From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52042 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751550AbeBZQXj (ORCPT ); Mon, 26 Feb 2018 11:23:39 -0500 Subject: Patch "x86/oprofile: Fix bogus GCC-8 warning in nmi_setup()" has been added to the 4.15-stable tree To: arnd@arndb.de, gregkh@linuxfoundation.org, jeyu@kernel.org, keescook@chromium.org, mingo@kernel.org, msebor@gcc.gnu.org, peterz@infradead.org, rric@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Mon, 26 Feb 2018 17:20:25 +0100 Message-ID: <151966202523270@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-oprofile-fix-bogus-gcc-8-warning-in-nmi_setup.patch and it can be found in the queue-4.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 85c615eb52222bc5fab6c7190d146bc59fac289e Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 20 Feb 2018 21:58:21 +0100 Subject: x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() From: Arnd Bergmann commit 85c615eb52222bc5fab6c7190d146bc59fac289e upstream. GCC-8 shows a warning for the x86 oprofile code that copies per-CPU data from CPU 0 to all other CPUs, which when building a non-SMP kernel turns into a memcpy() with identical source and destination pointers: arch/x86/oprofile/nmi_int.c: In function 'mux_clone': arch/x86/oprofile/nmi_int.c:285:2: error: 'memcpy' source argument is the same as destination [-Werror=restrict] memcpy(per_cpu(cpu_msrs, cpu).multiplex, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ per_cpu(cpu_msrs, 0).multiplex, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ sizeof(struct op_msr) * model->num_virt_counters); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/x86/oprofile/nmi_int.c: In function 'nmi_setup': arch/x86/oprofile/nmi_int.c:466:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict] arch/x86/oprofile/nmi_int.c:470:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict] I have analyzed a number of such warnings now: some are valid and the GCC warning is welcome. Others turned out to be false-positives, and GCC was changed to not warn about those any more. This is a corner case that is a false-positive but the GCC developers feel it's better to keep warning about it. In this case, it seems best to work around it by telling GCC a little more clearly that this code path is never hit with an IS_ENABLED() configuration check. Cc:stable as we also want old kernels to build cleanly with GCC-8. Signed-off-by: Arnd Bergmann Cc: Jessica Yu Cc: Kees Cook Cc: Linus Torvalds Cc: Martin Sebor Cc: Peter Zijlstra Cc: Robert Richter Cc: Thomas Gleixner Cc: oprofile-list@lists.sf.net Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20180220205826.2008875-1-arnd@arndb.de Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84095 Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/oprofile/nmi_int.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/oprofile/nmi_int.c +++ b/arch/x86/oprofile/nmi_int.c @@ -460,7 +460,7 @@ static int nmi_setup(void) goto fail; for_each_possible_cpu(cpu) { - if (!cpu) + if (!IS_ENABLED(CONFIG_SMP) || !cpu) continue; memcpy(per_cpu(cpu_msrs, cpu).counters, Patches currently in stable-queue which might be from arnd@arndb.de are queue-4.15/x86-oprofile-fix-bogus-gcc-8-warning-in-nmi_setup.patch queue-4.15/cfg80211-fix-cfg80211_beacon_dup.patch queue-4.15/kbuild-always-define-endianess-in-kconfig.h.patch