[PATCH bpf-next 4/6] riscv, bpf: Add necessary Zbb instructions

[Pu Lehui]

From: Pu Lehui <pulehui at huawei.com>

Add necessary Zbb instructions introduced by [0] to reduce code size and
improve performance of RV64 JIT. At the same time, a helper is added to
check whether the CPU supports Zbb instructions.

[0] https://github.com/riscv/riscv-bitmanip/releases/download/1.0.0/bitmanip-1.0.0-38-g865e7a7.pdf

Signed-off-by: Pu Lehui <pulehui at huawei.com>
---
 arch/riscv/net/bpf_jit.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
index 8e0ef4d08..7ee59d1f6 100644
--- a/arch/riscv/net/bpf_jit.h
+++ b/arch/riscv/net/bpf_jit.h
@@ -18,6 +18,11 @@ static inline bool rvc_enabled(void)
 	return IS_ENABLED(CONFIG_RISCV_ISA_C);
 }
 
+static inline bool rvzbb_enabled(void)
+{
+	return IS_ENABLED(CONFIG_RISCV_ISA_ZBB);
+}
+
 enum {
 	RV_REG_ZERO =	0,	/* The constant value 0 */
 	RV_REG_RA =	1,	/* Return address */
@@ -727,6 +732,27 @@ static inline u16 rvc_swsp(u32 imm8, u8 rs2)
 	return rv_css_insn(0x6, imm, rs2, 0x2);
 }
 
+/* RVZBB instrutions. */
+static inline u32 rvzbb_sextb(u8 rd, u8 rs1)
+{
+       return rv_i_insn(0x604, rs1, 1, rd, 0x13);
+}
+
+static inline u32 rvzbb_sexth(u8 rd, u8 rs1)
+{
+       return rv_i_insn(0x605, rs1, 1, rd, 0x13);
+}
+
+static inline u32 rvzbb_zexth(u8 rd, u8 rs)
+{
+       return rv_i_insn(0x80, rs, 4, rd, __riscv_xlen == 64 ? 0x3b : 0x33);
+}
+
+static inline u32 rvzbb_rev8(u8 rd, u8 rs)
+{
+       return rv_i_insn(__riscv_xlen == 64 ? 0x6b8 : 0x698, rs, 5, rd, 0x13);
+}
+
 /*
  * RV64-only instructions.
  *
-- 
2.25.1