diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile index c0d4ce50fc27..c06145d84df8 100644 --- a/scripts/gendwarfksyms/Makefile +++ b/scripts/gendwarfksyms/Makefile @@ -2,6 +2,7 @@ hostprogs-always-y += gendwarfksyms gendwarfksyms-objs += gendwarfksyms.o +gendwarfksyms-objs += cache.o gendwarfksyms-objs += die.o gendwarfksyms-objs += dwarf.o gendwarfksyms-objs += symbols.o diff --git a/scripts/gendwarfksyms/cache.c b/scripts/gendwarfksyms/cache.c new file mode 100644 index 000000000000..c9c19b86a686 --- /dev/null +++ b/scripts/gendwarfksyms/cache.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2024 Google LLC + */ + +#include "gendwarfksyms.h" + +struct cache_item { + unsigned long key; + int value; + struct hlist_node hash; +}; + +void cache_set(struct cache *cache, unsigned long key, int value) +{ + struct cache_item *ci; + + ci = xmalloc(sizeof(struct cache_item)); + ci->key = key; + ci->value = value; + hash_add(cache->cache, &ci->hash, hash_32(key)); +} + +int cache_get(struct cache *cache, unsigned long key) +{ + struct cache_item *ci; + + hash_for_each_possible(cache->cache, ci, hash, hash_32(key)) { + if (ci->key == key) + return ci->value; + } + + return -1; +} + +void cache_init(struct cache *cache) +{ + hash_init(cache->cache); +} + +void cache_free(struct cache *cache) +{ + struct hlist_node *tmp; + struct cache_item *ci; + + hash_for_each_safe(cache->cache, ci, tmp, hash) { + free(ci); + } + + hash_init(cache->cache); +} diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c index 6ec1138c459f..6b30e45a4e82 100644 --- a/scripts/gendwarfksyms/dwarf.c +++ b/scripts/gendwarfksyms/dwarf.c @@ -27,6 +27,7 @@ static void process_linebreak(struct die *cache, int n) !dwarf_form##attr(&da, value); \ } +DEFINE_GET_ATTR(flag, bool) DEFINE_GET_ATTR(udata, Dwarf_Word) static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value) @@ -80,6 +81,55 @@ static bool match_export_symbol(struct state *state, Dwarf_Die *die) return !!state->sym; } +/* DW_AT_decl_file -> struct srcfile */ +static struct cache srcfile_cache; + +static bool is_definition_private(Dwarf_Die *die) +{ + Dwarf_Word filenum; + Dwarf_Files *files; + Dwarf_Die cudie; + const char *s; + int res; + + /* + * Definitions in .c files cannot change the public ABI, + * so consider them private. + */ + if (!get_udata_attr(die, DW_AT_decl_file, &filenum)) + return false; + + res = cache_get(&srcfile_cache, filenum); + if (res >= 0) + return !!res; + + if (!dwarf_cu_die(die->cu, &cudie, NULL, NULL, NULL, NULL, NULL, NULL)) + error("dwarf_cu_die failed: '%s'", dwarf_errmsg(-1)); + + if (dwarf_getsrcfiles(&cudie, &files, NULL)) + error("dwarf_getsrcfiles failed: '%s'", dwarf_errmsg(-1)); + + s = dwarf_filesrc(files, filenum, NULL, NULL); + if (!s) + error("dwarf_filesrc failed: '%s'", dwarf_errmsg(-1)); + + s = strrchr(s, '.'); + res = s && !strcmp(s, ".c"); + cache_set(&srcfile_cache, filenum, res); + + return !!res; +} + +static bool is_kabi_definition(Dwarf_Die *die) +{ + bool value; + + if (get_flag_attr(die, DW_AT_declaration, &value) && value) + return false; + + return !is_definition_private(die); +} + /* * Type string processing */ @@ -456,19 +506,27 @@ static void __process_structure_type(struct state *state, struct die *cache, die_callback_t process_func, die_match_callback_t match_func) { + bool expand; + process(cache, type); process_fqn(cache, die); process(cache, " {"); process_linebreak(cache, 1); - check(process_die_container(state, cache, die, process_func, - match_func)); + expand = state->expand.expand && is_kabi_definition(die); + + if (expand) { + check(process_die_container(state, cache, die, process_func, + match_func)); + } process_linebreak(cache, -1); process(cache, "}"); - process_byte_size_attr(cache, die); - process_alignment_attr(cache, die); + if (expand) { + process_byte_size_attr(cache, die); + process_alignment_attr(cache, die); + } } #define DEFINE_PROCESS_STRUCTURE_TYPE(structure) \ @@ -553,6 +611,30 @@ static void process_cached(struct state *state, struct die *cache, } } +static void state_init(struct state *state) +{ + state->expand.expand = true; + cache_init(&state->expansion_cache); +} + +static void expansion_state_restore(struct expansion_state *state, + struct expansion_state *saved) +{ + state->expand = saved->expand; +} + +static void expansion_state_save(struct expansion_state *state, + struct expansion_state *saved) +{ + expansion_state_restore(saved, state); +} + +static bool is_expanded_type(int tag) +{ + return tag == DW_TAG_class_type || tag == DW_TAG_structure_type || + tag == DW_TAG_union_type || tag == DW_TAG_enumeration_type; +} + #define PROCESS_TYPE(type) \ case DW_TAG_##type##_type: \ process_##type##_type(state, cache, die); \ @@ -560,18 +642,39 @@ static void process_cached(struct state *state, struct die *cache, static int process_type(struct state *state, struct die *parent, Dwarf_Die *die) { + enum die_state want_state = DIE_COMPLETE; struct die *cache; + struct expansion_state saved; int tag = dwarf_tag(die); + expansion_state_save(&state->expand, &saved); + /* - * If we have the DIE already cached, use it instead of walking + * Structures and enumeration types are expanded only once per + * exported symbol. This is sufficient for detecting ABI changes + * within the structure. + */ + if (is_expanded_type(tag)) { + if (cache_was_expanded(&state->expansion_cache, die->addr)) + state->expand.expand = false; + + if (state->expand.expand) + cache_mark_expanded(&state->expansion_cache, die->addr); + else + want_state = DIE_UNEXPANDED; + } + + /* + * If we have want_state already cached, use it instead of walking * through DWARF. */ - cache = die_map_get(die, DIE_COMPLETE); + cache = die_map_get(die, want_state); - if (cache->state == DIE_COMPLETE) { + if (cache->state == want_state) { process_cached(state, cache, die); die_map_add_die(parent, cache); + + expansion_state_restore(&state->expand, &saved); return 0; } @@ -612,9 +715,10 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die) /* Update cache state and append to the parent (if any) */ cache->tag = tag; - cache->state = DIE_COMPLETE; + cache->state = want_state; die_map_add_die(parent, cache); + expansion_state_restore(&state->expand, &saved); return 0; } @@ -676,11 +780,14 @@ static int process_exported_symbols(struct state *unused, struct die *cache, if (!match_export_symbol(&state, die)) return 0; + state_init(&state); + if (tag == DW_TAG_subprogram) process_subprogram(&state, &state.die); else process_variable(&state, &state.die); + cache_free(&state.expansion_cache); return 0; } default: @@ -692,4 +799,6 @@ void process_cu(Dwarf_Die *cudie) { check(process_die_container(NULL, NULL, cudie, process_exported_symbols, match_all)); + + cache_free(&srcfile_cache); } diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h index 1796f71b3a34..941c4134da8e 100644 --- a/scripts/gendwarfksyms/gendwarfksyms.h +++ b/scripts/gendwarfksyms/gendwarfksyms.h @@ -102,6 +102,7 @@ void symbol_free(void); enum die_state { DIE_INCOMPLETE, + DIE_UNEXPANDED, DIE_COMPLETE, DIE_LAST = DIE_COMPLETE }; @@ -131,6 +132,7 @@ static inline const char *die_state_name(enum die_state state) { switch (state) { CASE_CONST_TO_STR(DIE_INCOMPLETE) + CASE_CONST_TO_STR(DIE_UNEXPANDED) CASE_CONST_TO_STR(DIE_COMPLETE) } @@ -153,16 +155,60 @@ void die_map_add_linebreak(struct die *pd, int linebreak); void die_map_add_die(struct die *pd, struct die *child); void die_map_free(void); +/* + * cache.c + */ + +#define CACHE_HASH_BITS 10 + +/* A cache for addresses we've already seen. */ +struct cache { + HASHTABLE_DECLARE(cache, 1 << CACHE_HASH_BITS); +}; + +void cache_set(struct cache *cache, unsigned long key, int value); +int cache_get(struct cache *cache, unsigned long key); +void cache_init(struct cache *cache); +void cache_free(struct cache *cache); + +static inline void __cache_mark_expanded(struct cache *cache, uintptr_t addr) +{ + cache_set(cache, addr, 1); +} + +static inline bool __cache_was_expanded(struct cache *cache, uintptr_t addr) +{ + return cache_get(cache, addr) == 1; +} + +static inline void cache_mark_expanded(struct cache *cache, void *addr) +{ + __cache_mark_expanded(cache, (uintptr_t)addr); +} + +static inline bool cache_was_expanded(struct cache *cache, void *addr) +{ + return __cache_was_expanded(cache, (uintptr_t)addr); +} + /* * dwarf.c */ +struct expansion_state { + bool expand; +}; + struct state { struct symbol *sym; Dwarf_Die die; /* List expansion */ bool first_list_item; + + /* Structure expansion */ + struct expansion_state expand; + struct cache expansion_cache; }; typedef int (*die_callback_t)(struct state *state, struct die *cache,