From patchwork Sat Jun 16 00:53:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Burton X-Patchwork-Id: 10467831 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 40592601C2 for ; Sat, 16 Jun 2018 00:57:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3AFC128EB0 for ; Sat, 16 Jun 2018 00:57:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2D14028EB5; Sat, 16 Jun 2018 00:57:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6314228EB0 for ; Sat, 16 Jun 2018 00:57:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936492AbeFPA5M (ORCPT ); Fri, 15 Jun 2018 20:57:12 -0400 Received: from 9pmail.ess.barracuda.com ([64.235.150.225]:35736 "EHLO 9pmail.ess.barracuda.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936486AbeFPA5L (ORCPT ); Fri, 15 Jun 2018 20:57:11 -0400 Received: from mipsdag02.mipstec.com (mail2.mips.com [12.201.5.32]) by mx29.ess.sfj.cudaops.com (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA256 bits=128 verify=NO); Sat, 16 Jun 2018 00:54:19 +0000 Received: from mipsdag02.mipstec.com (10.20.40.47) by mipsdag02.mipstec.com (10.20.40.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1415.2; Fri, 15 Jun 2018 17:54:00 -0700 Received: from pburton-laptop.mipstec.com (10.20.2.29) by mipsdag02.mipstec.com (10.20.40.47) with Microsoft SMTP Server id 15.1.1415.2 via Frontend Transport; Fri, 15 Jun 2018 17:54:00 -0700 From: Paul Burton To: CC: Mauro Carvalho Chehab , , Arnd Bergmann , Ingo Molnar , Matthew Wilcox , Thomas Gleixner , Douglas Anderson , Josh Poimboeuf , Andrew Morton , Matthias Kaehlcke , He Zhe , Benjamin Herrenschmidt , Michal Marek , Khem Raj , Christophe Leroy , Al Viro , Stafford Horne , Gideon Israel Dsouza , Masahiro Yamada , Kees Cook , Michael Ellerman , Heiko Carstens , , Paul Mackerras , , Paul Burton Subject: [PATCH 2/3] disable -Wattribute-alias warning for SYSCALL_DEFINEx() Date: Fri, 15 Jun 2018 17:53:21 -0700 Message-ID: <20180616005323.7938-3-paul.burton@mips.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180616005323.7938-1-paul.burton@mips.com> References: <20180616005323.7938-1-paul.burton@mips.com> MIME-Version: 1.0 X-BESS-ID: 1529110459-637139-29217-15683-1 X-BESS-VER: 2018.7-r1806151722 X-BESS-Apparent-Source-IP: 12.201.5.32 X-BESS-Envelope-From: Paul.Burton@mips.com X-BESS-Outbound-Spam-Score: 0.00 X-BESS-Outbound-Spam-Report: Code version 3.2, rules version 3.2.2.194099 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------- 0.00 BSF_BESS_OUTBOUND META: BESS Outbound X-BESS-Outbound-Spam-Status: SCORE=0.00 using account:ESS59374 scores of KILL_LEVEL=7.0 tests=BSF_BESS_OUTBOUND X-BESS-Orig-Rcpt: linux-kbuild@vger.kernel.org, paulus@samba.org, linux-kernel@vger.kernel.org, heiko.carstens@de.ibm.com, mpe@ellerman.id.au, keescook@chromium.org, yamada.masahiro@socionext.com, gidisrael@gmail.com, shorne@gmail.com, viro@zeniv.linux.org.uk, christophe.leroy@c-s.fr, raj.khem@gmail.com, michal.lkml@markovi.net, zhe.he@windriver.com, mka@chromium.org, akpm@linux-foundation.org, jpoimboe@redhat.com, dianders@chromium.org, tglx@linutronix.de, matthew@wil.cx, arnd@arndb.de, linux-mips@linux-mips.org, benh@kernel.crashing.org X-BESS-BRTS-Status: 1 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Arnd Bergmann gcc-8 warns for every single definition of a system call entry point, e.g.: include/linux/compat.h:56:18: error: 'compat_sys_rt_sigprocmask' alias between functions of incompatible types 'long int(int, compat_sigset_t *, compat_sigset_t *, compat_size_t)' {aka 'long int(int, struct *, struct *, unsigned int)'} and 'long int(long int, long int, long int, long int)' [-Werror=attribute-alias] asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\ ^~~~~~~~~~ include/linux/compat.h:45:2: note: in expansion of macro 'COMPAT_SYSCALL_DEFINEx' COMPAT_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__) ^~~~~~~~~~~~~~~~~~~~~~ kernel/signal.c:2601:1: note: in expansion of macro 'COMPAT_SYSCALL_DEFINE4' COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, ^~~~~~~~~~~~~~~~~~~~~~ include/linux/compat.h:60:18: note: aliased declaration here asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__))\ ^~~~~~~~~~ The new warning seems reasonable in principle, but it doesn't help us here, since we rely on the type mismatch to sanitize the system call arguments. After I reported this as GCC PR82435, a new -Wno-attribute-alias option was added that could be used to turn the warning off globally on the command line, but I'd prefer to do it a little more fine-grained. Interestingly, turning a warning off and on again inside of a single macro doesn't always work, in this case I had to add an extra statement inbetween and decided to copy the __SC_TEST one from the native syscall to the compat syscall macro. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 for more details about this. [paul.burton@mips.com: - Rebase atop current master. - Split GCC & version arguments to __diag_ignore() in order to match changes to the preceding patch. - Add the comment argument to match the preceding patch.] Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82435 Signed-off-by: Arnd Bergmann Signed-off-by: Paul Burton Cc: Michal Marek Cc: Masahiro Yamada Cc: Douglas Anderson Cc: Al Viro Cc: Heiko Carstens Cc: Mauro Carvalho Chehab Cc: Matthew Wilcox Cc: Matthias Kaehlcke Cc: Arnd Bergmann Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Kees Cook Cc: Andrew Morton Cc: Thomas Gleixner Cc: Gideon Israel Dsouza Cc: Christophe Leroy Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Stafford Horne Cc: Khem Raj Cc: He Zhe Cc: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linuxppc-dev@lists.ozlabs.org Tested-by: Christophe Leroy --- include/linux/compat.h | 8 +++++++- include/linux/syscalls.h | 4 ++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index b1a5562b3215..c68acc47da57 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -72,6 +72,9 @@ */ #ifndef COMPAT_SYSCALL_DEFINEx #define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ + __diag_push(); \ + __diag_ignore(GCC, 8, "-Wattribute-alias", \ + "Type aliasing is used to sanitize syscall arguments");\ asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ __attribute__((alias(__stringify(__se_compat_sys##name)))); \ @@ -80,8 +83,11 @@ asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ { \ - return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\ + long ret = __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\ + __MAP(x,__SC_TEST,__VA_ARGS__); \ + return ret; \ } \ + __diag_pop(); \ static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) #endif /* COMPAT_SYSCALL_DEFINEx */ diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 73810808cdf2..a368a68cb667 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -231,6 +231,9 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) */ #ifndef __SYSCALL_DEFINEx #define __SYSCALL_DEFINEx(x, name, ...) \ + __diag_push(); \ + __diag_ignore(GCC, 8, "-Wattribute-alias", \ + "Type aliasing is used to sanitize syscall arguments");\ asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ __attribute__((alias(__stringify(__se_sys##name)))); \ ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ @@ -243,6 +246,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ return ret; \ } \ + __diag_pop(); \ static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) #endif /* __SYSCALL_DEFINEx */