riscv, bpf: Add Zacas instructions

Add Zacas instructions introduced by [0] to reduce code size and
improve performance of RV64 JIT.

Signed-off-by: Pu Lehui <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Tested-by: Björn Töpel <[email protected]>
Reviewed-by: Björn Töpel <[email protected]>
Acked-by: Björn Töpel <[email protected]>
Link: https://github.com/riscvarchive/riscv-zacas/releases/download/v1.0/riscv-zacas.pdf [0]
Link: https://lore.kernel.org/bpf/[email protected]

Author: Pu Lehui

arch/riscv/net/bpf_jit.h

@@ -751,6 +751,17 @@ static inline u16 rvc_swsp(u32 imm8, u8 rs2)
 	return rv_css_insn(0x6, imm, rs2, 0x2);
 }
 
+/* RVZACAS instructions. */
+static inline u32 rvzacas_amocas_w(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
+{
+	return rv_amo_insn(0x5, aq, rl, rs2, rs1, 2, rd, 0x2f);
+}
+
+static inline u32 rvzacas_amocas_d(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
+{
+	return rv_amo_insn(0x5, aq, rl, rs2, rs1, 3, rd, 0x2f);
+}
+
 /* RVZBA instructions. */
 static inline u32 rvzba_sh2add(u8 rd, u8 rs1, u8 rs2)
 {