From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752958AbbI1TW3 (ORCPT ); Mon, 28 Sep 2015 15:22:29 -0400 Received: from mga11.intel.com ([192.55.52.93]:38980 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751666AbbI1TSX (ORCPT ); Mon, 28 Sep 2015 15:18:23 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,604,1437462000"; d="scan'208";a="814902367" Subject: [PATCH 13/25] mm: factor out VMA fault permission checking To: dave@sr71.net Cc: borntraeger@de.ibm.com, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, dave.hansen@linux.intel.com From: Dave Hansen Date: Mon, 28 Sep 2015 12:18:22 -0700 References: <20150928191817.035A64E2@viggo.jf.intel.com> In-Reply-To: <20150928191817.035A64E2@viggo.jf.intel.com> Message-Id: <20150928191822.DFCE608C@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen This code matches a fault condition up with the VMA and ensures that the VMA allows the fault to be handled instead of just erroring out. We will be extending this in a moment to comprehend protection keys. Signed-off-by: Dave Hansen --- b/mm/gup.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff -puN mm/gup.c~pkeys-10-pte-fault mm/gup.c --- a/mm/gup.c~pkeys-10-pte-fault 2015-09-28 11:39:46.790221164 -0700 +++ b/mm/gup.c 2015-09-28 11:39:46.794221345 -0700 @@ -554,6 +554,17 @@ next_page: } EXPORT_SYMBOL(__get_user_pages); +bool vma_permits_fault(struct vm_area_struct *vma, unsigned int fault_flags) +{ + vm_flags_t vm_flags = + (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; + + if (!(vm_flags & vma->vm_flags)) + return false; + + return true; +} + /* * fixup_user_fault() - manually resolve a user page fault * @tsk: the task_struct to use for page fault accounting, or @@ -585,15 +596,13 @@ int fixup_user_fault(struct task_struct unsigned long address, unsigned int fault_flags) { struct vm_area_struct *vma; - vm_flags_t vm_flags; int ret; vma = find_extend_vma(mm, address); if (!vma || address < vma->vm_start) return -EFAULT; - vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; - if (!(vm_flags & vma->vm_flags)) + if (!vma_permits_fault(vma, fault_flags)) return -EFAULT; ret = handle_mm_fault(mm, vma, address, fault_flags); _