Parse dwarf tag DW_TAG_LLVM_annotation. Only record annotations with btf_tag name which corresponds to btf_tag attributes in C code. Such information will be used later by btf_encoder for BTF conversion. LLVM implementation only supports btf_tag annotations on struct/union, func, func parameter and variable ([1]). So we only check existence of corresponding DW tags in these places. A flag "--skip_encoding_btf_tag" is introduced if for whatever reason this feature needs to be disabled. [1] https://reviews.llvm.org/D106614 Signed-off-by: Yonghong Song <yhs@xxxxxx> --- dwarf_loader.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++---- dwarves.h | 10 ++++++ pahole.c | 8 +++++ 3 files changed, 97 insertions(+), 6 deletions(-) diff --git a/dwarf_loader.c b/dwarf_loader.c index 0213e42..48e1bf0 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -52,6 +52,10 @@ #define DW_OP_addrx 0xa1 #endif +#ifndef DW_TAG_LLVM_annotation +#define DW_TAG_LLVM_annotation 0x6000 +#endif + static pthread_mutex_t libdw__lock = PTHREAD_MUTEX_INITIALIZER; static uint32_t hashtags__bits = 12; @@ -602,6 +606,7 @@ static void namespace__init(struct namespace *namespace, Dwarf_Die *die, { tag__init(&namespace->tag, cu, die); INIT_LIST_HEAD(&namespace->tags); + INIT_LIST_HEAD(&namespace->annots); namespace->name = attr_string(die, DW_AT_name, conf); namespace->nr_tags = 0; namespace->shared_tags = 0; @@ -719,6 +724,7 @@ static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf /* non-defining declaration of an object */ var->declaration = dwarf_hasattr(die, DW_AT_declaration); var->scope = VSCOPE_UNKNOWN; + INIT_LIST_HEAD(&var->annots); var->ip.addr = 0; if (!var->declaration && cu->has_addr_info) var->scope = dwarf__location(die, &var->ip.addr, &var->location); @@ -854,6 +860,51 @@ static int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t b return -ENOMEM; } +static int add_llvm_annotation(Dwarf_Die *die, int component_idx, struct conf_load *conf, + struct list_head *head) +{ + struct llvm_annotation *annot; + const char *name; + + if (conf->skip_encoding_btf_tag) + return 0; + + /* Only handle btf_tag annotation for now. */ + name = attr_string(die, DW_AT_name, conf); + if (strcmp(name, "btf_tag") != 0) + return 0; + + annot = zalloc(sizeof(*annot)); + if (!annot) + return -ENOMEM; + + annot->value = attr_string(die, DW_AT_const_value, conf); + annot->component_idx = component_idx; + list_add_tail(&annot->node, head); + return 0; +} + +static int add_child_llvm_annotations(Dwarf_Die *die, int component_idx, + struct conf_load *conf, struct list_head *head) +{ + Dwarf_Die child; + int ret; + + if (!dwarf_haschildren(die) || dwarf_child(die, &child) != 0) + return 0; + + die = &child; + do { + if (dwarf_tag(die) == DW_TAG_LLVM_annotation) { + ret = add_llvm_annotation(die, component_idx, conf, head); + if (ret) + return ret; + } + } while (dwarf_siblingof(die, die) == 0); + + return 0; +} + int class_member__dwarf_recode_bitfield(struct class_member *member, struct cu *cu) { @@ -1092,6 +1143,7 @@ static struct function *function__new(Dwarf_Die *die, struct cu *cu, struct conf func->accessibility = attr_numeric(die, DW_AT_accessibility); func->virtuality = attr_numeric(die, DW_AT_virtuality); INIT_LIST_HEAD(&func->vtable_node); + INIT_LIST_HEAD(&func->annots); INIT_LIST_HEAD(&func->tool_node); func->vtable_entry = -1; if (dwarf_hasattr(die, DW_AT_vtable_elem_location)) @@ -1304,16 +1356,21 @@ static struct tag *die__create_new_string_type(Dwarf_Die *die, struct cu *cu) static struct tag *die__create_new_parameter(Dwarf_Die *die, struct ftype *ftype, struct lexblock *lexblock, - struct cu *cu, struct conf_load *conf) + struct cu *cu, struct conf_load *conf, + int param_idx) { struct parameter *parm = parameter__new(die, cu, conf); if (parm == NULL) return NULL; - if (ftype != NULL) + if (ftype != NULL) { ftype__add_parameter(ftype, parm); - else { + if (param_idx >= 0) { + if (add_child_llvm_annotations(die, param_idx, conf, &(tag__function(&ftype->tag)->annots))) + return NULL; + } + } else { /* * DW_TAG_formal_parameters on a non DW_TAG_subprogram nor * DW_TAG_subroutine_type tag happens sometimes, likely due to @@ -1346,7 +1403,10 @@ static struct tag *die__create_new_variable(Dwarf_Die *die, struct cu *cu, struc { struct variable *var = variable__new(die, cu, conf); - return var ? &var->ip.tag : NULL; + if (var == NULL || add_child_llvm_annotations(die, -1, conf, &var->annots)) + return NULL; + + return &var->ip.tag; } static struct tag *die__create_new_subroutine_type(Dwarf_Die *die, @@ -1371,7 +1431,7 @@ static struct tag *die__create_new_subroutine_type(Dwarf_Die *die, tag__print_not_supported(dwarf_tag(die)); continue; case DW_TAG_formal_parameter: - tag = die__create_new_parameter(die, ftype, NULL, cu, conf); + tag = die__create_new_parameter(die, ftype, NULL, cu, conf, -1); break; case DW_TAG_unspecified_parameters: ftype->unspec_parms = 1; @@ -1455,6 +1515,7 @@ static int die__process_class(Dwarf_Die *die, struct type *class, struct cu *cu, struct conf_load *conf) { const bool is_union = tag__is_union(&class->namespace.tag); + int member_idx = 0; do { switch (dwarf_tag(die)) { @@ -1497,8 +1558,15 @@ static int die__process_class(Dwarf_Die *die, struct type *class, type__add_member(class, member); cu__hash(cu, &member->tag); + if (add_child_llvm_annotations(die, member_idx, conf, &class->namespace.annots)) + return -ENOMEM; + member_idx++; } continue; + case DW_TAG_LLVM_annotation: + if (add_llvm_annotation(die, -1, conf, &class->namespace.annots)) + return -ENOMEM; + continue; default: { struct tag *tag = die__process_tag(die, cu, 0, conf); @@ -1699,6 +1767,7 @@ static struct tag *die__create_new_inline_expansion(Dwarf_Die *die, static int die__process_function(Dwarf_Die *die, struct ftype *ftype, struct lexblock *lexblock, struct cu *cu, struct conf_load *conf) { + int param_idx = 0; Dwarf_Die child; struct tag *tag; @@ -1742,7 +1811,7 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype, tag__print_not_supported(dwarf_tag(die)); continue; case DW_TAG_formal_parameter: - tag = die__create_new_parameter(die, ftype, lexblock, cu, conf); + tag = die__create_new_parameter(die, ftype, lexblock, cu, conf, param_idx++); break; case DW_TAG_variable: tag = die__create_new_variable(die, cu, conf); @@ -1771,6 +1840,10 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype, if (die__create_new_lexblock(die, cu, lexblock, conf) != 0) goto out_enomem; continue; + case DW_TAG_LLVM_annotation: + if (add_llvm_annotation(die, -1, conf, &(tag__function(&ftype->tag)->annots))) + goto out_enomem; + continue; default: tag = die__process_tag(die, cu, 0, conf); diff --git a/dwarves.h b/dwarves.h index 0b69312..30d33fa 100644 --- a/dwarves.h +++ b/dwarves.h @@ -58,6 +58,7 @@ struct conf_load { bool ignore_inline_expansions; bool ignore_labels; bool ptr_table_stats; + bool skip_encoding_btf_tag; uint8_t hashtable_bits; uint8_t max_hashtable_bits; uint16_t kabi_prefix_len; @@ -594,6 +595,12 @@ static inline struct ptr_to_member_type * return (struct ptr_to_member_type *)tag; } +struct llvm_annotation { + const char *value; + int16_t component_idx; + struct list_head node; +}; + /** struct namespace - base class for enums, structs, unions, typedefs, etc * * @tags - class_member, enumerators, etc @@ -605,6 +612,7 @@ struct namespace { uint16_t nr_tags; uint8_t shared_tags; struct list_head tags; + struct list_head annots; }; static inline struct namespace *tag__namespace(const struct tag *tag) @@ -686,6 +694,7 @@ struct variable { enum vscope scope; struct location location; struct hlist_node tool_hnode; + struct list_head annots; struct variable *spec; }; @@ -818,6 +827,7 @@ struct function { uint8_t btf:1; int32_t vtable_entry; struct list_head vtable_node; + struct list_head annots; /* fields used by tools */ union { struct list_head tool_node; diff --git a/pahole.c b/pahole.c index 7f1771b..80271b5 100644 --- a/pahole.c +++ b/pahole.c @@ -1124,6 +1124,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version; #define ARGP_sort_output 328 #define ARGP_hashbits 329 #define ARGP_devel_stats 330 +#define ARGP_skip_encoding_btf_tag 331 static const struct argp_option pahole__options[] = { { @@ -1494,6 +1495,11 @@ static const struct argp_option pahole__options[] = { .key = ARGP_devel_stats, .doc = "Print internal data structures stats", }, + { + .name = "skip_encoding_btf_tag", + .key = ARGP_skip_encoding_btf_tag, + .doc = "Do not encode TAGs in BTF." + }, { .name = NULL, } @@ -1642,6 +1648,8 @@ static error_t pahole__options_parser(int key, char *arg, conf_load.hashtable_bits = atoi(arg); break; case ARGP_devel_stats: conf_load.ptr_table_stats = true; break; + case ARGP_skip_encoding_btf_tag: + conf_load.skip_encoding_btf_tag = true; break; default: return ARGP_ERR_UNKNOWN; } -- 2.30.2
