leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

objtool: Optimize read_sections()

Browse Source 
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@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.739153726@infradead.org
This commit is contained in:
Peter Zijlstra
2020-03-12 11:23:36 +01:00
parent cdb3d057a1
commit 8b5fa6bc32
5 changed files with 47 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
tools/objtool/elf.c
View File

@@ -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) {