[tip: objtool/core] objtool: Use sec_offset_hash() for insn_hash

From: tip-bot2 for Peter Zijlstra
Date: Wed Apr 22 2020 - 18:24:52 EST


The following commit has been merged into the objtool/core branch of tip:

Commit-ID: e499ccee47c429be75dee8a94d8f289aa133e3a0
Gitweb: https://git.kernel.org/tip/e499ccee47c429be75dee8a94d8f289aa133e3a0
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 16 Mar 2020 15:47:27 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 22 Apr 2020 23:10:07 +02:00

objtool: Use sec_offset_hash() for insn_hash

In preparation for find_insn_containing(), change insn_hash to use
sec_offset_hash().

This actually reduces runtime; probably because mixing in the section
index reduces the collisions due to text sections all starting their
instructions at offset 0.

Runtime on vmlinux.o from 3.1 to 2.5 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200416115119.227240432@xxxxxxxxxxxxx
---
tools/objtool/check.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 39d1d4f..584f221 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -34,9 +34,10 @@ struct instruction *find_insn(struct objtool_file *file,
{
struct instruction *insn;

- hash_for_each_possible(file->insn_hash, insn, hash, offset)
+ hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
if (insn->sec == sec && insn->offset == offset)
return insn;
+ }

return NULL;
}
@@ -282,7 +283,7 @@ static int decode_instructions(struct objtool_file *file)
if (ret)
goto err;

- hash_add(file->insn_hash, &insn->hash, insn->offset);
+ hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
list_add_tail(&insn->list, &file->insn_list);
nr_insns++;
}