From patchwork Wed Feb 5 18:19:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu-cheng Yu X-Patchwork-Id: 11366939 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 86C0717E0 for ; Wed, 5 Feb 2020 18:21:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5C1BF218AC for ; Wed, 5 Feb 2020 18:21:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C1BF218AC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 828186B0075; Wed, 5 Feb 2020 13:20:35 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 7E57D6B007B; Wed, 5 Feb 2020 13:20:35 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E1366B0080; Wed, 5 Feb 2020 13:20:35 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id 38E326B0075 for ; Wed, 5 Feb 2020 13:20:35 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id CBEEF180AD802 for ; Wed, 5 Feb 2020 18:20:34 +0000 (UTC) X-FDA: 76456888788.13.pipe30_796a792e1815e X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,yu-cheng.yu@intel.com,:x86@kernel.org:hpa@zytor.com:tglx@linutronix.de:mingo@redhat.com:linux-kernel@vger.kernel.org:linux-doc@vger.kernel.org::linux-arch@vger.kernel.org:linux-api@vger.kernel.org:arnd@arndb.de:luto@kernel.org:bsingharora@gmail.com:bp@alien8.de:gorcunov@gmail.com:dave.hansen@linux.intel.com:esyr@redhat.com:fweimer@redhat.com:hjl.tools@gmail.com:jannh@google.com:corbet@lwn.net:keescook@chromium.org:mike.kravetz@oracle.com:nadav.amit@gmail.com:oleg@redhat.com:pavel@ucw.cz:peterz@infradead.org:rdunlap@infradead.org:ravi.v.shankar@intel.com:vedvyas.shanbhogue@intel.com:dave.martin@arm.com:x86-patch-review@intel.com:yu-cheng.yu@intel.com,RULES_HIT:30003:30051:30054:30056:30064:30070,0,RBL:134.134.136.20:@intel.com:.lbl8.mailshell.net-62.50.0.100 64.95.201.95,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:ft,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: pipe30_796a792e1815e X-Filterd-Recvd-Size: 3900 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Wed, 5 Feb 2020 18:20:34 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2020 10:20:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,406,1574150400"; d="scan'208";a="279447824" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by FMSMGA003.fm.intel.com with ESMTP; 05 Feb 2020 10:20:28 -0800 From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , x86-patch-review@intel.com Cc: Yu-cheng Yu Subject: [RFC PATCH v9 18/27] x86/cet/shstk: Introduce WRUSS instruction Date: Wed, 5 Feb 2020 10:19:26 -0800 Message-Id: <20200205181935.3712-19-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: WRUSS is a new kernel-mode instruction but writes directly to user Shadow Stack (SHSTK) memory. This is used to construct a return address on SHSTK for the signal handler. This instruction can fault if the user SHSTK is not valid SHSTK memory. In that case, the kernel does a fixup. v4: - Change to asm goto. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/special_insns.h | 32 ++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 6d37b8fcfc77..1b9b2e79c353 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -222,6 +222,38 @@ static inline void clwb(volatile void *__p) : [pax] "a" (p)); } +#ifdef CONFIG_X86_INTEL_CET +#if defined(CONFIG_IA32_EMULATION) || defined(CONFIG_X86_X32) +static inline int write_user_shstk_32(unsigned long addr, unsigned int val) +{ + asm_volatile_goto("1: wrussd %1, (%0)\n" + _ASM_EXTABLE(1b, %l[fail]) + :: "r" (addr), "r" (val) + :: fail); + return 0; +fail: + return -EPERM; +} +#else +static inline int write_user_shstk_32(unsigned long addr, unsigned int val) +{ + WARN_ONCE(1, "%s used but not supported.\n", __func__); + return -EFAULT; +} +#endif + +static inline int write_user_shstk_64(unsigned long addr, unsigned long val) +{ + asm_volatile_goto("1: wrussq %1, (%0)\n" + _ASM_EXTABLE(1b, %l[fail]) + :: "r" (addr), "r" (val) + :: fail); + return 0; +fail: + return -EPERM; +} +#endif /* CONFIG_X86_INTEL_CET */ + #define nop() asm volatile ("nop")