[PATCH memory-model 4/7] tools/memory-model: Define applicable tags on operation in tools/...

Paul E. McKenney
2025-02-20T16:14:05Z

From: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>

Herd7 transforms reads, writes, and read-modify-writes by eliminating
'acquire tags from writes, 'release tags from reads, and 'acquire,
'release, and 'mb tags from failed read-modify-writes. We emulate this
behavior by redefining Acquire, Release, and Mb sets in linux-kernel.bell
to explicitly exclude those combinations.

Herd7 furthermore adds 'noreturn tag to certain reads. Currently herd7
does not allow specifying the 'noreturn tag manually, but such manual
declaration (e.g., through a syntax __atomic_op{noreturn}) would add
invalid 'noreturn tags to writes; in preparation, we already also exclude
this combination.

Signed-off-by: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
---
tools/memory-model/linux-kernel.bell | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell
index dba6b5b6dee01..7c9ae48b94377 100644
--- a/tools/memory-model/linux-kernel.bell
+++ b/tools/memory-model/linux-kernel.bell
@@ -36,6 +36,17 @@ enum Barriers = 'wmb (*smp_wmb*) ||
'after-srcu-read-unlock (*smp_mb__after_srcu_read_unlock*)
instructions F[Barriers]

+
+(*
+ * Filter out syntactic annotations that do not provide the corresponding
+ * semantic ordering, such as Acquire on a store or Mb on a failed RMW.
+ *)
+let FailedRMW = RMW \ (domain(rmw) | range(rmw))
+let Acquire = Acquire \ W \ FailedRMW
+let Release = Release \ R \ FailedRMW
+let Mb = Mb \ FailedRMW
+let Noreturn = Noreturn \ W
+
(* SRCU *)
enum SRCU = 'srcu-lock || 'srcu-unlock || 'sync-srcu
instructions SRCU[SRCU]
--
2.40.1