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[2001:1ae9:1c2:4c00:20f:c6b4:1e57:7965]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-388c8060679sm10987341f8f.105.2024.12.17.05.03.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2024 05:03:45 -0800 (PST) Date: Tue, 17 Dec 2024 14:03:44 +0100 From: Andrew Jones To: guoren@kernel.org Cc: paul.walmsley@sifive.com, palmer@dabbelt.com, bjorn@rivosinc.com, conor@kernel.org, leobras@redhat.com, alexghiti@rivosinc.com, christoph.muellner@vrull.eu, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, parri.andrea@gmail.com, ericchancf@google.com, Guo Ren Subject: Re: [PATCH V2] riscv: Implement smp_cond_load8/16() with Zawrs Message-ID: <20241217-aba8759654f30826104e5da0@orel> References: <20241217013910.1039923-1-guoren@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241217013910.1039923-1-guoren@kernel.org> On Mon, Dec 16, 2024 at 08:39:10PM -0500, guoren@kernel.org wrote: > From: Guo Ren > > RISC-V code uses the queued spinlock implementation, which calls > the macros smp_cond_load_acquire for one byte. So, complement the > implementation of byte and halfword versions. > > Signed-off-by: Guo Ren > Signed-off-by: Guo Ren > Cc: Andrew Jones > --- > Changes in V2: > - Fixup mask typo (0xf -> 0xff, 0xff -> 0xffff) by Andrew. > --- > arch/riscv/include/asm/cmpxchg.h | 38 +++++++++++++++++++++++++++++--- > 1 file changed, 35 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h > index 4cadc56220fe..aa4410beb065 100644 > --- a/arch/riscv/include/asm/cmpxchg.h > +++ b/arch/riscv/include/asm/cmpxchg.h > @@ -365,16 +365,48 @@ static __always_inline void __cmpwait(volatile void *ptr, > { > unsigned long tmp; > > + u32 *__ptr32b; > + ulong __s, __val, __mask; > + > asm goto(ALTERNATIVE("j %l[no_zawrs]", "nop", > 0, RISCV_ISA_EXT_ZAWRS, 1) > : : : : no_zawrs); > > switch (size) { > case 1: > - fallthrough; > + __ptr32b = (u32 *)((ulong)(ptr) & ~0x3); > + __s = ((ulong)(ptr) & 0x3) * BITS_PER_BYTE; > + __val = val << __s; > + __mask = 0xff << __s; > + > + asm volatile( > + " lr.w %0, %1\n" > + " and %0, %0, %3\n" > + " xor %0, %0, %2\n" > + " bnez %0, 1f\n" > + ZAWRS_WRS_NTO "\n" > + "1:" > + : "=&r" (tmp), "+A" (*(__ptr32b)) > + : "r" (__val), "r" (__mask) > + : "memory"); > + break; > case 2: > - /* RISC-V doesn't have lr instructions on byte and half-word. */ > - goto no_zawrs; > + __ptr32b = (u32 *)((ulong)(ptr) & ~0x3); > + __s = ((ulong)(ptr) & 0x2) * BITS_PER_BYTE; > + __val = val << __s; > + __mask = 0xffff << __s; > + > + asm volatile( > + " lr.w %0, %1\n" > + " and %0, %0, %3\n" > + " xor %0, %0, %2\n" > + " bnez %0, 1f\n" > + ZAWRS_WRS_NTO "\n" > + "1:" > + : "=&r" (tmp), "+A" (*(__ptr32b)) > + : "r" (__val), "r" (__mask) > + : "memory"); > + break; > case 4: > asm volatile( > " lr.w %0, %1\n" > -- > 2.40.1 > Reviewed-by: Andrew Jones