[PATCH bpf-next v3 3/6] resolve_btfids: Introduce enum btf_id_kind

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

Instead of using multiple flags, make struct btf_id tagged with an
enum value indicating its kind in the context of resolve_btfids.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/bpf/resolve_btfids/main.c | 76 ++++++++++++++++++++++-----------
 1 file changed, 52 insertions(+), 24 deletions(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index b4caae1170dd..cb1e69eb0bd7 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -98,6 +98,13 @@
 # error "Unknown machine endianness!"
 #endif
 
+enum btf_id_kind {
+	BTF_ID_KIND_NONE,
+	BTF_ID_KIND_SYM,
+	BTF_ID_KIND_SET,
+	BTF_ID_KIND_SET8
+};
+
 struct btf_id {
 	struct rb_node	 rb_node;
 	char		*name;
@@ -105,9 +112,8 @@ struct btf_id {
 		int	 id;
 		int	 cnt;
 	};
+	enum btf_id_kind kind;
 	int		 addr_cnt;
-	bool		 is_set;
-	bool		 is_set8;
 	Elf64_Addr	 addr[ADDR_CNT];
 };
 
@@ -197,8 +203,7 @@ static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
 	return NULL;
 }
 
-static struct btf_id *
-btf_id__add(struct rb_root *root, char *name, bool unique)
+static struct btf_id *btf_id__add(struct rb_root *root, char *name, enum btf_id_kind kind)
 {
 	struct rb_node **p = &root->rb_node;
 	struct rb_node *parent = NULL;
@@ -213,14 +218,19 @@ btf_id__add(struct rb_root *root, char *name, bool unique)
 			p = &(*p)->rb_left;
 		else if (cmp > 0)
 			p = &(*p)->rb_right;
-		else
-			return unique ? NULL : id;
+		else if (kind == BTF_ID_KIND_SYM && id->kind == BTF_ID_KIND_SYM)
+			return id;
+		else {
+			pr_err("Unexpected duplicate symbol %s of kind %d\n", name, id->kind);
+			return NULL;
+		}
 	}
 
 	id = zalloc(sizeof(*id));
 	if (id) {
 		pr_debug("adding symbol %s\n", name);
 		id->name = name;
+		id->kind = kind;
 		rb_link_node(&id->rb_node, parent, p);
 		rb_insert_color(&id->rb_node, root);
 	}
@@ -260,22 +270,36 @@ static char *get_id(const char *prefix_end)
 	return id;
 }
 
-static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
+static struct btf_id *add_set(struct object *obj, char *name, enum btf_id_kind kind)
 {
+	int len = strlen(name);
+	int prefixlen;
+	char *id;
+
 	/*
 	 * __BTF_ID__set__name
 	 * name =    ^
 	 * id   =         ^
 	 */
-	char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
-	int len = strlen(name);
+	switch (kind) {
+	case BTF_ID_KIND_SET:
+		prefixlen = sizeof(BTF_SET "__") - 1;
+		break;
+	case BTF_ID_KIND_SET8:
+		prefixlen = sizeof(BTF_SET8 "__") - 1;
+		break;
+	default:
+		pr_err("Unexpected kind %d passed to %s() for symbol %s\n", kind, __func__, name);
+		return NULL;
+	}
 
+	id = name + prefixlen - 1;
 	if (id >= name + len) {
 		pr_err("FAILED to parse set name: %s\n", name);
 		return NULL;
 	}
 
-	return btf_id__add(&obj->sets, id, true);
+	return btf_id__add(&obj->sets, id, kind);
 }
 
 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
@@ -288,7 +312,7 @@ static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 		return NULL;
 	}
 
-	return btf_id__add(root, id, false);
+	return btf_id__add(root, id, BTF_ID_KIND_SYM);
 }
 
 /* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
@@ -491,28 +515,24 @@ static int symbols_collect(struct object *obj)
 			id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
 		/* set8 */
 		} else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
-			id = add_set(obj, prefix, true);
+			id = add_set(obj, prefix, BTF_ID_KIND_SET8);
 			/*
 			 * SET8 objects store list's count, which is encoded
 			 * in symbol's size, together with 'cnt' field hence
 			 * that - 1.
 			 */
-			if (id) {
+			if (id)
 				id->cnt = sym.st_size / sizeof(uint64_t) - 1;
-				id->is_set8 = true;
-			}
 		/* set */
 		} else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
-			id = add_set(obj, prefix, false);
+			id = add_set(obj, prefix, BTF_ID_KIND_SET);
 			/*
 			 * SET objects store list's count, which is encoded
 			 * in symbol's size, together with 'cnt' field hence
 			 * that - 1.
 			 */
-			if (id) {
+			if (id)
 				id->cnt = sym.st_size / sizeof(int) - 1;
-				id->is_set = true;
-			}
 		} else {
 			pr_err("FAILED unsupported prefix %s\n", prefix);
 			return -1;
@@ -643,7 +663,7 @@ static int id_patch(struct object *obj, struct btf_id *id)
 	int i;
 
 	/* For set, set8, id->id may be 0 */
-	if (!id->id && !id->is_set && !id->is_set8) {
+	if (!id->id && id->kind != BTF_ID_KIND_SET && id->kind != BTF_ID_KIND_SET8) {
 		pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
 		warnings++;
 	}
@@ -696,6 +716,7 @@ static int sets_patch(struct object *obj)
 {
 	Elf_Data *data = obj->efile.idlist;
 	struct rb_node *next;
+	int cnt;
 
 	next = rb_first(&obj->sets);
 	while (next) {
@@ -715,11 +736,15 @@ static int sets_patch(struct object *obj)
 			return -1;
 		}
 
-		if (id->is_set) {
+		switch (id->kind) {
+		case BTF_ID_KIND_SET:
 			set = data->d_buf + off;
+			cnt = set->cnt;
 			qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
-		} else {
+			break;
+		case BTF_ID_KIND_SET8:
 			set8 = data->d_buf + off;
+			cnt = set8->cnt;
 			/*
 			 * Make sure id is at the beginning of the pairs
 			 * struct, otherwise the below qsort would not work.
@@ -744,10 +769,13 @@ static int sets_patch(struct object *obj)
 						bswap_32(set8->pairs[i].flags);
 				}
 			}
+			break;
+		default:
+			pr_err("Unexpected btf_id_kind %d for set '%s'\n", id->kind, id->name);
+			return -1;
 		}
 
-		pr_debug("sorting  addr %5lu: cnt %6d [%s]\n",
-			 off, id->is_set ? set->cnt : set8->cnt, id->name);
+		pr_debug("sorting  addr %5lu: cnt %6d [%s]\n", off, cnt, id->name);
 
 		next = rb_next(next);
 	}
-- 
2.52.0