From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2265RoVmSJ4DIIaTmW98b+URGLYAlTu1nVDsPSdjKai2aRXmy3zsz+BpZocUtTCI8GgkSxoJ ARC-Seal: i=1; a=rsa-sha256; t=1519676651; cv=none; d=google.com; s=arc-20160816; b=jYRMG/Nn3hWaq8TR7K3aqClybx8tFYibBdi6BjtgmK0Y4kSf+NgnagLm8zBZ8JLmwu mHJ8V1ZUrlJ+1TFlt4VrydI6YFkMp2RcNscQ1h7o+oWVCK/WRB/x79WZ9hYLLP5J20LM jIYhBq5jj7YeVX6tm+SDZMvfI1h2f+GQzKXWRHqZTHMHbdvvaUEAcBuLMcNTs4jSfOiF h9jxsuLNEknz+smR0Pbua5oLT18DN89SgUZJEzJpUiT0g13Wq8co9t+9XIurQNHoH0VE xyeT0IqexHsP41CzFYy3KZVZLhWlelN7h9+sHbTzLitPLwlsQWQDiKOY0uxv+CMiwXb5 pPSQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=4CAKnvNcIyJcCzCRCuLmpoyiA2j6Uerg9dWs5mEibF0=; b=dy45JnmKrCDaFUDChbROKLDXawOqfHArAHWn053djLeP10Fq0+9Xv/DEy06EFpVQwA bEmEi16j1Jow1Uj1jIUm4nF7eDFxf6966z7Rc4kwRB/Ymj5yYhvXPB8hNdyCMaB2citv foF9Zoneqrb6VatVwub3DUjmeDtuL3CKCnP9ZJQDA9MuOUNSPalEj/Lpn2xgtQ9RD7Qp EFAOUbzAu9mh9PzUWXYZZAt0VLhnCpFpI8+Hkz/Czl+VszG5bi/ALCJUgVz+yk8km6wz tdrPwSnoB1K41lijP30wJ9W/YSd1tJtasRkyGqj+Om4+VNp7mPUcH8lgTuc+RbNO2Tn5 PUyg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 83.175.124.243 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 83.175.124.243 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Jessica Yu , Kees Cook , Linus Torvalds , Martin Sebor , Peter Zijlstra , Robert Richter , Thomas Gleixner , oprofile-list@lists.sf.net, Ingo Molnar Subject: [PATCH 4.14 26/54] x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() Date: Mon, 26 Feb 2018 21:22:03 +0100 Message-Id: <20180226202145.709601114@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180226202144.375869933@linuxfoundation.org> References: <20180226202144.375869933@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593495973889701786?= X-GMAIL-MSGID: =?utf-8?q?1593496464390723071?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ 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,