From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753361AbbKQDmS (ORCPT ); Mon, 16 Nov 2015 22:42:18 -0500 Received: from mga01.intel.com ([192.55.52.88]:45741 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753077AbbKQDfg (ORCPT ); Mon, 16 Nov 2015 22:35:36 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,305,1444719600"; d="scan'208";a="687166134" Subject: [PATCH 18/37] mm: factor out VMA fault permission checking To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Dave Hansen , dave.hansen@linux.intel.com From: Dave Hansen Date: Mon, 16 Nov 2015 19:35:36 -0800 References: <20151117033511.BFFA1440@viggo.jf.intel.com> In-Reply-To: <20151117033511.BFFA1440@viggo.jf.intel.com> Message-Id: <20151117033536.8A3668CE@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 2015-11-16 12:35:43.275532100 -0800 +++ b/mm/gup.c 2015-11-16 12:35:43.279532282 -0800 @@ -557,6 +557,17 @@ 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 @@ -588,15 +599,13 @@ 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); _