From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757281Ab2CZKvS (ORCPT ); Mon, 26 Mar 2012 06:51:18 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:46901 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757222Ab2CZKvR (ORCPT ); Mon, 26 Mar 2012 06:51:17 -0400 X-AuditID: b753bd60-9658fba000007b1b-94-4f704a233334 X-AuditID: b753bd60-9658fba000007b1b-94-4f704a233334 Message-ID: <4F704A1E.2040401@hitachi.com> Date: Mon, 26 Mar 2012 19:51:10 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko/20120312 Thunderbird/11.0 MIME-Version: 1.0 To: Prashanth Nageshappa Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, acme@infradead.org, ananth@in.ibm.com, Srikar Dronamraju , rostedt@goodmis.org Subject: Re: [RESEND]Re: [PATCH] perf - probe finder fails to resolve function name to address References: <4F6AF410.1010400@linux.vnet.ibm.com> <4F6AFD92.4030603@linux.vnet.ibm.com> <4F6C721B.9060807@hitachi.com> <4F703FB9.9020407@linux.vnet.ibm.com> In-Reply-To: <4F703FB9.9020407@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2012/03/26 19:06), Prashanth Nageshappa wrote: > Fixing a coding style issue.. > > On 03/23/2012 06:22 PM, Masami Hiramatsu wrote: > >> Hi, >> >> (2012/03/22 19:23), Prashanth Nageshappa wrote: >>> probe finder fails to resolve valid function names into addresses for >>> functions which have more than one die entries in DWARF info. >>> >>> It is valid for DWARF info to contain more than 1 entries for a given >>> function name, where one entry corresponds to definition which has code >>> address/range attributes and remaining entries (which are only >>> declarations) does not have code address/range attributes. >>> (example: do_fork, sys_write, sys_wait4, sys_sync etc) >> >> Hmm, I'd like to reproduce and see what happened on debuginfo in those cases. >> Could you tell me your environment or actual dwarf dump of those entries as below? >> > > $ uname -r > 3.1.0-7.fc16.x86_64 > > $ sudo perf probe do_fork > Failed to get entry address of do_fork. > Error: Failed to add events. (-2) > > $ readelf -wi /usr/lib/debug/lib/modules/3.1.0-7.fc16.x86_64/vmlinux | grep do_fork -A 16 > <2691f7> DW_AT_name : (indirect string, offset: 0x1b1e0): do_fork > <2691fb> DW_AT_decl_file : 3 > <2691fc> DW_AT_decl_line : 2269 > <2691fe> DW_AT_prototyped : 1 > <2691fe> DW_AT_type : <0x2593d1> > <269202> DW_AT_declaration : 1 OK, compared with mine, this attribute is actually new one for this kind of (declaration) entries. [...] >> >> At least we must consider this lazy_line case. If I understand correctly, >> that can also affect find_probe_point_lazy(sp_die, pf); >> >> If I find the different attribute, I'd like to add a checker function and >> filter it out at early step in this function. >> > > Based on the above comments I have redone the patch: > > If die entries corresponding to declarations appear before definition > entry, probe finder returns error instead of continuing to look further > for a definition entry. > > This patch ensures we reach to the die entry corresponding to the > definition and get the function address. > > V2: A simpler solution based on Masami's suggestion. > > > Signed-off-by: Prashanth Nageshappa Well, OK. This looks good for me too :) Acked-by: Masami Hiramatsu > --- > > tools/perf/util/probe-finder.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c > index 5d73262..d5914ee 100644 > --- a/tools/perf/util/probe-finder.c > +++ b/tools/perf/util/probe-finder.c > @@ -963,10 +963,12 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data) > struct dwarf_callback_param *param = data; > struct probe_finder *pf = param->data; > struct perf_probe_point *pp = &pf->pev->point; > + Dwarf_Attribute attr; > > /* Check tag and diename */ > if (dwarf_tag(sp_die) != DW_TAG_subprogram || > - !die_compare_name(sp_die, pp->function)) > + !die_compare_name(sp_die, pp->function) || > + dwarf_attr(sp_die, DW_AT_declaration, &attr)) > return DWARF_CB_OK; > > /* Check declared file */ > > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com