From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arvind Sankar Subject: Re: [PATCH v4 08/17] arm64/mm: Remove needless section quotes Date: Mon, 29 Jun 2020 17:06:19 -0400 Message-ID: <20200629210619.GA1603907@rani.riverdale.lan> References: <20200629061840.4065483-1-keescook@chromium.org> <20200629061840.4065483-9-keescook@chromium.org> <202006291301.46FEF3B7@keescook> <20200629205448.GA1474367@rani.riverdale.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387498AbgF2VGX (ORCPT ); Mon, 29 Jun 2020 17:06:23 -0400 Content-Disposition: inline In-Reply-To: <20200629205448.GA1474367@rani.riverdale.lan> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Arvind Sankar Cc: Kees Cook , Nick Desaulniers , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Nathan Chancellor , Arnd Bergmann , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , clang-built-linux , linux-arch , linux-efi On Mon, Jun 29, 2020 at 04:54:48PM -0400, Arvind Sankar wrote: > On Mon, Jun 29, 2020 at 01:04:31PM -0700, Kees Cook wrote: > > On Mon, Jun 29, 2020 at 12:53:47PM -0700, Nick Desaulniers wrote: > > > On Sun, Jun 28, 2020 at 11:18 PM Kees Cook wrote: > > > > > > > > Fix a case of needless quotes in __section(), which Clang doesn't like. > > > > > > > > Acked-by: Will Deacon > > > > Signed-off-by: Kees Cook > > > > > > Yep, I remember bugs from this. Probably should scan the kernel for > > > other instances of this. +Joe for checkpatch.pl validation. > > > > I think the others are safe because they're in macros: > > Why does that make it safe -- the commit msg is a bit sparse, but I > assume the problem is that it generates > __attribute__((__section__("\".foo\""))) > from > __section(".foo") > after preprocessing, and clang keeps the quotes in the section name when > generating assembly, while gcc appears to strip them off. > > It does that even if nested in another macro, no? Yep, I can see things like: [25] ".discard.ksym" PROGBITS 0000000000000000 0000217c 0000000000000000 0000000000000000 WA 0 0 4 Doesn't seem to cause a build error, but that can't be good. > > > > > $ git grep -4 '__section("' > > include/linux/compiler.h-# define KENTRY(sym) \ > > Am I missing something, or is KENTRY unused in the tree? > > > include/linux/compiler.h- extern typeof(sym) sym; \ > > include/linux/compiler.h- static const unsigned long __kentry_##sym \ > > include/linux/compiler.h- __used \ > > include/linux/compiler.h: __section("___kentry" "+" #sym ) \ > > include/linux/compiler.h- = (unsigned long)&sym; > > -- > > include/linux/export.h-#define __ksym_marker(sym) \ > > include/linux/export.h: static int __ksym_marker_##sym[0] __section(".discard.ksym") __used > > -- > > include/linux/srcutree.h-# define __DEFINE_SRCU(name, is_static) \ > > include/linux/srcutree.h- is_static struct srcu_struct name; \ > > include/linux/srcutree.h- struct srcu_struct * const __srcu_struct_##name \ > > include/linux/srcutree.h: __section("___srcu_struct_ptrs") = &name > > > > > > > Reviewed-by: Nick Desaulniers > > > > Thanks! > > > > -- > > Kees Cook From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387498AbgF2VGX (ORCPT ); Mon, 29 Jun 2020 17:06:23 -0400 From: Arvind Sankar Date: Mon, 29 Jun 2020 17:06:19 -0400 Subject: Re: [PATCH v4 08/17] arm64/mm: Remove needless section quotes Message-ID: <20200629210619.GA1603907@rani.riverdale.lan> References: <20200629061840.4065483-1-keescook@chromium.org> <20200629061840.4065483-9-keescook@chromium.org> <202006291301.46FEF3B7@keescook> <20200629205448.GA1474367@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200629205448.GA1474367@rani.riverdale.lan> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Arvind Sankar Cc: Kees Cook , Nick Desaulniers , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Nathan Chancellor , Arnd Bergmann , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , clang-built-linux , linux-arch , linux-efi , Linux ARM , LKML , Joe Perches Message-ID: <20200629210619.DkrTAsnqm8qTknM-fOL6IONKPVnd9Nmo7XX4dcjj3II@z> On Mon, Jun 29, 2020 at 04:54:48PM -0400, Arvind Sankar wrote: > On Mon, Jun 29, 2020 at 01:04:31PM -0700, Kees Cook wrote: > > On Mon, Jun 29, 2020 at 12:53:47PM -0700, Nick Desaulniers wrote: > > > On Sun, Jun 28, 2020 at 11:18 PM Kees Cook wrote: > > > > > > > > Fix a case of needless quotes in __section(), which Clang doesn't like. > > > > > > > > Acked-by: Will Deacon > > > > Signed-off-by: Kees Cook > > > > > > Yep, I remember bugs from this. Probably should scan the kernel for > > > other instances of this. +Joe for checkpatch.pl validation. > > > > I think the others are safe because they're in macros: > > Why does that make it safe -- the commit msg is a bit sparse, but I > assume the problem is that it generates > __attribute__((__section__("\".foo\""))) > from > __section(".foo") > after preprocessing, and clang keeps the quotes in the section name when > generating assembly, while gcc appears to strip them off. > > It does that even if nested in another macro, no? Yep, I can see things like: [25] ".discard.ksym" PROGBITS 0000000000000000 0000217c 0000000000000000 0000000000000000 WA 0 0 4 Doesn't seem to cause a build error, but that can't be good. > > > > > $ git grep -4 '__section("' > > include/linux/compiler.h-# define KENTRY(sym) \ > > Am I missing something, or is KENTRY unused in the tree? > > > include/linux/compiler.h- extern typeof(sym) sym; \ > > include/linux/compiler.h- static const unsigned long __kentry_##sym \ > > include/linux/compiler.h- __used \ > > include/linux/compiler.h: __section("___kentry" "+" #sym ) \ > > include/linux/compiler.h- = (unsigned long)&sym; > > -- > > include/linux/export.h-#define __ksym_marker(sym) \ > > include/linux/export.h: static int __ksym_marker_##sym[0] __section(".discard.ksym") __used > > -- > > include/linux/srcutree.h-# define __DEFINE_SRCU(name, is_static) \ > > include/linux/srcutree.h- is_static struct srcu_struct name; \ > > include/linux/srcutree.h- struct srcu_struct * const __srcu_struct_##name \ > > include/linux/srcutree.h: __section("___srcu_struct_ptrs") = &name > > > > > > > Reviewed-by: Nick Desaulniers > > > > Thanks! > > > > -- > > Kees Cook