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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
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
~~~~~~~~~~~~~~~~~

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
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
bool "Only report races where watcher observed a data value change"
default y
depends on !KCSAN_STRICT
help
If enabled and a conflicting write is observed via a watchpoint, but
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
bool "Assume that plain aligned writes up to word size are atomic"
default y
depends on !KCSAN_STRICT
help
Assume that plain aligned writes up to word size are atomic by
default, and also not subject to other unsafe compiler optimizations
@ -206,6 +215,7 @@ config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC
config KCSAN_IGNORE_ATOMICS
bool "Do not instrument marked atomic accesses"
depends on !KCSAN_STRICT
help
Never instrument marked atomic accesses. This option can be used for
additional filtering. Conflicting marked atomic reads and plain