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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) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.261852348@infradead.org
This commit is contained in:
Peter Zijlstra 2020-03-10 18:39:45 +01:00
parent 36cc552055
commit 65fb11a7f6
2 changed files with 6 additions and 10 deletions
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13
tools/objtool/elf.c
View File

@ -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);

3
tools/objtool/elf.h
View File

@ -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);
};