Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755641AbdCGQEA (ORCPT ); Tue, 7 Mar 2017 11:04:00 -0500 Received: from max.feld.cvut.cz ([147.32.192.36]:34698 "EHLO max.feld.cvut.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932391AbdCGQDo (ORCPT ); Tue, 7 Mar 2017 11:03:44 -0500 From: Michal Sojka To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Cc: lisovy@gmail.com, Michal Sojka Subject: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions Date: Tue, 7 Mar 2017 15:09:46 +0100 Message-Id: <20170307140948.30099-1-sojkam1@fel.cvut.cz> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2689 Lines: 67 Since commit b65502879556 ("uio: we cannot mmap unaligned page contents") addresses and sizes of UIO memory regions must be page-aligned. If the address in the BAR register is not page-aligned, the mentioned commit forces the UIO driver to round the address down to the page size. Then, there is no easy way for user-space to learn the offset of the actual memory region within the page, because the offset seen in the sysfs is calculated from the rounded address and thus it is always zero. Fix that problem by including the offset in struct uio_mem. UIO drivers can set this field and its value is reported via sysfs. Drivers for hardware with page-aligned BARs need not to be modified provided that they initialize struct uio_info with zeros. Signed-off-by: Michal Sojka --- drivers/uio/uio.c | 2 +- include/linux/uio_driver.h | 13 ++++++++----- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index fba021f5736a..27c329131350 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -66,7 +66,7 @@ static ssize_t map_size_show(struct uio_mem *mem, char *buf) static ssize_t map_offset_show(struct uio_mem *mem, char *buf) { - return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK); + return sprintf(buf, "0x%llx\n", (unsigned long long)mem->offs); } struct map_sysfs_entry { diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h index 32c0e83d6239..89b53094f127 100644 --- a/include/linux/uio_driver.h +++ b/include/linux/uio_driver.h @@ -23,11 +23,13 @@ struct uio_map; /** * struct uio_mem - description of a UIO memory region * @name: name of the memory region for identification - * @addr: address of the device's memory (phys_addr is used since - * addr can be logical, virtual, or physical & phys_addr_t - * should always be large enough to handle any of the - * address types) - * @size: size of IO + * @addr: address of the device's memory rounded to page + * size (phys_addr is used since addr can be + * logical, virtual, or physical & phys_addr_t + * should always be large enough to handle any of + * the address types) + * @offs: offset of device memory within the page + * @size: size of IO (multiple of page size) * @memtype: type of memory addr points to * @internal_addr: ioremap-ped version of addr, for driver internal use * @map: for use by the UIO core only. @@ -35,6 +37,7 @@ struct uio_map; struct uio_mem { const char *name; phys_addr_t addr; + unsigned long offs;; resource_size_t size; int memtype; void __iomem *internal_addr; -- 2.11.0