Calculate symbol versions from the fully expanded type strings in type_map, and output the versions in a genksyms-compatible format.
Signed-off-by: Sami Tolvanen <samitolva...@google.com> Acked-by: Neal Gompa <n...@gompa.dev> --- scripts/gendwarfksyms/dwarf.c | 25 +++++- scripts/gendwarfksyms/gendwarfksyms.c | 10 ++- scripts/gendwarfksyms/gendwarfksyms.h | 13 ++- scripts/gendwarfksyms/symbols.c | 53 +++++++++++ scripts/gendwarfksyms/types.c | 122 +++++++++++++++++++++++++- 5 files changed, 215 insertions(+), 8 deletions(-) diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c index 3d2c1aa24960..1f63f28add4b 100644 --- a/scripts/gendwarfksyms/dwarf.c +++ b/scripts/gendwarfksyms/dwarf.c @@ -725,12 +725,33 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die) /* * Exported symbol processing */ +static struct die *get_symbol_cache(struct state *state, Dwarf_Die *die) +{ + struct die *cache; + + cache = die_map_get(die, DIE_SYMBOL); + + if (cache->state != DIE_INCOMPLETE) + return NULL; /* We already processed a symbol for this DIE */ + + cache->tag = dwarf_tag(die); + return cache; +} + static void process_symbol(struct state *state, Dwarf_Die *die, die_callback_t process_func) { + struct die *cache; + + symbol_set_die(state->sym, die); + + cache = get_symbol_cache(state, die); + if (!cache) + return; + debug("%s", state->sym->name); - check(process_func(state, NULL, die)); - state->sym->state = SYMBOL_MAPPED; + check(process_func(state, cache, die)); + cache->state = DIE_SYMBOL; if (dump_dies) fputs("\n", stderr); } diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c index 76a38b733ad2..fd2429ea198f 100644 --- a/scripts/gendwarfksyms/gendwarfksyms.c +++ b/scripts/gendwarfksyms/gendwarfksyms.c @@ -23,6 +23,8 @@ int dump_dies; int dump_die_map; /* Print out type strings (i.e. type_map) */ int dump_types; +/* Print out expanded type strings used for symbol versions */ +int dump_versions; /* Write a symtypes file */ int symtypes; static const char *symtypes_file; @@ -35,6 +37,7 @@ static void usage(void) " --dump-dies Dump DWARF DIE contents\n" " --dump-die-map Print debugging information about die_map changes\n" " --dump-types Dump type strings\n" + " --dump-versions Dump expanded type strings used for symbol versions\n" " -T, --symtypes file Write a symtypes file\n" " -h, --help Print this message\n" "\n", @@ -69,9 +72,10 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name, } while (cu); /* - * Use die_map to expand type strings and write them to `symfile`. + * Use die_map to expand type strings, write them to `symfile`, and + * calculate symbol versions. */ - generate_symtypes(symfile); + generate_symtypes_and_versions(symfile); die_map_free(); return DWARF_CB_OK; @@ -92,6 +96,7 @@ int main(int argc, char **argv) { "dump-dies", 0, &dump_dies, 1 }, { "dump-die-map", 0, &dump_die_map, 1 }, { "dump-types", 0, &dump_types, 1 }, + { "dump-versions", 0, &dump_versions, 1 }, { "symtypes", 1, NULL, 'T' }, { "help", 0, NULL, 'h' }, { 0, 0, NULL, 0 } }; @@ -164,6 +169,7 @@ int main(int argc, char **argv) if (symfile) check(fclose(symfile)); + symbol_print_versions(); symbol_free(); return 0; diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h index 835ebcea6e97..88a9c1c5db20 100644 --- a/scripts/gendwarfksyms/gendwarfksyms.h +++ b/scripts/gendwarfksyms/gendwarfksyms.h @@ -26,6 +26,7 @@ extern int debug; extern int dump_dies; extern int dump_die_map; extern int dump_types; +extern int dump_versions; extern int symtypes; /* @@ -98,6 +99,7 @@ static inline unsigned int addr_hash(uintptr_t addr) enum symbol_state { SYMBOL_UNPROCESSED, SYMBOL_MAPPED, + SYMBOL_PROCESSED }; struct symbol_addr { @@ -112,6 +114,7 @@ struct symbol { struct hlist_node name_hash; enum symbol_state state; uintptr_t die_addr; + unsigned long crc; }; typedef void (*symbol_callback_t)(struct symbol *, void *arg); @@ -119,6 +122,10 @@ typedef void (*symbol_callback_t)(struct symbol *, void *arg); void symbol_read_exports(FILE *file); void symbol_read_symtab(int fd); struct symbol *symbol_get(const char *name); +void symbol_set_die(struct symbol *sym, Dwarf_Die *die); +void symbol_set_crc(struct symbol *sym, unsigned long crc); +void symbol_for_each(symbol_callback_t func, void *arg); +void symbol_print_versions(void); void symbol_free(void); /* @@ -129,7 +136,8 @@ enum die_state { DIE_INCOMPLETE, DIE_UNEXPANDED, DIE_COMPLETE, - DIE_LAST = DIE_COMPLETE + DIE_SYMBOL, + DIE_LAST = DIE_SYMBOL }; enum die_fragment_type { @@ -159,6 +167,7 @@ static inline const char *die_state_name(enum die_state state) CASE_CONST_TO_STR(DIE_INCOMPLETE) CASE_CONST_TO_STR(DIE_UNEXPANDED) CASE_CONST_TO_STR(DIE_COMPLETE) + CASE_CONST_TO_STR(DIE_SYMBOL) } error("unexpected die_state: %d", state); @@ -246,6 +255,6 @@ void process_cu(Dwarf_Die *cudie); * types.c */ -void generate_symtypes(FILE *file); +void generate_symtypes_and_versions(FILE *file); #endif /* __GENDWARFKSYMS_H */ diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c index 6ed0c4769e6f..e0c9007f7250 100644 --- a/scripts/gendwarfksyms/symbols.c +++ b/scripts/gendwarfksyms/symbols.c @@ -66,6 +66,36 @@ static unsigned int for_each(const char *name, symbol_callback_t func, return 0; } +static void set_crc(struct symbol *sym, void *data) +{ + unsigned long *crc = data; + + if (sym->state == SYMBOL_PROCESSED && sym->crc != *crc) + warn("overriding version for symbol %s (crc %lx vs. %lx)", + sym->name, sym->crc, *crc); + + sym->state = SYMBOL_PROCESSED; + sym->crc = *crc; +} + +void symbol_set_crc(struct symbol *sym, unsigned long crc) +{ + if (for_each(sym->name, set_crc, &crc) == 0) + error("no matching symbols: '%s'", sym->name); +} + +static void set_die(struct symbol *sym, void *data) +{ + sym->die_addr = (uintptr_t)((Dwarf_Die *)data)->addr; + sym->state = SYMBOL_MAPPED; +} + +void symbol_set_die(struct symbol *sym, Dwarf_Die *die) +{ + if (for_each(sym->name, set_die, die) == 0) + error("no matching symbols: '%s'", sym->name); +} + static bool is_exported(const char *name) { return for_each(name, NULL, NULL) > 0; @@ -120,6 +150,16 @@ struct symbol *symbol_get(const char *name) return sym; } +void symbol_for_each(symbol_callback_t func, void *arg) +{ + struct hlist_node *tmp; + struct symbol *sym; + + hash_for_each_safe(symbol_names, sym, tmp, name_hash) { + func(sym, arg); + } +} + typedef void (*elf_symbol_callback_t)(const char *name, GElf_Sym *sym, Elf32_Word xndx, void *arg); @@ -244,6 +284,19 @@ void symbol_read_symtab(int fd) elf_for_each_global(fd, elf_set_symbol_addr, NULL); } +void symbol_print_versions(void) +{ + struct hlist_node *tmp; + struct symbol *sym; + + hash_for_each_safe(symbol_names, sym, tmp, name_hash) { + if (sym->state != SYMBOL_PROCESSED) + warn("no information for symbol %s", sym->name); + + printf("#SYMVER %s 0x%08lx\n", sym->name, sym->crc); + } +} + void symbol_free(void) { struct hlist_node *tmp; diff --git a/scripts/gendwarfksyms/types.c b/scripts/gendwarfksyms/types.c index c05811299eba..08886063363c 100644 --- a/scripts/gendwarfksyms/types.c +++ b/scripts/gendwarfksyms/types.c @@ -3,6 +3,7 @@ * Copyright (C) 2024 Google LLC */ +#include <crc32.h> #include "gendwarfksyms.h" static struct expansion_cache expansion_cache; @@ -174,6 +175,33 @@ static void type_map_free(void) hash_init(type_map); } +/* + * CRC for a type, with an optional fully expanded type string for + * debugging. + */ +struct version { + struct type_expansion type; + unsigned long crc; +}; + +static void version_init(struct version *version) +{ + version->crc = 0xffffffff; + type_expansion_init(&version->type); +} + +static void version_free(struct version *version) +{ + type_expansion_free(&version->type); +} + +static void version_add(struct version *version, const char *s) +{ + version->crc = partial_crc32(s, version->crc); + if (dump_versions) + type_expansion_append(&version->type, s, NULL); +} + /* * Type reference format: <prefix>#<name>, where prefix: * s -> structure @@ -183,6 +211,12 @@ static void type_map_free(void) * * Names with spaces are additionally wrapped in single quotes. */ +static inline bool is_type_prefix(const char *s) +{ + return (s[0] == 's' || s[0] == 'u' || s[0] == 'e' || s[0] == 't') && + s[1] == '#'; +} + static char get_type_prefix(int tag) { switch (tag) { @@ -210,6 +244,8 @@ static char *get_type_name(struct die *cache) warn("found incomplete cache entry: %p", cache); return NULL; } + if (cache->state == DIE_SYMBOL) + return NULL; if (!cache->fqn || !*cache->fqn) return NULL; @@ -227,6 +263,39 @@ static char *get_type_name(struct die *cache) return name; } +static void __calculate_version(struct version *version, struct list_head *list) +{ + struct type_list_entry *entry; + struct type_expansion *e; + + /* Calculate a CRC over an expanded type string */ + list_for_each_entry(entry, list, list) { + if (is_type_prefix(entry->str)) { + check(type_map_get(entry->str, &e)); + + /* + * It's sufficient to expand each type reference just + * once to detect changes. + */ + if (cache_was_expanded(&expansion_cache, e)) { + version_add(version, entry->str); + } else { + cache_mark_expanded(&expansion_cache, e); + __calculate_version(version, &e->expanded); + } + } else { + version_add(version, entry->str); + } + } +} + +static void calculate_version(struct version *version, struct list_head *list) +{ + version_init(version); + __calculate_version(version, list); + cache_clear_expanded(&expansion_cache); +} + static void __type_expand(struct die *cache, struct type_expansion *type, bool recursive); @@ -333,7 +402,49 @@ static void expand_type(struct die *cache, void *arg) free(name); } -void generate_symtypes(FILE *file) +static void expand_symbol(struct symbol *sym, void *arg) +{ + struct type_expansion type; + struct version version; + struct die *cache; + + /* + * No need to expand again unless we want a symtypes file entry + * for the symbol. Note that this means `sym` has the same address + * as another symbol that was already processed. + */ + if (!symtypes && sym->state == SYMBOL_PROCESSED) + return; + + if (__die_map_get(sym->die_addr, DIE_SYMBOL, &cache)) + return; /* We'll warn about missing CRCs later. */ + + type_expand(cache, &type, false); + + /* If the symbol already has a version, don't calculate it again. */ + if (sym->state != SYMBOL_PROCESSED) { + calculate_version(&version, &type.expanded); + symbol_set_crc(sym, version.crc); + debug("%s = %lx", sym->name, version.crc); + + if (dump_versions) { + checkp(fputs(sym->name, stderr)); + checkp(fputs(" ", stderr)); + type_list_write(&version.type.expanded, stderr); + checkp(fputs("\n", stderr)); + } + + version_free(&version); + } + + /* These aren't needed in type_map unless we want a symtypes file. */ + if (symtypes) + type_map_add(sym->name, &type); + + type_expansion_free(&type); +} + +void generate_symtypes_and_versions(FILE *file) { hash_init(expansion_cache.cache); @@ -351,7 +462,14 @@ void generate_symtypes(FILE *file) die_map_for_each(expand_type, NULL); /* - * 2. If a symtypes file is requested, write type_map contents to + * 2. For each exported symbol, expand the die_map type, and use + * type_map expansions to calculate a symbol version from the + * fully expanded type string. + */ + symbol_for_each(expand_symbol, NULL); + + /* + * 3. If a symtypes file is requested, write type_map contents to * the file. */ type_map_write(file); -- 2.47.0.163.g1226f6d8fa-goog