From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751950AbcBLVE3 (ORCPT ); Fri, 12 Feb 2016 16:04:29 -0500 Received: from mga02.intel.com ([134.134.136.20]:38063 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751804AbcBLVCj (ORCPT ); Fri, 12 Feb 2016 16:02:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,437,1449561600"; d="scan'208";a="901773996" Subject: [PATCH 17/33] mm: factor out VMA fault permission checking To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, torvalds@linux-foundation.org, Dave Hansen , dave.hansen@linux.intel.com From: Dave Hansen Date: Fri, 12 Feb 2016 13:02:16 -0800 References: <20160212210152.9CAD15B0@viggo.jf.intel.com> In-Reply-To: <20160212210152.9CAD15B0@viggo.jf.intel.com> Message-Id: <20160212210216.C3824032@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 Reviewed-by: Thomas Gleixner --- b/mm/gup.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff -puN mm/gup.c~pkeys-10-pte-fault mm/gup.c --- a/mm/gup.c~pkeys-10-pte-fault 2016-02-12 10:44:21.164472103 -0800 +++ b/mm/gup.c 2016-02-12 10:44:21.167472240 -0800 @@ -610,6 +610,18 @@ 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; + + 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 @@ -645,7 +657,6 @@ int fixup_user_fault(struct task_struct bool *unlocked) { struct vm_area_struct *vma; - vm_flags_t vm_flags; int ret, major = 0; if (unlocked) @@ -656,8 +667,7 @@ retry: 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); _