From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932279AbdCFVV0 (ORCPT ); Mon, 6 Mar 2017 16:21:26 -0500 Received: from mail.kernel.org ([198.145.29.136]:33566 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753902AbdCFVVT (ORCPT ); Mon, 6 Mar 2017 16:21:19 -0500 Date: Mon, 6 Mar 2017 22:14:52 +0100 From: Masami Hiramatsu To: "Naveen N. Rao" Cc: Arnaldo Carvalho de Melo , Steven Rostedt , Ingo Molnar , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ananth N Mavinakayanahalli , Michael Ellerman Subject: Re: [PATCH v4 2/3] perf: kretprobes: offset from reloc_sym if kernel supports it Message-Id: <20170306221452.3368809af710e573d582689d@kernel.org> In-Reply-To: <20170306150410.GA7467@naverao1-tp.localdomain> References: <20170304094911.5f96a10a9f075b6f16fe90d3@kernel.org> <20170306150410.GA7467@naverao1-tp.localdomain> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 6 Mar 2017 20:34:10 +0530 "Naveen N. Rao" wrote: > On 2017/03/04 09:49AM, Masami Hiramatsu wrote: > > On Thu, 2 Mar 2017 23:25:06 +0530 > > "Naveen N. Rao" wrote: > > > > > We indicate support for accepting sym+offset with kretprobes through a > > > line in ftrace README. Parse the same to identify support and choose the > > > appropriate format for kprobe_events. > > > > Could you give us an example of this change here? :) > > for example, comment of commit 613f050d68a8 . > > > > I think the code is OK, but we need actual example of result. > > Sure :) > As an example, without this perf patch, but with the ftrace changes: > > naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/tracing/README | grep kretprobe > place (kretprobe): [:][+]| > naveen@ubuntu:~/linux/tools/perf$ > naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return > probe-definition(0): do_open%return > symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) > 0 arguments > Looking at the vmlinux_path (8 entries long) > Using /boot/vmlinux for symbols > Open Debuginfo file: /boot/vmlinux > Try to find probe point from debuginfo. > Matched function: do_open [2d0c7d8] > Probe point found: do_open+0 > Matched function: do_open [35d76b5] > found inline addr: 0xc0000000004ba984 > Failed to find "do_open%return", > because do_open is an inlined function and has no return point. > An error occurred in debuginfo analysis (-22). > Trying to use symbols. > Opening /sys/kernel/debug/tracing//kprobe_events write=1 > Writing event: r:probe/do_open do_open+0 > Writing event: r:probe/do_open_1 do_open+0 > Added new events: > probe:do_open (on do_open%return) > probe:do_open_1 (on do_open%return) > > You can now use it in all perf tools, such as: > > perf record -e probe:do_open_1 -aR sleep 1 > > naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/kprobes/list > c000000000041370 k kretprobe_trampoline+0x0 [OPTIMIZED] > c0000000004433d0 r do_open+0x0 [DISABLED] > c0000000004433d0 r do_open+0x0 [DISABLED] > > And after this patch (and the subsequent powerpc patch): > > naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return > probe-definition(0): do_open%return > symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) > 0 arguments > Looking at the vmlinux_path (8 entries long) > Using /boot/vmlinux for symbols > Open Debuginfo file: /boot/vmlinux > Try to find probe point from debuginfo. > Matched function: do_open [2d0c7d8] > Probe point found: do_open+0 > Matched function: do_open [35d76b5] > found inline addr: 0xc0000000004ba984 > Failed to find "do_open%return", > because do_open is an inlined function and has no return point. > An error occurred in debuginfo analysis (-22). > Trying to use symbols. > Opening /sys/kernel/debug/tracing//README write=0 > Opening /sys/kernel/debug/tracing//kprobe_events write=1 > Writing event: r:probe/do_open _text+4469712 > Writing event: r:probe/do_open_1 _text+4956248 > Added new events: > probe:do_open (on do_open%return) > probe:do_open_1 (on do_open%return) > > You can now use it in all perf tools, such as: > > perf record -e probe:do_open_1 -aR sleep 1 > > naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/kprobes/list > c000000000041370 k kretprobe_trampoline+0x0 [OPTIMIZED] > c0000000004433d0 r do_open+0x0 [DISABLED] > c0000000004ba058 r do_open+0x8 [DISABLED] Ok, with this usage example. Acked-by: Masami Hiramatsu Thanks, > > > Thanks, > - Naveen > -- Masami Hiramatsu