From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8D5941F12E7; Mon, 3 Mar 2025 09:25:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740993904; cv=none; b=Oei4ixUk4gyWY78cDP68Kz56AUkvguN2KTg1mOowp2G9vMsb8Q8Qd4r238cnho1qPWd7e6Ga1qNLmYvuWWAU63dGgoh86XVWsjOIKhsdXVME5sNfrNLgi8l4fBIUlVYdl/EDns1TCYfgZTWcxo4tQdzRR4LU0rFWminhnlm83d4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740993904; c=relaxed/simple; bh=anrVdYlvp+vutF77M+oNBrnX/luGXvKRsTQJKbdwgXY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Nod9g1i3kcKbUIzThnlVJ0cX39c5d2OXA1x5ErnvN/NADA7wsJRLqZLg9BiR+miGVheMv9wb2bYCQBQwR+QA0WOrFW6O1ugQdaQpXto5R3gBr070dqiLdMKHXcFuTxvJ2KIawUnqXJz0GhIo89wiA9hC8kM5Bf+MEKRqOo/WyK4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=p4SoJfID; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="p4SoJfID" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=vzlWwoYxaOsW2jKVbAk8xYIOxalJ85AZ7FYYDeZecek=; b=p4SoJfIDMgnfsHECQWncTbzWJf tHz8k1bZxPYtEtUzeMhqdI++F75l0/DlIRW00IoIoCe08qrQA2lJr/qVAsuZumhuKHglIPwPCfPyh CH+MFKGl57g4wZIF+IYhWj5aF9oGyFKNhcHxBTVvWvwlSb8gEuUnkgEd7xQSAnGyL4nF9AxuyX865 vU3vchbEmgWsMrlBRCt6mk205kA1+qOJ45m9yQSd6vMRv0AQC5dK1iLK4Gm5G/yWpDMp1VEQi66Wu dqWuhkIdBuD+FJOKUxFcT+5r/7CE7JGUF8GoFbAG4GeuQREZdgTk4/gGotvwXl+W9ZGboQNb9w7uY Q2vqDgeA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tp22m-00000004Wrl-0mFb; Mon, 03 Mar 2025 09:25:00 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id BE6B930049D; Mon, 3 Mar 2025 10:24:59 +0100 (CET) Date: Mon, 3 Mar 2025 10:24:59 +0100 From: Peter Zijlstra To: kernel test robot Cc: llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, x86@kernel.org, Ingo Molnar , Kees Cook Subject: Re: [tip:x86/core 16/17] vmlinux.o: warning: objtool: do_jit+0x276: relocation to !ENDBR: .noinstr.text+0x6a60 Message-ID: <20250303092459.GI5880@noisy.programming.kicks-ass.net> References: <202503030704.H9KFysNS-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202503030704.H9KFysNS-lkp@intel.com> On Mon, Mar 03, 2025 at 07:47:57AM +0800, kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/core > head: dfebe7362f6f461d771cdb9ac2c5172a4721f064 > commit: 0c92385dc05ee9637c04372ea95a11bbf6e010ff [16/17] x86/ibt: Implement FineIBT-BHI mitigation > config: x86_64-randconfig-071-20250303 (https://download.01.org/0day-ci/archive/20250303/202503030704.H9KFysNS-lkp@intel.com/config) > compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90) > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250303/202503030704.H9KFysNS-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-kbuild-all/202503030704.H9KFysNS-lkp@intel.com/ > > All warnings (new ones prefixed by >>): > > >> vmlinux.o: warning: objtool: do_jit+0x276: relocation to !ENDBR: .noinstr.text+0x6a60 Thanks, below seems to cure it for me. --- Subject: x86/ibt: Make cfi_bhi a constant for FINEIBT_BHI=n From: Peter Zijlstra Date: Mon Mar 3 10:21:47 CET 2025 Robot yielded a .config that tripped: vmlinux.o: warning: objtool: do_jit+0x276: relocation to !ENDBR: .noinstr.text+0x6a60 This is the result of using __bhi_args[1] in unreachable code; make sure the compiler is able to determine this is unreachable and trigger DCE. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202503030704.H9KFysNS-lkp@intel.com/ Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/cfi.h | 5 +++++ arch/x86/kernel/alternative.c | 3 +++ 2 files changed, 8 insertions(+) --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -100,7 +100,12 @@ enum cfi_mode { }; extern enum cfi_mode cfi_mode; + +#ifdef CONFIG_FINEIBT_BHI extern bool cfi_bhi; +#else +#define cfi_bhi (0) +#endif typedef u8 bhi_thunk[32]; extern bhi_thunk __bhi_args[]; --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -936,7 +936,10 @@ void __init_or_module apply_seal_endbr(s #endif enum cfi_mode cfi_mode __ro_after_init = __CFI_DEFAULT; + +#ifdef CONFIG_FINEIBT_BHI bool cfi_bhi __ro_after_init = false; +#endif #ifdef CONFIG_CFI_CLANG struct bpf_insn;