From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FC4CC4332F for ; Tue, 15 Nov 2022 19:38:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 44E606B0072; Tue, 15 Nov 2022 14:38:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FBE78E0001; Tue, 15 Nov 2022 14:38:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 29DAD6B0074; Tue, 15 Nov 2022 14:38:43 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 1B1966B0072 for ; Tue, 15 Nov 2022 14:38:43 -0500 (EST) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DCB1EAB7FA for ; Tue, 15 Nov 2022 19:38:42 +0000 (UTC) X-FDA: 80136688884.23.6F615B9 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf17.hostedemail.com (Postfix) with ESMTP id 7366840002 for ; Tue, 15 Nov 2022 19:38:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=m/idPlmlMSHYNd4VPV/uZ+42R303Fem83Y9Bl6HGhEk=; b=QB/jjPrQQAT8hA+XnNLKn5newW 3sIB6p85AcVqg9GDTQd5XWrkPSGYi7VE7q/AVPmk3oA5zsywMXiE2K9+PbdWTCSfcSsBQQ/rat+Zq 69IMgrgyQ1lr9mR6+2Z+yLZ0MOqLL9g8Eqx9nzn3mGUmjIPmdJyZvm/Ux4PM9ZDRSxvF9allMdE6h r48VCIodLTC3ZoFqCUFvx/x6AE/BaoBzheW3DGE4ScZYnDQ/Xgoa594c/Ns9X0PNh+xB56z/RtxdX kFFbMpPqHRpwE7hXwGN0JkqawQrlYLsjvzVEeAUouU8S6FJNz5HjDXNvDEiMY76cQne9+ZCPCzS5T 19aD/+KA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ov1lT-00GYBj-0V; Tue, 15 Nov 2022 19:38:35 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 21F70300C6F; Tue, 15 Nov 2022 13:32:32 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 094CE2C36896F; Tue, 15 Nov 2022 13:32:31 +0100 (CET) Date: Tue, 15 Nov 2022 13:32:31 +0100 From: Peter Zijlstra To: Rick Edgecombe Cc: 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 , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Yu-cheng Yu Subject: Re: [PATCH v3 25/37] x86/shstk: Add user-mode shadow stack support Message-ID: References: <20221104223604.29615-1-rick.p.edgecombe@intel.com> <20221104223604.29615-26-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221104223604.29615-26-rick.p.edgecombe@intel.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668541122; a=rsa-sha256; cv=none; b=l5GazPxOsyYSM3UQIKn5hci+Nj9xex7mEiNiAZ8QYWyLEdrVMfpAhUdZWeSeYK6qg5I+bY hssBulxyKQP4wd8KmJqZZWFwYoigtgaG587rpgtJQkBB73zyictbuiI/bGk2ctdm2nkWuN neisUkTNRv56Jlg6PmQyR6u1NOGPxkU= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b="QB/jjPrQ"; spf=none (imf17.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668541122; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=m/idPlmlMSHYNd4VPV/uZ+42R303Fem83Y9Bl6HGhEk=; b=IKWPeaW5W7EpP2r5wAloa8Bs8J9zr852LIY2mXKm9A9ewCrt9SSU03CKeZeisRoIdM3Vqv tPPu/JO9tRnrCHPvf/JimhEj7NLHbj4uufgb5Rj83/Y2sP32gJncy9s6ToXB0mb93EMFv2 2XZSvc52Yh/8FKcYECj/9XO2IqsVCIE= X-Stat-Signature: xh5t5jqkeeq8sjd9eiceks4ttndpk55s X-Rspamd-Queue-Id: 7366840002 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b="QB/jjPrQ"; spf=none (imf17.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1668541122-460821 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: On Fri, Nov 04, 2022 at 03:35:52PM -0700, Rick Edgecombe wrote: > +static int shstk_setup(void) > +{ > + struct thread_shstk *shstk = ¤t->thread.shstk; > + unsigned long addr, size; > + > + /* Already enabled */ > + if (features_enabled(CET_SHSTK)) > + return 0; > + > + /* Also not supported for 32 bit and x32 */ > + if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) || in_32bit_syscall()) > + return -EOPNOTSUPP; > + > + size = adjust_shstk_size(0); > + addr = alloc_shstk(size); > + if (IS_ERR_VALUE(addr)) > + return PTR_ERR((void *)addr); > + > + fpregs_lock_and_load(); > + wrmsrl(MSR_IA32_PL3_SSP, addr + size); > + wrmsrl(MSR_IA32_U_CET, CET_SHSTK_EN); This.. > + fpregs_unlock(); > + > + shstk->base = addr; > + shstk->size = size; > + features_set(CET_SHSTK); > + > + return 0; > +} > +static int shstk_disable(void) > +{ > + if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK)) > + return -EOPNOTSUPP; > + > + /* Already disabled? */ > + if (!features_enabled(CET_SHSTK)) > + return 0; > + > + fpregs_lock_and_load(); > + /* Disable WRSS too when disabling shadow stack */ > + set_clr_bits_msrl(MSR_IA32_U_CET, 0, CET_SHSTK_EN); And this... aren't very consistent in approach. Given there is no U_IBT yet, why complicate matters like this? > + wrmsrl(MSR_IA32_PL3_SSP, 0); > + fpregs_unlock(); > + > + shstk_free(current); > + features_clr(CET_SHSTK); > + > + return 0; > +}