From 34f7c96d96d5e11b03a612017fcc3a6e645bb481 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 12 Mar 2020 14:29:38 +0100 Subject: [PATCH] objtool: Optimize !vmlinux.o again When doing kbuild tests to see if the objtool changes affected those I found that there was a measurable regression: pre post real 1m13.594 1m16.488s user 34m58.246s 35m23.947s sys 4m0.393s 4m27.312s Perf showed that for small files the increased hash-table sizes were a measurable difference. Since we already have -l "vmlinux" to distinguish between the modes, make it also use a smaller portion of the hash-tables. This flips it into a small win: real 1m14.143s user 34m49.292s sys 3m44.746s Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200416115119.167588731@infradead.org Signed-off-by: Ingo Molnar --- tools/objtool/elf.c | 62 ++++++++++++++++++++++++++++++++++--------------- tools/objtool/elf.h | 13 +++++++---- tools/objtool/orc_gen.c | 3 +-- 3 files changed, 52 insertions(+), 26 deletions(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index c4857fa..f26bb3e 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -27,6 +27,22 @@ static inline u32 str_hash(const char *str) return jhash(str, strlen(str), 0); } +static inline int elf_hash_bits(void) +{ + return vmlinux ? ELF_HASH_BITS : 16; +} + +#define elf_hash_add(hashtable, node, key) \ + hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())]) + +static void elf_hash_init(struct hlist_head *table) +{ + __hash_init(table, 1U << elf_hash_bits()); +} + +#define elf_hash_for_each_possible(name, obj, member, key) \ + hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member) + static void rb_add(struct rb_root *tree, struct rb_node *node, int (*cmp)(struct rb_node *, const struct rb_node *)) { @@ -115,7 +131,7 @@ struct section *find_section_by_name(struct elf *elf, const char *name) { struct section *sec; - hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name)) + elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name)) if (!strcmp(sec->name, name)) return sec; @@ -127,7 +143,7 @@ static struct section *find_section_by_index(struct elf *elf, { struct section *sec; - hash_for_each_possible(elf->section_hash, sec, hash, idx) + elf_hash_for_each_possible(elf->section_hash, sec, hash, idx) if (sec->idx == idx) return sec; @@ -138,7 +154,7 @@ static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) { struct symbol *sym; - hash_for_each_possible(elf->symbol_hash, sym, hash, idx) + elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx) if (sym->idx == idx) return sym; @@ -205,7 +221,7 @@ struct symbol *find_symbol_by_name(struct elf *elf, const char *name) { struct symbol *sym; - hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name)) + elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name)) if (!strcmp(sym->name, name)) return sym; @@ -224,7 +240,7 @@ struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec, sec = sec->rela; for_offset_range(o, offset, offset + len) { - hash_for_each_possible(elf->rela_hash, rela, hash, + elf_hash_for_each_possible(elf->rela_hash, rela, hash, sec_offset_hash(sec, o)) { if (rela->sec != sec) continue; @@ -309,8 +325,8 @@ static int read_sections(struct elf *elf) sec->len = sec->sh.sh_size; list_add_tail(&sec->list, &elf->sections); - hash_add(elf->section_hash, &sec->hash, sec->idx); - hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); + elf_hash_add(elf->section_hash, &sec->hash, sec->idx); + elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); } if (stats) @@ -394,8 +410,8 @@ static int read_symbols(struct elf *elf) else entry = &sym->sec->symbol_list; list_add(&sym->list, entry); - hash_add(elf->symbol_hash, &sym->hash, sym->idx); - hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name)); + elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx); + elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name)); } if (stats) @@ -456,6 +472,14 @@ err: return -1; } +void elf_add_rela(struct elf *elf, struct rela *rela) +{ + struct section *sec = rela->sec; + + list_add_tail(&rela->list, &sec->rela_list); + elf_hash_add(elf->rela_hash, &rela->hash, rela_hash(rela)); +} + static int read_relas(struct elf *elf) { struct section *sec; @@ -503,8 +527,7 @@ static int read_relas(struct elf *elf) return -1; } - list_add_tail(&rela->list, &sec->rela_list); - hash_add(elf->rela_hash, &rela->hash, rela_hash(rela)); + elf_add_rela(elf, rela); nr_rela++; } max_rela = max(max_rela, nr_rela); @@ -531,15 +554,16 @@ struct elf *elf_read(const char *name, int flags) perror("malloc"); return NULL; } - memset(elf, 0, sizeof(*elf)); + memset(elf, 0, offsetof(struct elf, sections)); - hash_init(elf->symbol_hash); - hash_init(elf->symbol_name_hash); - hash_init(elf->section_hash); - hash_init(elf->section_name_hash); - hash_init(elf->rela_hash); INIT_LIST_HEAD(&elf->sections); + elf_hash_init(elf->symbol_hash); + elf_hash_init(elf->symbol_name_hash); + elf_hash_init(elf->section_hash); + elf_hash_init(elf->section_name_hash); + elf_hash_init(elf->rela_hash); + elf->fd = open(name, flags); if (elf->fd == -1) { fprintf(stderr, "objtool: Can't open '%s': %s\n", @@ -676,8 +700,8 @@ struct section *elf_create_section(struct elf *elf, const char *name, shstrtab->changed = true; list_add_tail(&sec->list, &elf->sections); - hash_add(elf->section_hash, &sec->hash, sec->idx); - hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); + elf_hash_add(elf->section_hash, &sec->hash, sec->idx); + elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name)); return sec; } diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index eb79cb9..2811d04 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -70,17 +70,19 @@ struct rela { bool jump_table_start; }; +#define ELF_HASH_BITS 20 + struct elf { Elf *elf; GElf_Ehdr ehdr; int fd; char *name; struct list_head sections; - DECLARE_HASHTABLE(symbol_hash, 20); - DECLARE_HASHTABLE(symbol_name_hash, 20); - DECLARE_HASHTABLE(section_hash, 16); - DECLARE_HASHTABLE(section_name_hash, 16); - DECLARE_HASHTABLE(rela_hash, 20); + DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS); + DECLARE_HASHTABLE(symbol_name_hash, ELF_HASH_BITS); + DECLARE_HASHTABLE(section_hash, ELF_HASH_BITS); + DECLARE_HASHTABLE(section_name_hash, ELF_HASH_BITS); + DECLARE_HASHTABLE(rela_hash, ELF_HASH_BITS); }; #define OFFSET_STRIDE_BITS 4 @@ -127,6 +129,7 @@ struct section *elf_create_rela_section(struct elf *elf, struct section *base); int elf_rebuild_rela_section(struct section *sec); int elf_write(struct elf *elf); void elf_close(struct elf *elf); +void elf_add_rela(struct elf *elf, struct rela *rela); #define for_each_sec(file, sec) \ list_for_each_entry(sec, &file->elf->sections, list) diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c index 2cf640f..9d2bf2d 100644 --- a/tools/objtool/orc_gen.c +++ b/tools/objtool/orc_gen.c @@ -130,8 +130,7 @@ static int create_orc_entry(struct elf *elf, struct section *u_sec, struct secti rela->offset = idx * sizeof(int); rela->sec = ip_relasec; - list_add_tail(&rela->list, &ip_relasec->rela_list); - hash_add(elf->rela_hash, &rela->hash, rela_hash(rela)); + elf_add_rela(elf, rela); return 0; } -- 2.7.4