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Fri, 04 Aug 2023 01:49:20 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH+UFfE5kIqjMnJEnmHBbkiyastZJTrRw0+4RxwlYLXQBsPZsV+LE6/4Sbj30UIpvzm+AUyKg== X-Received: by 2002:a4a:3947:0:b0:566:f763:8fb7 with SMTP id x7-20020a4a3947000000b00566f7638fb7mr1209698oog.2.1691138960284; Fri, 04 Aug 2023 01:49:20 -0700 (PDT) Received: from localhost.localdomain ([2804:1b3:a801:d380:694f:4f52:764c:4b7f]) by smtp.gmail.com with ESMTPSA id f8-20020a4ab008000000b0055516447257sm685679oon.29.2023.08.04.01.49.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Aug 2023 01:49:19 -0700 (PDT) From: Leonardo Bras To: Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Albert Ou , Leonardo Bras , Andrea Parri , Geert Uytterhoeven , Andrzej Hajda , Palmer Dabbelt , Guo Ren Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: [RFC PATCH v3 0/5] Rework & improve riscv cmpxchg.h and atomic.h Date: Fri, 4 Aug 2023 05:48:53 -0300 Message-ID: <20230804084900.1135660-2-leobras@redhat.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230804_014927_852963_16C5B26A X-CRM114-Status: GOOD ( 16.05 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org While studying riscv's cmpxchg.h file, I got really interested in understanding how RISCV asm implemented the different versions of {cmp,}xchg. When I understood the pattern, it made sense for me to remove the duplications and create macros to make it easier to understand what exactly changes between the versions: Instruction sufixes & barriers. Also, did the same kind of work on atomic.c. After that, I noted both cmpxchg and xchg only accept variables of size 4 and 8, compared to x86 and arm64 which do 1,2,4,8. Now that deduplication is done, it is quite direct to implement them for variable sizes 1 and 2, so I did it. Then Guo Ren already presented me some possible users :) I did compare the generated asm on a test.c that contained usage for every changed function, and could not detect any change on patches 1 + 2 + 3 compared with upstream. Pathes 4 & 5 were compiled-tested, but I could not run-test them yet. Thanks! Leo Changes since squashed cmpxchg RFCv2: - Removed rc parameter from the new macro: it can be internal to the macro - 2 new patches: cmpxchg size 1 and 2, xchg size 1 and 2 https://lore.kernel.org/all/20230803051401.710236-2-leobras@redhat.com/ Changes since squashed cmpxchg RFCv1: - Unified with atomic.c patchset - Rebased on top of torvalds/master (thanks Andrea Parri!) - Removed helper macros that were not being used elsewhere in the kernel. https://lore.kernel.org/all/20230419062505.257231-1-leobras@redhat.com/ https://lore.kernel.org/all/20230406082018.70367-1-leobras@redhat.com/ Changes since (cmpxchg) RFCv3: - Squashed the 6 original patches in 2: one for cmpxchg and one for xchg https://lore.kernel.org/all/20230404163741.2762165-1-leobras@redhat.com/ Changes since (cmpxchg) RFCv2: - Fixed macros that depend on having a local variable with a magic name - Previous cast to (long) is now only applied on 4-bytes cmpxchg https://lore.kernel.org/all/20230321074249.2221674-1-leobras@redhat.com/ Changes since (cmpxchg) RFCv1: - Fixed patch 4/6 suffix from 'w.aqrl' to '.w.aqrl', to avoid build error https://lore.kernel.org/all/20230318080059.1109286-1-leobras@redhat.com/ Leonardo Bras (5): riscv/cmpxchg: Deduplicate xchg() asm functions riscv/cmpxchg: Deduplicate cmpxchg() asm and macros riscv/atomic.h : Deduplicate arch_atomic.* riscv/cmpxchg: Implement cmpxchg for variables of size 1 and 2 riscv/cmpxchg: Implement xchg for variables of size 1 and 2 arch/riscv/include/asm/atomic.h | 164 ++++++------- arch/riscv/include/asm/cmpxchg.h | 393 ++++++++++--------------------- 2 files changed, 195 insertions(+), 362 deletions(-)