From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754780AbaHTMQi (ORCPT ); Wed, 20 Aug 2014 08:16:38 -0400 Received: from mail-ob0-f169.google.com ([209.85.214.169]:49436 "EHLO mail-ob0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753604AbaHTMQf (ORCPT ); Wed, 20 Aug 2014 08:16:35 -0400 MIME-Version: 1.0 In-Reply-To: <20140819122653.GH23128@arm.com> References: <1407949593-16121-1-git-send-email-keescook@chromium.org> <1407949593-16121-3-git-send-email-keescook@chromium.org> <20140819122653.GH23128@arm.com> Date: Wed, 20 Aug 2014 07:16:34 -0500 X-Google-Sender-Auth: PU0qxHa-MCQjZWCgTSSXtQA_IlU Message-ID: Subject: Re: [PATCH v4 2/8] ARM: expand fixmap region to 3MB From: Kees Cook To: Will Deacon Cc: "linux-kernel@vger.kernel.org" , Rob Herring , Laura Abbott , Leif Lindholm , Stephen Boyd , "msalter@redhat.com" , Rabin Vincent , Liu hua , Nikolay Borisov , Nicolas Pitre , Tomasz Figa , Doug Anderson , Jason Wessel , Catalin Marinas , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" , "linux-doc@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 19, 2014 at 7:26 AM, Will Deacon wrote: > Hi Kees, Rob, > > On Wed, Aug 13, 2014 at 06:06:27PM +0100, Kees Cook wrote: >> From: Rob Herring >> >> With commit a05e54c103b0 ("ARM: 8031/2: change fixmap mapping region to >> support 32 CPUs"), the fixmap region was expanded to 2MB, but it >> precluded any other uses of the fixmap region. In order to support other >> uses the fixmap region needs to be expanded beyond 2MB. Fortunately, the >> adjacent 1MB range 0xffe00000-0xfff00000 is availabe. >> >> Remove fixmap_page_table ptr and lookup the page table via the virtual >> address so that the fixmap region can span more that one pmd. The 2nd >> pmd is already created since it is shared with the vector page. > > [...] > >> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c >> index 45aeaaca9052..81061987ac45 100644 >> --- a/arch/arm/mm/highmem.c >> +++ b/arch/arm/mm/highmem.c >> @@ -18,19 +18,20 @@ >> #include >> #include "mm.h" >> >> -pte_t *fixmap_page_table; >> - >> static inline void set_fixmap_pte(int idx, pte_t pte) >> { >> unsigned long vaddr = __fix_to_virt(idx); >> - set_pte_ext(fixmap_page_table + idx, pte, 0); >> + pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr); >> + >> + set_pte_ext(ptep, pte, 0); >> local_flush_tlb_kernel_page(vaddr); >> } > > Minor comment, but we can drop the ifx parameter here now, right? It looks a > bit weird having a setter/getter pair of functions where the type signatures > aren't the inverse. idx is used to get the vaddr here. I suppose the various users of these functions in highmem could be reworked, but that doesn't look sensible either. Maybe it's just the names of the functions that are confusing? -Kees -- Kees Cook Chrome OS Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: keescook@chromium.org (Kees Cook) Date: Wed, 20 Aug 2014 07:16:34 -0500 Subject: [PATCH v4 2/8] ARM: expand fixmap region to 3MB In-Reply-To: <20140819122653.GH23128@arm.com> References: <1407949593-16121-1-git-send-email-keescook@chromium.org> <1407949593-16121-3-git-send-email-keescook@chromium.org> <20140819122653.GH23128@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Aug 19, 2014 at 7:26 AM, Will Deacon wrote: > Hi Kees, Rob, > > On Wed, Aug 13, 2014 at 06:06:27PM +0100, Kees Cook wrote: >> From: Rob Herring >> >> With commit a05e54c103b0 ("ARM: 8031/2: change fixmap mapping region to >> support 32 CPUs"), the fixmap region was expanded to 2MB, but it >> precluded any other uses of the fixmap region. In order to support other >> uses the fixmap region needs to be expanded beyond 2MB. Fortunately, the >> adjacent 1MB range 0xffe00000-0xfff00000 is availabe. >> >> Remove fixmap_page_table ptr and lookup the page table via the virtual >> address so that the fixmap region can span more that one pmd. The 2nd >> pmd is already created since it is shared with the vector page. > > [...] > >> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c >> index 45aeaaca9052..81061987ac45 100644 >> --- a/arch/arm/mm/highmem.c >> +++ b/arch/arm/mm/highmem.c >> @@ -18,19 +18,20 @@ >> #include >> #include "mm.h" >> >> -pte_t *fixmap_page_table; >> - >> static inline void set_fixmap_pte(int idx, pte_t pte) >> { >> unsigned long vaddr = __fix_to_virt(idx); >> - set_pte_ext(fixmap_page_table + idx, pte, 0); >> + pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr); >> + >> + set_pte_ext(ptep, pte, 0); >> local_flush_tlb_kernel_page(vaddr); >> } > > Minor comment, but we can drop the ifx parameter here now, right? It looks a > bit weird having a setter/getter pair of functions where the type signatures > aren't the inverse. idx is used to get the vaddr here. I suppose the various users of these functions in highmem could be reworked, but that doesn't look sensible either. Maybe it's just the names of the functions that are confusing? -Kees -- Kees Cook Chrome OS Security