From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsnLeFtUJB+AVQ7MhIFwV+T8od3Q6o86jnuh7jdaD0L2vfw0EAzU6nSAN/UGhwRyp2A9aKH ARC-Seal: i=1; a=rsa-sha256; t=1519676829; cv=none; d=google.com; s=arc-20160816; b=yQfCn8bOUOA1HXbm7ejBYArfGOT9AmG1bIdW8aJEAYuaj9pdZ7O3p/Dfvt9lY3RxmM imyn72dHVKWmzKTxKoAurtZQEGH2lot2OQSJmvi0Nu2S+etVtUoFo/4Iv+Tl97pkT+cQ MbitjrauLKvBZubypd5dACDGv8n0Zhq/JkezGuI71zYIMRPcuaZ44Qre+AbgeNgcMGKq y/NUb/Z2ui94vxk+CbnYjGEX8vwq2cMkj7bVfWWS8kcEOF86OWnopogHcnXQqvqG7nE2 ijbcw2mJvipPsJRqKfXjg9sD/awMSs6wGMk/SX0gosMj8EauOka6gv7dBn6DUuYUxSaH 35tA== 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=O8HXuaisIAo+trrkGYx/d0JXH3YCvGFIqWS6/pzt+aI=; b=sdKZBFTu/wh92gJqJytOgpWviL5f+yWR/9Q4PhxljBo9BlxSofeTnOrBRPO1MSaZVj g6mr8LoLLRCUToYGW9v6Lczud7hOrU2wO22qcRGu9Oz90wdJVaL1cCw3tKpbSNXJ8MV8 3vqlzfr0RNoEMxmJbkn6rebt6xbDbWYW5GAvBbP6QYYZ9Qrv3iPMmBJ00hwOw+oSLd4v SBvhQZMYRRdDSZzRVXZY/6rklBHIJla7zowDHKcxhCEI9+wQlTZLb+7cNJBIBiJiRYyf ulo5GHTFIszeTYRBlsEn8qHdgvS1akpuyYx20hIsEJALy2i3W1Lc9pOJIL+1z/zgpEAu jxpQ== 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 4.15 28/64] x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() Date: Mon, 26 Feb 2018 21:22:05 +0100 Message-Id: <20180226202154.656148557@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180226202153.453363333@linuxfoundation.org> References: <20180226202153.453363333@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?1593496651181518327?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-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,