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Tue, 26 Aug 2025 07:58:06 -0700 (PDT) From: Xu Lu To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, ajones@ventanamicro.com, brs@rivosinc.com Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xu Lu Subject: [RFC PATCH 4/4] riscv: Use Zalasr for smp_load_acquire/smp_store_release Date: Tue, 26 Aug 2025 22:57:40 +0800 Message-Id: <20250826145740.92276-5-luxu.kernel@bytedance.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250826145740.92276-1-luxu.kernel@bytedance.com> References: <20250826145740.92276-1-luxu.kernel@bytedance.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 Content-Type: text/plain; charset="utf-8" Replace fence instructions with Zalasr instructions during acquire or release operations. Signed-off-by: Xu Lu --- arch/riscv/include/asm/barrier.h | 79 +++++++++++++++++++++++++++----- 1 file changed, 68 insertions(+), 11 deletions(-) diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barr= ier.h index b8c5726d86acb..b1d2a9a85256d 100644 --- a/arch/riscv/include/asm/barrier.h +++ b/arch/riscv/include/asm/barrier.h @@ -51,19 +51,76 @@ */ #define smp_mb__after_spinlock() RISCV_FENCE(iorw, iorw) =20 -#define __smp_store_release(p, v) \ -do { \ - compiletime_assert_atomic_type(*p); \ - RISCV_FENCE(rw, w); \ - WRITE_ONCE(*p, v); \ +extern void __bad_size_call_parameter(void); + +#define __smp_store_release(p, v) \ +do { \ + compiletime_assert_atomic_type(*p); \ + switch (sizeof(*p)) { \ + case 1: \ + asm volatile(ALTERNATIVE("fence rw, w;\t\nsb %0, 0(%1)\t\n", \ + SB_RL(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : : "r" (v), "r" (p) : "memory"); \ + break; \ + case 2: \ + asm volatile(ALTERNATIVE("fence rw, w;\t\nsh %0, 0(%1)\t\n", \ + SH_RL(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : : "r" (v), "r" (p) : "memory"); \ + break; \ + case 4: \ + asm volatile(ALTERNATIVE("fence rw, w;\t\nsw %0, 0(%1)\t\n", \ + SW_RL(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : : "r" (v), "r" (p) : "memory"); \ + break; \ + case 8: \ + asm volatile(ALTERNATIVE("fence rw, w;\t\nsd %0, 0(%1)\t\n", \ + SD_RL(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : : "r" (v), "r" (p) : "memory"); \ + break; \ + default: \ + __bad_size_call_parameter(); \ + break; \ + } \ } while (0) =20 -#define __smp_load_acquire(p) \ -({ \ - typeof(*p) ___p1 =3D READ_ONCE(*p); \ - compiletime_assert_atomic_type(*p); \ - RISCV_FENCE(r, rw); \ - ___p1; \ +#define __smp_load_acquire(p) \ +({ \ + TYPEOF_UNQUAL(*p) val; \ + compiletime_assert_atomic_type(*p); \ + switch (sizeof(*p)) { \ + case 1: \ + asm volatile(ALTERNATIVE("lb %0, 0(%1)\t\nfence r, rw\t\n", \ + LB_AQ(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : "=3Dr" (val) : "r" (p) : "memory"); \ + break; \ + case 2: \ + asm volatile(ALTERNATIVE("lh %0, 0(%1)\t\nfence r, rw\t\n", \ + LH_AQ(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : "=3Dr" (val) : "r" (p) : "memory"); \ + break; \ + case 4: \ + asm volatile(ALTERNATIVE("lw %0, 0(%1)\t\nfence r, rw\t\n", \ + LW_AQ(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : "=3Dr" (val) : "r" (p) : "memory"); \ + break; \ + case 8: \ + asm volatile(ALTERNATIVE("ld %0, 0(%1)\t\nfence r, rw\t\n", \ + LD_AQ(%0, %1) "\t\nnop\t\n", \ + 0, RISCV_ISA_EXT_ZALASR, 1) \ + : "=3Dr" (val) : "r" (p) : "memory"); \ + break; \ + default: \ + __bad_size_call_parameter(); \ + break; \ + } \ + val; \ }) =20 #ifdef CONFIG_RISCV_ISA_ZAWRS --=20 2.20.1