diff --git a/dwarf_loader.c b/dwarf_loader.c index 1b07a62..e30b03c 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -1206,6 +1206,89 @@ static struct tag *die__create_new_tag(Dwarf_Die *die, struct cu *cu) return tag; } +static struct btf_type_tag_ptr_type *die__create_new_btf_type_tag_ptr_type(Dwarf_Die *die, struct cu *cu) +{ + struct btf_type_tag_ptr_type *tag; + + tag = tag__alloc_with_spec(cu, sizeof(struct btf_type_tag_ptr_type)); + if (tag == NULL) + return NULL; + + tag__init(&tag->tag, cu, die); + tag->tag.has_btf_type_tag = true; + INIT_LIST_HEAD(&tag->tags); + return tag; +} + +static struct btf_type_tag_type *die__create_new_btf_type_tag_type(Dwarf_Die *die, struct cu *cu, + struct conf_load *conf) +{ + struct btf_type_tag_type *tag; + + tag = tag__alloc_with_spec(cu, sizeof(struct btf_type_tag_type)); + if (tag == NULL) + return NULL; + + tag__init(&tag->tag, cu, die); + tag->value = attr_string(die, DW_AT_const_value, conf); + return tag; +} + +static struct tag *die__create_new_pointer_tag(Dwarf_Die *die, struct cu *cu, + struct conf_load *conf) +{ + struct btf_type_tag_ptr_type *tag = NULL; + struct btf_type_tag_type *annot; + Dwarf_Die *cdie, child; + const char *name; + uint32_t id; + + /* If no child tags or skipping btf_type_tag encoding, just create a new tag + * and return + */ + if (!dwarf_haschildren(die) || dwarf_child(die, &child) != 0 || + conf->skip_encoding_btf_type_tag) + return tag__new(die, cu); + + /* Otherwise, check DW_TAG_LLVM_annotation child tags */ + cdie = &child; + do { + if (dwarf_tag(cdie) != DW_TAG_LLVM_annotation) + continue; + + /* Only check btf_type_tag annotations */ + name = attr_string(cdie, DW_AT_name, conf); + if (strcmp(name, "btf_type_tag") != 0) + continue; + + if (tag == NULL) { + /* Create a btf_type_tag_ptr type. */ + tag = die__create_new_btf_type_tag_ptr_type(die, cu); + if (!tag) + return NULL; + } + + /* Create a btf_type_tag type for this annotation. */ + annot = die__create_new_btf_type_tag_type(cdie, cu, conf); + if (annot == NULL) + return NULL; + + if (cu__table_add_tag(cu, &annot->tag, &id) < 0) + return NULL; + + struct dwarf_tag *dtag = annot->tag.priv; + dtag->small_id = id; + cu__hash(cu, &annot->tag); + + /* For a list of DW_TAG_LLVM_annotation like tag1 -> tag2 -> tag3, + * the tag->tags contains tag3 -> tag2 -> tag1. + */ + list_add(&annot->node, &tag->tags); + } while (dwarf_siblingof(cdie, cdie) == 0); + + return tag ? &tag->tag : tag__new(die, cu); +} + static struct tag *die__create_new_ptr_to_member_type(Dwarf_Die *die, struct cu *cu) { @@ -1903,12 +1986,13 @@ static struct tag *__die__process_tag(Dwarf_Die *die, struct cu *cu, case DW_TAG_const_type: case DW_TAG_imported_declaration: case DW_TAG_imported_module: - case DW_TAG_pointer_type: case DW_TAG_reference_type: case DW_TAG_restrict_type: case DW_TAG_unspecified_type: case DW_TAG_volatile_type: tag = die__create_new_tag(die, cu); break; + case DW_TAG_pointer_type: + tag = die__create_new_pointer_tag(die, cu, conf); break; case DW_TAG_ptr_to_member_type: tag = die__create_new_ptr_to_member_type(die, cu); break; case DW_TAG_enumeration_type: @@ -2192,6 +2276,45 @@ static void lexblock__recode_dwarf_types(struct lexblock *tag, struct cu *cu) } } +static void dwarf_cu__recode_btf_type_tag_ptr(struct btf_type_tag_ptr_type *tag, + uint32_t pointee_type) +{ + struct btf_type_tag_type *annot; + struct dwarf_tag *annot_dtag; + struct tag *prev_tag; + + /* Given source like + * int tag1 tag2 tag3 *p; + * the tag->tags contains tag3 -> tag2 -> tag1, the final type chain looks like: + * pointer -> tag3 -> tag2 -> tag1 -> pointee + * + * Basically it means + * - '*' applies to "int tag1 tag2 tag3" + * - tag3 applies to "int tag1 tag2" + * - tag2 applies to "int tag1" + * - tag1 applies to "int" + * + * This also makes final source code (format c) easier as we can do + * emit for "tag3 -> tag2 -> tag1 -> int" + * emit '*' + * + * For 'tag3 -> tag2 -> tag1 -> int": + * emit for "tag2 -> tag1 -> int" + * emit tag3 + * + * Eventually we can get the source code like + * int tag1 tag2 tag3 *p; + * and this matches the user/kernel code. + */ + prev_tag = &tag->tag; + list_for_each_entry(annot, &tag->tags, node) { + annot_dtag = annot->tag.priv; + prev_tag->type = annot_dtag->small_id; + prev_tag = &annot->tag; + } + prev_tag->type = pointee_type; +} + static int tag__recode_dwarf_type(struct tag *tag, struct cu *cu) { struct dwarf_tag *dtag = tag->priv; @@ -2301,7 +2424,10 @@ static int tag__recode_dwarf_type(struct tag *tag, struct cu *cu) } if (dtag->type.off == 0) { - tag->type = 0; /* void */ + if (tag->tag != DW_TAG_pointer_type || !tag->has_btf_type_tag) + tag->type = 0; /* void */ + else + dwarf_cu__recode_btf_type_tag_ptr(tag__btf_type_tag_ptr(tag), 0); return 0; } @@ -2313,7 +2439,11 @@ check_type: return 0; } out: - tag->type = dtype->small_id; + if (tag->tag != DW_TAG_pointer_type || !tag->has_btf_type_tag) + tag->type = dtype->small_id; + else + dwarf_cu__recode_btf_type_tag_ptr(tag__btf_type_tag_ptr(tag), dtype->small_id); + return 0; } diff --git a/dwarves.h b/dwarves.h index 0d3e204..4425d3c 100644 --- a/dwarves.h +++ b/dwarves.h @@ -63,6 +63,7 @@ struct conf_load { bool ptr_table_stats; bool skip_encoding_btf_decl_tag; bool skip_missing; + bool skip_encoding_btf_type_tag; uint8_t hashtable_bits; uint8_t max_hashtable_bits; uint16_t kabi_prefix_len; @@ -413,6 +414,7 @@ struct tag { uint16_t tag; bool visited; bool top_level; + bool has_btf_type_tag; uint16_t recursivity_level; void *priv; }; @@ -533,7 +535,8 @@ static inline int tag__is_tag_type(const struct tag *tag) tag->tag == DW_TAG_restrict_type || tag->tag == DW_TAG_subroutine_type || tag->tag == DW_TAG_unspecified_type || - tag->tag == DW_TAG_volatile_type; + tag->tag == DW_TAG_volatile_type || + tag->tag == DW_TAG_LLVM_annotation; } static inline const char *tag__decl_file(const struct tag *tag, @@ -606,6 +609,34 @@ struct llvm_annotation { struct list_head node; }; +/** struct btf_type_tag_type - representing a btf_type_tag annotation + * + * @tag - DW_TAG_LLVM_annotation tag + * @value - btf_type_tag value string + * @node - list_head node + */ +struct btf_type_tag_type { + struct tag tag; + const char *value; + struct list_head node; +}; + +/** The struct btf_type_tag_ptr_type - type containing both pointer type and + * its btf_type_tag annotations + * + * @tag - pointer type tag + * @tags - btf_type_tag annotations for the pointer type + */ +struct btf_type_tag_ptr_type { + struct tag tag; + struct list_head tags; +}; + +static inline struct btf_type_tag_ptr_type *tag__btf_type_tag_ptr(struct tag *tag) +{ + return (struct btf_type_tag_ptr_type *)tag; +} + /** struct namespace - base class for enums, structs, unions, typedefs, etc * * @tags - class_member, enumerators, etc diff --git a/pahole.c b/pahole.c index 5fc1cca..f3a51cb 100644 --- a/pahole.c +++ b/pahole.c @@ -1126,6 +1126,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version; #define ARGP_devel_stats 330 #define ARGP_skip_encoding_btf_decl_tag 331 #define ARGP_skip_missing 332 +#define ARGP_skip_encoding_btf_type_tag 333 static const struct argp_option pahole__options[] = { { @@ -1506,6 +1507,11 @@ static const struct argp_option pahole__options[] = { .key = ARGP_skip_missing, .doc = "skip missing types passed to -C rather than stop", }, + { + .name = "skip_encoding_btf_type_tag", + .key = ARGP_skip_encoding_btf_type_tag, + .doc = "Do not encode TAGs in BTF." + }, { .name = NULL, } @@ -1658,6 +1664,8 @@ static error_t pahole__options_parser(int key, char *arg, conf_load.skip_encoding_btf_decl_tag = true; break; case ARGP_skip_missing: conf_load.skip_missing = true; break; + case ARGP_skip_encoding_btf_type_tag: + conf_load.skip_encoding_btf_type_tag = true; break; default: return ARGP_ERR_UNKNOWN; }