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 16:54:48 -0400 Message-ID: <20200629205448.GA1474367@rani.riverdale.lan> References: <20200629061840.4065483-1-keescook@chromium.org> <20200629061840.4065483-9-keescook@chromium.org> <202006291301.46FEF3B7@keescook> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729267AbgF2Uyw (ORCPT ); Mon, 29 Jun 2020 16:54:52 -0400 Content-Disposition: inline In-Reply-To: <202006291301.46FEF3B7@keescook> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Nick Desaulniers , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , 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 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? > > $ 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]:60092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729267AbgF2Uyw (ORCPT ); Mon, 29 Jun 2020 16:54:52 -0400 From: Arvind Sankar Date: Mon, 29 Jun 2020 16:54:48 -0400 Subject: Re: [PATCH v4 08/17] arm64/mm: Remove needless section quotes Message-ID: <20200629205448.GA1474367@rani.riverdale.lan> References: <20200629061840.4065483-1-keescook@chromium.org> <20200629061840.4065483-9-keescook@chromium.org> <202006291301.46FEF3B7@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <202006291301.46FEF3B7@keescook> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Nick Desaulniers , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , 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: <20200629205448.fHqpvtf07AfL5IumTBI9ls7_IBnLnW1hLS0UnsSaknI@z> 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? > > $ 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