From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932460AbcLHMww (ORCPT ); Thu, 8 Dec 2016 07:52:52 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60946 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932115AbcLHMwu (ORCPT ); Thu, 8 Dec 2016 07:52:50 -0500 Subject: Re: [PATCH] gcov: support GCC 7.1 To: =?UTF-8?Q?Martin_Li=c5=a1ka?= References: <8c4084fa-3885-29fe-5fc4-0d4ca199c785@suse.cz> <85a7ed9a-4915-49d9-f17b-888b838107c6@linux.vnet.ibm.com> Cc: lkml , Andrew Morton From: Peter Oberparleiter Date: Thu, 8 Dec 2016 13:52:45 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16120812-0024-0000-0000-0000026F6DEF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16120812-0025-0000-0000-0000218E9985 Message-Id: <3e73df5c-f253-576d-22c3-4f05d96113a0@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-12-08_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1612080205 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.11.2016 13:46, Martin Liška wrote: > On 11/09/2016 10:21 AM, Peter Oberparleiter wrote: >> On 31.10.2016 10:35, Martin Liška wrote: >>> Starting from GCC 7.1, __gcov_exit is a new symbol expected >>> to be implemented in a profiling runtime. >> >> I tested your patch with kernel 4.9-rc4 compiled with GCC 7.0.0 20161107 >> (experimental) and validated that it fixes the build error due to a >> missing __gcov_exit symbol. >> >> An attempt to read from one of the .gcda files generated by a kernel >> compiled this way resulted in a crash though. It appears that the number >> of GCOV_COUNTERS has changed again for GCC 7.x and must be adjusted in >> the kernel as well. Could you add that to your patch as well? > > Hello. > > Sorry, this is fixed in second version of the patch. > >> Given that GCC 7.1 has not yet been released, I'm wondering if it is >> safe to program against interfaces that have not yet been fully >> finalized. Can you provide an indication on whether these gcov-related >> aspects of GCC might still be changed until release? > > Well, we just flipped to stage3 which means that any new features should > be added to current master. If you prefer we can commit the patch after > a release of 7.1 will be done? I've given this some more thought: if your patch is not applied, GCOV kernel profiling will definitely not work with GCC 7.x. If it is applied, there is a high probability that it will work, and a small chance that additional patches will be required. Overall I would say this justifies applying the patch now. >> As a side note, please post your patches inline instead of as attachment >> as that helps quoting them in replies. See also >> linux/Documentation/SubmittingPatches. > > Sure, thanks for info. I'm attaching new version: > > Starting from GCC 7.1, __gcov_exit is a new symbol expected > to be implemented in a profiling runtime. Update number of profile > counters. > > Signed-off-by: Martin Liska Looks good, thanks! Tested successfully with GCC 7.0.0 20161208 (experimental) on Linux kernel 4.9-rc8 (compiles successfully and produces valid kernel .gcda files). Andrew, could you pick this change up via your tree? Reviewed-by: Peter Oberparleiter Tested-by: Peter Oberparleiter > --- > kernel/gcov/base.c | 6 ++++++ > kernel/gcov/gcc_4_7.c | 4 +++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/gcov/base.c b/kernel/gcov/base.c > index 2f9df37..85dca5d 100644 > --- a/kernel/gcov/base.c > +++ b/kernel/gcov/base.c > @@ -98,6 +98,12 @@ void __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters) > } > EXPORT_SYMBOL(__gcov_merge_icall_topn); > > +void __gcov_exit (void) > +{ > + /* Unused. */ > +} > +EXPORT_SYMBOL(__gcov_exit); > + > /** > * gcov_enable_events - enable event reporting through gcov_event() > * > diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c > index 6a5c239..46a18e7 100644 > --- a/kernel/gcov/gcc_4_7.c > +++ b/kernel/gcov/gcc_4_7.c > @@ -18,7 +18,9 @@ > #include > #include "gcov.h" > > -#if (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1) > +#if (__GNUC__ >= 7) > +#define GCOV_COUNTERS 9 > +#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1) > #define GCOV_COUNTERS 10 > #elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9 > #define GCOV_COUNTERS 9 > -- Peter Oberparleiter Linux on z Systems Development - IBM Germany