From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0032EC83F27 for ; Tue, 22 Jul 2025 08:34:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kuuTJENQGq/Zz+2Fmj2uqyE+Z7pIgJqUmUnrGJSBurU=; b=N7DGLKhpZ6Flu9 ZMaEQhY4xJ/MT0COuAqxDWmApbJeMiBAJgrLNPX5Bz9ZEDGntj1BZGmJ8Y2MVhtqSvqRdQfgJvEpA UbXol/p4fTwSLv6tKgNbIe5NDe67Ei+IAxXk9fTOlKMkpoAMLYivzcZ3RxvL77JiZmE6AsoHcBqvV S37pjdjG5edDpRirCkKNqAzFE7ews1thL6L4q16ii7KPZ/kHlBSuWHHmIVbrQRigp0SdvvEM1UEFm N7PV8uhqMKGe//xV30uRJQxAeXNyOGGJMNDMIeWC0e1xOqmpz7IrwxDiFXC+7yWEOvR1SotsLvCBa s6gDyKs2rTKb3pKme5GA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ue8ST-00000001qQV-1he7; Tue, 22 Jul 2025 08:34:45 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1ue8L4-00000001pVA-2fZW; Tue, 22 Jul 2025 08:27:06 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 017F7600AC; Tue, 22 Jul 2025 08:27:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A537C4CEF5; Tue, 22 Jul 2025 08:26:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753172825; bh=yGkRA/6qnjLPhMkWmaVYag52FJSXvc8HTUW6Y3Xuzs4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ftIKtFsS+75DjkESBKR4C/0fTfhjTO5EAQaosz6bDp0SBtC0xu6jrbFmvS+RKsdrx f4dMY3bCIrRdjzyHRTqQ2IS3DbC0aaJA20FDQXMOHNRYWFh4FtQSBKE6qcpYZfqwwn EBlY5p7lMzTdcc4tj5YJJGVzamw8NuZS2DY35/I8OtpLoIXd1OL5/ZeHJymCJvh1YO fQNqEpJ2tIsXeilrIIv/4unMX0gRI4A5tYLUiPoiE/g7dGzpTCnD1Qfrv0OCm/INtf +6BTjWwe4qdBcxVcEwQyD1qD72/jVzjC0CRHbF2sbB7CBVIvfoxl37x9XjTdsKkyQI 517UWQRiFJG/g== Date: Tue, 22 Jul 2025 11:26:46 +0300 From: Mike Rapoport To: Kees Cook Cc: Will Deacon , Arnd Bergmann , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paolo Bonzini , Vitaly Kuznetsov , Henrique de Moraes Holschuh , Hans de Goede , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , "Rafael J. Wysocki" , Len Brown , Masami Hiramatsu , Ard Biesheuvel , Michal Wilczynski , Juergen Gross , Andy Shevchenko , "Kirill A. Shutemov" , Roger Pau Monne , David Woodhouse , Usama Arif , "Guilherme G. Piccoli" , Thomas Huth , Brian Gerst , kvm@vger.kernel.org, ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, linux-acpi@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , "Gustavo A. R. Silva" , Christoph Hellwig , Andrey Konovalov , Andrey Ryabinin , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v3 04/13] x86: Handle KCOV __init vs inline mismatches Message-ID: References: <20250717231756.make.423-kees@kernel.org> <20250717232519.2984886-4-kees@kernel.org> <202507181541.B8CFAC7E@keescook> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <202507181541.B8CFAC7E@keescook> X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Jul 18, 2025 at 03:51:28PM -0700, Kees Cook wrote: > On Fri, Jul 18, 2025 at 11:36:32AM +0300, Mike Rapoport wrote: > > Hi Kees, > > > > On Thu, Jul 17, 2025 at 04:25:09PM -0700, Kees Cook wrote: > > > When KCOV is enabled all functions get instrumented, unless the > > > __no_sanitize_coverage attribute is used. To prepare for > > > __no_sanitize_coverage being applied to __init functions, we have to > > > handle differences in how GCC's inline optimizations get resolved. For > > > x86 this means forcing several functions to be inline with > > > __always_inline. > > > > > > Signed-off-by: Kees Cook > > > > ... > > > > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > > > index bb19a2534224..b96746376e17 100644 > > > --- a/include/linux/memblock.h > > > +++ b/include/linux/memblock.h > > > @@ -463,7 +463,7 @@ static inline void *memblock_alloc_raw(phys_addr_t size, > > > NUMA_NO_NODE); > > > } > > > > > > -static inline void *memblock_alloc_from(phys_addr_t size, > > > +static __always_inline void *memblock_alloc_from(phys_addr_t size, > > > phys_addr_t align, > > > phys_addr_t min_addr) > > > > I'm curious why from all memblock_alloc* wrappers this is the only one that > > needs to be __always_inline? > > Thread-merge[1], adding Will Deacon, who was kind of asking the same > question. > > Based on what I can tell, GCC has kind of fragile inlining logic, in the > sense that it can change whether or not it inlines something based on > optimizations. It looks like the kcov instrumentation being added (or in > this case, removed) from a function changes the optimization results, > and some functions marked "inline" are _not_ inlined. In that case, we end up > with __init code calling a function not marked __init, and we get the > build warnings I'm trying to eliminate. > > So, to Will's comment, yes, the problem is somewhat fragile (though > using either __always_inline or __init will deterministically solve it). > We've tripped over this before with GCC and the solution has usually > been to just use __always_inline and move on. > > For memblock_alloc*, it appears to be that the heuristic GCC uses > resulted in only memblock_alloc_from() being a problem in this case. I > can certainly mark them all as __always_inline if that is preferred. We had a few of those already converted to __always_inline, so I'm ok with continuing to fix them one at at time. Gives a feeling of job security ;-) > -- > Kees Cook -- Sincerely yours, Mike. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv