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authorPeter Zijlstra <peterz@infradead.org>2020-03-12 11:32:10 +0300
committerPeter Zijlstra <peterz@infradead.org>2020-03-25 20:28:29 +0300
commitae358196fac3a0b4d2a7d47a4f401e3421027b03 (patch)
tree183b84e1a566c504bffc71cb65afea6270d96135 /tools/objtool/elf.c
parent530389968739883a61192767e1c215653ba4ba2b (diff)
downloadlinux-ae358196fac3a0b4d2a7d47a4f401e3421027b03.tar.xz
objtool: Optimize find_section_by_name()
In order to avoid yet another linear search of (20k) sections, add a name based hash. This reduces objtool runtime on vmlinux.o by some 10s to around 35s. 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/20200324160924.440174280@infradead.org
Diffstat (limited to 'tools/objtool/elf.c')
-rw-r--r--tools/objtool/elf.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 900771365ae3..20fe40d5101d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -22,11 +22,16 @@
#define MAX_NAME_LEN 128
+static inline u32 str_hash(const char *str)
+{
+ return jhash(str, strlen(str), 0);
+}
+
struct section *find_section_by_name(struct elf *elf, const char *name)
{
struct section *sec;
- list_for_each_entry(sec, &elf->sections, list)
+ hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
if (!strcmp(sec->name, name))
return sec;
@@ -202,6 +207,7 @@ static int read_sections(struct elf *elf)
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));
}
if (stats)
@@ -441,6 +447,7 @@ struct elf *elf_read(const char *name, int flags)
hash_init(elf->symbol_hash);
hash_init(elf->section_hash);
+ hash_init(elf->section_name_hash);
INIT_LIST_HEAD(&elf->sections);
elf->fd = open(name, flags);
@@ -581,6 +588,7 @@ struct section *elf_create_section(struct elf *elf, const char *name,
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));
return sec;
}