From patchwork Thu Apr 30 21:19:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeremy Linton X-Patchwork-Id: 11521635 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E421692C for ; Thu, 30 Apr 2020 21:19:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5C5220836 for ; Thu, 30 Apr 2020 21:19:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726548AbgD3VTY (ORCPT ); Thu, 30 Apr 2020 17:19:24 -0400 Received: from foss.arm.com ([217.140.110.172]:33902 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726449AbgD3VTY (ORCPT ); Thu, 30 Apr 2020 17:19:24 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E6D241FB; Thu, 30 Apr 2020 14:19:23 -0700 (PDT) Received: from mammon-tx2.austin.arm.com (mammon-tx2.austin.arm.com [10.118.28.62]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DF1733F68F; Thu, 30 Apr 2020 14:19:23 -0700 (PDT) From: Jeremy Linton To: linux-usb@vger.kernel.org Cc: gregkh@linuxfoundation.org, stern@rowland.harvard.edu, git@thegavinli.com, jarkko.sakkinen@linux.intel.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jeremy Linton Subject: [PATCH] usb: usbfs: correct kernel->user page attribute mismatch Date: Thu, 30 Apr 2020 16:19:22 -0500 Message-Id: <20200430211922.929165-1-jeremy.linton@arm.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On arm64, and possibly other architectures, requesting IO coherent memory may return Normal-NC if the underlying hardware isn't coherent. If these pages are then remapped into userspace as Normal, that defeats the purpose of getting Normal-NC, as well as resulting in mappings with differing cache attributes. In particular this happens with libusb, when it attempts to create zero-copy buffers as is used by rtl-sdr, and maybe other applications. The result is usually application death. If dma_mmap_attr() is used instead of remap_pfn_range, the page cache/etc attributes can be matched between the kernel and userspace. Signed-off-by: Jeremy Linton --- drivers/usb/core/devio.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 6833c918abce..1e7458dd6e5d 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -217,6 +217,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) { struct usb_memory *usbm = NULL; struct usb_dev_state *ps = file->private_data; + struct usb_hcd *hcd = bus_to_hcd(ps->dev->bus); size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags; @@ -250,9 +251,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist); - if (remap_pfn_range(vma, vma->vm_start, - virt_to_phys(usbm->mem) >> PAGE_SHIFT, - size, vma->vm_page_prot) < 0) { + if (dma_mmap_attrs(hcd->self.sysdev, vma, mem, dma_handle, size, 0)) { dec_usb_memory_use_count(usbm, &usbm->vma_use_count); return -EAGAIN; }