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kcsan: Introduce CONFIG_KCSAN_STRICT

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Add a simpler Kconfig variable to configure KCSAN's "strict" mode. This
makes it simpler in documentation or messages to suggest just a single
configuration option to select the strictest checking mode (vs.
currently having to list several options).

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Marco Elver
2021-06-07 14:56:49 +02:00
committed by Paul E. McKenney
parent a7a7369736
commit e675d2533a
2 changed files with 14 additions and 0 deletions
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4
Documentation/dev-tools/kcsan.rst
View File

@@ -127,6 +127,10 @@ Kconfig options:
causes KCSAN to not report data races due to conflicts where the only plain causes KCSAN to not report data races due to conflicts where the only plain
accesses are aligned writes up to word size. accesses are aligned writes up to word size.
To use the strictest possible rules, select ``CONFIG_KCSAN_STRICT=y``, which
configures KCSAN to follow the Linux-kernel memory consistency model (LKMM) as
closely as possible.
DebugFS interface DebugFS interface
~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~

10
lib/Kconfig.kcsan
View File

@@ -183,9 +183,17 @@ config KCSAN_REPORT_RACE_UNKNOWN_ORIGIN
reported if it was only possible to infer a race due to a data value 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. change while an access is being delayed on a watchpoint.
config KCSAN_STRICT
bool "Strict data-race checking"
help
KCSAN will report data races with the strictest possible rules, which
closely aligns with the rules defined by the Linux-kernel memory
consistency model (LKMM).
config KCSAN_REPORT_VALUE_CHANGE_ONLY config KCSAN_REPORT_VALUE_CHANGE_ONLY
bool "Only report races where watcher observed a data value change" bool "Only report races where watcher observed a data value change"
default y default y
depends on !KCSAN_STRICT
help help
If enabled and a conflicting write is observed via a 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 the data value of the memory location was observed to remain
@@ -194,6 +202,7 @@ config KCSAN_REPORT_VALUE_CHANGE_ONLY
config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC
bool "Assume that plain aligned writes up to word size are atomic" bool "Assume that plain aligned writes up to word size are atomic"
default y default y
depends on !KCSAN_STRICT
help help
Assume that plain aligned writes up to word size are atomic by Assume that plain aligned writes up to word size are atomic by
default, and also not subject to other unsafe compiler optimizations default, and also not subject to other unsafe compiler optimizations
@@ -206,6 +215,7 @@ config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC
config KCSAN_IGNORE_ATOMICS config KCSAN_IGNORE_ATOMICS
bool "Do not instrument marked atomic accesses" bool "Do not instrument marked atomic accesses"
depends on !KCSAN_STRICT
help help
Never instrument marked atomic accesses. This option can be used for Never instrument marked atomic accesses. This option can be used for
additional filtering. Conflicting marked atomic reads and plain additional filtering. Conflicting marked atomic reads and plain