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Violators will be prosecuted for from ; Mon, 6 Mar 2017 20:34:22 +0530 Received: from d28relay06.in.ibm.com (d28relay06.in.ibm.com [9.184.220.150]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 62104394005E for ; Mon, 6 Mar 2017 20:34:20 +0530 (IST) Received: from d28av06.in.ibm.com (d28av06.in.ibm.com [9.184.220.48]) by d28relay06.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v26F4KmT8978468 for ; Mon, 6 Mar 2017 20:34:20 +0530 Received: from d28av06.in.ibm.com (localhost [127.0.0.1]) by d28av06.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v26F4IxR012843 for ; Mon, 6 Mar 2017 20:34:20 +0530 Date: Mon, 6 Mar 2017 20:34:10 +0530 From: "Naveen N. Rao" To: Masami Hiramatsu 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 References: <20170304094911.5f96a10a9f075b6f16fe90d3@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20170304094911.5f96a10a9f075b6f16fe90d3@kernel.org> Message-Id: <20170306150410.GA7467@naverao1-tp.localdomain> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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] Thanks, - Naveen