From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754807Ab2APNMe (ORCPT ); Mon, 16 Jan 2012 08:12:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:32207 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754525Ab2APNMc (ORCPT ); Mon, 16 Jan 2012 08:12:32 -0500 Date: Mon, 16 Jan 2012 14:11:37 +0100 From: Jiri Olsa To: Srikar Dronamraju Cc: Peter Zijlstra , Linus Torvalds , Oleg Nesterov , Ingo Molnar , Andrew Morton , LKML , Linux-mm , Andi Kleen , Christoph Hellwig , Steven Rostedt , Roland McGrath , Thomas Gleixner , Masami Hiramatsu , Arnaldo Carvalho de Melo , Anton Arapov , Ananth N Mavinakayanahalli , Jim Keniston , Stephen Rothwell Subject: Re: [PATCH v9 3.2 7/9] tracing: uprobes trace_event interface Message-ID: <20120116131137.GB5265@m.brq.redhat.com> References: <20120110114821.17610.9188.sendpatchset@srdronam.in.ibm.com> <20120110114943.17610.28293.sendpatchset@srdronam.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120110114943.17610.28293.sendpatchset@srdronam.in.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 10, 2012 at 05:19:43PM +0530, Srikar Dronamraju wrote: > > Implements trace_event support for uprobes. In its current form it can > be used to put probes at a specified offset in a file and dump the > required registers when the code flow reaches the probed address. > > The following example shows how to dump the instruction pointer and %ax > a register at the probed text address. Here we are trying to probe > zfree in /bin/zsh > > # cd /sys/kernel/debug/tracing/ > # cat /proc/`pgrep zsh`/maps | grep /bin/zsh | grep r-xp > 00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh > # objdump -T /bin/zsh | grep -w zfree > 0000000000446420 g DF .text 0000000000000012 Base zfree > # echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events > # cat uprobe_events > p:uprobes/p_zsh_0x46420 /bin/zsh:0x0000000000046420 > # echo 1 > events/uprobes/enable > # sleep 20 > # echo 0 > events/uprobes/enable > # cat trace > # tracer: nop > # > # TASK-PID CPU# TIMESTAMP FUNCTION > # | | | | | > zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 > zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 > zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 > zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 > > TODO: Connect a filter to a consumer. hi, It looks to me the perf/trace filtering is already working with the small fix attached. In another email discussion I think you suggested to use the 'filter property of uprobe consumer' for the perf/trace filtering. The current code does the filtering in the handler itself, and it's same for other perf/trace based events. I discussed the 'filter property of uprobe consumer' with Oleg, and he is not sure why it was added.. was it only for the perf/trace filtering? I've tested following event: echo "p:probe_libc/free /lib64/libc-2.13.so:0x7a4f0 %ax" > ./uprobe_events and commands like: perf record -a -e probe_libc:free --filter "common_pid == 1127" perf record -e probe_libc:free --filter "arg1 == 0xa" ls got me proper results. thanks, jirka --- The preemption needs to be disabled when submitting data into perf. --- kernel/trace/trace_uprobe.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index af29368..4d3857c 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -653,9 +653,11 @@ static void uprobe_perf_func(struct trace_uprobe *tp, struct pt_regs *regs) "profile buffer not large enough")) return; + preempt_disable(); + entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx); if (!entry) - return; + goto out; entry->ip = get_uprobe_bkpt_addr(task_pt_regs(current)); data = (u8 *)&entry[1]; @@ -665,6 +667,8 @@ static void uprobe_perf_func(struct trace_uprobe *tp, struct pt_regs *regs) head = this_cpu_ptr(call->perf_events); perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head); + out: + preempt_enable(); } #endif /* CONFIG_PERF_EVENTS */ -- 1.7.1