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Tue, 12 Dec 2023 17:18:45 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id cy26-20020a056830699a00b006d9a339773csm172548otb.27.2023.12.12.17.18.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Dec 2023 17:18:45 -0800 (PST) From: Charlie Jenkins Date: Tue, 12 Dec 2023 17:18:40 -0800 Subject: [PATCH v12 3/5] riscv: Add checksum header MIME-Version: 1.0 Message-Id: <20231212-optimize_checksum-v12-3-419a4ba6d666@rivosinc.com> References: <20231212-optimize_checksum-v12-0-419a4ba6d666@rivosinc.com> In-Reply-To: <20231212-optimize_checksum-v12-0-419a4ba6d666@rivosinc.com> To: Charlie Jenkins , Palmer Dabbelt , Conor Dooley , Samuel Holland , David Laight , Xiao Wang , Evan Green , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: Paul Walmsley , Albert Ou , Arnd Bergmann , Conor Dooley X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1702430319; l=3074; i=charlie@rivosinc.com; s=20231120; h=from:subject:message-id; bh=adYqZ1MwkI2tixiO6Vqw0pA42pYvaEcycoXrFZjPpmw=; b=4z6EVBErljGKcQ6ywUy9p67X640GJzGAFaxbGt7gS99Jj7/mlk/GsHCbAxkR6srBT0KNEL31G eknW7cffrFTCzO5tfzpRKWsA02wygpgNME7+EVpuGtD9DRR31izxRFl X-Developer-Key: i=charlie@rivosinc.com; a=ed25519; pk=t4RSWpMV1q5lf/NWIeR9z58bcje60/dbtxxmoSfBEcs= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231212_171848_741095_7462AAB8 X-CRM114-Status: GOOD ( 14.88 ) 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 Provide checksum algorithms that have been designed to leverage riscv instructions such as rotate. In 64-bit, can take advantage of the larger register to avoid some overflow checking. Signed-off-by: Charlie Jenkins Acked-by: Conor Dooley Reviewed-by: Xiao Wang --- arch/riscv/include/asm/checksum.h | 82 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) diff --git a/arch/riscv/include/asm/checksum.h b/arch/riscv/include/asm/checksum.h new file mode 100644 index 000000000000..2fcf864186e7 --- /dev/null +++ b/arch/riscv/include/asm/checksum.h @@ -0,0 +1,82 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Checksum routines + * + * Copyright (C) 2023 Rivos Inc. + */ +#ifndef __ASM_RISCV_CHECKSUM_H +#define __ASM_RISCV_CHECKSUM_H + +#include +#include + +#define ip_fast_csum ip_fast_csum + +/* Define riscv versions of functions before importing asm-generic/checksum.h */ +#include + +/** + * Quickly compute an IP checksum with the assumption that IPv4 headers will + * always be in multiples of 32-bits, and have an ihl of at least 5. + * + * @ihl: the number of 32 bit segments and must be greater than or equal to 5. + * @iph: assumed to be word aligned given that NET_IP_ALIGN is set to 2 on + * riscv, defining IP headers to be aligned. + */ +static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) +{ + unsigned long csum = 0; + int pos = 0; + + do { + csum += ((const unsigned int *)iph)[pos]; + if (IS_ENABLED(CONFIG_32BIT)) + csum += csum < ((const unsigned int *)iph)[pos]; + } while (++pos < ihl); + + /* + * ZBB only saves three instructions on 32-bit and five on 64-bit so not + * worth checking if supported without Alternatives. + */ + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && + IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { + unsigned long fold_temp; + + asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : + : + : + : no_zbb); + + if (IS_ENABLED(CONFIG_32BIT)) { + asm(".option push \n\ + .option arch,+zbb \n\ + not %[fold_temp], %[csum] \n\ + rori %[csum], %[csum], 16 \n\ + sub %[csum], %[fold_temp], %[csum] \n\ + .option pop" + : [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp)); + } else { + asm(".option push \n\ + .option arch,+zbb \n\ + rori %[fold_temp], %[csum], 32 \n\ + add %[csum], %[fold_temp], %[csum] \n\ + srli %[csum], %[csum], 32 \n\ + not %[fold_temp], %[csum] \n\ + roriw %[csum], %[csum], 16 \n\ + subw %[csum], %[fold_temp], %[csum] \n\ + .option pop" + : [csum] "+r" (csum), [fold_temp] "=&r" (fold_temp)); + } + return csum >> 16; + } +no_zbb: +#ifndef CONFIG_32BIT + csum += ror64(csum, 32); + csum >>= 32; +#endif + return csum_fold((__force __wsum)csum); +} + +#endif /* __ASM_RISCV_CHECKSUM_H */