nfp: bpf: add verification and codegen for map lookups

Verify our current constraints on the location of the key are
met and generate the code for calling map lookup on the datapath.

New relocation types have to be added - for helpers and return
addresses.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
index 7890d95d4018..f867577cc315 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
@@ -110,9 +110,11 @@ static int
 nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 		   struct nfp_insn_meta *meta)
 {
+	const struct bpf_reg_state *reg1 = cur_regs(env) + BPF_REG_1;
 	const struct bpf_reg_state *reg2 = cur_regs(env) + BPF_REG_2;
 	struct nfp_app_bpf *bpf = nfp_prog->bpf;
 	u32 func_id = meta->insn.imm;
+	s64 off, old_off;
 
 	switch (func_id) {
 	case BPF_FUNC_xdp_adjust_head:
@@ -127,11 +129,48 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 
 		nfp_record_adjust_head(bpf, nfp_prog, meta, reg2);
 		break;
+
+	case BPF_FUNC_map_lookup_elem:
+		if (!bpf->helpers.map_lookup) {
+			pr_info("map_lookup: not supported by FW\n");
+			return -EOPNOTSUPP;
+		}
+		if (reg2->type != PTR_TO_STACK) {
+			pr_info("map_lookup: unsupported key ptr type %d\n",
+				reg2->type);
+			return -EOPNOTSUPP;
+		}
+		if (!tnum_is_const(reg2->var_off)) {
+			pr_info("map_lookup: variable key pointer\n");
+			return -EOPNOTSUPP;
+		}
+
+		off = reg2->var_off.value + reg2->off;
+		if (-off % 4) {
+			pr_info("map_lookup: unaligned stack pointer %lld\n",
+				-off);
+			return -EOPNOTSUPP;
+		}
+
+		/* Rest of the checks is only if we re-parse the same insn */
+		if (!meta->func_id)
+			break;
+
+		old_off = meta->arg2.var_off.value + meta->arg2.off;
+		meta->arg2_var_off |= off != old_off;
+
+		if (meta->arg1.map_ptr != reg1->map_ptr) {
+			pr_info("map_lookup: called for different map\n");
+			return -EOPNOTSUPP;
+		}
+		break;
 	default:
 		pr_vlog(env, "unsupported function id: %d\n", func_id);
 		return -EOPNOTSUPP;
 	}
 
+	meta->func_id = func_id;
+	meta->arg1 = *reg1;
 	meta->arg2 = *reg2;
 
 	return 0;