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objtool: Optimize read_sections()

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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

21
tools/objtool/elf.h
View File

@@ -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);