1 files changed, 96 insertions, 1 deletions

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 87e3020ac1bc..0f9079b9539e 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -24,6 +24,8 @@
                 ((k) == BTF_KIND_CONST) || \
                 ((k) == BTF_KIND_RESTRICT))
 
+#define IS_VAR(k) ((k) == BTF_KIND_VAR)
+
 static struct btf_type btf_void;
 
 struct btf {
@@ -212,6 +214,10 @@ static int btf_type_size(struct btf_type *t)
                 return base_size + vlen * sizeof(struct btf_member);
         case BTF_KIND_FUNC_PROTO:
                 return base_size + vlen * sizeof(struct btf_param);
+        case BTF_KIND_VAR:
+                return base_size + sizeof(struct btf_var);
+        case BTF_KIND_DATASEC:
+                return base_size + vlen * sizeof(struct btf_var_secinfo);
         default:
                 pr_debug("Unsupported BTF_KIND:%u\n", BTF_INFO_KIND(t->info));
                 return -EINVAL;
@@ -283,6 +289,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
                 case BTF_KIND_STRUCT:
                 case BTF_KIND_UNION:
                 case BTF_KIND_ENUM:
+                case BTF_KIND_DATASEC:
                         size = t->size;
                         goto done;
                 case BTF_KIND_PTR:
@@ -292,6 +299,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
                 case BTF_KIND_VOLATILE:
                 case BTF_KIND_CONST:
                 case BTF_KIND_RESTRICT:
+                case BTF_KIND_VAR:
                         type_id = t->type;
                         break;
                 case BTF_KIND_ARRAY:
@@ -326,7 +334,8 @@ int btf__resolve_type(const struct btf *btf, __u32 type_id)
         t = btf__type_by_id(btf, type_id);
         while (depth < MAX_RESOLVE_DEPTH &&
                !btf_type_is_void_or_null(t) &&
-               IS_MODIFIER(BTF_INFO_KIND(t->info))) {
+               (IS_MODIFIER(BTF_INFO_KIND(t->info)) ||
+                IS_VAR(BTF_INFO_KIND(t->info)))) {
                 type_id = t->type;
                 t = btf__type_by_id(btf, type_id);
                 depth++;
@@ -408,6 +417,92 @@ done:
         return btf;
 }
 
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+        const struct btf_var_secinfo *a = _a;
+        const struct btf_var_secinfo *b = _b;
+
+        return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+                             struct btf_type *t)
+{
+        __u32 size = 0, off = 0, i, vars = BTF_INFO_VLEN(t->info);
+        const char *name = btf__name_by_offset(btf, t->name_off);
+        const struct btf_type *t_var;
+        struct btf_var_secinfo *vsi;
+        struct btf_var *var;
+        int ret;
+
+        if (!name) {
+                pr_debug("No name found in string section for DATASEC kind.\n");
+                return -ENOENT;
+        }
+
+        ret = bpf_object__section_size(obj, name, &size);
+        if (ret || !size || (t->size && t->size != size)) {
+                pr_debug("Invalid size for section %s: %u bytes\n", name, size);
+                return -ENOENT;
+        }
+
+        t->size = size;
+
+        for (i = 0, vsi = (struct btf_var_secinfo *)(t + 1);
+             i < vars; i++, vsi++) {
+                t_var = btf__type_by_id(btf, vsi->type);
+                var = (struct btf_var *)(t_var + 1);
+
+                if (BTF_INFO_KIND(t_var->info) != BTF_KIND_VAR) {
+                        pr_debug("Non-VAR type seen in section %s\n", name);
+                        return -EINVAL;
+                }
+
+                if (var->linkage == BTF_VAR_STATIC)
+                        continue;
+
+                name = btf__name_by_offset(btf, t_var->name_off);
+                if (!name) {
+                        pr_debug("No name found in string section for VAR kind\n");
+                        return -ENOENT;
+                }
+
+                ret = bpf_object__variable_offset(obj, name, &off);
+                if (ret) {
+                        pr_debug("No offset found in symbol table for VAR %s\n", name);
+                        return -ENOENT;
+                }
+
+                vsi->offset = off;
+        }
+
+        qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
+        return 0;
+}
+
+int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+        int err = 0;
+        __u32 i;
+
+        for (i = 1; i <= btf->nr_types; i++) {
+                struct btf_type *t = btf->types[i];
+
+                /* Loader needs to fix up some of the things compiler
+                 * couldn't get its hands on while emitting BTF. This
+                 * is section size and global variable offset. We use
+                 * the info from the ELF itself for this purpose.
+                 */
+                if (BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC) {
+                        err = btf_fixup_datasec(obj, btf, t);
+                        if (err)
+                                break;
+                }
+        }
+
+        return err;
+}
+
 int btf__load(struct btf *btf)
 {
         __u32 log_buf_size = BPF_LOG_BUF_SIZE;