From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754654Ab1KFTPl (ORCPT ); Sun, 6 Nov 2011 14:15:41 -0500 Received: from mail-wy0-f174.google.com ([74.125.82.174]:40579 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754566Ab1KFTPi (ORCPT ); Sun, 6 Nov 2011 14:15:38 -0500 From: Daniel Vetter To: intel-gfx Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Daniel Vetter , linux-mm@kvack.org Subject: [PATCH 11/13] mm: extend prefault helpers to fault in more than PAGE_SIZE Date: Sun, 6 Nov 2011 20:13:58 +0100 Message-Id: <1320606840-21132-12-git-send-email-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 1.7.6.4 In-Reply-To: <1320606840-21132-1-git-send-email-daniel.vetter@ffwll.ch> References: <1320606840-21132-1-git-send-email-daniel.vetter@ffwll.ch> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org drm/i915 wants to read/write more than one page in its fastpath and hence needs to prefault more than PAGE_SIZE bytes. I've checked the callsites and they all already clamp size when calling fault_in_pages_* to the same as for the subsequent __copy_to|from_user and hence don't rely on the implicit clamping to PAGE_SIZE. Also kill a copy&pasted spurious space in both functions while at it. Cc: linux-mm@kvack.org Signed-off-by: Daniel Vetter --- include/linux/pagemap.h | 28 ++++++++++++++++++---------- 1 files changed, 18 insertions(+), 10 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index cfaaa69..689527d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -408,6 +408,7 @@ extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter); static inline int fault_in_pages_writeable(char __user *uaddr, int size) { int ret; + char __user *end = uaddr + size - 1; if (unlikely(size == 0)) return 0; @@ -416,17 +417,20 @@ static inline int fault_in_pages_writeable(char __user *uaddr, int size) * Writing zeroes into userspace here is OK, because we know that if * the zero gets there, we'll be overwriting it. */ - ret = __put_user(0, uaddr); + while (uaddr <= end) { + ret = __put_user(0, uaddr); + if (ret != 0) + return ret; + uaddr += PAGE_SIZE; + } if (ret == 0) { - char __user *end = uaddr + size - 1; - /* * If the page was already mapped, this will get a cache miss * for sure, so try to avoid doing it. */ - if (((unsigned long)uaddr & PAGE_MASK) != + if (((unsigned long)uaddr & PAGE_MASK) == ((unsigned long)end & PAGE_MASK)) - ret = __put_user(0, end); + ret = __put_user(0, end); } return ret; } @@ -435,17 +439,21 @@ static inline int fault_in_pages_readable(const char __user *uaddr, int size) { volatile char c; int ret; + const char __user *end = uaddr + size - 1; if (unlikely(size == 0)) return 0; - ret = __get_user(c, uaddr); + while (uaddr <= end) { + ret = __get_user(c, uaddr); + if (ret != 0) + return ret; + uaddr += PAGE_SIZE; + } if (ret == 0) { - const char __user *end = uaddr + size - 1; - - if (((unsigned long)uaddr & PAGE_MASK) != + if (((unsigned long)uaddr & PAGE_MASK) == ((unsigned long)end & PAGE_MASK)) { - ret = __get_user(c, end); + ret = __get_user(c, end); (void)c; } } -- 1.7.6.4