The following commit has been merged into the core/objtool branch of tip: Commit-ID: 8b5fa6bc326bf02f293b5a39a8f5b3de816265d3 Gitweb: https://git.kernel.org/tip/8b5fa6bc326bf02f293b5a39a8f5b3de816265d3 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Thu, 12 Mar 2020 11:23:36 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 25 Mar 2020 18:28:30 +01:00 objtool: Optimize read_sections() Perf showed that __hash_init() is a significant portion of read_sections(), so instead of doing a per section rela_hash, use an elf-wide rela_hash. Statistics show us there are about 1.1 million relas, so size it accordingly. This reduces the objtool on vmlinux.o runtime to a third, from 15 to 5 seconds. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Miroslav Benes <mbenes@xxxxxxx> Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20200324160924.739153726@xxxxxxxxxxxxx --- tools/objtool/check.c | 18 +++++++++--------- tools/objtool/elf.c | 24 ++++++++++++++---------- tools/objtool/elf.h | 21 +++++++++++++++++---- tools/objtool/orc_gen.c | 9 +++++---- tools/objtool/special.c | 4 ++-- 5 files changed, 47 insertions(+), 29 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 6df1bae..54a6043 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -569,8 +569,8 @@ static int add_jump_destinations(struct objtool_file *file) if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) continue; - rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); + rela = find_rela_by_dest_range(file->elf, insn->sec, + insn->offset, insn->len); if (!rela) { dest_sec = insn->sec; dest_off = insn->offset + insn->len + insn->immediate; @@ -666,8 +666,8 @@ static int add_call_destinations(struct objtool_file *file) if (insn->type != INSN_CALL) continue; - rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); + rela = find_rela_by_dest_range(file->elf, insn->sec, + insn->offset, insn->len); if (!rela) { dest_off = insn->offset + insn->len + insn->immediate; insn->call_dest = find_func_by_offset(insn->sec, dest_off); @@ -796,7 +796,7 @@ static int handle_group_alt(struct objtool_file *file, */ if ((insn->offset != special_alt->new_off || (insn->type != INSN_CALL && !is_static_jump(insn))) && - find_rela_by_dest_range(insn->sec, insn->offset, insn->len)) { + find_rela_by_dest_range(file->elf, insn->sec, insn->offset, insn->len)) { WARN_FUNC("unsupported relocation in alternatives section", insn->sec, insn->offset); @@ -1066,8 +1066,8 @@ static struct rela *find_jump_table(struct objtool_file *file, break; /* look for a relocation which references .rodata */ - text_rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); + text_rela = find_rela_by_dest_range(file->elf, insn->sec, + insn->offset, insn->len); if (!text_rela || text_rela->sym->type != STT_SECTION || !text_rela->sym->sec->rodata) continue; @@ -1096,7 +1096,7 @@ static struct rela *find_jump_table(struct objtool_file *file, * should reference text in the same function as the original * instruction. */ - table_rela = find_rela_by_dest(table_sec, table_offset); + table_rela = find_rela_by_dest(file->elf, table_sec, table_offset); if (!table_rela) continue; dest_insn = find_insn(file, table_rela->sym->sec, table_rela->addend); @@ -1232,7 +1232,7 @@ static int read_unwind_hints(struct objtool_file *file) for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { hint = (struct unwind_hint *)sec->data->d_buf + i; - rela = find_rela_by_dest(sec, i * sizeof(*hint)); + rela = find_rela_by_dest(file->elf, sec, i * sizeof(*hint)); if (!rela) { WARN("can't find rela for unwind_hints[%d]", i); return -1; diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 43abae7..8a0a1bc 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -212,8 +212,8 @@ struct symbol *find_symbol_by_name(struct elf *elf, const char *name) return NULL; } -struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, - unsigned int len) +struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec, + unsigned long offset, unsigned int len) { struct rela *rela; unsigned long o; @@ -221,17 +221,22 @@ struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, if (!sec->rela) return NULL; - for (o = offset; o < offset + len; o++) - hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) - if (rela->offset == o) + sec = sec->rela; + + for (o = offset; o < offset + len; o++) { + hash_for_each_possible(elf->rela_hash, rela, hash, + sec_offset_hash(sec, o)) { + if (rela->sec == sec && rela->offset == o) return rela; + } + } return NULL; } -struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) +struct rela *find_rela_by_dest(struct elf *elf, struct section *sec, unsigned long offset) { - return find_rela_by_dest_range(sec, offset, 1); + return find_rela_by_dest_range(elf, sec, offset, 1); } static int read_sections(struct elf *elf) @@ -261,7 +266,6 @@ static int read_sections(struct elf *elf) INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); - hash_init(sec->rela_hash); s = elf_getscn(elf->elf, i); if (!s) { @@ -493,7 +497,7 @@ static int read_relas(struct elf *elf) } list_add_tail(&rela->list, &sec->rela_list); - hash_add(sec->rela_hash, &rela->hash, rela->offset); + hash_add(elf->rela_hash, &rela->hash, rela_hash(rela)); nr_rela++; } max_rela = max(max_rela, nr_rela); @@ -526,6 +530,7 @@ struct elf *elf_read(const char *name, int flags) 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->fd = open(name, flags); @@ -586,7 +591,6 @@ 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); s = elf_newscn(elf->elf); if (!s) { diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index 3088d92..dfd2431 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -33,7 +33,6 @@ struct section { struct rb_root symbol_tree; struct list_head symbol_list; struct list_head rela_list; - DECLARE_HASHTABLE(rela_hash, 16); struct section *base, *rela; struct symbol *sym; Elf_Data *data; @@ -81,8 +80,22 @@ struct elf { DECLARE_HASHTABLE(symbol_name_hash, 20); DECLARE_HASHTABLE(section_hash, 16); DECLARE_HASHTABLE(section_name_hash, 16); + DECLARE_HASHTABLE(rela_hash, 20); }; +static inline u32 sec_offset_hash(struct section *sec, unsigned long offset) +{ + u32 ol = offset, oh = offset >> 32, idx = sec->idx; + + __jhash_mix(ol, oh, idx); + + return ol; +} + +static inline u32 rela_hash(struct rela *rela) +{ + return sec_offset_hash(rela->sec, rela->offset); +} struct elf *elf_read(const char *name, int flags); struct section *find_section_by_name(struct elf *elf, const char *name); @@ -90,9 +103,9 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset); struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset); struct symbol *find_symbol_by_name(struct elf *elf, const char *name); struct symbol *find_symbol_containing(struct section *sec, unsigned long offset); -struct rela *find_rela_by_dest(struct section *sec, unsigned long offset); -struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, - unsigned int len); +struct rela *find_rela_by_dest(struct elf *elf, struct section *sec, unsigned long offset); +struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec, + unsigned long offset, unsigned int len); struct symbol *find_func_containing(struct section *sec, unsigned long offset); struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr); diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c index 27a4112..41e4a27 100644 --- a/tools/objtool/orc_gen.c +++ b/tools/objtool/orc_gen.c @@ -81,7 +81,7 @@ int create_orc(struct objtool_file *file) return 0; } -static int create_orc_entry(struct section *u_sec, struct section *ip_relasec, +static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relasec, unsigned int idx, struct section *insn_sec, unsigned long insn_off, struct orc_entry *o) { @@ -109,9 +109,10 @@ static int create_orc_entry(struct section *u_sec, struct section *ip_relasec, rela->addend = insn_off; rela->type = R_X86_64_PC32; rela->offset = idx * sizeof(int); + rela->sec = ip_relasec; list_add_tail(&rela->list, &ip_relasec->rela_list); - hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset); + hash_add(elf->rela_hash, &rela->hash, rela_hash(rela)); return 0; } @@ -182,7 +183,7 @@ int create_orc_sections(struct objtool_file *file) if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc, sizeof(struct orc_entry))) { - if (create_orc_entry(u_sec, ip_relasec, idx, + if (create_orc_entry(file->elf, u_sec, ip_relasec, idx, insn->sec, insn->offset, &insn->orc)) return -1; @@ -194,7 +195,7 @@ int create_orc_sections(struct objtool_file *file) /* section terminator */ if (prev_insn) { - if (create_orc_entry(u_sec, ip_relasec, idx, + if (create_orc_entry(file->elf, u_sec, ip_relasec, idx, prev_insn->sec, prev_insn->offset + prev_insn->len, &empty)) diff --git a/tools/objtool/special.c b/tools/objtool/special.c index fdbaa61..e74e018 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -118,7 +118,7 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry, } } - orig_rela = find_rela_by_dest(sec, offset + entry->orig); + orig_rela = find_rela_by_dest(elf, sec, offset + entry->orig); if (!orig_rela) { WARN_FUNC("can't find orig rela", sec, offset + entry->orig); return -1; @@ -133,7 +133,7 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry, alt->orig_off = orig_rela->addend; if (!entry->group || alt->new_len) { - new_rela = find_rela_by_dest(sec, offset + entry->new); + new_rela = find_rela_by_dest(elf, sec, offset + entry->new); if (!new_rela) { WARN_FUNC("can't find new rela", sec, offset + entry->new);
![]() |