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 X-Spam-Level: X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 396A7C47082 for ; Thu, 3 Jun 2021 09:38:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B49F613E4 for ; Thu, 3 Jun 2021 09:38:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229727AbhFCJkj (ORCPT ); Thu, 3 Jun 2021 05:40:39 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:2975 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229610AbhFCJki (ORCPT ); Thu, 3 Jun 2021 05:40:38 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4FwgkK4zVLz6tlp; Thu, 3 Jun 2021 17:35:53 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 3 Jun 2021 17:38:52 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 3 Jun 2021 17:38:51 +0800 Subject: Re: [PATCH v2 7/7] ARM: mm: Fix PXN process with LPAE feature To: "Russell King (Oracle)" CC: , Catalin Marinas , , Andrew Morton , Jungseung Lee References: <20210602070246.83990-1-wangkefeng.wang@huawei.com> <20210602070246.83990-8-wangkefeng.wang@huawei.com> <20210602105255.GK30436@shell.armlinux.org.uk> <62f08378-85e7-2a07-3fd0-b287047ce1b5@huawei.com> <20210602155843.GN30436@shell.armlinux.org.uk> From: Kefeng Wang Message-ID: Date: Thu, 3 Jun 2021 17:38:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20210602155843.GN30436@shell.armlinux.org.uk> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/6/2 23:58, Russell King (Oracle) wrote: > On Wed, Jun 02, 2021 at 11:13:14PM +0800, Kefeng Wang wrote: >>   IFSR format when using the Short-descriptor translation table format >> >>     Domain fault      01001            First level   01011     Second level >> >>     Permission fault 01101            First level   01111     Second level >> >>   IFSR format when using the Long-descriptor translation table format >> >>    0011LL Permission fault. LL bits indicate levelb. >> >> After check the ARM spec, I think for the permission fault,  we should panic >> with or without LPAE, will change to > As I explained in one of the previous patches, the page tables that get > used for mapping kernel space are the _tasks_ own page tables. Any new > kernel mappings are lazily copied to the task page tables - such as > when a module is loaded. > > The first time we touch a page, we could end up with a page translation > fault. This will call do_page_fault(), and so with your proposal, > loading a module will potentially cause a kernel panic in this case, > probably leading to systems that panic early during userspace boot. Could we add some FSR_FS check， only panic when the permission fault， eg， +static inline bool is_permission_fault(unsigned int fsr) +{ +       int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE +       if ((fs & FS_PERM_NOLL_MASK) == FS_PERM_NOLL) +               return true; +#else +       if (fs == FS_L1_PERM || fs == ) +               return true; +#endif +       return false; +} +  static int __kprobes  do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)  { @@ -255,8 +268,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)         if (fsr & FSR_LNX_PF) {                 vm_flags = VM_EXEC; - -               if (!user_mode(regs)) +               if (is_permission_fault && !user_mode(regs))                         die_kernel_fault("execution of memory",                                          mm, addr, fsr, regs);         } diff --git a/arch/arm/mm/fault.h b/arch/arm/mm/fault.h index 9ecc2097a87a..187954b4acca 100644 --- a/arch/arm/mm/fault.h +++ b/arch/arm/mm/fault.h @@ -14,6 +14,8 @@  #ifdef CONFIG_ARM_LPAE  #define FSR_FS_AEA             17 +#define FS_PERM_NOLL           0xC +#define FS_PERM_NOLL_MASK      0x3C  static inline int fsr_fs(unsigned int fsr)  { @@ -21,6 +23,8 @@ static inline int fsr_fs(unsigned int fsr)  }  #else  #define FSR_FS_AEA             22 +#define FS_L1_PERM             0xD +#define FS_L2_PERM             0xF and suggestion or proper solution to solve the issue？ >