Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2019-08-31

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) Fix 32-bit zero-extension during constant blinding which
   has been causing a regression on ppc64, from Naveen.

2) Fix a latency bug in nfp driver when updating stack index
   register, from Jiong.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/bpf/jit.c

@@ -1163,7 +1163,7 @@ mem_op_stack(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 	     bool clr_gpr, lmem_step step)
 {
 	s32 off = nfp_prog->stack_frame_depth + meta->insn.off + ptr_off;
-	bool first = true, last;
+	bool first = true, narrow_ld, last;
 	bool needs_inc = false;
 	swreg stack_off_reg;
 	u8 prev_gpr = 255;
@@ -1209,13 +1209,22 @@ mem_op_stack(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 
 		needs_inc = true;
 	}
+
+	narrow_ld = clr_gpr && size < 8;
+
 	if (lm3) {
+		unsigned int nop_cnt;
+
 		emit_csr_wr(nfp_prog, imm_b(nfp_prog), NFP_CSR_ACT_LM_ADDR3);
-		/* For size < 4 one slot will be filled by zeroing of upper. */
-		wrp_nops(nfp_prog, clr_gpr && size < 8 ? 2 : 3);
+		/* For size < 4 one slot will be filled by zeroing of upper,
+		 * but be careful, that zeroing could be eliminated by zext
+		 * optimization.
+		 */
+		nop_cnt = narrow_ld && meta->flags & FLAG_INSN_DO_ZEXT ? 2 : 3;
+		wrp_nops(nfp_prog, nop_cnt);
 	}
 
-	if (clr_gpr && size < 8)
+	if (narrow_ld)
 		wrp_zext(nfp_prog, meta, gpr);
 
 	while (size) {

kernel/bpf/core.c

@@ -890,7 +890,8 @@ int bpf_jit_get_func_addr(const struct bpf_prog *prog,
 
 static int bpf_jit_blind_insn(const struct bpf_insn *from,
 			      const struct bpf_insn *aux,
-			      struct bpf_insn *to_buff)
+			      struct bpf_insn *to_buff,
+			      bool emit_zext)
 {
 	struct bpf_insn *to = to_buff;
 	u32 imm_rnd = get_random_int();
@@ -1005,6 +1006,8 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
 	case 0: /* Part 2 of BPF_LD | BPF_IMM | BPF_DW. */
 		*to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[0].imm);
 		*to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+		if (emit_zext)
+			*to++ = BPF_ZEXT_REG(BPF_REG_AX);
 		*to++ = BPF_ALU64_REG(BPF_OR,  aux[0].dst_reg, BPF_REG_AX);
 		break;
 
@@ -1088,7 +1091,8 @@ struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog)
 		    insn[1].code == 0)
 			memcpy(aux, insn, sizeof(aux));
 
-		rewritten = bpf_jit_blind_insn(insn, aux, insn_buff);
+		rewritten = bpf_jit_blind_insn(insn, aux, insn_buff,
+						clone->aux->verifier_zext);
 		if (!rewritten)
 			continue;