From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755521AbcECHvi (ORCPT ); Tue, 3 May 2016 03:51:38 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37372 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755414AbcECHvg (ORCPT ); Tue, 3 May 2016 03:51:36 -0400 Date: Tue, 3 May 2016 00:50:06 -0700 From: tip-bot for Stas Sergeev Message-ID: Cc: sasha.levin@oracle.com, linux-kernel@vger.kernel.org, hpa@zytor.com, shuahkh@osg.samsung.com, xemul@parallels.com, luto@amacapital.net, mingo@kernel.org, vdavydov@parallels.com, torvalds@linux-foundation.org, amanieu@gmail.com, peterz@infradead.org, stsp@list.ru, viro@zeniv.linux.org.uk, tglx@linutronix.de, oleg@redhat.com, mhocko@suse.com, dvlasenk@redhat.com, akpm@linux-foundation.org, bp@alien8.de, brgerst@gmail.com, richard@nod.at Reply-To: peterz@infradead.org, amanieu@gmail.com, vdavydov@parallels.com, torvalds@linux-foundation.org, luto@amacapital.net, mingo@kernel.org, xemul@parallels.com, shuahkh@osg.samsung.com, sasha.levin@oracle.com, linux-kernel@vger.kernel.org, hpa@zytor.com, richard@nod.at, brgerst@gmail.com, bp@alien8.de, akpm@linux-foundation.org, mhocko@suse.com, dvlasenk@redhat.com, stsp@list.ru, viro@zeniv.linux.org.uk, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <1460665206-13646-3-git-send-email-stsp@list.ru> References: <1460665206-13646-3-git-send-email-stsp@list.ru> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/signals] signals/sigaltstack: Prepare to add new SS_xxx flags Git-Commit-ID: 407bc16ad1769f5cb8ad9555611cb198187ef4cd X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 407bc16ad1769f5cb8ad9555611cb198187ef4cd Gitweb: http://git.kernel.org/tip/407bc16ad1769f5cb8ad9555611cb198187ef4cd Author: Stas Sergeev AuthorDate: Thu, 14 Apr 2016 23:20:03 +0300 Committer: Ingo Molnar CommitDate: Tue, 3 May 2016 08:37:59 +0200 signals/sigaltstack: Prepare to add new SS_xxx flags This patch adds SS_FLAG_BITS - the mask that splits sigaltstack mode values and bit-flags. Since there is no bit-flags yet, the mask is defined to 0. The flags are added by subsequent patches. With every new flag, the mask should have the appropriate bit cleared. This makes sure if some flag is tried on a kernel that doesn't support it, the -EINVAL error will be returned, because such a flag will be treated as an invalid mode rather than the bit-flag. That way the existence of the particular features can be probed at run-time. This change was suggested by Andy Lutomirski: https://lkml.org/lkml/2016/3/6/158 Signed-off-by: Stas Sergeev Cc: Al Viro Cc: Amanieu d'Antras Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Michal Hocko Cc: Oleg Nesterov Cc: Pavel Emelyanov Cc: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Richard Weinberger Cc: Sasha Levin Cc: Shuah Khan Cc: Thomas Gleixner Cc: Vladimir Davydov Cc: linux-api@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1460665206-13646-3-git-send-email-stsp@list.ru Signed-off-by: Ingo Molnar --- include/uapi/linux/signal.h | 3 +++ kernel/signal.c | 16 ++++++---------- 2 files changed, 9 insertions(+), 10 deletions(-) diff --git a/include/uapi/linux/signal.h b/include/uapi/linux/signal.h index e1bd50c2..7c73165 100644 --- a/include/uapi/linux/signal.h +++ b/include/uapi/linux/signal.h @@ -7,4 +7,7 @@ #define SS_ONSTACK 1 #define SS_DISABLE 2 +/* mask for all SS_xxx flags */ +#define SS_FLAG_BITS 0 + #endif /* _UAPI_LINUX_SIGNAL_H */ diff --git a/kernel/signal.c b/kernel/signal.c index aa9bf00..b1c6eb4 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3104,7 +3104,8 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s if (uss) { void __user *ss_sp; size_t ss_size; - int ss_flags; + unsigned ss_flags; + int ss_mode; error = -EFAULT; if (!access_ok(VERIFY_READ, uss, sizeof(*uss))) @@ -3119,18 +3120,13 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s if (on_sig_stack(sp)) goto out; + ss_mode = ss_flags & ~SS_FLAG_BITS; error = -EINVAL; - /* - * Note - this code used to test ss_flags incorrectly: - * old code may have been written using ss_flags==0 - * to mean ss_flags==SS_ONSTACK (as this was the only - * way that worked) - this fix preserves that older - * mechanism. - */ - if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0) + if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK && + ss_mode != 0) goto out; - if (ss_flags == SS_DISABLE) { + if (ss_mode == SS_DISABLE) { ss_size = 0; ss_sp = NULL; } else {