bpf: Print function name in addition to function id

The verifier currently prints raw function ids when printing CALL
instructions or when complaining:

	5: (85) call 23
	unknown func 23

print a meaningful function name instead:

	5: (85) call bpf_redirect#23
	unknown func bpf_redirect#23

Moves the function documentation to a single comment and renames all
helpers names in the list to conform to the bpf_ prefix notation so
they can be greped in the kernel source.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/bpf/verifier.c

@@ -19,6 +19,7 @@
 #include <net/netlink.h>
 #include <linux/file.h>
 #include <linux/vmalloc.h>
+#include <linux/stringify.h>
 
 /* bpf_check() is a static code analyzer that walks eBPF program
  * instruction by instruction and updates register/stack state.
@@ -190,6 +191,22 @@ static const char * const reg_type_str[] = {
 	[PTR_TO_PACKET_END]	= "pkt_end",
 };
 
+#define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
+static const char * const func_id_str[] = {
+	__BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
+};
+#undef __BPF_FUNC_STR_FN
+
+static const char *func_id_name(int id)
+{
+	BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
+
+	if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
+		return func_id_str[id];
+	else
+		return "unknown";
+}
+
 static void print_verifier_state(struct bpf_verifier_state *state)
 {
 	struct bpf_reg_state *reg;
@@ -354,7 +371,8 @@ static void print_bpf_insn(struct bpf_insn *insn)
 		u8 opcode = BPF_OP(insn->code);
 
 		if (opcode == BPF_CALL) {
-			verbose("(%02x) call %d\n", insn->code, insn->imm);
+			verbose("(%02x) call %s#%d\n", insn->code,
+				func_id_name(insn->imm), insn->imm);
 		} else if (insn->code == (BPF_JMP | BPF_JA)) {
 			verbose("(%02x) goto pc%+d\n",
 				insn->code, insn->off);
@@ -1114,8 +1132,8 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
 
 	return 0;
 error:
-	verbose("cannot pass map_type %d into func %d\n",
-		map->map_type, func_id);
+	verbose("cannot pass map_type %d into func %s#%d\n",
+		map->map_type, func_id_name(func_id), func_id);
 	return -EINVAL;
 }
 
@@ -1172,7 +1190,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
 
 	/* find function prototype */
 	if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
-		verbose("invalid func %d\n", func_id);
+		verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
 		return -EINVAL;
 	}
 
@@ -1180,7 +1198,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
 		fn = env->prog->aux->ops->get_func_proto(func_id);
 
 	if (!fn) {
-		verbose("unknown func %d\n", func_id);
+		verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
 		return -EINVAL;
 	}
 
@@ -1200,7 +1218,8 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
 	 */
 	err = check_raw_mode(fn);
 	if (err) {
-		verbose("kernel subsystem misconfigured func %d\n", func_id);
+		verbose("kernel subsystem misconfigured func %s#%d\n",
+			func_id_name(func_id), func_id);
 		return err;
 	}
 
@@ -1256,8 +1275,8 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
 		regs[BPF_REG_0].map_ptr = meta.map_ptr;
 		regs[BPF_REG_0].id = ++env->id_gen;
 	} else {
-		verbose("unknown return type %d of func %d\n",
-			fn->ret_type, func_id);
+		verbose("unknown return type %d of func %s#%d\n",
+			fn->ret_type, func_id_name(func_id), func_id);
 		return -EINVAL;
 	}