Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161088AbbENRdD (ORCPT ); Thu, 14 May 2015 13:33:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37434 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964929AbbENRb6 (ORCPT ); Thu, 14 May 2015 13:31:58 -0400 From: Andrea Arcangeli To: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-api@vger.kernel.org Cc: Pavel Emelyanov , Sanidhya Kashyap , zhang.zhanghailiang@huawei.com, Linus Torvalds , "Kirill A. Shutemov" , Andres Lagar-Cavilla , Dave Hansen , Paolo Bonzini , Rik van Riel , Mel Gorman , Andy Lutomirski , Hugh Dickins , Peter Feiner , "Dr. David Alan Gilbert" , Johannes Weiner , "Huangpeng (Peter)" Subject: [PATCH 23/23] userfaultfd: UFFDIO_COPY and UFFDIO_ZEROPAGE Date: Thu, 14 May 2015 19:31:20 +0200 Message-Id: <1431624680-20153-24-git-send-email-aarcange@redhat.com> In-Reply-To: <1431624680-20153-1-git-send-email-aarcange@redhat.com> References: <1431624680-20153-1-git-send-email-aarcange@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3773 Lines: 128 These two ioctl allows to either atomically copy or to map zeropages into the virtual address space. This is used by the thread that opened the userfaultfd to resolve the userfaults. Signed-off-by: Andrea Arcangeli --- fs/userfaultfd.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 6772c22..65704cb 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -942,6 +942,96 @@ out: return ret; } +static int userfaultfd_copy(struct userfaultfd_ctx *ctx, + unsigned long arg) +{ + __s64 ret; + struct uffdio_copy uffdio_copy; + struct uffdio_copy __user *user_uffdio_copy; + struct userfaultfd_wake_range range; + + user_uffdio_copy = (struct uffdio_copy __user *) arg; + + ret = -EFAULT; + if (copy_from_user(&uffdio_copy, user_uffdio_copy, + /* don't copy "copy" last field */ + sizeof(uffdio_copy)-sizeof(__s64))) + goto out; + + ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); + if (ret) + goto out; + /* + * double check for wraparound just in case. copy_from_user() + * will later check uffdio_copy.src + uffdio_copy.len to fit + * in the userland range. + */ + ret = -EINVAL; + if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src) + goto out; + if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE) + goto out; + + ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, + uffdio_copy.len); + if (unlikely(put_user(ret, &user_uffdio_copy->copy))) + return -EFAULT; + if (ret < 0) + goto out; + BUG_ON(!ret); + /* len == 0 would wake all */ + range.len = ret; + if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) { + range.start = uffdio_copy.dst; + wake_userfault(ctx, &range); + } + ret = range.len == uffdio_copy.len ? 0 : -EAGAIN; +out: + return ret; +} + +static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, + unsigned long arg) +{ + __s64 ret; + struct uffdio_zeropage uffdio_zeropage; + struct uffdio_zeropage __user *user_uffdio_zeropage; + struct userfaultfd_wake_range range; + + user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg; + + ret = -EFAULT; + if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage, + /* don't copy "zeropage" last field */ + sizeof(uffdio_zeropage)-sizeof(__s64))) + goto out; + + ret = validate_range(ctx->mm, uffdio_zeropage.range.start, + uffdio_zeropage.range.len); + if (ret) + goto out; + ret = -EINVAL; + if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE) + goto out; + + ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, + uffdio_zeropage.range.len); + if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) + return -EFAULT; + if (ret < 0) + goto out; + /* len == 0 would wake all */ + BUG_ON(!ret); + range.len = ret; + if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) { + range.start = uffdio_zeropage.range.start; + wake_userfault(ctx, &range); + } + ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN; +out: + return ret; +} + /* * userland asks for a certain API version and we return which bits * and ioctl commands are implemented in this kernel for such API @@ -997,6 +1087,12 @@ static long userfaultfd_ioctl(struct file *file, unsigned cmd, case UFFDIO_WAKE: ret = userfaultfd_wake(ctx, arg); break; + case UFFDIO_COPY: + ret = userfaultfd_copy(ctx, arg); + break; + case UFFDIO_ZEROPAGE: + ret = userfaultfd_zeropage(ctx, arg); + break; } return ret; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/