From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
peterz@infradead.org, mhiramat@kernel.org, mbenes@suse.cz,
brgerst@gmail.com
Subject: [PATCH v2 08/19] objtool: Optimize find_section_by_name()
Date: Tue, 17 Mar 2020 18:02:42 +0100 [thread overview]
Message-ID: <20200317170910.238357020@infradead.org> (raw)
In-Reply-To: 20200317170234.897520633@infradead.org
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>
---
tools/objtool/elf.c | 10 +++++++++-
tools/objtool/elf.h | 3 +++
2 files changed, 12 insertions(+), 1 deletion(-)
--- 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, i
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(struc
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;
}
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -10,6 +10,7 @@
#include <gelf.h>
#include <linux/list.h>
#include <linux/hashtable.h>
+#include <linux/jhash.h>
#ifdef LIBELF_USE_DEPRECATED
# define elf_getshdrnum elf_getshnum
@@ -26,6 +27,7 @@
struct section {
struct list_head list;
struct hlist_node hash;
+ struct hlist_node name_hash;
GElf_Shdr sh;
struct list_head symbol_list;
struct list_head rela_list;
@@ -73,6 +75,7 @@ struct elf {
struct list_head sections;
DECLARE_HASHTABLE(symbol_hash, 20);
DECLARE_HASHTABLE(section_hash, 16);
+ DECLARE_HASHTABLE(section_name_hash, 16);
};
next prev parent reply other threads:[~2020-03-17 17:12 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 17:02 [PATCH v2 00/19] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 01/19] objtool: Introduce validate_return() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 02/19] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 03/19] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 04/19] x86/kexec: Use RIP relative addressing Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 05/19] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 06/19] objtool: Add a statistics mode Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 07/19] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-17 17:02 ` Peter Zijlstra [this message]
2020-03-17 17:02 ` [PATCH v2 09/19] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 10/19] objtool: Rename find_containing_func() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 11/19] objtool: Resize insn_hash Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 12/19] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 13/19] objtool: Optimize read_sections() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 14/19] objtool: Delete cleanup() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 15/19] objtool: Optimize find_rela_by_dest_range() Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 16/19] objtool: Implement noinstr validation Peter Zijlstra
2020-03-17 21:00 ` Josh Poimboeuf
2020-03-18 9:03 ` Peter Zijlstra
2020-03-18 10:06 ` Peter Zijlstra
2020-03-18 13:21 ` Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 17/19] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-18 13:20 ` Peter Zijlstra
2020-03-20 16:20 ` Miroslav Benes
2020-03-21 15:14 ` Peter Zijlstra
2020-03-21 16:11 ` Peter Zijlstra
2020-03-23 7:27 ` Miroslav Benes
2020-03-17 17:02 ` [PATCH v2 18/19] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-03-17 17:02 ` [PATCH v2 19/19] objtool: Detect loading function pointers across noinstr Peter Zijlstra
2020-03-17 23:39 ` kbuild test robot
2020-03-17 23:43 ` Nick Desaulniers
2020-03-18 11:02 ` Peter Zijlstra
2020-03-18 7:18 ` kbuild test robot
2020-03-17 21:05 ` [PATCH v2 00/19] objtool: vmlinux.o and noinstr validation Josh Poimboeuf
2020-03-18 13:18 ` [RFC][PATCH v2 20/19] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-03-18 14:13 ` Peter Zijlstra
2020-03-18 18:34 ` Josh Poimboeuf
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