From nobody Fri Feb 13 01:41:51 2026 Received: from frasgout12.his.huawei.com (frasgout12.his.huawei.com [14.137.139.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3481D145A03 for ; Tue, 4 Jun 2024 16:05:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717517123; cv=none; b=Le37VeW0myioU7Mwn1QeOOhaPRcYFROQMqQN31d6dc25mmHxTqDAZQo6/7ZlVITqPyF5QgWvSc+c9Od6JAYMl4MDkrc1b/DkOxqyfSVDMCluqoe/kYH2Yx51t5wYzVcOW6uZWUrn+GpA3V8ng9l8+eT47Hlw9qDss6T3ryq2SWU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717517123; c=relaxed/simple; bh=ppigp21ZNg99k5SITpZMtUx3HYzasDubNk9q/zf7x3I=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=aif8CwIG9FauVwBYO825DdVVv/7u30j1Fcr/gFPFhgV8+IRgifNNieN8isdm5I+k5kOxSSBehoNVPlXsPSpy+kxR4R/7++WYMU+8hoAFraoACJNQuDppDmeYzC0HuCUOELPqxc41yvfxpLpALy+4EMw8AHVCzAd1GUCQIDz35qA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.186.29]) by frasgout12.his.huawei.com (SkyGuard) with ESMTP id 4VtvxQ6GRkz9v7JM for ; Tue, 4 Jun 2024 23:42:50 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.27]) by mail.maildlp.com (Postfix) with ESMTP id E4982140FAA for ; Wed, 5 Jun 2024 00:04:58 +0800 (CST) Received: from huaweicloud.com (unknown [10.206.133.88]) by APP2 (Coremail) with SMTP id GxC2BwBnoCQdO19myvaGCQ--.14358S2; Tue, 04 Jun 2024 17:04:58 +0100 (CET) From: Jonas Oberhauser 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, Jonas Oberhauser , Viktor Vafeiadis Subject: [PATCHv2 3/4] tools/memory-model: Define effect of Mb tags on RMWs in tools/... Date: Tue, 4 Jun 2024 18:04:40 +0200 Message-Id: <20240604160440.498332-1-jonas.oberhauser@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240604152922.495908-1-jonas.oberhauser@huaweicloud.com> References: <20240604152922.495908-1-jonas.oberhauser@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: GxC2BwBnoCQdO19myvaGCQ--.14358S2 X-Coremail-Antispam: 1UD129KBjvJXoW7KFWUZry5tFWkCFW8JrWDurg_yoW8WFy3pr ZYgw15Gr4kKryUu3Z3ZanxZF1rWa1xtF13WFn7A34fZr43XrW7Z34rtan0qF9xXFsI9a45 Zr4jv3WkCa4kAFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv014x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r1j6r1xM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x0267AKxVW8JV W8Jr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26F4j6r4UJwCI42IY6xAIw20EY4v20xvaj40_Gr0_Zr1lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUb CPfPUUUUU== X-CM-SenderInfo: 5mrqt2oorev25kdx2v3u6k3tpzhluzxrxghudrp/ Content-Type: text/plain; charset="utf-8" Herd7 transforms successful RMW with Mb tags by inserting smp_mb() fences around them. We emulate this by considering imaginary po-edges before the RMW read and before the RMW write, and extending the smp_mb() ordering rule, which currently only applies to real po edges that would be found around a really inserted smp_mb(), also to cases of the only imagined po edges. Reported-by: Viktor Vafeiadis Suggested-by: Alan Stern Signed-off-by: Jonas Oberhauser --- tools/memory-model/linux-kernel.cat | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux= -kernel.cat index adf3c4f41229..d7e7bf13c831 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -34,6 +34,16 @@ let R4rmb =3D R \ Noreturn (* Reads for which rmb works = *) let rmb =3D [R4rmb] ; fencerel(Rmb) ; [R4rmb] let wmb =3D [W] ; fencerel(Wmb) ; [W] let mb =3D ([M] ; fencerel(Mb) ; [M]) | + (* + * full-barrier RMWs (successful cmpxchg(), xchg(), etc.) act as + * though there were enclosed by smp_mb(). + * The effect of these virtual smp_mb() is formalized by adding + * Mb tags to the read and write of the operation, and providing + * the same ordering as though there were additional po edges + * between the Mb tag and the read resp. write. + *) + ([M] ; po ; [Mb & R]) | + ([Mb & W] ; po ; [M]) | ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) | ([M] ; po? ; [RMW] ; fencerel(After-atomic) ; [M]) | ([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M]) | --=20 2.34.1