From patchwork Tue Dec 5 16:06:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 120712 Delivered-To: patch@linaro.org Received: by 10.140.22.227 with SMTP id 90csp5930418qgn; Tue, 5 Dec 2017 08:07:39 -0800 (PST) X-Google-Smtp-Source: AGs4zMaYLTgCvFCWZTHumSGuPcOyZKLQU6GRqu+YDBhBCfghAdX2QkQrrnTYQELaaSA1QSRXybxK X-Received: by 10.159.194.1 with SMTP id x1mr18424875pln.235.1512490059184; Tue, 05 Dec 2017 08:07:39 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1512490059; cv=none; d=google.com; s=arc-20160816; b=yxnpxu76F1RNmqVcHKdGoc5YrF/yRuVNAU3U87bh9yaEenfO3Xj8/TXIbVLAnlkvFF 8YoElmo0xVTvkPozMasBOO0/aZjJsHdwa2rMUUqLDncBpokvoNBvXcIbtkZW4JJLgX5b OTXujln8OE/c4jI0IsMYLGYcAFrK0ACijRMC8G5+YaVEP33FuRu4FXdUZxNOkz5qTysP 4vfmGhgePC7pEPQAWAKN9TCY6tnclUS4N2mSRKt8lIfD9Yqs3DMgar7Vqk6IvBSScuA/ f1iGzZFbHlD2hyKD7Yi6zJt1M/jNBKrbfYhgcXeqTTXD7QLs8g33YxJM6SPITv0C4JDs RO9Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=0UdWpQA69chh1fAimRno3XgrnrpVNzyYyCCuTaoc6fs=; b=xjIhHyOu6Rpm4pa8VKrxT0KE1mTHjdM/q1wFnfGa5NsgRmKdfTUu3orHFp8shMtQ9P xXKhz56VmTgx2invGD12TgCaUP8DOmL3l2E5noZIlXWERxjminKiZROTlEZn4tN9PGIB R9aleEv0/NDxYs1Jiyz+imR9qDZy7WjdLwWC/8HeSBwWK4AnOCtHTLnulDVrGlwJ+L+j egUBmyqLaGpx/nUXQbGaJAXaUcOKYr3bFQZFJnTTg/7ax80D3w/HzaxcFJCTeYPZ4b9o 87+o2wsmkT6IxANEXvtLz1hlxN2d/OcrUpD0dUNUoElvujodU6WfCbLXrQIbYlU1IqDy UgFQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id j14si253027pga.407.2017.12.05.08.07.38; Tue, 05 Dec 2017 08:07:39 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783AbdLEQHh (ORCPT + 28 others); Tue, 5 Dec 2017 11:07:37 -0500 Received: from mout.kundenserver.de ([212.227.126.134]:52496 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752151AbdLEQHe (ORCPT ); Tue, 5 Dec 2017 11:07:34 -0500 Received: from wuerfel.lan ([149.172.96.106]) by mrelayeu.kundenserver.de (mreue001 [212.227.15.129]) with ESMTPA (Nemesis) id 0LjR72-1exWRM2RLM-00ba0Y; Tue, 05 Dec 2017 17:06:56 +0100 From: Arnd Bergmann To: linux-kbuild@vger.kernel.org Cc: Michal Marek , Masahiro Yamada , Douglas Anderson , Al Viro , Heiko Carstens , Mauro Carvalho Chehab , Matthew Wilcox , Matthias Kaehlcke , Arnd Bergmann , Deepa Dinamani , Thomas Gleixner , Frederic Weisbecker , Stephan Mueller , "David S. Miller" , Yonghong Song , Thomas Garnier , David Howells , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH 2/2] [RFC] disable -Wattribute-alias warning for SYSCALL_DEFINEx() Date: Tue, 5 Dec 2017 17:06:31 +0100 Message-Id: <20171205160651.2920270-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20171205153259.2522368-1-arnd@arndb.de> References: <20171205153259.2522368-1-arnd@arndb.de> X-Provags-ID: V03:K0:riqrdhpkPRQTQMaH8El28ozZ0JbWDYmgBRsKidykT9KgqwL+n2w Js4Hz7phj/cmHKp4h+1pHhuemMOGVShBZJBbBYFNz1y64BB0l+qXDJ3g8q/uq8jfaIWBX/R zShUqjT8xB/TQO2D7acDuVnrKkwpn1VNyeCaTwddznKobabCAZfbVkTOmWkLZr+V+Jv20c6 5yJ6572XZCkds5JLfjmJQ== X-UI-Out-Filterresults: notjunk:1; V01:K0:a8cEjts1WmA=:rsc8ELXnMsVqtcr5yAt6QR wA8GqIKhZuBz9TJ1iEYPM1UqFH0rT56oPoxVXy0Y3leOkYvv2JK7hH5AbHRcpfukbO8J41U14 cUD/Y6gSX1QSALDitT6IWcA+0WBgycXreX3jy9V7nZo1GBkkJvwzFEIHIKtQe7fQozCye44at PWz15e3MJYuWeTl/lHafNR4+cKXMiAWHaXDFAoacyUyB8ebXn4HlCSW2ybu0+HJkF+CxYlGX7 TZ3qufzVZV2dQg0pKwCrzaX2AF/DLLJDkLvf+rAEfx8Gk8GvjxVGHcXhk2SSjCLWsddFCswDw kDDIgNxxtOVF4jk2KrykPw20kXMYqQkss77CNp3BJkbdHEra4oCEnlsjMOQy52oBQm8bBCtji PUCa8g8LUb2ubdQIa962nf6vex3kMTR8NmCm8KrZMPl9/7kpLva3ouWQqQWeenNgGs7rOszwS nejrMwasFK/mSIKC1GGeZ6IrDEwAA70SbsGJBbXOM0eZOrK+1MX9UcM1zQGvytzGr8GQe5vNu mKn9TEmXKM4FhwzAF8SzTQoX4SRKrP2Zjs2ILvginbpofHnCTX2EERStFLpLpTfcaEmhevdeS dvYf2GjJczRXY5nH5+i3biFU9ogayMsLFkteJVFgcLmmqtpvRxs1JOXx16bB+q7ogTSCRKbFp ZssU0al4olOjETaJxAYDsT371EO5hOlrao5hBls6njv5JpC0xXAu7qSVzVMtgcSfZqRm0VnLM uS044NplVKLfnUiVIShjiCXw8E3frvka2YgSoQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82435 Signed-off-by: Arnd Bergmann --- include/linux/compat.h | 7 ++++++- include/linux/syscalls.h | 3 +++ 2 files changed, 9 insertions(+), 1 deletion(-) -- 2.9.0 diff --git a/include/linux/compat.h b/include/linux/compat.h index 1165036d091f..27b4a429df77 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -49,14 +49,19 @@ COMPAT_SYSCALL_DEFINEx(6, _##name, __VA_ARGS__) #define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ + __diag_push(); \ + __diag_ignore(GCC_8, "-Wattribute-alias"); \ asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\ __attribute__((alias(__stringify(compat_SyS##name)))); \ static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__));\ asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__))\ { \ - return C_SYSC##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \ + long ret = C_SYSC##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\ + __MAP(x,__SC_TEST,__VA_ARGS__); \ + return ret; \ } \ + __diag_pop(); \ static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) #ifdef CONFIG_COMPAT diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 4df16a70b0d7..dcf6ceabda44 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -208,6 +208,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) #define __PROTECT(...) asmlinkage_protect(__VA_ARGS__) #define __SYSCALL_DEFINEx(x, name, ...) \ + __diag_push(); \ + __diag_ignore(GCC_8, "-Wattribute-alias"); \ asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ __attribute__((alias(__stringify(SyS##name)))); \ static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ @@ -219,6 +221,7 @@ 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 SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) /*