linux-kernel - [RFC PATCH V3 03/11] riscv: Extending cpufeature.c to detect V-extension

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Message-Id: <20200308094954.13258-4-guoren@kernel.org>
Date:   Sun,  8 Mar 2020 17:49:46 +0800
From:   guoren@...nel.org
To:     paul.walmsley@...ive.com, palmer@...belt.com, Anup.Patel@....com,
        greentime.hu@...ive.com
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        arnd@...db.de, linux-csky@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Guo Ren <guoren@...ux.alibaba.com>,
        Dave Martin <Dave.Martin@....com>
Subject: [RFC PATCH V3 03/11] riscv: Extending cpufeature.c to detect V-extension

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

From: Guo Ren <ren_guo@...ky.com>

Current cpufeature.c doesn't support detecting V-extension, because
"rv64" also contain a 'v' letter and we need to skip it.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Reviewed-by: Anup Patel <anup@...infault.org>
---
 arch/riscv/include/uapi/asm/hwcap.h | 1 +
 arch/riscv/kernel/cpufeature.c      | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/uapi/asm/hwcap.h b/arch/riscv/include/uapi/asm/hwcap.h
index dee98ee28318..a913e9a38819 100644
--- a/arch/riscv/include/uapi/asm/hwcap.h
+++ b/arch/riscv/include/uapi/asm/hwcap.h
@@ -21,5 +21,6 @@
 #define COMPAT_HWCAP_ISA_F	(1 << ('F' - 'A'))
 #define COMPAT_HWCAP_ISA_D	(1 << ('D' - 'A'))
 #define COMPAT_HWCAP_ISA_C	(1 << ('C' - 'A'))
+#define COMPAT_HWCAP_ISA_V	(1 << ('V' - 'A'))
 
 #endif /* _UAPI_ASM_RISCV_HWCAP_H */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index a5ad00043104..c8527d770c98 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -30,6 +30,7 @@ void riscv_fill_hwcap(void)
 	isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
 	isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
 	isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
+	isa2hwcap['v'] = isa2hwcap['V'] = COMPAT_HWCAP_ISA_V;
 
 	elf_hwcap = 0;
 
@@ -44,7 +45,8 @@ void riscv_fill_hwcap(void)
 			continue;
 		}
 
-		for (i = 0; i < strlen(isa); ++i)
+		/* Skip rv64/rv32 to support v/V:vector */
+		for (i = 4; i < strlen(isa); ++i)
 			this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
 
 		/*
-- 
2.17.0