From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f47.google.com (mail-wm0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id DB4146B0259 for ; Thu, 19 Nov 2015 17:34:06 -0500 (EST) Received: by wmww144 with SMTP id w144so257174579wmw.1 for ; Thu, 19 Nov 2015 14:34:06 -0800 (PST) Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id kv9si14144939wjb.199.2015.11.19.14.34.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Nov 2015 14:34:01 -0800 (PST) Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.15.0.59/8.15.0.59) with SMTP id tAJMWOt4029274 for ; Thu, 19 Nov 2015 14:33:59 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by m0001303.ppops.net with ESMTP id 1y8rtt7812-2 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Thu, 19 Nov 2015 14:33:59 -0800 Received: from facebook.com (2401:db00:11:d0a2:face:0:39:0) by mx-out.facebook.com (10.212.236.89) with ESMTP id 9d560a388f0d11e599990002c95209d8-233f8230 for ; Thu, 19 Nov 2015 14:33:54 -0800 From: Shaohua Li Subject: [RFC 2/8] userfaultfd: support write protection for userfault vma range Date: Thu, 19 Nov 2015 14:33:47 -0800 Message-ID: <60c73a4374d16d15e3975c590b48a2d2d384c23e.1447964595.git.shli@fb.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: kernel-team@fb.com, Andrew Morton , Andrea Arcangeli , Pavel Emelyanov , Rik van Riel , "Kirill A. Shutemov" , Mel Gorman , Hugh Dickins , Johannes Weiner Add API to enable/disable writeprotect a vma range. Unlike mprotect, this doesn't split/merge vmas. Cc: Andrea Arcangeli Cc: Pavel Emelyanov Cc: Rik van Riel Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Hugh Dickins Cc: Johannes Weiner Signed-off-by: Shaohua Li --- include/linux/userfaultfd_k.h | 2 ++ mm/userfaultfd.c | 52 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 54 insertions(+) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 4e22d11..44f5b09 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -35,6 +35,8 @@ extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long len); +extern int mwriteprotect_range(struct mm_struct *dst_mm, + unsigned long start, unsigned long len, bool enable_wp); /* mm helpers */ static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 77fee93..3e97e24 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -306,3 +306,55 @@ ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, { return __mcopy_atomic(dst_mm, start, 0, len, true); } + +int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, + unsigned long len, bool enable_wp) +{ + struct vm_area_struct *dst_vma; + pgprot_t newprot; + int err; + + /* + * Sanitize the command parameters: + */ + BUG_ON(start & ~PAGE_MASK); + BUG_ON(len & ~PAGE_MASK); + + /* Does the address range wrap, or is the span zero-sized? */ + BUG_ON(start + len <= start); + + down_read(&dst_mm->mmap_sem); + + /* + * Make sure the vma is not shared, that the dst range is + * both valid and fully within a single existing vma. + */ + err = -EINVAL; + dst_vma = find_vma(dst_mm, start); + if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) + goto out_unlock; + if (start < dst_vma->vm_start || + start + len > dst_vma->vm_end) + goto out_unlock; + + if (!dst_vma->vm_userfaultfd_ctx.ctx) + goto out_unlock; + if (!userfaultfd_wp(dst_vma)) + goto out_unlock; + + if (dst_vma->vm_ops) + goto out_unlock; + + if (enable_wp) + newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); + else + newprot = vm_get_page_prot(dst_vma->vm_flags); + + change_protection(dst_vma, start, start + len, newprot, + !enable_wp, 0); + + err = 0; +out_unlock: + up_read(&dst_mm->mmap_sem); + return err; +} -- 2.4.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org