We could turn some of them into boot parameters, but given they should +# not be switched normally, let's keep them here to simplify configuration. +# +# The defaults below are chosen to be very conservative, and may miss certain +# bugs. + +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 a watchpoint, but + the data value of the memory location was observed to remain + unchanged, do not report the data race. + +config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC + bool "Assume that plain aligned writes up to word size are atomic" + default y + help + Assume that plain aligned writes up to word size are atomic by + default, and also not subject to other unsafe compiler optimizations + resulting in data races. This will cause KCSAN to not report data + races due to conflicts where the only plain accesses are aligned + writes up to word size: conflicts between marked reads and plain + aligned writes up to word size will not be reported as data races; + notice that data races between two conflicting plain aligned writes + will also not be reported. + +config KCSAN_IGNORE_ATOMICS + bool "Do not instrument marked atomic accesses" + help + Never instrument marked atomic accesses. This option can be used for + additional filtering. Conflicting marked atomic reads and plain + writes will never be reported as a data race, however, will cause + plain reads and marked writes to result in "unknown origin" reports. + If combined with CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN=n, data + races where at least one access is marked atomic will never be + reported. + + Similar to KCSAN_ASSUME_PLAIN_WRITES_ATOMIC, but including unaligned + accesses, conflicting marked atomic reads and plain writes will not + be reported as data races; however, unlike that option, data races + due to two conflicting plain writes will be reported (aligned and + unaligned, if CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n). + +endif # KCSAN |