From 65fb11a7f6aeae678043738d06248a4e21f4e4e4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 10 Mar 2020 18:39:45 +0100 Subject: [PATCH] objtool: Optimize find_symbol_by_index() The symbol index is object wide, not per section, so it makes no sense to have the symbol_hash be part of the section object. By moving it to the elf object we avoid the linear sections iteration. This reduces the runtime of objtool on vmlinux.o from over 3 hours (I gave up) to a few minutes. The defconfig vmlinux.o has around 20k sections. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200324160924.261852348@infradead.org --- tools/objtool/elf.c | 13 +++++-------- tools/objtool/elf.h | 3 +-- 2 files changed, 6 insertions(+), 10 deletions(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index cc4601c..b188b3e 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -46,13 +46,11 @@ static struct section *find_section_by_index(struct elf *elf, static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) { - struct section *sec; struct symbol *sym; - list_for_each_entry(sec, &elf->sections, list) - hash_for_each_possible(sec->symbol_hash, sym, hash, idx) - if (sym->idx == idx) - return sym; + hash_for_each_possible(elf->symbol_hash, sym, hash, idx) + if (sym->idx == idx) + return sym; return NULL; } @@ -166,7 +164,6 @@ static int read_sections(struct elf *elf) INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); - hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); @@ -299,7 +296,7 @@ static int read_symbols(struct elf *elf) } sym->alias = alias; list_add(&sym->list, entry); - hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); + hash_add(elf->symbol_hash, &sym->hash, sym->idx); } /* Create parent/child links for any cold subfunctions */ @@ -425,6 +422,7 @@ struct elf *elf_read(const char *name, int flags) } memset(elf, 0, sizeof(*elf)); + hash_init(elf->symbol_hash); INIT_LIST_HEAD(&elf->sections); elf->fd = open(name, flags); @@ -486,7 +484,6 @@ struct section *elf_create_section(struct elf *elf, const char *name, INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); - hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index a196325..1222980 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -27,7 +27,6 @@ struct section { struct list_head list; GElf_Shdr sh; struct list_head symbol_list; - DECLARE_HASHTABLE(symbol_hash, 8); struct list_head rela_list; DECLARE_HASHTABLE(rela_hash, 16); struct section *base, *rela; @@ -71,7 +70,7 @@ struct elf { int fd; char *name; struct list_head sections; - DECLARE_HASHTABLE(rela_hash, 16); + DECLARE_HASHTABLE(symbol_hash, 20); }; -- 2.7.4