linux-kernel - [PATCH v3 08/13] riscv: Add xtheadvector instruction definitions

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Message-Id: <20240619-xtheadvector-v3-8-bff39eb9668e@rivosinc.com>
Date: Wed, 19 Jun 2024 16:57:21 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Jisheng Zhang <jszhang@...nel.org>, Chen-Yu Tsai <wens@...e.org>, 
 Jernej Skrabec <jernej.skrabec@...il.com>, 
 Samuel Holland <samuel@...lland.org>, Jonathan Corbet <corbet@....net>, 
 Shuah Khan <shuah@...nel.org>, Guo Ren <guoren@...nel.org>, 
 Evan Green <evan@...osinc.com>, Andy Chiu <andy.chiu@...ive.com>, 
 Jessica Clarke <jrtc27@...c27.com>
Cc: linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-sunxi@...ts.linux.dev, 
 linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Charlie Jenkins <charlie@...osinc.com>, Heiko Stuebner <heiko@...ech.de>
Subject: [PATCH v3 08/13] riscv: Add xtheadvector instruction definitions

xtheadvector uses different encodings than standard vector for
vsetvli and vector loads/stores. Write the instruction formats to be
used in assembly code.

Co-developed-by: Heiko Stuebner <heiko@...ech.de>
Signed-off-by: Heiko Stuebner <heiko@...ech.de>
Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
---
 arch/riscv/include/asm/vendor_extensions/thead.h | 26 ++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/riscv/include/asm/vendor_extensions/thead.h b/arch/riscv/include/asm/vendor_extensions/thead.h
index 48421d1553ad..27a253a20ab8 100644
--- a/arch/riscv/include/asm/vendor_extensions/thead.h
+++ b/arch/riscv/include/asm/vendor_extensions/thead.h
@@ -13,4 +13,30 @@
 
 extern struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_thead;
 
+/* Extension specific helpers */
+
+/*
+ * Vector 0.7.1 as used for example on T-Head Xuantie cores, uses an older
+ * encoding for vsetvli (ta, ma vs. d1), so provide an instruction for
+ * vsetvli	t4, x0, e8, m8, d1
+ */
+#define THEAD_VSETVLI_T4X0E8M8D1	".long	0x00307ed7\n\t"
+#define THEAD_VSETVLI_X0X0E8M8D1	".long	0x00307057\n\t"
+
+/*
+ * While in theory, the vector-0.7.1 vsb.v and vlb.v result in the same
+ * encoding as the standard vse8.v and vle8.v, compilers seem to optimize
+ * the call resulting in a different encoding and then using a value for
+ * the "mop" field that is not part of vector-0.7.1
+ * So encode specific variants for vstate_save and _restore.
+ */
+#define THEAD_VSB_V_V0T0		".long	0x02028027\n\t"
+#define THEAD_VSB_V_V8T0		".long	0x02028427\n\t"
+#define THEAD_VSB_V_V16T0		".long	0x02028827\n\t"
+#define THEAD_VSB_V_V24T0		".long	0x02028c27\n\t"
+#define THEAD_VLB_V_V0T0		".long	0x012028007\n\t"
+#define THEAD_VLB_V_V8T0		".long	0x012028407\n\t"
+#define THEAD_VLB_V_V16T0		".long	0x012028807\n\t"
+#define THEAD_VLB_V_V24T0		".long	0x012028c07\n\t"
+
 #endif

-- 
2.34.1