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From: guoren@kernel.org
To: paul.walmsley@sifive.com,
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	guoren@kernel.org,
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Cc: linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Guo Ren <guoren@linux.alibaba.com>
Subject: [PATCH V2 1/3] riscv: Add Zicbop instruction definitions & cpufeature
Date: Sun, 31 Dec 2023 03:29:51 -0500
Message-Id: <20231231082955.16516-2-guoren@kernel.org>
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From: Guo Ren <guoren@linux.alibaba.com>

Cache-block prefetch instructions are HINTs to the hardware to
indicate that software intends to perform a particular type of
memory access in the near future. This patch adds prefetch.i,
prefetch.r and prefetch.w instruction definitions by
RISCV_ISA_EXT_ZICBOP cpufeature.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 arch/riscv/Kconfig                | 15 ++++++++
 arch/riscv/include/asm/hwcap.h    |  1 +
 arch/riscv/include/asm/insn-def.h | 60 +++++++++++++++++++++++++++++++
 arch/riscv/kernel/cpufeature.c    |  1 +
 4 files changed, 77 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 24c1799e2ec4..fcbd417d65ea 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -579,6 +579,21 @@ config RISCV_ISA_ZICBOZ
 
 	   If you don't know what to do here, say Y.
 
+config RISCV_ISA_ZICBOP
+	bool "Zicbop extension support for cache block prefetch"
+	depends on MMU
+	depends on RISCV_ALTERNATIVE
+	default y
+	help
+	  Adds support to dynamically detect the presence of the ZICBOP
+	  extension (Cache Block Prefetch Operations) and enable its
+	  usage.
+
+	  The Zicbop extension can be used to prefetch cache block for
+	  read/write fetch.
+
+	  If you don't know what to do here, say Y.
+
 config TOOLCHAIN_HAS_ZIHINTPAUSE
 	bool
 	default y
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 06d30526ef3b..77d3b6ee25ab 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -57,6 +57,7 @@
 #define RISCV_ISA_EXT_ZIHPM		42
 #define RISCV_ISA_EXT_SMSTATEEN		43
 #define RISCV_ISA_EXT_ZICOND		44
+#define RISCV_ISA_EXT_ZICBOP		45
 
 #define RISCV_ISA_EXT_MAX		64
 
diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
index e27179b26086..bbda350a63bf 100644
--- a/arch/riscv/include/asm/insn-def.h
+++ b/arch/riscv/include/asm/insn-def.h
@@ -18,6 +18,13 @@
 #define INSN_I_RD_SHIFT			 7
 #define INSN_I_OPCODE_SHIFT		 0
 
+#define INSN_S_SIMM7_SHIFT		25
+#define INSN_S_RS2_SHIFT		20
+#define INSN_S_RS1_SHIFT		15
+#define INSN_S_FUNC3_SHIFT		12
+#define INSN_S_SIMM5_SHIFT		 7
+#define INSN_S_OPCODE_SHIFT		 0
+
 #ifdef __ASSEMBLY__
 
 #ifdef CONFIG_AS_HAS_INSN
@@ -30,6 +37,10 @@
 	.insn	i \opcode, \func3, \rd, \rs1, \simm12
 	.endm
 
+	.macro insn_s, opcode, func3, rs2, simm12, rs1
+	.insn	s \opcode, \func3, \rs2, \simm12(\rs1)
+	.endm
+
 #else
 
 #include <asm/gpr-num.h>
@@ -51,10 +62,20 @@
 		 (\simm12 << INSN_I_SIMM12_SHIFT))
 	.endm
 
+	.macro insn_s, opcode, func3, rs2, simm12, rs1
+	.4byte	((\opcode << INSN_S_OPCODE_SHIFT) |		\
+		 (\func3 << INSN_S_FUNC3_SHIFT) |		\
+		 (.L__gpr_num_\rs2 << INSN_S_RS2_SHIFT) |	\
+		 (.L__gpr_num_\rs1 << INSN_S_RS1_SHIFT) |	\
+		 ((\simm12 & 0x1f) << INSN_S_SIMM5_SHIFT) |	\
+		 (((\simm12 >> 5) & 0x7f) << INSN_S_SIMM7_SHIFT))
+	.endm
+
 #endif
 
 #define __INSN_R(...)	insn_r __VA_ARGS__
 #define __INSN_I(...)	insn_i __VA_ARGS__
+#define __INSN_S(...)	insn_s __VA_ARGS__
 
 #else /* ! __ASSEMBLY__ */
 
@@ -66,6 +87,9 @@
 #define __INSN_I(opcode, func3, rd, rs1, simm12)	\
 	".insn	i " opcode ", " func3 ", " rd ", " rs1 ", " simm12 "\n"
 
+#define __INSN_S(opcode, func3, rs2, simm12, rs1)	\
+	".insn	s " opcode ", " func3 ", " rs2 ", " simm12 "(" rs1 ")\n"
+
 #else
 
 #include <linux/stringify.h>
@@ -92,12 +116,26 @@
 "		 (\\simm12 << " __stringify(INSN_I_SIMM12_SHIFT) "))\n"	\
 "	.endm\n"
 
+#define DEFINE_INSN_S							\
+	__DEFINE_ASM_GPR_NUMS						\
+"	.macro insn_s, opcode, func3, rs2, simm12, rs1\n"		\
+"	.4byte	((\\opcode << " __stringify(INSN_S_OPCODE_SHIFT) ") |"	\
+"		 (\\func3 << " __stringify(INSN_S_FUNC3_SHIFT) ") |"	\
+"		 (.L__gpr_num_\\rs2 << " __stringify(INSN_S_RS2_SHIFT) ") |" \
+"		 (.L__gpr_num_\\rs1 << " __stringify(INSN_S_RS1_SHIFT) ") |" \
+"		 ((\\simm12 & 0x1f) << " __stringify(INSN_S_SIMM5_SHIFT) ") |" \
+"		 (((\\simm12 >> 5) & 0x7f) << " __stringify(INSN_S_SIMM7_SHIFT) "))\n" \
+"	.endm\n"
+
 #define UNDEFINE_INSN_R							\
 "	.purgem insn_r\n"
 
 #define UNDEFINE_INSN_I							\
 "	.purgem insn_i\n"
 
+#define UNDEFINE_INSN_S							\
+"	.purgem insn_s\n"
+
 #define __INSN_R(opcode, func3, func7, rd, rs1, rs2)			\
 	DEFINE_INSN_R							\
 	"insn_r " opcode ", " func3 ", " func7 ", " rd ", " rs1 ", " rs2 "\n" \
@@ -108,6 +146,11 @@
 	"insn_i " opcode ", " func3 ", " rd ", " rs1 ", " simm12 "\n" \
 	UNDEFINE_INSN_I
 
+#define __INSN_S(opcode, func3, rs2, simm12, rs1)			\
+	DEFINE_INSN_S							\
+	"insn_s " opcode ", " func3 ", " rs2 ", " simm12 ", " rs1 "\n"	\
+	UNDEFINE_INSN_S
+
 #endif
 
 #endif /* ! __ASSEMBLY__ */
@@ -120,6 +163,10 @@
 	__INSN_I(RV_##opcode, RV_##func3, RV_##rd,		\
 		 RV_##rs1, RV_##simm12)
 
+#define INSN_S(opcode, func3, rs2, simm12, rs1)			\
+	__INSN_S(RV_##opcode, RV_##func3, RV_##rs2,		\
+		 RV_##simm12, RV_##rs1)
+
 #define RV_OPCODE(v)		__ASM_STR(v)
 #define RV_FUNC3(v)		__ASM_STR(v)
 #define RV_FUNC7(v)		__ASM_STR(v)
@@ -133,6 +180,7 @@
 #define RV___RS2(v)		__RV_REG(v)
 
 #define RV_OPCODE_MISC_MEM	RV_OPCODE(15)
+#define RV_OPCODE_OP_IMM	RV_OPCODE(19)
 #define RV_OPCODE_SYSTEM	RV_OPCODE(115)
 
 #define HFENCE_VVMA(vaddr, asid)				\
@@ -196,4 +244,16 @@
 	INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0),		\
 	       RS1(base), SIMM12(4))
 
+#define CBO_PREFETCH_I(base, offset)				\
+	INSN_S(OPCODE_OP_IMM, FUNC3(6), __RS2(0),		\
+	       SIMM12(offset), RS1(base))
+
+#define CBO_PREFETCH_R(base, offset)				\
+	INSN_S(OPCODE_OP_IMM, FUNC3(6), __RS2(1),		\
+	       SIMM12(offset), RS1(base))
+
+#define CBO_PREFETCH_W(base, offset)				\
+	INSN_S(OPCODE_OP_IMM, FUNC3(6), __RS2(3),		\
+	       SIMM12(offset), RS1(base))
+
 #endif /* __ASM_INSN_DEF_H */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index b3785ffc1570..bdb02b066041 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -168,6 +168,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
 	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
 	__RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
+	__RISCV_ISA_EXT_DATA(zicbop, RISCV_ISA_EXT_ZICBOP),
 	__RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
 	__RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND),
 	__RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
-- 
2.40.1