From patchwork Tue Feb 2 19:47:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ira Weiny X-Patchwork-Id: 12062803 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39B06C433E6 for ; Tue, 2 Feb 2021 19:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00BF264EAC for ; Tue, 2 Feb 2021 19:48:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240096AbhBBTsb (ORCPT ); Tue, 2 Feb 2021 14:48:31 -0500 Received: from mga12.intel.com ([192.55.52.136]:59530 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240105AbhBBTsG (ORCPT ); Tue, 2 Feb 2021 14:48:06 -0500 IronPort-SDR: tlPE7OtDk3GARKC32FM4shschAq86pOK45D/KS/Qfh7cvKJhHMnhCb/DG7DpZmLLMHixdmjYGq i2q9bFIdosIQ== X-IronPort-AV: E=McAfee;i="6000,8403,9883"; a="160085954" X-IronPort-AV: E=Sophos;i="5.79,396,1602572400"; d="scan'208";a="160085954" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2021 11:47:23 -0800 IronPort-SDR: ntK1Mk+MSO00uLgQKnlwECoJCqiWLz/B+9uBhYJGtNCKgvpRm6lC4jSzEjLexLOqVfoPdKevxA o6RjS635jy7g== X-IronPort-AV: E=Sophos;i="5.79,396,1602572400"; d="scan'208";a="372088150" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2021 11:47:22 -0800 From: ira.weiny@intel.com To: Jarkko Sakkinen Cc: Ira Weiny , Dave Hansen , Sean Christopherson , Jethro Beekman , linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org Subject: [PATCH V3] x86: Remove unnecessary kmap() from sgx_ioc_enclave_init() Date: Tue, 2 Feb 2021 11:47:19 -0800 Message-Id: <20210202194719.3525076-1-ira.weiny@intel.com> X-Mailer: git-send-email 2.28.0.rc0.12.gb6a658bd00c9 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org From: Ira Weiny kmap is inefficient and we are trying to reduce the usage in the kernel. There is no readily apparent reason why initp_page needs to be allocated and kmap'ed() but sigstruct needs to be page aligned and token 512 byte aligned. kmalloc() can give us this alignment but we need to allocate PAGE_SIZE bytes to do so. Rather than change this kmap() to kmap_local_page() use kmalloc() instead. Remove the alloc_page()/kmap() and replace with kmalloc() to get a kernel address to use. In addition add a comment to document the alignment requirements so that others like myself don't attempt to 'fix' this again. Finally, add 2 BUILD_BUG_ON's to ensure future changes to sigstruct and token do not go unnoticed and cause a bug. Cc: Dave Hansen Cc: Sean Christopherson Cc: Jethro Beekman Signed-off-by: Ira Weiny --- Changes from v2[1]: When allocating a power of 2 size kmalloc() now guarantees the alignment of the respective size. So go back to using kmalloc() but with a PAGE_SIZE allocation to get the alignment. This also follows the pattern in sgx_ioc_enclave_create() Changes from v1[1]: Use page_address() instead of kcmalloc() to ensure sigstruct is page aligned Use BUILD_BUG_ON to ensure token and sigstruct don't collide. [1] https://lore.kernel.org/lkml/20210129001459.1538805-1-ira.weiny@intel.com/ [2] https://lore.kernel.org/lkml/20210202013725.3514671-1-ira.weiny@intel.com/ --- arch/x86/kernel/cpu/sgx/ioctl.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 90a5caf76939..e0c3301ccd67 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -604,7 +604,6 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) { struct sgx_sigstruct *sigstruct; struct sgx_enclave_init init_arg; - struct page *initp_page; void *token; int ret; @@ -615,11 +614,16 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) if (copy_from_user(&init_arg, arg, sizeof(init_arg))) return -EFAULT; - initp_page = alloc_page(GFP_KERNEL); - if (!initp_page) + /* + * sigstruct must be on a page boundry and token on a 512 byte boundry + * kmalloc() gives us this alignment when allocating PAGE_SIZE bytes + */ + sigstruct = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!sigstruct) return -ENOMEM; - sigstruct = kmap(initp_page); + BUILD_BUG_ON(sizeof(*sigstruct) > (PAGE_SIZE/2)); + BUILD_BUG_ON(SGX_LAUNCH_TOKEN_SIZE > (PAGE_SIZE/2)); token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2); memset(token, 0, SGX_LAUNCH_TOKEN_SIZE); @@ -645,8 +649,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) ret = sgx_encl_init(encl, sigstruct, token); out: - kunmap(initp_page); - __free_page(initp_page); + kfree(sigstruct); return ret; }