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objtool: Add several performance improvements

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Use hash tables for instruction and rela lookups (and keep the linked
lists around for sequential access).

Also cache the section struct for the "__func_stack_frame_non_standard"
section.

With this change, "objtool check net/wireless/nl80211.o" goes from:

  real	0m1.168s
  user	0m1.163s
  sys	0m0.005s

to:

  real	0m0.059s
  user	0m0.042s
  sys	0m0.017s

for a 20x speedup.

With the same object, it should be noted that the memory heap usage grew
from 8MB to 62MB.  Reducing the memory usage is on the TODO list.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/dd0d8e1449506cfa7701b4e7ba73577077c44253.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-03-09 00:07:00 -06:00 • committed by Ingo Molnar
parent 1698872b5c
commit 042ba73fe7
3 changed files with 35 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

18
tools/objtool/builtin-check.c
View file

@ -34,6 +34,8 @@
#include "arch.h"
#include "warn.h"
#include <linux/hashtable.h>
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#define STATE_FP_SAVED 0x1
@ -42,6 +44,7 @@
struct instruction {
struct list_head list;
struct hlist_node hash;
struct section *sec;
unsigned long offset;
unsigned int len, state;
@ -61,7 +64,8 @@ struct alternative {
struct objtool_file {
struct elf *elf;
struct list_head insn_list;
struct section *rodata;
DECLARE_HASHTABLE(insn_hash, 16);
struct section *rodata, *whitelist;
};
const char *objname;
@ -72,7 +76,7 @@ static struct instruction *find_insn(struct objtool_file *file,
{
struct instruction *insn;
list_for_each_entry(insn, &file->insn_list, list)
hash_for_each_possible(file->insn_hash, insn, hash, offset)
if (insn->sec == sec && insn->offset == offset)
return insn;
@ -111,14 +115,12 @@ static struct instruction *next_insn_same_sec(struct objtool_file *file,
*/
static bool ignore_func(struct objtool_file *file, struct symbol *func)
{
struct section *macro_sec;
struct rela *rela;
struct instruction *insn;
/* check for STACK_FRAME_NON_STANDARD */
macro_sec = find_section_by_name(file->elf, "__func_stack_frame_non_standard");
if (macro_sec && macro_sec->rela)
list_for_each_entry(rela, &macro_sec->rela->rela_list, list)
if (file->whitelist && file->whitelist->rela)
list_for_each_entry(rela, &file->whitelist->rela->rela_list, list)
if (rela->sym->sec == func->sec &&
rela->addend == func->offset)
return true;
@ -276,6 +278,7 @@ static int decode_instructions(struct objtool_file *file)
return -1;
}
hash_add(file->insn_hash, &insn->hash, insn->offset);
list_add_tail(&insn->list, &file->insn_list);
}
}
@ -729,6 +732,7 @@ static int decode_sections(struct objtool_file *file)
{
int ret;
file->whitelist = find_section_by_name(file->elf, "__func_stack_frame_non_standard");
file->rodata = find_section_by_name(file->elf, ".rodata");
ret = decode_instructions(file);
@ -1091,6 +1095,7 @@ static void cleanup(struct objtool_file *file)
free(alt);
}
list_del(&insn->list);
hash_del(&insn->hash);
free(insn);
}
elf_close(file->elf);
@ -1125,6 +1130,7 @@ int cmd_check(int argc, const char **argv)
}
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
ret = decode_sections(&file);
if (ret < 0)