X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=lib%2FKconfig.kcsan;h=5ee88e5119c2815ffaf91fa9ba1f89d3dbd9371e;hb=751645789f7cffddb0715d51fd9e72986ad9ecaf;hp=5dd464e52ab4329a27470a5b6bc399d12dccda47;hpb=8e1d58ae0c8d4af9ab0141f7e8a9ca95720df01c;p=mirror_ubuntu-hirsute-kernel.git diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan index 5dd464e52ab4..5ee88e5119c2 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -3,26 +3,63 @@ config HAVE_ARCH_KCSAN bool +config HAVE_KCSAN_COMPILER + def_bool CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-distinguish-volatile=1) + help + For the list of compilers that support KCSAN, please see + . + +config KCSAN_KCOV_BROKEN + def_bool KCOV && CC_HAS_SANCOV_TRACE_PC + depends on CC_IS_CLANG + depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=thread -fsanitize-coverage=trace-pc) + help + Some versions of clang support either KCSAN and KCOV but not the + combination of the two. + See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status + in newer releases. + menuconfig KCSAN - bool "KCSAN: watchpoint-based dynamic data race detector" - depends on HAVE_ARCH_KCSAN && !KASAN && STACKTRACE - default n + bool "KCSAN: dynamic data race detector" + depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER + depends on DEBUG_KERNEL && !KASAN + depends on !KCSAN_KCOV_BROKEN + select STACKTRACE help - Kernel Concurrency Sanitizer is a dynamic data race detector, which - uses a watchpoint-based sampling approach to detect races. See - for more details. + The Kernel Concurrency Sanitizer (KCSAN) is a dynamic + data-race detector that relies on compile-time instrumentation. + KCSAN uses a watchpoint-based sampling approach to detect races. + + While KCSAN's primary purpose is to detect data races, it + also provides assertions to check data access constraints. + These assertions can expose bugs that do not manifest as + data races. + + See for more details. if KCSAN +config KCSAN_VERBOSE + bool "Show verbose reports with more information about system state" + depends on PROVE_LOCKING + help + If enabled, reports show more information about the system state that + may help better analyze and debug races. This includes held locks and + IRQ trace events. + + While this option should generally be benign, we call into more + external functions on report generation; if a race report is + generated from any one of them, system stability may suffer due to + deadlocks or recursion. If in doubt, say N. + 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. + Run KCSAN selftests on boot. On test failure, causes the kernel to panic. config KCSAN_EARLY_ENABLE bool "Early enable during boot" @@ -62,7 +99,8 @@ config KCSAN_DELAY_RANDOMIZE 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. + 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" @@ -82,13 +120,34 @@ config KCSAN_SKIP_WATCH_RANDOMIZE 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_INTERRUPT_WATCHER + bool "Interruptible watchers" + help + If enabled, a task that set up a watchpoint may be interrupted while + delayed. This option will allow KCSAN to detect races between + interrupted tasks and other threads of execution on the same CPU. + + Currently disabled by default, because not all safe per-CPU access + primitives and patterns may be accounted for, and therefore could + result in false positives. + +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" @@ -103,16 +162,38 @@ 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 + 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" - 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. + 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