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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98075C83F27 for ; Tue, 22 Jul 2025 13:29:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 790A06B00AA; Tue, 22 Jul 2025 09:29:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 767F16B00AB; Tue, 22 Jul 2025 09:29:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 67D9D6B00AC; Tue, 22 Jul 2025 09:29:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 5946A6B00AA for ; Tue, 22 Jul 2025 09:29:36 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E0FE51DA62E for ; Tue, 22 Jul 2025 13:29:35 +0000 (UTC) X-FDA: 83691982710.08.957848A Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf07.hostedemail.com (Postfix) with ESMTP id 303FE40004 for ; Tue, 22 Jul 2025 13:29:34 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=icCzbYE3; spf=pass (imf07.hostedemail.com: domain of will@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=will@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1753190974; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=1rBiQqj/Tcg+yYn70Z3uULhGEZLBEASKzOk/gNIAvos=; b=cuSO0S0xA+QiJ6BQMAg6WgyA18vbuzTG/AkBN2flPOO4UD/GUinkmtQ5e3+Uza6y13xDOi FE/Runh8dU9qDSAgfhtfv5VdlHttcodKrQv6v2AAVECThQLGGrFfEQrEElmjNST4/5ZXqU O3MXuDmF1wpXSvf4T4n5BmzwVzqVD8c= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1753190974; a=rsa-sha256; cv=none; b=jj18KXEt8AudWSy9ZiBePsoXcYAqA8z0IAVyM920+Cu2/U9tYFQtL6GXTM/E5jFBtOM2eW kefDgoey3pHgK1n2L9DHvSC2fQdw3+JVR0nJE8FgE2Emzbo5FFpHkRFYbk/RDLvpWMKy+g evCUyUNN/HLXrOVNxoU/uVKC6bMF24Q= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=icCzbYE3; spf=pass (imf07.hostedemail.com: domain of will@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=will@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id EB0C9439BA; Tue, 22 Jul 2025 13:29:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B00BC4CEEB; Tue, 22 Jul 2025 13:29:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753190972; bh=v5BLSIwd7srHi/OWA5ndIBkdalmEzmLEQmrp+RewTTQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=icCzbYE3Gw4FMkjzZQGdd5PRl3DLgwJi4XEJMOcR2bhXW2g1yFhd+T0X/aqMi3/BP CibFuID4nbj6OAYkc1NMOYpqf8N3QkVei13FupO8PIGWwd7LMLFew2Gjxu4KdVUg1O DkTKaYgXxxbbsiX0+w7BLz0w/qJZtmL94y+JVE7CzC9ZZx6kQNyfp3ET4nPZ9scvga Dn2CpPG5UqY1IGli6LRySAYz4YmMRdxPp1TJllyeOcCWdL2WRYt94l/h9D04DE4+Uc MGgZG1jWvtMVVXZVVriPuhmhhcn2IesGNkPl/Ho6XBcy/wvha6uvWcQ0AKEDdQ4Ukm HjjZtlQLlu8FQ== Date: Tue, 22 Jul 2025 14:29:19 +0100 From: Will Deacon To: Ard Biesheuvel Cc: Kees Cook , Mike Rapoport , 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 , 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> <202507211311.8DAC4C7@keescook> <202507211349.D93679FB25@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 303FE40004 X-Stat-Signature: sh5btj19tmknj4qayqpima1pgfse4383 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1753190973-188640 X-HE-Meta: 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 jHKyleAv 0g4kwRUKeFB2ORsbBEF8HjLKcIiyFTp+pbVkU7T6mjNBR1nhBJdBUpdBd8Bp6CLz8ItNShOBQgL2I0P2MSv6a9XIklVm4p2FoTvWKuauEsSBkoGFs4Zo7bSOLTZnpArZ+RdQ9PLtNLaVAMze9VFY3a+qjvk5aWNE/cGu4UWgo24Xw7/S9szVifwlG/u5NlhzfkuZd1IKHXkQhwvfCzfyz1kVtO42S/uaWgOFBNG6Q+3aYETfmQ88j2vI8smAj/bbKmOJH2Hq1DLPdrc4XPOeWJs5mDiK/6zCOUGKb4Ry8vTgBcVVjuhv7asEyG3RldAUMAnCLllTIFGfCHzhgsXnbvZ1WLSHfL8aIvhXMDnjrv2S5JXguiU2G78HYxg+k6oBm3gDsUQ8DRjA8V+1jhBquiWDHz63Z6tG5ovnuUw9Y92pyFbMvJH4sjGcqOQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 22, 2025 at 04:55:47PM +1000, Ard Biesheuvel wrote: > On Tue, 22 Jul 2025 at 06:49, Kees Cook wrote: > > > > On Mon, Jul 21, 2025 at 01:14:36PM -0700, Kees Cook wrote: > > > On Mon, Jul 21, 2025 at 01:47:55PM +0100, Will Deacon wrote: > > > > On Sun, Jul 20, 2025 at 04:10:01PM +1000, Ard Biesheuvel wrote: > > > > > On Sat, 19 Jul 2025 at 08:51, Kees Cook wrote: > > > > > > On Fri, Jul 18, 2025 at 11:36:32AM +0300, Mike Rapoport wrote: > > > > > > > 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. > > > > > > > > Got it, thanks for the explanation! > > > > > > > > > > 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. > > > > > > > > > > > > > > > > Given that 'inline' is already a macro in the kernel, could we just > > > > > add __attribute__((__always_inline__)) to it when KCOV is enabled? > > > > > > > > That sounds like a more robust approach and, by the sounds of it, we > > > > could predicate it on GCC too. That would also provide a neat place for > > > > a comment describing the problem. > > > > > > > > Kees, would that work for you? > > > > > > That seems like an extremely large hammer for this problem, IMO. It > > > feels like it could cause new strange corner cases. I'd much prefer the > > > small fixes I've currently got since it keeps it focused. KCOV is > > > already enabled for "allmodconfig", so any new instances would be found > > > very quickly, etc. (And GCC's fragility in this regard has already been > > > exposed to these cases -- it's just that I changed one of the > > > combinations of __init vs inline vs instrumentation. > > > > > > I could give it a try, if you really prefer the big hammer approach... > > > > I gave it a try -- it fails spectacularly. ;) Let's stick to my small > > fixes instead? > > > > Fair enough :-) (but please add the helpful explanation you provided to the commit message!) Will