| /* |
| SPDX-License-Identifier: GPL-2.0-only |
| |
| Copyright (C) 2019 Facebook |
| |
| Derived from ctf_encoder.c, which is: |
| |
| Copyright (C) Arnaldo Carvalho de Melo <acme@redhat.com> |
| Copyright (C) Red Hat Inc |
| */ |
| |
| #include "dwarves.h" |
| #include "libbtf.h" |
| #include "lib/bpf/include/uapi/linux/btf.h" |
| #include "hash.h" |
| #include "elf_symtab.h" |
| #include "btf_encoder.h" |
| |
| #include <ctype.h> /* for isalpha() and isalnum() */ |
| #include <inttypes.h> |
| |
| /* |
| * This corresponds to the same macro defined in |
| * include/linux/kallsyms.h |
| */ |
| #define KSYM_NAME_LEN 128 |
| |
| static bool btf_name_char_ok(char c, bool first) |
| { |
| if (c == '_' || c == '.') |
| return true; |
| |
| return first ? isalpha(c) : isalnum(c); |
| } |
| |
| /* Check whether the given name is valid in vmlinux btf. */ |
| static bool btf_name_valid(const char *p) |
| { |
| const char *limit; |
| |
| if (!btf_name_char_ok(*p, true)) |
| return false; |
| |
| /* set a limit on identifier length */ |
| limit = p + KSYM_NAME_LEN; |
| p++; |
| while (*p && p < limit) { |
| if (!btf_name_char_ok(*p, false)) |
| return false; |
| p++; |
| } |
| |
| return !*p; |
| } |
| |
| static void dump_invalid_symbol(const char *msg, const char *sym, const char *cu, |
| int verbose, bool force) |
| { |
| if (force) { |
| if (verbose) |
| fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s', cu: '%s').\n", |
| msg, sym, cu); |
| return; |
| } |
| |
| fprintf(stderr, "PAHOLE: Error: %s (sym: '%s', cu: '%s').\n", msg, sym, cu); |
| fprintf(stderr, "PAHOLE: Error: Use '-j' or '--force' to ignore such symbols and force emit the btf.\n"); |
| } |
| |
| static int tag__check_id_drift(const struct tag *tag, |
| uint32_t core_id, uint32_t btf_type_id, |
| uint32_t type_id_off) |
| { |
| if (btf_type_id != (core_id + type_id_off)) { |
| fprintf(stderr, |
| "%s: %s id drift, core_id: %u, btf_type_id: %u, type_id_off: %u\n", |
| __func__, dwarf_tag_name(tag->tag), |
| core_id, btf_type_id, type_id_off); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| static int32_t structure_type__encode(struct btf_elf *btfe, struct tag *tag, uint32_t type_id_off) |
| { |
| struct type *type = tag__type(tag); |
| struct class_member *pos; |
| bool kind_flag = false; |
| int32_t type_id; |
| uint8_t kind; |
| |
| kind = (tag->tag == DW_TAG_union_type) ? |
| BTF_KIND_UNION : BTF_KIND_STRUCT; |
| |
| /* Although no_bitfield_type_recode has been set true |
| * in pahole.c if BTF encoding is requested, we still check |
| * the value here. So if no_bitfield_type_recode is set |
| * to false for whatever reason, we do not accidentally |
| * set kind_flag incorrectly. |
| */ |
| if (no_bitfield_type_recode) { |
| /* kind_flag only set where there is a bitfield |
| * in the struct. |
| */ |
| type__for_each_data_member(type, pos) { |
| if (pos->bitfield_size) { |
| kind_flag = true; |
| break; |
| } |
| } |
| } |
| |
| type_id = btf_elf__add_struct(btfe, kind, type->namespace.name, kind_flag, type->size, type->nr_members); |
| if (type_id < 0) |
| return type_id; |
| |
| type__for_each_data_member(type, pos) { |
| /* |
| * dwarf_loader uses DWARF's recommended bit offset addressing |
| * scheme, which conforms to BTF requirement, so no conversion |
| * is required. |
| */ |
| if (btf_elf__add_member(btfe, pos->name, type_id_off + pos->tag.type, kind_flag, pos->bitfield_size, pos->bit_offset)) |
| return -1; |
| } |
| |
| return type_id; |
| } |
| |
| static uint32_t array_type__nelems(struct tag *tag) |
| { |
| int i; |
| uint32_t nelem = 1; |
| struct array_type *array = tag__array_type(tag); |
| |
| for (i = array->dimensions - 1; i >= 0; --i) |
| nelem *= array->nr_entries[i]; |
| |
| return nelem; |
| } |
| |
| static int32_t enumeration_type__encode(struct btf_elf *btfe, struct tag *tag) |
| { |
| struct type *etype = tag__type(tag); |
| struct enumerator *pos; |
| int32_t type_id; |
| |
| type_id = btf_elf__add_enum(btfe, etype->namespace.name, etype->size, etype->nr_members); |
| if (type_id < 0) |
| return type_id; |
| |
| type__for_each_enumerator(etype, pos) |
| if (btf_elf__add_enum_val(btfe, pos->name, pos->value)) |
| return -1; |
| |
| return type_id; |
| } |
| |
| static int tag__encode_btf(struct tag *tag, uint32_t core_id, struct btf_elf *btfe, |
| uint32_t array_index_id, uint32_t type_id_off) |
| { |
| /* single out type 0 as it represents special type "void" */ |
| uint32_t ref_type_id = tag->type == 0 ? 0 : type_id_off + tag->type; |
| |
| switch (tag->tag) { |
| case DW_TAG_base_type: |
| return btf_elf__add_base_type(btfe, tag__base_type(tag)); |
| case DW_TAG_const_type: |
| return btf_elf__add_ref_type(btfe, BTF_KIND_CONST, ref_type_id, 0, false); |
| case DW_TAG_pointer_type: |
| return btf_elf__add_ref_type(btfe, BTF_KIND_PTR, ref_type_id, 0, false); |
| case DW_TAG_restrict_type: |
| return btf_elf__add_ref_type(btfe, BTF_KIND_RESTRICT, ref_type_id, 0, false); |
| case DW_TAG_volatile_type: |
| return btf_elf__add_ref_type(btfe, BTF_KIND_VOLATILE, ref_type_id, 0, false); |
| case DW_TAG_typedef: |
| return btf_elf__add_ref_type(btfe, BTF_KIND_TYPEDEF, ref_type_id, tag__namespace(tag)->name, false); |
| case DW_TAG_structure_type: |
| case DW_TAG_union_type: |
| case DW_TAG_class_type: |
| if (tag__type(tag)->declaration) |
| return btf_elf__add_ref_type(btfe, BTF_KIND_FWD, 0, tag__namespace(tag)->name, tag->tag == DW_TAG_union_type); |
| else |
| return structure_type__encode(btfe, tag, type_id_off); |
| case DW_TAG_array_type: |
| /* TODO: Encode one dimension at a time. */ |
| return btf_elf__add_array(btfe, ref_type_id, array_index_id, array_type__nelems(tag)); |
| case DW_TAG_enumeration_type: |
| return enumeration_type__encode(btfe, tag); |
| case DW_TAG_subroutine_type: |
| return btf_elf__add_func_proto(btfe, tag__ftype(tag), type_id_off); |
| default: |
| fprintf(stderr, "Unsupported DW_TAG_%s(0x%x)\n", |
| dwarf_tag_name(tag->tag), tag->tag); |
| return -1; |
| } |
| } |
| |
| /* |
| * FIXME: Its in the DWARF loader, we have to find a better handoff |
| * mechanizm... |
| */ |
| extern struct strings *strings; |
| |
| static struct btf_elf *btfe; |
| static uint32_t array_index_id; |
| |
| int btf_encoder__encode() |
| { |
| int err; |
| |
| err = btf_elf__encode(btfe, 0); |
| btf_elf__delete(btfe); |
| btfe = NULL; |
| |
| return err; |
| } |
| |
| #define HASHADDR__BITS 8 |
| #define HASHADDR__SIZE (1UL << HASHADDR__BITS) |
| #define hashaddr__fn(key) hash_64(key, HASHADDR__BITS) |
| |
| static struct variable *hashaddr__find_variable(const struct hlist_head hashtable[], |
| const uint64_t addr) |
| { |
| struct variable *variable; |
| struct hlist_node *pos; |
| uint16_t bucket = hashaddr__fn(addr); |
| const struct hlist_head *head = &hashtable[bucket]; |
| |
| hlist_for_each_entry(variable, pos, head, tool_hnode) { |
| if (variable->ip.addr == addr) |
| return variable; |
| } |
| |
| return NULL; |
| } |
| |
| int cu__encode_btf(struct cu *cu, int verbose, bool force, |
| bool skip_encoding_vars) |
| { |
| bool add_index_type = false; |
| uint32_t type_id_off; |
| uint32_t core_id; |
| struct function *fn; |
| struct tag *pos; |
| int err = 0; |
| struct hlist_head hash_addr[HASHADDR__SIZE]; |
| struct variable *var; |
| bool has_global_var = false; |
| GElf_Sym sym; |
| |
| if (btfe && strcmp(btfe->filename, cu->filename)) { |
| err = btf_encoder__encode(); |
| if (err) |
| goto out; |
| |
| /* Finished one file, add one empty line */ |
| if (verbose) |
| printf("\n"); |
| } |
| |
| if (!btfe) { |
| btfe = btf_elf__new(cu->filename, cu->elf); |
| if (!btfe) |
| return -1; |
| btf_elf__set_strings(btfe, &strings->gb); |
| |
| /* cu__find_base_type_by_name() takes "type_id_t *id" */ |
| type_id_t id; |
| if (!cu__find_base_type_by_name(cu, "int", &id)) { |
| add_index_type = true; |
| id = cu->types_table.nr_entries; |
| } |
| array_index_id = id; |
| |
| if (verbose) |
| printf("File %s:\n", btfe->filename); |
| } |
| |
| btf_elf__verbose = verbose; |
| type_id_off = btfe->type_index; |
| |
| cu__for_each_type(cu, core_id, pos) { |
| int32_t btf_type_id = tag__encode_btf(pos, core_id, btfe, array_index_id, type_id_off); |
| |
| if (btf_type_id < 0 || |
| tag__check_id_drift(pos, core_id, btf_type_id, type_id_off)) { |
| err = -1; |
| goto out; |
| } |
| } |
| |
| if (add_index_type) { |
| struct base_type bt = {}; |
| |
| bt.name = 0; |
| bt.bit_size = 32; |
| btf_elf__add_base_type(btfe, &bt); |
| } |
| |
| cu__for_each_function(cu, core_id, fn) { |
| int btf_fnproto_id, btf_fn_id; |
| |
| if (fn->declaration || !fn->external) |
| continue; |
| |
| btf_fnproto_id = btf_elf__add_func_proto(btfe, &fn->proto, type_id_off); |
| btf_fn_id = btf_elf__add_ref_type(btfe, BTF_KIND_FUNC, btf_fnproto_id, fn->name, false); |
| if (btf_fnproto_id < 0 || btf_fn_id < 0) { |
| err = -1; |
| printf("error: failed to encode function '%s'\n", function__name(fn, cu)); |
| goto out; |
| } |
| } |
| |
| if (skip_encoding_vars) |
| goto out; |
| |
| if (btfe->percpu_shndx == 0 || !btfe->symtab) |
| goto out; |
| |
| if (verbose) |
| printf("search cu '%s' for percpu global variables.\n", cu->name); |
| |
| /* cache variables' addresses, preparing for searching in symtab. */ |
| for (core_id = 0; core_id < HASHADDR__SIZE; ++core_id) |
| INIT_HLIST_HEAD(&hash_addr[core_id]); |
| |
| cu__for_each_variable(cu, core_id, pos) { |
| struct hlist_head *head; |
| |
| var = tag__variable(pos); |
| if (var->declaration) |
| continue; |
| /* percpu variables are allocated in global space */ |
| if (variable__scope(var) != VSCOPE_GLOBAL) |
| continue; |
| has_global_var = true; |
| head = &hash_addr[hashaddr__fn(var->ip.addr)]; |
| hlist_add_head(&var->tool_hnode, head); |
| } |
| if (!has_global_var) { |
| if (verbose) |
| printf("cu has no global variable defined, skip.\n"); |
| goto out; |
| } |
| |
| /* search within symtab for percpu variables */ |
| elf_symtab__for_each_symbol(btfe->symtab, core_id, sym) { |
| uint32_t linkage, type, size, offset, name; |
| int32_t btf_var_id, btf_var_secinfo_id; |
| uint64_t addr; |
| const char *sym_name; |
| |
| /* compare a symbol's shndx to determine if it's a percpu variable */ |
| if (elf_sym__section(&sym) != btfe->percpu_shndx) |
| continue; |
| if (elf_sym__type(&sym) != STT_OBJECT) |
| continue; |
| |
| addr = elf_sym__value(&sym); |
| /* |
| * Store only those symbols that have allocated space in the percpu section. |
| * This excludes the following three types of symbols: |
| * |
| * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols. |
| * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids. |
| * 3. __exitcall(fn), functions which are labeled as exit calls. |
| * |
| * In addition, the variables defined using DEFINE_PERCPU_FIRST are |
| * also not included, which currently includes: |
| * |
| * 1. fixed_percpu_data |
| */ |
| if (!addr) |
| continue; |
| var = hashaddr__find_variable(hash_addr, addr); |
| if (var == NULL) |
| continue; |
| |
| sym_name = elf_sym__name(&sym, btfe->symtab); |
| if (!btf_name_valid(sym_name)) { |
| dump_invalid_symbol("Found symbol of invalid name when encoding btf", |
| sym_name, cu->name, verbose, force); |
| if (force) |
| continue; |
| err = -1; |
| break; |
| } |
| name = strings__add(strings, sym_name); |
| type = var->ip.tag.type + type_id_off; |
| size = elf_sym__size(&sym); |
| if (!size) { |
| dump_invalid_symbol("Found symbol of zero size when encoding btf", |
| sym_name, cu->name, verbose, force); |
| if (force) |
| continue; |
| err = -1; |
| break; |
| } |
| |
| if (verbose) |
| printf("symbol '%s' of address 0x%lx encoded\n", |
| sym_name, addr); |
| |
| /* add a BTF_KIND_VAR in btfe->types */ |
| linkage = var->external ? BTF_VAR_GLOBAL_ALLOCATED : BTF_VAR_STATIC; |
| btf_var_id = btf_elf__add_var_type(btfe, type, name, linkage); |
| if (btf_var_id < 0) { |
| err = -1; |
| printf("error: failed to encode variable '%s'\n", sym_name); |
| break; |
| } |
| |
| /* |
| * add a BTF_VAR_SECINFO in btfe->percpu_secinfo, which will be added into |
| * btfe->types later when we add BTF_VAR_DATASEC. |
| */ |
| type = btf_var_id; |
| offset = addr - btfe->percpu_base_addr; |
| btf_var_secinfo_id = btf_elf__add_var_secinfo(&btfe->percpu_secinfo, |
| type, offset, size); |
| if (btf_var_secinfo_id < 0) { |
| err = -1; |
| printf("error: failed to encode var secinfo '%s'\n", sym_name); |
| break; |
| } |
| } |
| |
| out: |
| if (err) |
| btf_elf__delete(btfe); |
| return err; |
| } |