Message ID | 20210227165911.32757-1-chang.seok.bae@intel.com |
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Return-Path: <libc-alpha-bounces@sourceware.org> X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 46D803834419; Sat, 27 Feb 2021 17:04:03 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 46D803834419 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1614445443; bh=oI7coSus3mMLde4Qnyq6fgNisqoBh2OLXPf/ybaG1aY=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=kk950OJgV318nnoHp7z44nrsrwxiRew6sXf2UghcExhzFnmdj0LEjTaSeoGIxpXsI Ocx5sZ14G0FqZU9PcInLlq/AY0WiiUQlJt5WgVU3RT5+qK7LDU5wltBDVFg2tsuZYN IUjhr70dkIqjbvhyQTvkFdLvr5FegRI+y0pJm5IA= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by sourceware.org (Postfix) with ESMTPS id 54C403858022 for <libc-alpha@sourceware.org>; Sat, 27 Feb 2021 17:03:59 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 54C403858022 IronPort-SDR: Qm8IzGT2V/lMcW56uOjZw2mIt43MX+YIvNEoOik6gI1ae/PMTbCh1cQ+Ky5Lj8EMAXnn5XIA+1 JDna6YJYPh6Q== X-IronPort-AV: E=McAfee;i="6000,8403,9908"; a="183680700" X-IronPort-AV: E=Sophos;i="5.81,211,1610438400"; d="scan'208";a="183680700" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Feb 2021 09:03:58 -0800 IronPort-SDR: LA7o83PvWQmj39wNcGHGThah0FxynPD/l3gspiFgA6WRWHht1a6ovIZ2i9d5p9t4uUCPhZRjDU cmTtJ5XQ+UnA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,211,1610438400"; d="scan'208";a="503906838" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga001.fm.intel.com with ESMTP; 27 Feb 2021 09:03:58 -0800 To: bp@suse.de, tglx@linutronix.de, mingo@kernel.org, luto@kernel.org, x86@kernel.org Subject: [PATCH v6 0/6] x86: Improve Minimum Alternate Stack Size Date: Sat, 27 Feb 2021 08:59:05 -0800 Message-Id: <20210227165911.32757-1-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 X-Spam-Status: No, score=-3.3 required=5.0 tests=AC_FROM_MANY_DOTS, BAYES_00, KAM_DMARC_STATUS, KAM_SHORT, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list <libc-alpha.sourceware.org> List-Unsubscribe: <https://sourceware.org/mailman/options/libc-alpha>, <mailto:libc-alpha-request@sourceware.org?subject=unsubscribe> List-Archive: <https://sourceware.org/pipermail/libc-alpha/> List-Post: <mailto:libc-alpha@sourceware.org> List-Help: <mailto:libc-alpha-request@sourceware.org?subject=help> List-Subscribe: <https://sourceware.org/mailman/listinfo/libc-alpha>, <mailto:libc-alpha-request@sourceware.org?subject=subscribe> From: "Chang S. Bae via Libc-alpha" <libc-alpha@sourceware.org> Reply-To: "Chang S. Bae" <chang.seok.bae@intel.com> Cc: linux-arch@vger.kernel.org, len.brown@intel.com, tony.luck@intel.com, libc-alpha@sourceware.org, ravi.v.shankar@intel.com, chang.seok.bae@intel.com, jannh@google.com, linux-kernel@vger.kernel.org, dave.hansen@intel.com, linux-api@vger.kernel.org, Dave.Martin@arm.com Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" <libc-alpha-bounces@sourceware.org> |
Series |
x86: Improve Minimum Alternate Stack Size
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Message
Chang S. Bae
Feb. 27, 2021, 4:59 p.m. UTC
During signal entry, the kernel pushes data onto the normal userspace stack. On x86, the data pushed onto the user stack includes XSAVE state, which has grown over time as new features and larger registers have been added to the architecture. MINSIGSTKSZ is a constant provided in the kernel signal.h headers and typically distributed in lib-dev(el) packages, e.g. [1]. Its value is compiled into programs and is part of the user/kernel ABI. The MINSIGSTKSZ constant indicates to userspace how much data the kernel expects to push on the user stack, [2][3]. However, this constant is much too small and does not reflect recent additions to the architecture. For instance, when AVX-512 states are in use, the signal frame size can be 3.5KB while MINSIGSTKSZ remains 2KB. The bug report [4] explains this as an ABI issue. The small MINSIGSTKSZ can cause user stack overflow when delivering a signal. In this series, we suggest a couple of things: 1. Provide a variable minimum stack size to userspace, as a similar approach to [5]. 2. Avoid using a too-small alternate stack. Changes form v5 [10]: * Fixed the overflow detection. (Andy Lutomirski) * Reverted the AT_MINSIGSTKSZ removal on arm64. (Dave Martin) * Added a documentation about the x86 AT_MINSIGSTKSZ. * Supported the existing sigaltstack test to use the new aux vector. Changes from v4 [9]: * Moved the aux vector define to the generic header. (Carlos O'Donell) Changes from v3 [8]: * Updated the changelog. (Borislav Petkov) * Revised the test messages again. (Borislav Petkov) Changes from v2 [7]: * Simplified the sigaltstack overflow prevention. (Jann Horn) * Renamed fpstate size helper with cleanup. (Borislav Petkov) * Cleaned up the signframe struct size defines. (Borislav Petkov) * Revised the selftest messages. (Borislav Petkov) * Revised a changelog. (Borislav Petkov) Changes from v1 [6]: * Took stack alignment into account for sigframe size. (Dave Martin) [1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/bits/sigstack.h;h=b9dca794da093dc4d41d39db9851d444e1b54d9b;hb=HEAD [2]: https://www.gnu.org/software/libc/manual/html_node/Signal-Stack.html [3]: https://man7.org/linux/man-pages/man2/sigaltstack.2.html [4]: https://bugzilla.kernel.org/show_bug.cgi?id=153531 [5]: https://blog.linuxplumbersconf.org/2017/ocw/system/presentations/4671/original/plumbers-dm-2017.pdf [6]: https://lore.kernel.org/lkml/20200929205746.6763-1-chang.seok.bae@intel.com/ [7]: https://lore.kernel.org/lkml/20201119190237.626-1-chang.seok.bae@intel.com/ [8]: https://lore.kernel.org/lkml/20201223015312.4882-1-chang.seok.bae@intel.com/ [9]: https://lore.kernel.org/lkml/20210115211038.2072-1-chang.seok.bae@intel.com/ [10]: https://lore.kernel.org/lkml/20210203172242.29644-1-chang.seok.bae@intel.com/ Chang S. Bae (6): uapi: Define the aux vector AT_MINSIGSTKSZ x86/signal: Introduce helpers to get the maximum signal frame size x86/elf: Support a new ELF aux vector AT_MINSIGSTKSZ selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available x86/signal: Detect and prevent an alternate signal stack overflow selftest/x86/signal: Include test cases for validating sigaltstack Documentation/x86/elf_auxvec.rst | 56 ++++++++++ arch/x86/include/asm/elf.h | 4 + arch/x86/include/asm/fpu/signal.h | 2 + arch/x86/include/asm/sigframe.h | 2 + arch/x86/include/uapi/asm/auxvec.h | 4 +- arch/x86/kernel/cpu/common.c | 3 + arch/x86/kernel/fpu/signal.c | 19 ++++ arch/x86/kernel/signal.c | 72 +++++++++++- include/uapi/linux/auxvec.h | 3 + tools/testing/selftests/sigaltstack/sas.c | 20 +++- tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/sigaltstack.c | 128 ++++++++++++++++++++++ 12 files changed, 302 insertions(+), 13 deletions(-) create mode 100644 Documentation/x86/elf_auxvec.rst create mode 100644 tools/testing/selftests/x86/sigaltstack.c base-commit: f40ddce88593482919761f74910f42f4b84c004b