btf: extract BTF type size calculation

This pre-patch extracts calculation of amount of space taken by BTF type descriptor
for later reuse by btf_dedup functionality.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 7ec0463..06bd1a6 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -182,6 +182,37 @@ static int btf_parse_str_sec(struct btf *btf)
        return 0;
 }
 
+static int btf_type_size(struct btf_type *t)
+{
+       int base_size = sizeof(struct btf_type);
+       __u16 vlen = BTF_INFO_VLEN(t->info);
+
+       switch (BTF_INFO_KIND(t->info)) {
+       case BTF_KIND_FWD:
+       case BTF_KIND_CONST:
+       case BTF_KIND_VOLATILE:
+       case BTF_KIND_RESTRICT:
+       case BTF_KIND_PTR:
+       case BTF_KIND_TYPEDEF:
+       case BTF_KIND_FUNC:
+               return base_size;
+       case BTF_KIND_INT:
+               return base_size + sizeof(__u32);
+       case BTF_KIND_ENUM:
+               return base_size + vlen * sizeof(struct btf_enum);
+       case BTF_KIND_ARRAY:
+               return base_size + sizeof(struct btf_array);
+       case BTF_KIND_STRUCT:
+       case BTF_KIND_UNION:
+               return base_size + vlen * sizeof(struct btf_member);
+       case BTF_KIND_FUNC_PROTO:
+               return base_size + vlen * sizeof(struct btf_param);
+       default:
+               pr_debug("Unsupported BTF_KIND:%u\n", BTF_INFO_KIND(t->info));
+               return -EINVAL;
+       }
+}
+
 static int btf_parse_type_sec(struct btf *btf)
 {
        struct btf_header *hdr = btf->hdr;
@@ -191,41 +222,13 @@ static int btf_parse_type_sec(struct btf *btf)
 
        while (next_type < end_type) {
                struct btf_type *t = next_type;
-               __u16 vlen = BTF_INFO_VLEN(t->info);
+               int type_size;
                int err;
 
-               next_type += sizeof(*t);
-               switch (BTF_INFO_KIND(t->info)) {
-               case BTF_KIND_INT:
-                       next_type += sizeof(int);
-                       break;
-               case BTF_KIND_ARRAY:
-                       next_type += sizeof(struct btf_array);
-                       break;
-               case BTF_KIND_STRUCT:
-               case BTF_KIND_UNION:
-                       next_type += vlen * sizeof(struct btf_member);
-                       break;
-               case BTF_KIND_ENUM:
-                       next_type += vlen * sizeof(struct btf_enum);
-                       break;
-               case BTF_KIND_FUNC_PROTO:
-                       next_type += vlen * sizeof(struct btf_param);
-                       break;
-               case BTF_KIND_FUNC:
-               case BTF_KIND_TYPEDEF:
-               case BTF_KIND_PTR:
-               case BTF_KIND_FWD:
-               case BTF_KIND_VOLATILE:
-               case BTF_KIND_CONST:
-               case BTF_KIND_RESTRICT:
-                       break;
-               default:
-                       pr_debug("Unsupported BTF_KIND:%u\n",
-                            BTF_INFO_KIND(t->info));
-                       return -EINVAL;
-               }
-
+               type_size = btf_type_size(t);
+               if (type_size < 0)
+                       return type_size;
+               next_type += type_size;
                err = btf_add_type(btf, t);
                if (err)
                        return err;
@@ -252,21 +255,6 @@ static bool btf_type_is_void_or_null(const struct btf_type *t)
        return !t || btf_type_is_void(t);
 }
 
-static __s64 btf_type_size(const struct btf_type *t)
-{
-       switch (BTF_INFO_KIND(t->info)) {
-       case BTF_KIND_INT:
-       case BTF_KIND_STRUCT:
-       case BTF_KIND_UNION:
-       case BTF_KIND_ENUM:
-               return t->size;
-       case BTF_KIND_PTR:
-               return sizeof(void *);
-       default:
-               return -EINVAL;
-       }
-}
-
 #define MAX_RESOLVE_DEPTH 32
 
 __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
@@ -280,11 +268,16 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
        t = btf__type_by_id(btf, type_id);
        for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
             i++) {
-               size = btf_type_size(t);
-               if (size >= 0)
-                       break;
-
                switch (BTF_INFO_KIND(t->info)) {
+               case BTF_KIND_INT:
+               case BTF_KIND_STRUCT:
+               case BTF_KIND_UNION:
+               case BTF_KIND_ENUM:
+                       size = t->size;
+                       goto done;
+               case BTF_KIND_PTR:
+                       size = sizeof(void *);
+                       goto done;
                case BTF_KIND_TYPEDEF:
                case BTF_KIND_VOLATILE:
                case BTF_KIND_CONST:
@@ -308,6 +301,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
        if (size < 0)
                return -EINVAL;
 
+done:
        if (nelems && size > UINT32_MAX / nelems)
                return -E2BIG;