From: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
To: paulmck@kernel.org
Cc: stern@rowland.harvard.edu, parri.andrea@gmail.com,
will@kernel.org, peterz@infradead.org, boqun.feng@gmail.com,
npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
luc.maranget@inria.fr, akiyks@gmail.com, dlustig@nvidia.com,
joel@joelfernandes.org, urezki@gmail.com,
quic_neeraju@quicinc.com, frederic@kernel.org,
linux-kernel@vger.kernel.org, lkmm@lists.linux.dev,
hernan.poncedeleon@huaweicloud.com,
Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Subject: [PATCH v3 1/5] tools/memory-model: Legitimize current use of tags in LKMM macros
Date: Thu, 19 Sep 2024 15:06:30 +0200 [thread overview]
Message-ID: <20240919130634.298181-2-jonas.oberhauser@huaweicloud.com> (raw)
In-Reply-To: <20240919130634.298181-1-jonas.oberhauser@huaweicloud.com>
The current macros in linux-kernel.def reference instructions such as
__xchg{mb} or __cmpxchg{acquire}, which are invalid combinations of tags
and instructions according to the declarations in linux-kernel.bell.
This works with current herd7 because herd7 removes these tags anyways
and does not actually enforce validity of combinations at all.
If a future herd7 version no longer applies these hardcoded
transformations, then all currently invalid combinations will actually
appear on some instruction.
We therefore adjust the declarations to make the resulting combinations
valid, by adding the 'mb tag to the set of Accesses and allowing all
Accesses to appear on all read, write, and RMW instructions.
Signed-off-by: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
---
tools/memory-model/linux-kernel.bell | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell
index ce068700939c..dba6b5b6dee0 100644
--- a/tools/memory-model/linux-kernel.bell
+++ b/tools/memory-model/linux-kernel.bell
@@ -16,10 +16,11 @@
enum Accesses = 'once (*READ_ONCE,WRITE_ONCE*) ||
'release (*smp_store_release*) ||
'acquire (*smp_load_acquire*) ||
- 'noreturn (* R of non-return RMW *)
-instructions R[{'once,'acquire,'noreturn}]
-instructions W[{'once,'release}]
-instructions RMW[{'once,'acquire,'release}]
+ 'noreturn (* R of non-return RMW *) ||
+ 'mb (*xchg(),cmpxchg(),...*)
+instructions R[Accesses]
+instructions W[Accesses]
+instructions RMW[Accesses]
enum Barriers = 'wmb (*smp_wmb*) ||
'rmb (*smp_rmb*) ||
--
2.34.1
next prev parent reply other threads:[~2024-09-19 13:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-19 13:06 [PATCH v3 0/5] tools/memory-model: Define more of LKMM in tools/memory-model Jonas Oberhauser
2024-09-19 13:06 ` Jonas Oberhauser [this message]
2024-09-19 13:06 ` [PATCH v3 2/5] tools/memory-model: Define applicable tags on operation in tools/ Jonas Oberhauser
2024-09-19 13:06 ` [PATCH v3 3/5] tools/memory-model: Define effect of Mb tags on RMWs " Jonas Oberhauser
2024-09-19 13:06 ` [PATCH v3 4/5] tools/memory-model: Switch to softcoded herd7 tags Jonas Oberhauser
2024-09-20 12:23 ` Hernan Ponce de Leon
2024-09-21 2:44 ` Akira Yokosawa
2024-09-21 7:39 ` Jonas Oberhauser
2024-09-21 11:28 ` Akira Yokosawa
2024-09-19 13:06 ` [PATCH v3 5/5] tools/memory-model: Distinguish between syntactic and semantic tags Jonas Oberhauser
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