From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752356AbcEMLHw (ORCPT ); Fri, 13 May 2016 07:07:52 -0400 Received: from mail-wm0-f51.google.com ([74.125.82.51]:38455 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693AbcEMLHu (ORCPT ); Fri, 13 May 2016 07:07:50 -0400 To: Josh Poimboeuf Cc: "Linux-Kernel@Vger. Kernel. Org" From: Nikolay Borisov Subject: Stack trace of csum_partial_copy_generic Message-ID: <5735B583.6090500@kyup.com> Date: Fri, 13 May 2016 14:07:47 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Josh, I'd like to ask you whether objtool is supposed to produce a warning when arch/x86/lib/csum-copy_64.o (produced from arch/x86/lib/csum-copy_64.S). Since I cannot see any specific usage of rbp for defining a stackframe. I'm chasing against poor performance of a network benchmark and this is what perf produces: # Overhead Command Shared Object Symbol # ........ ............... ..................... ............................................. # 37.30% iperf [kernel.kallsyms] [k] csum_partial_copy_generic | --- csum_partial_copy_generic | |--99.98%-- 0x7f809108b7cd | | | |--69.72%-- 0x20000 | | | --30.28%-- 0x7f809108b7c2 | 0x20000 --0.02%-- [...] So this is not very helpful in tracing where this is being called from. Presumably somewhere from the networking layer. So should objtool catch this or since csum_partial_copy_generic is a leaf function reliable stack trace isn't needed? Furthermore this function is called from C wrapper in csum-wrappers_64.c - shouldn't at least they be present in the callstack? This is on 4.6 master from linus and CONFIG_FRAME_POINTER being enabled. Regards, Nikolay