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Sun, 8 Apr 2018 20:21:06 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Will Deacon , Catalin Marinas , Sasha Levin Subject: [PATCH AUTOSEL for 4.15 156/189] arm64: spinlock: Fix theoretical trylock() A-B-A with LSE atomics Thread-Topic: [PATCH AUTOSEL for 4.15 156/189] arm64: spinlock: Fix theoretical trylock() A-B-A with LSE atomics Thread-Index: AQHTz5hXrnHqT7NipEi+j2IpHQkKWQ== Date: Mon, 9 Apr 2018 00:18:53 +0000 Message-ID: <20180409001637.162453-156-alexander.levin@microsoft.com> References: <20180409001637.162453-1-alexander.levin@microsoft.com> In-Reply-To: <20180409001637.162453-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB0920;7:KSL+az0CvQISkJdcK3UohJ1kYS+DJNXPsk+F8s2ijjZYt/VngH1vRUDjcqpSV4JlD7E6fzBMmQ1Nx0hG0ckfX2U8IRaEpbHuz6FlJGUou2mpR1Af7uv/6I/JCgY7qZOewYrEjDK/Qm83LJGCcmfKWNcCnn5NvXvGU7zFrEiLEQJRARclwuQyozL87aRcZ4f0u6EqBXLgIQQOhjn9RFBtKkvHRcAKSFeoKg2+8EJVWpvfIP/AEb9seXaCfdi7kJ4w;20:HlFQHDpy76vi/y81noRsdiR/MGHg1CswWc68oYq6JxKKFchHlOfkxUnNzI+ERMq2Bwjst7RJro9vC5tvGbZsA5QJ/0iv5OWWUDAv9ullZ+XEiCjxHHwfnUap/iaaA4ESKwdm+EMjMw2CvmnqdXwGZMYVqRJZN/J3f4YDdIlR/A8= X-MS-Office365-Filtering-Correlation-Id: f48875b7-4507-4501-b416-08d59dafc5a3 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(5600026)(4604075)(3008032)(48565401081)(2017052603328)(7193020);SRVR:DM5PR2101MB0920; 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This patch fixes the issue by performing a full 32-bit check of the lock word when trying to determine whether or not the CASA instruction updated memory. Reported-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- arch/arm64/include/asm/spinlock.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spi= nlock.h index fdb827c7832f..ebdae15d665d 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -87,8 +87,8 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock= ) " cbnz %w1, 1f\n" " add %w1, %w0, %3\n" " casa %w0, %w1, %2\n" - " and %w1, %w1, #0xffff\n" - " eor %w1, %w1, %w0, lsr #16\n" + " sub %w1, %w1, %3\n" + " eor %w1, %w1, %w0\n" "1:") : "=3D&r" (lockval), "=3D&r" (tmp), "+Q" (*lock) : "I" (1 << TICKET_SHIFT) --=20 2.15.1