From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755379AbcC2Ift (ORCPT ); Tue, 29 Mar 2016 04:35:49 -0400 Received: from eddie.linux-mips.org ([148.251.95.138]:50420 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753468AbcC2Ifs (ORCPT ); Tue, 29 Mar 2016 04:35:48 -0400 Date: Tue, 29 Mar 2016 10:35:43 +0200 From: Ralf Baechle To: Paul Burton Cc: linux-mips@linux-mips.org, Lars Persson , linux-kernel@vger.kernel.org, Andrew Morton , "Kirill A. Shutemov" Subject: Re: [PATCH 2/4] MIPS: Flush highmem pages in __flush_dcache_page Message-ID: <20160329083543.GD11282@linux-mips.org> References: <1456799879-14711-1-git-send-email-paul.burton@imgtec.com> <1456799879-14711-3-git-send-email-paul.burton@imgtec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1456799879-14711-3-git-send-email-paul.burton@imgtec.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 01, 2016 at 02:37:57AM +0000, Paul Burton wrote: > When flush_dcache_page is called on an executable page, that page is > about to be provided to userland & we can presume that the icache > contains no valid entries for its address range. However if the icache > does not fill from the dcache then we cannot presume that the pages > content has been written back as far as the memories that the dcache > will fill from (ie. L2 or further out). > > This was being done for lowmem pages, but not for highmem which can lead > to icache corruption. Fix this by mapping highmem pages & flushing their > content from the dcache in __flush_dcache_page before providing the page > to userland, just as is done for lowmem pages. > > Signed-off-by: Paul Burton > Cc: Lars Persson > --- > > arch/mips/mm/cache.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c > index 3f159ca..5a67d8c 100644 > --- a/arch/mips/mm/cache.c > +++ b/arch/mips/mm/cache.c > @@ -16,6 +16,7 @@ > #include > > #include > +#include > #include > #include > #include > @@ -83,8 +84,6 @@ void __flush_dcache_page(struct page *page) > struct address_space *mapping = page_mapping(page); > unsigned long addr; > > - if (PageHighMem(page)) > - return; > if (mapping && !mapping_mapped(mapping)) { > SetPageDcacheDirty(page); > return; > @@ -95,8 +94,15 @@ void __flush_dcache_page(struct page *page) > * case is for exec env/arg pages and those are %99 certainly going to > * get faulted into the tlb (and thus flushed) anyways. > */ > - addr = (unsigned long) page_address(page); > + if (PageHighMem(page)) > + addr = (unsigned long)kmap_atomic(page); > + else > + addr = (unsigned long)page_address(page); > + > flush_data_cache_page(addr); > + > + if (PageHighMem(page)) > + __kunmap_atomic((void *)addr); > } > > EXPORT_SYMBOL(__flush_dcache_page); I don't see how this should work with cache aliases. If the page is unmapped kmap_atomic will pick a deterministic address only under some circumstances, kmap won't. As the result the wrong cache way will be flushed out, I think. Ralf