linux-kernel - [RFC PATCH v5 07/13] riscv: Add has_vector/riscv

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Message-Id: <e699220610dd3f114d1216c46e0930632d73a0e2.1590646208.git.greentime.hu@sifive.com>
Date:   Thu, 28 May 2020 14:40:55 +0800
From:   Greentime Hu <greentime.hu@...ive.com>
To:     greentime.hu@...ive.com, guoren@...ux.alibaba.com,
        vincent.chen@...ive.com, paul.walmsley@...ive.com,
        palmerdabbelt@...gle.com, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, oleg@...hat.com
Subject: [RFC PATCH v5 07/13] riscv: Add has_vector/riscv_vsize to save vector features.

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

This patch is used to detect vector support status of CPU and use
riscv_vsize to save the size of all the vector registers. It assumes
all harts has the same capabilities in SMP system.

[greentime.hu@...ive.com: add support for dynamic vlen]
Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
---
 arch/riscv/kernel/cpufeature.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index c8527d770c98..5a68a926da68 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -16,6 +16,10 @@ unsigned long elf_hwcap __read_mostly;
 #ifdef CONFIG_FPU
 bool has_fpu __read_mostly;
 #endif
+#ifdef CONFIG_VECTOR
+bool has_vector __read_mostly;
+unsigned long riscv_vsize __read_mostly;
+#endif
 
 void riscv_fill_hwcap(void)
 {
@@ -73,4 +77,11 @@ void riscv_fill_hwcap(void)
 	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
 		has_fpu = true;
 #endif
+
+#ifdef CONFIG_VECTOR
+	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+		has_vector = true;
+		riscv_vsize = csr_read(CSR_VLENB) * 32;
+	}
+#endif
 }
-- 
2.26.2