Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   guoren@kernel.org
To:     arnd@arndb.de, guoren@kernel.org, palmer@rivosinc.com,
        tglx@linutronix.de, peterz@infradead.org, luto@kernel.org,
        conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org,
        chenhuacai@kernel.org, apatel@ventanamicro.com,
        atishp@atishpatra.org, mark.rutland@arm.com, bjorn@kernel.org,
        paul.walmsley@sifive.com, catalin.marinas@arm.com, will@kernel.org,
        rppt@kernel.org, anup@brainfault.org, shihua@iscas.ac.cn,
        jiawei@iscas.ac.cn, liweiwei@iscas.ac.cn, luxufan@iscas.ac.cn,
        chunyu@iscas.ac.cn, tsu.yubo@gmail.com, wefu@redhat.com,
        wangjunqiang@iscas.ac.cn, kito.cheng@sifive.com,
        andy.chiu@sifive.com, vincent.chen@sifive.com,
        greentime.hu@sifive.com, corbet@lwn.net, wuwei2016@iscas.ac.cn,
        jrtc27@jrtc27.com
Cc:     linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org, Guo Ren <guoren@linux.alibaba.com>
Subject: [RFC PATCH 15/22] riscv: s64ilp32: Enable native atomic64
Date:   Thu, 18 May 2023 09:10:06 -0400
Message-Id: <20230518131013.3366406-16-guoren@kernel.org>
In-Reply-To: <20230518131013.3366406-1-guoren@kernel.org>
References: <20230518131013.3366406-1-guoren@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Guo Ren <guoren@linux.alibaba.com>

The traditional rv32 Linux (s32ilp32) uses a generic version of the
lib/atomic64.c, which are inaccurate atomic64 primitives and couldn't
co-work with READ_ONCE/WRITE_ONCE,  atomic_8/16/32. The s64ilp32 could
use native AMO instructions to implement accurate atomic64 primitives.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 arch/riscv/Kconfig              | 2 +-
 arch/riscv/include/asm/atomic.h | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 9c458496ec3a..33fe624ef6d3 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -60,7 +60,7 @@ config RISCV
 	select CPU_PM if CPU_IDLE
 	select EDAC_SUPPORT
 	select GENERIC_ARCH_TOPOLOGY
-	select GENERIC_ATOMIC64 if !64BIT
+	select GENERIC_ATOMIC64 if ARCH_RV32I
 	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_ENTRY
diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
index 0dfe9d857a76..edfa6a74fe04 100644
--- a/arch/riscv/include/asm/atomic.h
+++ b/arch/riscv/include/asm/atomic.h
@@ -16,6 +16,12 @@
 # endif
 #endif
 
+#ifdef CONFIG_ARCH_RV64ILP32
+typedef struct {
+	s64 counter;
+} atomic64_t;
+#endif
+
 #include <asm/cmpxchg.h>
 #include <asm/barrier.h>
 
-- 
2.36.1