nfp: bpf: add map updates from the datapath

Support calling map_update_elem() from the datapath programs
by calling into FW-provided helper.  Value pointer is passed
in LM pointer #2.  Keeping track of old state for arg3 is not
necessary, since LM pointer #2 will be always loaded in this
case, the trivial optimization for value at the bottom of the
stack can't be done here.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -1372,6 +1372,8 @@ map_call_stack_common(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 	/* Set LM0 to start of key */
 	if (load_lm_ptr)
 		emit_csr_wr(nfp_prog, reg_b(2 * 2), NFP_CSR_ACT_LM_ADDR0);
+	if (meta->func_id == BPF_FUNC_map_update_elem)
+		emit_csr_wr(nfp_prog, reg_b(3 * 2), NFP_CSR_ACT_LM_ADDR2);
 
 	/* Load map ID into a register, it should actually fit as an immediate
 	 * but in case it doesn't deal with it here, not in the delay slots.
@@ -2326,6 +2328,7 @@ static int call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 	case BPF_FUNC_xdp_adjust_head:
 		return adjust_head(nfp_prog, meta);
 	case BPF_FUNC_map_lookup_elem:
+	case BPF_FUNC_map_update_elem:
 		return map_call_stack_common(nfp_prog, meta);
 	default:
 		WARN_ONCE(1, "verifier allowed unsupported function\n");
@@ -3210,6 +3213,9 @@ void *nfp_bpf_relo_for_vnic(struct nfp_prog *nfp_prog, struct nfp_bpf_vnic *bv)
 			case BPF_FUNC_map_lookup_elem:
 				val = nfp_prog->bpf->helpers.map_lookup;
 				break;
+			case BPF_FUNC_map_update_elem:
+				val = nfp_prog->bpf->helpers.map_update;
+				break;
 			default:
 				pr_err("relocation of unknown helper %d\n",
 				       val);

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

@@ -284,6 +284,9 @@ nfp_bpf_parse_cap_func(struct nfp_app_bpf *bpf, void __iomem *value, u32 length)
 	case BPF_FUNC_map_lookup_elem:
 		bpf->helpers.map_lookup = readl(&cap->func_addr);
 		break;
+	case BPF_FUNC_map_update_elem:
+		bpf->helpers.map_update = readl(&cap->func_addr);
+		break;
 	}
 
 	return 0;

drivers/net/ethernet/netronome/nfp/bpf/main.h

@@ -128,6 +128,7 @@ enum pkt_vec {
  *
  * @helpers:		helper addressess for various calls
  * @helpers.map_lookup:		map lookup helper address
+ * @helpers.map_update:		map update helper address
  */
 struct nfp_app_bpf {
 	struct nfp_app *app;
@@ -162,6 +163,7 @@ struct nfp_app_bpf {
 
 	struct {
 		u32 map_lookup;
+		u32 map_update;
 	} helpers;
 };
 

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

@@ -167,6 +167,7 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 {
 	const struct bpf_reg_state *reg1 = cur_regs(env) + BPF_REG_1;
 	const struct bpf_reg_state *reg2 = cur_regs(env) + BPF_REG_2;
+	const struct bpf_reg_state *reg3 = cur_regs(env) + BPF_REG_3;
 	struct nfp_app_bpf *bpf = nfp_prog->bpf;
 	u32 func_id = meta->insn.imm;
 
@@ -191,6 +192,15 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 					  meta->func_id ? &meta->arg2 : NULL))
 			return -EOPNOTSUPP;
 		break;
+
+	case BPF_FUNC_map_update_elem:
+		if (!nfp_bpf_map_call_ok("map_update", env, meta,
+					 bpf->helpers.map_update, reg1) ||
+		    !nfp_bpf_stack_arg_ok("map_update", env, reg2,
+					  meta->func_id ? &meta->arg2 : NULL) ||
+		    !nfp_bpf_stack_arg_ok("map_update", env, reg3, NULL))
+			return -EOPNOTSUPP;
+		break;
 	default:
 		pr_vlog(env, "unsupported function id: %d\n", func_id);
 		return -EOPNOTSUPP;