From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754633AbcFPPoh (ORCPT ); Thu, 16 Jun 2016 11:44:37 -0400 Received: from foss.arm.com ([217.140.101.70]:44726 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754156AbcFPPof (ORCPT ); Thu, 16 Jun 2016 11:44:35 -0400 Date: Thu, 16 Jun 2016 16:44:12 +0100 From: Mark Rutland To: Alexander Potapenko , Catalin Marinas Cc: James Morse , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , marc.zyngier@arm.com, Will Deacon , LKML , Quentin Casasnovas , Kostya Serebryany , syzkaller , Christoffer Dall , Andrew Morton , Dmitriy Vyukov Subject: Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Message-ID: <20160616154412.GC31477@leverpostej> References: <1465923441-107596-1-git-send-email-glider@google.com> <20160614175543.GA2468@leverpostej> <20160615092509.GA3984@leverpostej> <20160615114438.GC3984@leverpostej> <20160615142550.GA7971@leverpostej> <576283B9.9050900@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Thu, Jun 16, 2016 at 05:20:03PM +0200, Alexander Potapenko wrote: > On Thu, Jun 16, 2016 at 12:47 PM, James Morse wrote: > > On 15/06/16 15:25, Mark Rutland wrote: > >> On Wed, Jun 15, 2016 at 01:53:03PM +0200, Alexander Potapenko wrote: > >>> On Wed, Jun 15, 2016 at 1:44 PM, Mark Rutland wrote: > >>>> On Wed, Jun 15, 2016 at 10:25:10AM +0100, Mark Rutland wrote: > >>>>> On Tue, Jun 14, 2016 at 08:16:08PM +0200, Alexander Potapenko wrote: > >>>>>> On Tue, Jun 14, 2016 at 7:55 PM, Mark Rutland wrote: > >>>>>>> I built and booted (via EFI) a kernel with this feature enabled (also > >>>>>>> with the boot/Makefile change removed). I haven't tested the feature > >>>>>>> itself as such, as I'm not sure how to do that. > >>>>>> You can test it by running the test program from Documentation/kcov.txt. > >>>>> > >>>>> Ah, I hadn't spotted that. If I get the chance I'll try to give that a > >>>>> go. > >>>> > >>>> I just had a go (with this applied atop of v4.7-rc3), and I get: > >>>> > >>>> root@ribbensteg:/home/nanook# ./kcov > >>>> mmap: No such device > >>>> > >>>> The device exists (it was able to open the fd, evidently): > >>>> > >>>> root@ribbensteg:/home/nanook# ls -al /sys/kernel/debug/kcov > >>>> -rw------- 1 root root 0 Jan 1 1970 /sys/kernel/debug/kcov > >>>> > >>>> Strace show me: > >>>> > >>>> openat(AT_FDCWD, "/sys/kernel/debug/kcov", O_RDWR) = 3 > >>>> ioctl(3, CHIOMOVE or CM_IOCGATR, 0x10000) = 0 > >>>> mmap(NULL, 524288, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = -1 ENODEV (No such device) > >>>> > >>>> It doesn't look like the error paths in kcov_mmap are hitting. > >>>> > >>>> Any ideas? > >>> According to Dmitry (thanks, Dmitry!) this has regressed recently, but > >>> there's a pending patch that should probably fix the problem: > >>> http://lkml.iu.edu/hypermail/linux/kernel/1605.2/04379.html > >> > >> Thanks for the pointer! With that applied, the program runs. > >> > >> However, it looks like I missed a warning from the kernel build system, > >> and my toolchain doesn't actually support -fsanitize-coverage=trace-pc, > >> so I'm not going to be able to test that further. > > > > I dusted off a compiler that supports this, and ran the sample program under > > Documentation with the above unproxify patch. > > > > Tested-by: James Morse > I think it's time to ask now :) > If I receive "Tested-by" or "Acked-by" responses, do I need to send > out a patch adding them, or should I rely on the maintainer taking the > patch to the tree? > The first option reduces the amount of work done by the maintainer, > while the second one reduces the traffic in the list. > Sorry, I couldn't find the answer in the manuals. It's up to the maintainer, so it varies. The best thing to do is to ask the maintainer what they'd prefer. >>From my experience, Catalin is usually happy to add tags, so I suspect he'd be happy to do so for this patch (assuming he's happy to pick it up). I'll leave it for him to say either way. Thanks, Mark.