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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGmD0-0002Ts-MQ; Tue, 24 Mar 2020 16:15:18 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGmCw-0002TH-TH for linux-arm-kernel@lists.infradead.org; Tue, 24 Mar 2020 16:15:16 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D66701FB; Tue, 24 Mar 2020 09:15:11 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7E4523F52E; Tue, 24 Mar 2020 09:15:10 -0700 (PDT) Date: Tue, 24 Mar 2020 16:15:08 +0000 From: Catalin Marinas To: Amit Kachhap Subject: Re: [arm64:for-next/kernel-ptrauth 16/18] aarch64-linux-objdump: warning: fs/squashfs/decompressor_multi.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 Message-ID: <20200324161507.GA3901@mbp> References: <202003211202.2NuTbuJb%lkp@intel.com> <20200323114837.GA4892@mbp> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200324_091514_989331_F668DA2D X-CRM114-Status: GOOD ( 19.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kbuild-all@lists.01.org, kbuild test robot , Szabolcs Nagy , daniel.kiss@arm.com, Kristina Martsenko , Vincenzo Frascino , linux-arm-kernel@lists.infradead.org, Kees Cook Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 23, 2020 at 10:36:15PM +0530, Amit Kachhap wrote: > On 3/23/20 5:18 PM, Catalin Marinas wrote: > > On Sat, Mar 21, 2020 at 12:28:06PM +0800, kbuild test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/kernel-ptrauth > > > head: 3b446c7d27ddd06342901bb35211363f6944291a > > > commit: 74afda4016a7437e6e425c3370e4b93b47be8ddf [16/18] arm64: compile the kernel with ptrauth return address signing > > > config: arm64-randconfig-a001-20200321 (attached as .config) > > > compiler: aarch64-linux-gcc (GCC) 9.2.0 > > > reproduce: > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > chmod +x ~/bin/make.cross > > > git checkout 74afda4016a7437e6e425c3370e4b93b47be8ddf > > > # save the attached .config to linux build tree > > > GCC_VERSION=9.2.0 make.cross ARCH=arm64 > > > > > > If you fix the issue, kindly add following tag > > > Reported-by: kbuild test robot > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > aarch64-linux-objdump: warning: fs/squashfs/decompressor_multi.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 > > > -- > > > > > aarch64-linux-objdump: warning: drivers/gpio/gpio-bt8xx.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 > > > > Just to make sure I understand the cause of this warning: gcc generates > > a .note.gnu.property when PAC is enabled for the kernel but binutils > > doesn't understand it. Is there a way to check for this via the Kconfig > > options? > > Yes you are right. In this case the binutils version lesser than 2.33 do not > recognize the GNU_PROPERTY_AARCH64_FEATURE_1_PAC property. Are there gcc versions supporting PAC but not generating the .note.gnu.property? > However we can disable pauth in this case by checking linker version > and GNU_PROPERTY feature as, > (readelf -S --wide tmp.o | grep .note.gnu.property) && (ld-ifversion -ge > 233000000). > > But I feel disabling pauth in this case seems too aggressive as the current > way do not break any functionality even though it generates confusing > warning messages. If there isn't a way to silence the linker or objdump, could we align the compiler version we know that generates this note with a minimum binutils? Something like: depends on (GCC_VERSION < X) || (LD_VERSION >= 233...) -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel