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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4ECD6ECAAD3 for ; Mon, 19 Sep 2022 10:46:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229828AbiISKqe (ORCPT ); Mon, 19 Sep 2022 06:46:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229812AbiISKqC (ORCPT ); Mon, 19 Sep 2022 06:46:02 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AA2C6595 for ; Mon, 19 Sep 2022 03:29:03 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MWLQr0bnZzQj7k; Mon, 19 Sep 2022 18:25:08 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 19 Sep 2022 18:29:00 +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 15.1.2375.31; Mon, 19 Sep 2022 18:29:00 +0800 Message-ID: <269c06a8-3885-dbcf-a26e-e7c2312d435d@huawei.com> Date: Mon, 19 Sep 2022 18:29:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] ARM: mm: Provide better fault message for permission fault Content-Language: en-US To: Russell King CC: , References: <20220919051130.1339-1-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: <20220919051130.1339-1-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) 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 Sorry, is_permission_fault() could be used if CONFIG_MMU disabled, will resend. On 2022/9/19 13:11, Kefeng Wang wrote: > If there is a permission fault in __do_kernel_fault(), we only > print the generic "paging request" message which don't show > read, write or execute information, let's provide better fault > message for them. > > Signed-off-by: Kefeng Wang > --- > arch/arm/mm/fault.c | 35 +++++++++++++++++++++-------------- > 1 file changed, 21 insertions(+), 14 deletions(-) > > diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c > index 46cccd6bf705..d1b848f0f7ed 100644 > --- a/arch/arm/mm/fault.c > +++ b/arch/arm/mm/fault.c > @@ -95,6 +95,19 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr) > > pr_cont("\n"); > } > + > +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 == FS_L2_PERM) > + return true; > +#endif > + return false; > +} > #else /* CONFIG_MMU */ > void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr) > { } > @@ -137,7 +150,14 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, > /* > * No handler, we'll have to terminate things with extreme prejudice. > */ > - if (addr < PAGE_SIZE) { > + if (is_permission_fault(fsr)) { > + if (fsr & FSR_WRITE) > + msg = "write to read-only memory"; > + else if (fsr & FSR_LNX_PF) > + msg = "execute from non-executable memory"; > + else > + msg = "read from unreadable memory"; > + } else if (addr < PAGE_SIZE) { > msg = "NULL pointer dereference"; > } else { > if (kfence_handle_page_fault(addr, is_write_fault(fsr), regs)) > @@ -204,19 +224,6 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) > #define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000) > #define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000) > > -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 == FS_L2_PERM) > - return true; > -#endif > - return false; > -} > - > static vm_fault_t __kprobes > __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags, > unsigned long vma_flags, struct pt_regs *regs)