arm64: bpf: add 'shift by register' instructions

Commit 72b603ee8cfc ("bpf: x86: add missing 'shift by register'
instructions to x64 eBPF JIT") noted support for 'shift by register'
in eBPF and added support for it for x64. Let's enable this for arm64
as well.

The arm64 eBPF JIT compiler now passes the new 'shift by register'
test case introduced in the same commit 72b603ee8cfc.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/net/bpf_jit.h

@@ -144,8 +144,12 @@
 
 /* Data-processing (2 source) */
 /* Rd = Rn OP Rm */
-#define A64_UDIV(sf, Rd, Rn, Rm) aarch64_insn_gen_data2(Rd, Rn, Rm, \
-	A64_VARIANT(sf), AARCH64_INSN_DATA2_UDIV)
+#define A64_DATA2(sf, Rd, Rn, Rm, type) aarch64_insn_gen_data2(Rd, Rn, Rm, \
+	A64_VARIANT(sf), AARCH64_INSN_DATA2_##type)
+#define A64_UDIV(sf, Rd, Rn, Rm) A64_DATA2(sf, Rd, Rn, Rm, UDIV)
+#define A64_LSLV(sf, Rd, Rn, Rm) A64_DATA2(sf, Rd, Rn, Rm, LSLV)
+#define A64_LSRV(sf, Rd, Rn, Rm) A64_DATA2(sf, Rd, Rn, Rm, LSRV)
+#define A64_ASRV(sf, Rd, Rn, Rm) A64_DATA2(sf, Rd, Rn, Rm, ASRV)
 
 /* Data-processing (3 source) */
 /* Rd = Ra + Rn * Rm */

arch/arm64/net/bpf_jit_comp.c

@@ -261,6 +261,18 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 		emit(A64_MUL(is64, tmp, tmp, src), ctx);
 		emit(A64_SUB(is64, dst, dst, tmp), ctx);
 		break;
+	case BPF_ALU | BPF_LSH | BPF_X:
+	case BPF_ALU64 | BPF_LSH | BPF_X:
+		emit(A64_LSLV(is64, dst, dst, src), ctx);
+		break;
+	case BPF_ALU | BPF_RSH | BPF_X:
+	case BPF_ALU64 | BPF_RSH | BPF_X:
+		emit(A64_LSRV(is64, dst, dst, src), ctx);
+		break;
+	case BPF_ALU | BPF_ARSH | BPF_X:
+	case BPF_ALU64 | BPF_ARSH | BPF_X:
+		emit(A64_ASRV(is64, dst, dst, src), ctx);
+		break;
 	/* dst = -dst */
 	case BPF_ALU | BPF_NEG:
 	case BPF_ALU64 | BPF_NEG: