2 files changed, 345 insertions, 9 deletions

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index ba4ffa831aa4..88a52ae56fc6 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -17,6 +17,7 @@ extern "C" {
 
 #define BTF_ELF_SEC ".BTF"
 #define BTF_EXT_ELF_SEC ".BTF.ext"
+#define MAPS_ELF_SEC ".maps"
 
 struct btf;
 struct btf_ext;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index da942ab2f06a..585e3a2f1eb4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -262,6 +262,7 @@ struct bpf_object {
                 } *reloc;
                 int nr_reloc;
                 int maps_shndx;
+                int btf_maps_shndx;
                 int text_shndx;
                 int data_shndx;
                 int rodata_shndx;
@@ -514,6 +515,7 @@ static struct bpf_object *bpf_object__new(const char *path,
         obj->efile.obj_buf = obj_buf;
         obj->efile.obj_buf_sz = obj_buf_sz;
         obj->efile.maps_shndx = -1;
+        obj->efile.btf_maps_shndx = -1;
         obj->efile.data_shndx = -1;
         obj->efile.rodata_shndx = -1;
         obj->efile.bss_shndx = -1;
@@ -1007,6 +1009,312 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
         return 0;
 }
 
+static const struct btf_type *skip_mods_and_typedefs(const struct btf *btf,
+                                                     __u32 id)
+{
+        const struct btf_type *t = btf__type_by_id(btf, id);
+
+        while (true) {
+                switch (BTF_INFO_KIND(t->info)) {
+                case BTF_KIND_VOLATILE:
+                case BTF_KIND_CONST:
+                case BTF_KIND_RESTRICT:
+                case BTF_KIND_TYPEDEF:
+                        t = btf__type_by_id(btf, t->type);
+                        break;
+                default:
+                        return t;
+                }
+        }
+}
+
+static bool get_map_field_int(const char *map_name,
+                              const struct btf *btf,
+                              const struct btf_type *def,
+                              const struct btf_member *m,
+                              const void *data, __u32 *res) {
+        const struct btf_type *t = skip_mods_and_typedefs(btf, m->type);
+        const char *name = btf__name_by_offset(btf, m->name_off);
+        __u32 int_info = *(const __u32 *)(const void *)(t + 1);
+
+        if (BTF_INFO_KIND(t->info) != BTF_KIND_INT) {
+                pr_warning("map '%s': attr '%s': expected INT, got %u.\n",
+                           map_name, name, BTF_INFO_KIND(t->info));
+                return false;
+        }
+        if (t->size != 4 || BTF_INT_BITS(int_info) != 32 ||
+            BTF_INT_OFFSET(int_info)) {
+                pr_warning("map '%s': attr '%s': expected 32-bit non-bitfield integer, "
+                           "got %u-byte (%d-bit) one with bit offset %d.\n",
+                           map_name, name, t->size, BTF_INT_BITS(int_info),
+                           BTF_INT_OFFSET(int_info));
+                return false;
+        }
+        if (BTF_INFO_KFLAG(def->info) && BTF_MEMBER_BITFIELD_SIZE(m->offset)) {
+                pr_warning("map '%s': attr '%s': bitfield is not supported.\n",
+                           map_name, name);
+                return false;
+        }
+        if (m->offset % 32) {
+                pr_warning("map '%s': attr '%s': unaligned fields are not supported.\n",
+                           map_name, name);
+                return false;
+        }
+
+        *res = *(const __u32 *)(data + m->offset / 8);
+        return true;
+}
+
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+                                         const struct btf_type *sec,
+                                         int var_idx, int sec_idx,
+                                         const Elf_Data *data, bool strict)
+{
+        const struct btf_type *var, *def, *t;
+        const struct btf_var_secinfo *vi;
+        const struct btf_var *var_extra;
+        const struct btf_member *m;
+        const void *def_data;
+        const char *map_name;
+        struct bpf_map *map;
+        int vlen, i;
+
+        vi = (const struct btf_var_secinfo *)(const void *)(sec + 1) + var_idx;
+        var = btf__type_by_id(obj->btf, vi->type);
+        var_extra = (const void *)(var + 1);
+        map_name = btf__name_by_offset(obj->btf, var->name_off);
+        vlen = BTF_INFO_VLEN(var->info);
+
+        if (map_name == NULL || map_name[0] == '\0') {
+                pr_warning("map #%d: empty name.\n", var_idx);
+                return -EINVAL;
+        }
+        if ((__u64)vi->offset + vi->size > data->d_size) {
+                pr_warning("map '%s' BTF data is corrupted.\n", map_name);
+                return -EINVAL;
+        }
+        if (BTF_INFO_KIND(var->info) != BTF_KIND_VAR) {
+                pr_warning("map '%s': unexpected var kind %u.\n",
+                           map_name, BTF_INFO_KIND(var->info));
+                return -EINVAL;
+        }
+        if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+            var_extra->linkage != BTF_VAR_STATIC) {
+                pr_warning("map '%s': unsupported var linkage %u.\n",
+                           map_name, var_extra->linkage);
+                return -EOPNOTSUPP;
+        }
+
+        def = skip_mods_and_typedefs(obj->btf, var->type);
+        if (BTF_INFO_KIND(def->info) != BTF_KIND_STRUCT) {
+                pr_warning("map '%s': unexpected def kind %u.\n",
+                           map_name, BTF_INFO_KIND(var->info));
+                return -EINVAL;
+        }
+        if (def->size > vi->size) {
+                pr_warning("map '%s': invalid def size.\n", map_name);
+                return -EINVAL;
+        }
+
+        map = bpf_object__add_map(obj);
+        if (IS_ERR(map))
+                return PTR_ERR(map);
+        map->name = strdup(map_name);
+        if (!map->name) {
+                pr_warning("map '%s': failed to alloc map name.\n", map_name);
+                return -ENOMEM;
+        }
+        map->libbpf_type = LIBBPF_MAP_UNSPEC;
+        map->def.type = BPF_MAP_TYPE_UNSPEC;
+        map->sec_idx = sec_idx;
+        map->sec_offset = vi->offset;
+        pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+                 map_name, map->sec_idx, map->sec_offset);
+
+        def_data = data->d_buf + vi->offset;
+        vlen = BTF_INFO_VLEN(def->info);
+        m = (const void *)(def + 1);
+        for (i = 0; i < vlen; i++, m++) {
+                const char *name = btf__name_by_offset(obj->btf, m->name_off);
+
+                if (!name) {
+                        pr_warning("map '%s': invalid field #%d.\n",
+                                   map_name, i);
+                        return -EINVAL;
+                }
+                if (strcmp(name, "type") == 0) {
+                        if (!get_map_field_int(map_name, obj->btf, def, m,
+                                               def_data, &map->def.type))
+                                return -EINVAL;
+                        pr_debug("map '%s': found type = %u.\n",
+                                 map_name, map->def.type);
+                } else if (strcmp(name, "max_entries") == 0) {
+                        if (!get_map_field_int(map_name, obj->btf, def, m,
+                                               def_data, &map->def.max_entries))
+                                return -EINVAL;
+                        pr_debug("map '%s': found max_entries = %u.\n",
+                                 map_name, map->def.max_entries);
+                } else if (strcmp(name, "map_flags") == 0) {
+                        if (!get_map_field_int(map_name, obj->btf, def, m,
+                                               def_data, &map->def.map_flags))
+                                return -EINVAL;
+                        pr_debug("map '%s': found map_flags = %u.\n",
+                                 map_name, map->def.map_flags);
+                } else if (strcmp(name, "key_size") == 0) {
+                        __u32 sz;
+
+                        if (!get_map_field_int(map_name, obj->btf, def, m,
+                                               def_data, &sz))
+                                return -EINVAL;
+                        pr_debug("map '%s': found key_size = %u.\n",
+                                 map_name, sz);
+                        if (map->def.key_size && map->def.key_size != sz) {
+                                pr_warning("map '%s': conflictling key size %u != %u.\n",
+                                           map_name, map->def.key_size, sz);
+                                return -EINVAL;
+                        }
+                        map->def.key_size = sz;
+                } else if (strcmp(name, "key") == 0) {
+                        __s64 sz;
+
+                        t = btf__type_by_id(obj->btf, m->type);
+                        if (!t) {
+                                pr_warning("map '%s': key type [%d] not found.\n",
+                                           map_name, m->type);
+                                return -EINVAL;
+                        }
+                        if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+                                pr_warning("map '%s': key spec is not PTR: %u.\n",
+                                           map_name, BTF_INFO_KIND(t->info));
+                                return -EINVAL;
+                        }
+                        sz = btf__resolve_size(obj->btf, t->type);
+                        if (sz < 0) {
+                                pr_warning("map '%s': can't determine key size for type [%u]: %lld.\n",
+                                           map_name, t->type, sz);
+                                return sz;
+                        }
+                        pr_debug("map '%s': found key [%u], sz = %lld.\n",
+                                 map_name, t->type, sz);
+                        if (map->def.key_size && map->def.key_size != sz) {
+                                pr_warning("map '%s': conflictling key size %u != %lld.\n",
+                                           map_name, map->def.key_size, sz);
+                                return -EINVAL;
+                        }
+                        map->def.key_size = sz;
+                        map->btf_key_type_id = t->type;
+                } else if (strcmp(name, "value_size") == 0) {
+                        __u32 sz;
+
+                        if (!get_map_field_int(map_name, obj->btf, def, m,
+                                               def_data, &sz))
+                                return -EINVAL;
+                        pr_debug("map '%s': found value_size = %u.\n",
+                                 map_name, sz);
+                        if (map->def.value_size && map->def.value_size != sz) {
+                                pr_warning("map '%s': conflictling value size %u != %u.\n",
+                                           map_name, map->def.value_size, sz);
+                                return -EINVAL;
+                        }
+                        map->def.value_size = sz;
+                } else if (strcmp(name, "value") == 0) {
+                        __s64 sz;
+
+                        t = btf__type_by_id(obj->btf, m->type);
+                        if (!t) {
+                                pr_warning("map '%s': value type [%d] not found.\n",
+                                           map_name, m->type);
+                                return -EINVAL;
+                        }
+                        if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+                                pr_warning("map '%s': value spec is not PTR: %u.\n",
+                                           map_name, BTF_INFO_KIND(t->info));
+                                return -EINVAL;
+                        }
+                        sz = btf__resolve_size(obj->btf, t->type);
+                        if (sz < 0) {
+                                pr_warning("map '%s': can't determine value size for type [%u]: %lld.\n",
+                                           map_name, t->type, sz);
+                                return sz;
+                        }
+                        pr_debug("map '%s': found value [%u], sz = %lld.\n",
+                                 map_name, t->type, sz);
+                        if (map->def.value_size && map->def.value_size != sz) {
+                                pr_warning("map '%s': conflictling value size %u != %lld.\n",
+                                           map_name, map->def.value_size, sz);
+                                return -EINVAL;
+                        }
+                        map->def.value_size = sz;
+                        map->btf_value_type_id = t->type;
+                } else {
+                        if (strict) {
+                                pr_warning("map '%s': unknown field '%s'.\n",
+                                           map_name, name);
+                                return -ENOTSUP;
+                        }
+                        pr_debug("map '%s': ignoring unknown field '%s'.\n",
+                                 map_name, name);
+                }
+        }
+
+        if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
+                pr_warning("map '%s': map type isn't specified.\n", map_name);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict)
+{
+        const struct btf_type *sec = NULL;
+        int nr_types, i, vlen, err;
+        const struct btf_type *t;
+        const char *name;
+        Elf_Data *data;
+        Elf_Scn *scn;
+
+        if (obj->efile.btf_maps_shndx < 0)
+                return 0;
+
+        scn = elf_getscn(obj->efile.elf, obj->efile.btf_maps_shndx);
+        if (scn)
+                data = elf_getdata(scn, NULL);
+        if (!scn || !data) {
+                pr_warning("failed to get Elf_Data from map section %d (%s)\n",
+                           obj->efile.maps_shndx, MAPS_ELF_SEC);
+                return -EINVAL;
+        }
+
+        nr_types = btf__get_nr_types(obj->btf);
+        for (i = 1; i <= nr_types; i++) {
+                t = btf__type_by_id(obj->btf, i);
+                if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
+                        continue;
+                name = btf__name_by_offset(obj->btf, t->name_off);
+                if (strcmp(name, MAPS_ELF_SEC) == 0) {
+                        sec = t;
+                        break;
+                }
+        }
+
+        if (!sec) {
+                pr_warning("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+                return -ENOENT;
+        }
+
+        vlen = BTF_INFO_VLEN(sec->info);
+        for (i = 0; i < vlen; i++) {
+                err = bpf_object__init_user_btf_map(obj, sec, i,
+                                                    obj->efile.btf_maps_shndx,
+                                                    data, strict);
+                if (err)
+                        return err;
+        }
+
+        return 0;
+}
+
 static int bpf_object__init_maps(struct bpf_object *obj, int flags)
 {
         bool strict = !(flags & MAPS_RELAX_COMPAT);
@@ -1016,6 +1324,10 @@ static int bpf_object__init_maps(struct bpf_object *obj, int flags)
         if (err)
                 return err;
 
+        err = bpf_object__init_user_btf_maps(obj, strict);
+        if (err)
+                return err;
+
         err = bpf_object__init_global_data_maps(obj);
         if (err)
                 return err;
@@ -1113,10 +1425,16 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
         }
 }
 
+static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj)
+{
+        return obj->efile.btf_maps_shndx >= 0;
+}
+
 static int bpf_object__init_btf(struct bpf_object *obj,
                                 Elf_Data *btf_data,
                                 Elf_Data *btf_ext_data)
 {
+        bool btf_required = bpf_object__is_btf_mandatory(obj);
         int err = 0;
 
         if (btf_data) {
@@ -1150,10 +1468,18 @@ static int bpf_object__init_btf(struct bpf_object *obj,
         }
 out:
         if (err || IS_ERR(obj->btf)) {
+                if (btf_required)
+                        err = err ? : PTR_ERR(obj->btf);
+                else
+                        err = 0;
                 if (!IS_ERR_OR_NULL(obj->btf))
                         btf__free(obj->btf);
                 obj->btf = NULL;
         }
+        if (btf_required && !obj->btf) {
+                pr_warning("BTF is required, but is missing or corrupted.\n");
+                return err == 0 ? -ENOENT : err;
+        }
         return 0;
 }
 
@@ -1173,6 +1499,8 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
                            BTF_ELF_SEC, err);
                 btf__free(obj->btf);
                 obj->btf = NULL;
+                if (bpf_object__is_btf_mandatory(obj))
+                        return err;
         }
         return 0;
 }
@@ -1236,6 +1564,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
                                 return err;
                 } else if (strcmp(name, "maps") == 0) {
                         obj->efile.maps_shndx = idx;
+                } else if (strcmp(name, MAPS_ELF_SEC) == 0) {
+                        obj->efile.btf_maps_shndx = idx;
                 } else if (strcmp(name, BTF_ELF_SEC) == 0) {
                         btf_data = data;
                 } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
@@ -1355,7 +1685,8 @@ static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
 static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
                                       int shndx)
 {
-        return shndx == obj->efile.maps_shndx;
+        return shndx == obj->efile.maps_shndx ||
+               shndx == obj->efile.btf_maps_shndx;
 }
 
 static bool bpf_object__relo_in_known_section(const struct bpf_object *obj,
@@ -1399,14 +1730,14 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
         prog->nr_reloc = nrels;
 
         for (i = 0; i < nrels; i++) {
-                GElf_Sym sym;
-                GElf_Rel rel;
-                unsigned int insn_idx;
-                unsigned int shdr_idx;
                 struct bpf_insn *insns = prog->insns;
                 enum libbpf_map_type type;
+                unsigned int insn_idx;
+                unsigned int shdr_idx;
                 const char *name;
                 size_t map_idx;
+                GElf_Sym sym;
+                GElf_Rel rel;
 
                 if (!gelf_getrel(data, i, &rel)) {
                         pr_warning("relocation: failed to get %d reloc\n", i);
@@ -1500,14 +1831,18 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
         return 0;
 }
 
-static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
+static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
 {
         struct bpf_map_def *def = &map->def;
         __u32 key_type_id = 0, value_type_id = 0;
         int ret;
 
+        /* if it's BTF-defined map, we don't need to search for type IDs */
+        if (map->sec_idx == obj->efile.btf_maps_shndx)
+                return 0;
+
         if (!bpf_map__is_internal(map)) {
-                ret = btf__get_map_kv_tids(btf, map->name, def->key_size,
+                ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,
                                            def->value_size, &key_type_id,
                                            &value_type_id);
         } else {
@@ -1515,7 +1850,7 @@ static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
                  * LLVM annotates global data differently in BTF, that is,
                  * only as '.data', '.bss' or '.rodata'.
                  */
-                ret = btf__find_by_name(btf,
+                ret = btf__find_by_name(obj->btf,
                                 libbpf_type_to_btf_name[map->libbpf_type]);
         }
         if (ret < 0)
@@ -1805,7 +2140,7 @@ bpf_object__create_maps(struct bpf_object *obj)
                     map->inner_map_fd >= 0)
                         create_attr.inner_map_fd = map->inner_map_fd;
 
-                if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
+                if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
                         create_attr.btf_fd = btf__fd(obj->btf);
                         create_attr.btf_key_type_id = map->btf_key_type_id;
                         create_attr.btf_value_type_id = map->btf_value_type_id;