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From: "Paul E. McKenney" <paulmck@kernel.org>
To: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	kernel-team@fb.com, mingo@kernel.org
Cc: elver@google.com, andreyknvl@google.com, glider@google.com,
	dvyukov@google.com, cai@lca.pw, boqun.feng@gmail.com,
	Mark Rutland <mark.rutland@arm.com>,
	"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH kcsan 3/8] kcsan: Introduce CONFIG_KCSAN_STRICT
Date: Wed, 21 Jul 2021 14:08:07 -0700	[thread overview]
Message-ID: <20210721210812.844740-3-paulmck@kernel.org> (raw)
In-Reply-To: <20210721210726.GA828672@paulmck-ThinkPad-P17-Gen-1>

From: Marco Elver <elver@google.com>

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>
---
 Documentation/dev-tools/kcsan.rst |  4 ++++
 lib/Kconfig.kcsan                 | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst
index 6a600cf8430b1..69dc9c502ccc5 100644
--- a/Documentation/dev-tools/kcsan.rst
+++ b/Documentation/dev-tools/kcsan.rst
@@ -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
 ~~~~~~~~~~~~~~~~~
 
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 5304f211f81f1..c76fbb3ee09ec 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -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
-- 
2.31.1.189.g2e36527f23


  parent reply	other threads:[~2021-07-21 21:08 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21 21:07 [PATCH kcsan 0/8] KCSAN updates for v5.15 Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 1/8] kcsan: Improve some Kconfig comments Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 2/8] kcsan: Remove CONFIG_KCSAN_DEBUG Paul E. McKenney
2021-07-21 21:08 ` Paul E. McKenney [this message]
2021-07-21 21:08 ` [PATCH kcsan 4/8] kcsan: Reduce get_ctx() uses in kcsan_found_watchpoint() Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 5/8] kcsan: Rework atomic.h into permissive.h Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 6/8] kcsan: Print if strict or non-strict during init Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 7/8] kcsan: permissive: Ignore data-racy 1-bit value changes Paul E. McKenney
2021-07-21 21:08 ` [PATCH kcsan 8/8] kcsan: Make strict mode imply interruptible watchers Paul E. McKenney
2021-07-21 21:10 ` [PATCH memory-model 1/4] tools/memory-model: Make read_foo_diagnostic() more clearly diagnostic Paul E. McKenney
2021-07-21 21:10 ` [PATCH memory-model 2/4] tools/memory-model: Add example for heuristic lockless reads Paul E. McKenney
2021-07-23  2:08   ` Alan Stern
2021-07-23  6:52     ` Manfred Spraul
2021-07-23 13:05       ` Alan Stern
2021-07-23 13:57         ` Manfred Spraul
2021-07-23 16:30         ` Paul E. McKenney
2021-07-23 17:08           ` Alan Stern
2021-07-23 20:32             ` Paul E. McKenney
2021-07-23 21:03               ` Alan Stern
2021-07-23 22:29                 ` Paul E. McKenney
2021-07-23 16:24     ` Paul E. McKenney
2021-07-23 16:59       ` Alan Stern
2021-07-23 17:30         ` Paul E. McKenney
2021-07-23 18:11           ` Alan Stern
2021-07-23 20:28             ` Paul E. McKenney
2021-07-28 17:40   ` [PATCH v2 " Paul E. McKenney
2021-07-21 21:10 ` [PATCH memory-model 3/4] tools/memory-model: Heuristics using data_race() must handle all values Paul E. McKenney
2021-07-21 21:10 ` [PATCH memory-model 4/4] tools/memory-model: Document data_race(READ_ONCE()) Paul E. McKenney

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