[PATCH dwarves v4 3/3] btf_encoder: Factor out BPF kfunc emission

[Ihor Solodrai <ihor.solodrai@linux.dev>]

Generating BTF for BPF kernel functions requires special
handling. Consolidate this behavior into btf_encoder__add_bpf_kfunc(),
which uses simplified btf_encoder_add_func().

No functional changes.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
---
 btf_encoder.c | 51 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/btf_encoder.c b/btf_encoder.c
index bdda7d0..b37ee7f 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -773,6 +773,7 @@ static int btf__tag_bpf_arena_arg(struct btf *btf, struct btf_encoder_func_state
 	return id;
 }
 
+/* Modifies state->ret_type_id and state->parms[i].type_id for flagged kfuncs */
 static int btf__add_bpf_arena_type_tags(struct btf *btf, struct btf_encoder_func_state *state)
 {
 	uint32_t flags = state->elf->kfunc_flags;
@@ -883,11 +884,6 @@ static int32_t btf_encoder__add_func_proto_for_state(struct btf_encoder *encoder
 	const char *name;
 	bool is_last;
 
-	/* Beware: btf__add_bpf_arena_type_tags may change some members of the state */
-	if (is_kfunc_state(state) && encoder->tag_kfuncs && encoder->encode_attributes)
-		if (btf__add_bpf_arena_type_tags(encoder->btf, state) < 0)
-			return -1;
-
 	type_id = state->ret_type_id;
 	nr_params = state->nr_parms;
 
@@ -1357,14 +1353,13 @@ static int btf__tag_kfunc(struct btf *btf, struct elf_function *kfunc, __u32 btf
 static int32_t btf_encoder__add_func(struct btf_encoder *encoder,
 				     struct btf_encoder_func_state *state)
 {
-	struct elf_function *func = state->elf;
 	int btf_fnproto_id, btf_fn_id, tag_type_id = 0;
+	struct elf_function *func = state->elf;
+	char tmp_value[KSYM_NAME_LEN];
 	int16_t component_idx = -1;
-	const char *name;
 	const char *value;
-	char tmp_value[KSYM_NAME_LEN];
+	const char *name;
 	uint16_t idx;
-	int err;
 
 	btf_fnproto_id = btf_encoder__add_func_proto_for_state(encoder, state);
 	name = func->name;
@@ -1377,15 +1372,6 @@ static int32_t btf_encoder__add_func(struct btf_encoder *encoder,
 		return -1;
 	}
 
-	if (func->kfunc && encoder->tag_kfuncs && !encoder->skip_encoding_decl_tag) {
-		err = btf__tag_kfunc(encoder->btf, func, btf_fn_id);
-		if (err < 0)
-			return err;
-	}
-
-	if (state->nr_annots == 0)
-		return 0;
-
 	for (idx = 0; idx < state->nr_annots; idx++) {
 		struct btf_encoder_func_annot *a = &state->annots[idx];
 
@@ -1408,6 +1394,30 @@ static int32_t btf_encoder__add_func(struct btf_encoder *encoder,
 		return -1;
 	}
 
+	return btf_fn_id;
+}
+
+static int btf_encoder__add_bpf_kfunc(struct btf_encoder *encoder,
+				      struct btf_encoder_func_state *state)
+{
+	int btf_fn_id, err;
+
+	if (encoder->tag_kfuncs && encoder->encode_attributes) {
+		err = btf__add_bpf_arena_type_tags(encoder->btf, state);
+		if (err < 0)
+			return err;
+	}
+
+	btf_fn_id = btf_encoder__add_func(encoder, state);
+	if (btf_fn_id < 0)
+		return -1;
+
+	if (encoder->tag_kfuncs && !encoder->skip_encoding_decl_tag) {
+		err = btf__tag_kfunc(encoder->btf, state->elf, btf_fn_id);
+		if (err < 0)
+			return err;
+	}
+
 	return 0;
 }
 
@@ -1507,7 +1517,10 @@ static int btf_encoder__add_saved_funcs(struct btf_encoder *encoder, bool skip_e
 					0, 0);
 
 		if (add_to_btf) {
-			err = btf_encoder__add_func(encoder, state);
+			if (is_kfunc_state(state))
+				err = btf_encoder__add_bpf_kfunc(encoder, state);
+			else
+				err = btf_encoder__add_func(encoder, state);
 			if (err < 0)
 				goto out;
 		}
-- 
2.51.1