From patchwork Fri Feb 5 15:50:53 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 77361 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o15FpC6Q009925 for ; Fri, 5 Feb 2010 15:51:12 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753634Ab0BEPvL (ORCPT ); Fri, 5 Feb 2010 10:51:11 -0500 Received: from cantor2.suse.de ([195.135.220.15]:52409 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753586Ab0BEPvH (ORCPT ); Fri, 5 Feb 2010 10:51:07 -0500 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.221.2]) by mx2.suse.de (Postfix) with ESMTP id 9654389E74; Fri, 5 Feb 2010 16:51:06 +0100 (CET) From: James Bottomley To: linux-arch@vger.kernel.org Cc: linux-parisc@vger.kernel.org, rmk@arm.linux.org.uk, lethal@linux-sh.org, torvalds@linux-foundation.org, hch@lst.de, James Bottomley Subject: [PATCHv3 1/5] mm: add coherence API for DMA to vmalloc/vmap areas Date: Fri, 5 Feb 2010 09:50:53 -0600 Message-Id: <1265385057-2575-2-git-send-email-James.Bottomley@suse.de> X-Mailer: git-send-email 1.6.5 In-Reply-To: <1265385057-2575-1-git-send-email-James.Bottomley@suse.de> References: <1265385057-2575-1-git-send-email-James.Bottomley@suse.de> Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Fri, 05 Feb 2010 15:51:12 +0000 (UTC) diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt index da42ab4..b231414 100644 --- a/Documentation/cachetlb.txt +++ b/Documentation/cachetlb.txt @@ -377,3 +377,27 @@ maps this page at its virtual address. All the functionality of flush_icache_page can be implemented in flush_dcache_page and update_mmu_cache. In 2.7 the hope is to remove this interface completely. + +The final category of APIs is for I/O to deliberately aliased address +ranges inside the kernel. Such aliases are set up by use of the +vmap/vmalloc API. Since kernel I/O goes via physical pages, the I/O +subsystem assumes that the user mapping and kernel offset mapping are +the only aliases. This isn't true for vmap aliases, so anything in +the kernel trying to do I/O to vmap areas must manually manage +coherency. It must do this by flushing the vmap range before doing +I/O and invalidating it after the I/O returns. + + void flush_kernel_vmap_range(void *vaddr, int size) + flushes the kernel cache for a given virtual address range in + the vmap area. This is to make sure that any data the kernel + modified in the vmap range is made visible to the physical + page. The design is to make this area safe to perform I/O on. + Note that this API does *not* also flush the offset map alias + of the area. + + void invalidate_kernel_vmap_range(void *vaddr, int size) invalidates + the cache for a given virtual address range in the vmap area + which prevents the processor from making the cache stale by + speculatively reading data while the I/O was occurring to the + physical pages. This is only necessary for data reads into the + vmap area. diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 211ff44..adfe101 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -17,6 +17,12 @@ static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page static inline void flush_kernel_dcache_page(struct page *page) { } +static inline void flush_kernel_vmap_range(void *vaddr, int size) +{ +} +static inline void invalidate_kernel_vmap_range(void *vaddr, int size) +{ +} #endif #include