libbpf: Make few internal helpers available outside of libbpf.c

Make skip_mods_and_typedefs(), btf_kind_str(), and btf_func_linkage() helpers
available outside of libbpf.c, to be used by static linker code.

Also do few cleanups (error code fixes, comment clean up, etc) that don't
deserve their own commit.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-9-andrii@kernel.org

tools/lib/bpf/libbpf.c

@@ -69,8 +69,6 @@
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
-static const struct btf_type *
-skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
 static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
 
 static int __base_pr(enum libbpf_print_level level, const char *format,
@@ -1906,7 +1904,7 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 	return 0;
 }
 
-static const struct btf_type *
+const struct btf_type *
 skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
 {
 	const struct btf_type *t = btf__type_by_id(btf, id);
@@ -1961,16 +1959,11 @@ static const char *__btf_kind_str(__u16 kind)
 	}
 }
 
-static const char *btf_kind_str(const struct btf_type *t)
+const char *btf_kind_str(const struct btf_type *t)
 {
 	return __btf_kind_str(btf_kind(t));
 }
 
-static enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
-{
-	return (enum btf_func_linkage)BTF_INFO_VLEN(t->info);
-}
-
 /*
  * Fetch integer attribute of BTF map definition. Such attributes are
  * represented using a pointer to an array, in which dimensionality of array
@@ -7036,7 +7029,7 @@ static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id
 	return false;
 }
 
-static int bpf_object__sanitize_prog(struct bpf_object* obj, struct bpf_program *prog)
+static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
 {
 	struct bpf_insn *insn = prog->insns;
 	enum bpf_func_id func_id;

tools/lib/bpf/libbpf_internal.h

@@ -132,6 +132,13 @@ struct btf;
 struct btf_type;
 
 struct btf_type *btf_type_by_id(struct btf *btf, __u32 type_id);
+const char *btf_kind_str(const struct btf_type *t);
+const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
+
+static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
+{
+	return (enum btf_func_linkage)(int)btf_vlen(t);
+}
 
 static inline __u32 btf_type_info(int kind, int vlen, int kflag)
 {

tools/lib/bpf/linker.c

@@ -123,9 +123,7 @@ struct bpf_linker {
 };
 
 #define pr_warn_elf(fmt, ...)									\
-do {												\
+	libbpf_print(LIBBPF_WARN, "libbpf: " fmt ": %s\n", ##__VA_ARGS__, elf_errmsg(-1))
-	libbpf_print(LIBBPF_WARN, "libbpf: " fmt ": %s\n", ##__VA_ARGS__, elf_errmsg(-1));	\
-} while (0)
 
 static int init_output_elf(struct bpf_linker *linker, const char *file);
 
@@ -284,7 +282,7 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
 
 	/* ELF header */
 	linker->elf_hdr = elf64_newehdr(linker->elf);
-	if (!linker->elf_hdr){
+	if (!linker->elf_hdr) {
 		pr_warn_elf("failed to create ELF header");
 		return -EINVAL;
 	}
@@ -925,13 +923,13 @@ static int init_sec(struct bpf_linker *linker, struct dst_sec *dst_sec, struct s
 
 	scn = elf_newscn(linker->elf);
 	if (!scn)
-		return -1;
+		return -ENOMEM;
 	data = elf_newdata(scn);
 	if (!data)
-		return -1;
+		return -ENOMEM;
 	shdr = elf64_getshdr(scn);
 	if (!shdr)
-		return -1;
+		return -ENOMEM;
 
 	dst_sec->scn = scn;
 	dst_sec->shdr = shdr;
@@ -1221,7 +1219,7 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
 				return err;
 			}
 		} else if (!secs_match(dst_sec, src_sec)) {
-			pr_warn("Secs %s are not compatible\n", src_sec->sec_name);
+			pr_warn("sections %s are not compatible\n", src_sec->sec_name);
 			return -1;
 		}