Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751736Ab0HYFrw (ORCPT ); Wed, 25 Aug 2010 01:47:52 -0400 Received: from mail4.hitachi.co.jp ([133.145.228.5]:40241 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751306Ab0HYFru (ORCPT ); Wed, 25 Aug 2010 01:47:50 -0400 X-AuditID: b753bd60-aa2deba000000a18-47-4c74ae836b45 Message-ID: <4C74AE7B.1010705@hitachi.com> Date: Wed, 25 Aug 2010 14:47:39 +0900 From: Masami Hiramatsu Organization: Systems Development Lab., Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; ja; rv:1.9.2.8) Gecko/20100802 Thunderbird/3.1.2 MIME-Version: 1.0 To: Srikar Dronamraju Cc: Arnaldo Carvalho de Melo , Ananth N Mavinakayanahalli , Steven Rostedt , Fr?d?ric Weisbecker , 2nddept-manager@sdl.hitachi.co.jp, Ingo Molnar , linux-kernel Subject: Re: Using perf probe with arguments throws a fatal error. References: <20100824045758.GA14431@linux.vnet.ibm.com> <4C738411.8080602@hitachi.com> <20100824085401.GB14431@linux.vnet.ibm.com> <4C738F09.3080108@hitachi.com> <20100824095658.GC14431@linux.vnet.ibm.com> In-Reply-To: <20100824095658.GC14431@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== X-FMFTCR: RANGEC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3002 Lines: 77 (2010/08/24 18:56), Srikar Dronamraju wrote: >>> >>> 1000 [srikar@llm69 uprobesv3.git]$ cat >>> /sys/kernel/debug/tracing/events/probe/do_fork/format >>> name: do_fork >>> ID: 817 >>> format: >>> field:unsigned short common_type; offset:0; size:2; signed:0; >>> field:unsigned char common_flags; offset:2; size:1; signed:0; >>> field:unsigned char common_preempt_count; offset:3; size:1; signed:0; >>> field:int common_pid; offset:4; size:4; signed:1; >>> field:int common_lock_depth; offset:8; size:4; signed:1; >>> >>> field:unsigned long __probe_ip; offset:16; size:8; signed:0; >>> field:u64 %ip; offset:24; size:8; signed:0; >> >> Hmm, it could be caused by "u64"... >> OK, maybe I should update perf to support those. >> >> BTW, let me check that you use perf for the latest kernel? >> > > > Yes, I am using perf from latest kernel and this happens on both x86 > and x86_64 boxes. > > Just for curiosity I tried printing the format for perf probe > do_fork ip=%ip and here it is > > 1001 [srikar@llm69 uprobesv3.git]$ sudo perf probe do_fork ip=%ip > 1001 [srikar@llm69 uprobesv3.git]$ cat /sys/kernel/debug/tracing/events/probe/do_fork/format > name: do_fork > ID: 818 > format: > field:unsigned short common_type; offset:0; size:2; signed:0; > field:unsigned char common_flags; offset:2; size:1; signed:0; > field:unsigned char common_preempt_count; offset:3; size:1; signed:0; > field:int common_pid; offset:4; size:4; signed:1; > field:int common_lock_depth; offset:8; size:4; signed:1; > > field:unsigned long __probe_ip; offset:16; size:8; signed:0; > field:u64 ip; offset:24; size:8; signed:0; > ^^ > > print fmt: "(%lx) ip=%llx", REC->__probe_ip, REC->ip > ^^ ^^ > > The differences I see when a name is given we refer the name, while in > the previous case we refer the register %ip. Ah, I remembered that, yeah, perf doesn't support those raw regsiters, dereferences, etc. Hmm, this should be solved, but not so simple as just removing "%", because there are also special variables ($retval, $stack) and dereferences(+8(+10(%sp)), etc). I think the simplest solution is just setting "argX" name for each argument (if user omitted its name) in kprobe-tracer (because trace-cmd will face same problem). e.g. # echo "p do_fork %ip" > tracing/kprobe_events will be translated as below # echo "p do_fork arg1=%ip" > tracing/kprobe_events Thank you, -- Masami HIRAMATSU 2nd Dept. Linux Technology Center Hitachi, Ltd., Systems Development Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/