s390: bpf: eliminate zero extension code-gen

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

arch/s390/net/bpf_jit_comp.c

@@ -299,9 +299,11 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
 
 #define EMIT_ZERO(b1)						\
 ({								\
+	if (!fp->aux->verifier_zext) {				\
 		/* llgfr %dst,%dst (zero extend to 64 bit) */	\
 		EMIT4(0xb9160000, b1, b1);			\
 		REG_SET_SEEN(b1);				\
+	}							\
 })
 
 /*
@@ -520,6 +522,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 	case BPF_ALU | BPF_MOV | BPF_X: /* dst = (u32) src */
 		/* llgfr %dst,%src */
 		EMIT4(0xb9160000, dst_reg, src_reg);
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
 		/* lgr %dst,%src */
@@ -528,6 +532,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 	case BPF_ALU | BPF_MOV | BPF_K: /* dst = (u32) imm */
 		/* llilf %dst,imm */
 		EMIT6_IMM(0xc00f0000, dst_reg, imm);
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	case BPF_ALU64 | BPF_MOV | BPF_K: /* dst = imm */
 		/* lgfi %dst,imm */
@@ -639,6 +645,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		EMIT4(0xb9970000, REG_W0, src_reg);
 		/* llgfr %dst,%rc */
 		EMIT4(0xb9160000, dst_reg, rc_reg);
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	}
 	case BPF_ALU64 | BPF_DIV | BPF_X: /* dst = dst / src */
@@ -676,6 +684,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 			      EMIT_CONST_U32(imm));
 		/* llgfr %dst,%rc */
 		EMIT4(0xb9160000, dst_reg, rc_reg);
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	}
 	case BPF_ALU64 | BPF_DIV | BPF_K: /* dst = dst / imm */
@@ -864,8 +874,11 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		case 16: /* dst = (u16) cpu_to_be16(dst) */
 			/* llghr %dst,%dst */
 			EMIT4(0xb9850000, dst_reg, dst_reg);
+			if (insn_is_zext(&insn[1]))
+				insn_count = 2;
 			break;
 		case 32: /* dst = (u32) cpu_to_be32(dst) */
+			if (!fp->aux->verifier_zext)
 				/* llgfr %dst,%dst */
 				EMIT4(0xb9160000, dst_reg, dst_reg);
 			break;
@@ -882,10 +895,13 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 			EMIT4_DISP(0x88000000, dst_reg, REG_0, 16);
 			/* llghr %dst,%dst */
 			EMIT4(0xb9850000, dst_reg, dst_reg);
+			if (insn_is_zext(&insn[1]))
+				insn_count = 2;
 			break;
 		case 32: /* dst = (u32) cpu_to_le32(dst) */
 			/* lrvr %dst,%dst */
 			EMIT4(0xb91f0000, dst_reg, dst_reg);
+			if (!fp->aux->verifier_zext)
 				/* llgfr %dst,%dst */
 				EMIT4(0xb9160000, dst_reg, dst_reg);
 			break;
@@ -968,16 +984,22 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		/* llgc %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg, REG_0, off);
 		jit->seen |= SEEN_MEM;
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
 		/* llgh %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg, REG_0, off);
 		jit->seen |= SEEN_MEM;
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
 		/* llgf %dst,off(%src) */
 		jit->seen |= SEEN_MEM;
 		EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg, REG_0, off);
+		if (insn_is_zext(&insn[1]))
+			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
 		/* lg %dst,0(off,%src) */
@@ -1282,6 +1304,11 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp)
 	return 0;
 }
 
+bool bpf_jit_needs_zext(void)
+{
+	return true;
+}
+
 /*
  * Compile eBPF program "fp"
  */