Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933085AbbBBImE (ORCPT ); Mon, 2 Feb 2015 03:42:04 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:52344 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932904AbbBBImA (ORCPT ); Mon, 2 Feb 2015 03:42:00 -0500 Message-ID: <54CF3850.4010103@hitachi.com> Date: Mon, 02 Feb 2015 17:41:52 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , namhyung@kernel.org, Ingo Molnar , Linux Kernel Mailing List Subject: Re: [PATCH perf/core 1/2] [BUGFIX] perf-probe: Fix to handle optimized not-inlined but has no instance References: <20150130093741.30575.41526.stgit@localhost.localdomain> <20150130093744.30575.43290.stgit@localhost.localdomain> <20150130142135.GA3101@kernel.org> <20150130143220.GB3101@kernel.org> In-Reply-To: <20150130143220.GB3101@kernel.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5758 Lines: 160 (2015/01/30 23:32), Arnaldo Carvalho de Melo wrote: > Em Fri, Jan 30, 2015 at 11:21:35AM -0300, Arnaldo Carvalho de Melo escreveu: >> Em Fri, Jan 30, 2015 at 06:37:44PM +0900, Masami Hiramatsu escreveu: >>> Fix to handle optimized no-inline functions which have >>> only function definition but no actual instance at >>> that point. To fix this problem, we need to find actual >>> instance of the function. >>> >>> Without this patch: >>> ---- >>> # perf probe -a __up >>> Failed to get entry address of __up. >>> Error: Failed to add events. >>> # perf probe -L __up >>> Specified source line is not found. >>> Error: Failed to show lines. >>> ---- >>> >>> With this patch: >>> ---- >>> # perf probe -a __up >>> Added new event: >>> probe:__up (on __up) >>> >>> You can now use it in all perf tools, such as: >>> >>> perf record -e probe:__up -aR sleep 1 >>> >>> # perf probe -L __up >>> <__up@/home/fedora/ksrc/linux-3/kernel/locking/semaphore.c:0> >>> 0 static noinline void __sched __up(struct semaphore *sem) >>> { >>> struct semaphore_waiter *waiter = list_first_entry(&sem->wait_ >>> struct semaphore_waite >>> 4 list_del(&waiter->list); >>> 5 waiter->up = true; >>> 6 wake_up_process(waiter->task); >>> 7 } >>> ---- >> >> Since __up here was built in some other way, I looked for another > > Nah, I saw you trying to add "perf probe -a __up" and stopped there, > hadn't seen that it fails _as well_ for just listing the source code... > > Yes, I managed to reproduce the problem and test your fix, it works: Thanks for testing! > > [root@zoo ~]# perf probe --del __up > Removed event: probe:__up > [root@zoo ~]# perf probe -L __up > Specified source line is not found. > Error: Failed to show lines. > > ---->>>>>> APPLY THE PATCH, rebuild and try again: > > [root@zoo ~]# > [root@zoo ~]# perf probe -L __up > <__up@/home/git/linux/kernel/locking/semaphore.c:0> > 0 static noinline void __sched __up(struct semaphore *sem) > { > struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list, > struct semaphore_waiter, list); > 4 list_del(&waiter->list); > 5 waiter->up = true; > 6 wake_up_process(waiter->task); > 7 } > [root@zoo ~]# > > -------------------------------------------------------------- > > So its just this other case that fails, vmalloc_fault, can you check > this one? Does it happen in your machine as well? OK, I'll try reproducing this and dig deeper. > > Applying your patch, thanks, Thank you! > > - Arnaldo > >> 'noinline' function to try, and it failed here: >> >> [root@zoo ~]# perf probe -L vmalloc_fault | head -5 >> >> 0 static noinline int vmalloc_fault(unsigned long address) >> 1 { >> pgd_t *pgd, *pgd_ref; >> pud_t *pud, *pud_ref; >> [root@zoo ~]# perf probe vmalloc_fault >> Added new event: >> Failed to write event: Invalid argument >> Error: Failed to add events. >> >> ---->>>>>> APPLY THE PATCH, rebuild and try again: >> >> [root@zoo ~]# perf probe vmalloc_fault >> Added new event: >> Failed to write event: Invalid argument >> Error: Failed to add events. >> [root@zoo ~]# perf probe -v vmalloc_fault >> probe-definition(0): vmalloc_fault >> symbol:vmalloc_fault file:(null) line:0 offset:0 return:0 lazy:(null) >> 0 arguments >> Looking at the vmlinux_path (7 entries long) >> Using /lib/modules/3.19.0-rc6+/build/vmlinux for symbols >> Open Debuginfo file: /lib/modules/3.19.0-rc6+/build/vmlinux >> Try to find probe point from debuginfo. >> Probe point found: vmalloc_fault+0 >> Found 1 probe_trace_events. >> Opening /sys/kernel/debug/tracing/kprobe_events write=1 >> Added new event: >> Writing event: p:probe/vmalloc_fault _text+289600 >> Failed to write event: Invalid argument >> Error: Failed to add events. Reason: Invalid argument (Code: -22) >> [root@zoo ~]# grep -w vmalloc_fault /proc/kallsyms >> ffffffff81046b40 t vmalloc_fault >> [root@zoo ~]# grep -w _text /proc/kallsyms >> ffffffff81000000 T _text >> [root@zoo ~]# python >> Python 2.7.5 (default, Nov 3 2014, 14:26:24) >> [GCC 4.8.3 20140911 (Red Hat 4.8.3-7)] on linux2 >> Type "help", "copyright", "credits" or "license" for more information. >> >>> 0xffffffff81046b40 - 0xffffffff81000000 >> 289600L >> >>> >> [root@zoo ~]# readelf -s /lib/modules/3.19.0-rc6+/build/vmlinux | egrep -w _text\|vmalloc_fault >> 3499: ffffffff81046b40 410 FUNC LOCAL DEFAULT 1 vmalloc_fault >> 48873: ffffffff81000000 0 NOTYPE GLOBAL DEFAULT 1 _text >> [root@zoo ~]# >> >> --------------------------------------------------------------------------- >> >> So perhaps I need a 'noinline' _and_ '__sched', so that I have a "optimized >> no-inline functions which have only function definition but no actual instance >> at that point"? >> >> Looking for one, will post here after objdump -dS finishes... >> >> - Arnaldo > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research 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/