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

[tip-bot2 for Peter Zijlstra]

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

Commit-ID:     87ecb582f0ac85886398dde8c3cdb2225cac7786
Gitweb:        https://git.kernel.org/tip/87ecb582f0ac85886398dde8c3cdb2225cac7786
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Mon, 16 Mar 2020 15:47:27 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 22 Apr 2020 10:53:50 +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
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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 87e528c..923652b 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++;
 		}