From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933806AbcAKQZQ (ORCPT ); Mon, 11 Jan 2016 11:25:16 -0500 Received: from foss.arm.com ([217.140.101.70]:56567 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933793AbcAKQZL (ORCPT ); Mon, 11 Jan 2016 11:25:11 -0500 Date: Mon, 11 Jan 2016 16:24:49 +0000 From: Mark Rutland To: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org, kernel-hardening@lists.openwall.com, will.deacon@arm.com, catalin.marinas@arm.com, leif.lindholm@linaro.org, keescook@chromium.org, linux-kernel@vger.kernel.org, stuart.yoder@freescale.com, bhupesh.sharma@freescale.com, arnd@arndb.de, marc.zyngier@arm.com, christoffer.dall@linaro.org Subject: Re: [PATCH v3 06/21] arm64: pgtable: implement static [pte|pmd|pud]_offset variants Message-ID: <20160111162449.GP6499@leverpostej> References: <1452518355-4606-1-git-send-email-ard.biesheuvel@linaro.org> <1452518355-4606-7-git-send-email-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1452518355-4606-7-git-send-email-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 11, 2016 at 02:18:59PM +0100, Ard Biesheuvel wrote: > The page table accessors pte_offset(), pud_offset() and pmd_offset() > rely on __va translations, so they can only be used after the linear > mapping has been installed. For the early fixmap and kasan init routines, > whose page tables are allocated statically in the kernel image, these > functions will return bogus values. So implement pmd_offset_kimg() and > pud_offset_kimg(), which can be used instead before any page tables have > been allocated dynamically. > > Signed-off-by: Ard Biesheuvel This looks good to me. One possible suggsetion below, but either way: Reviewed-by: Mark Rutland > --- > arch/arm64/include/asm/pgtable.h | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 6129f6755081..7b4e16068c9f 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -449,6 +449,9 @@ static inline phys_addr_t pmd_page_paddr(pmd_t pmd) > > #define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK)) > > +/* use ONLY for statically allocated translation tables */ > +#define pte_offset_kimg(dir,addr) ((pte_t *)__phys_to_kimg(pte_offset_phys((dir), (addr)))) > + Given that we're probably only going to use this during one-off setup, maybe it's worth something like: #define IN_KERNEL_IMAGE(p) ({ \ unsigned long __p = (unsigned long)p; \ KIMAGE_VADDR <= __p && __p < _end; \ }) #define pte_offset_kimg(dir,addr) ({ \ BUG_ON(!IN_KERNEL_IMAGE(dir)); \ ((pte_t *)__phys_to_kimg(pte_offset_phys((dir), (addr)))); \ }) That might be overkill, though, given all it does is turn one runtime failure into another runtime failure. Mark. > /* > * Conversion functions: convert a page and protection to a page entry, > * and a page entry and page directory to the page they refer to. > @@ -492,6 +495,9 @@ static inline phys_addr_t pud_page_paddr(pud_t pud) > > #define pud_page(pud) pfn_to_page(__phys_to_pfn(pud_val(pud) & PHYS_MASK)) > > +/* use ONLY for statically allocated translation tables */ > +#define pmd_offset_kimg(dir,addr) ((pmd_t *)__phys_to_kimg(pmd_offset_phys((dir), (addr)))) > + > #else > > #define pud_page_paddr(pud) ({ BUILD_BUG(); 0; }) > @@ -502,6 +508,8 @@ static inline phys_addr_t pud_page_paddr(pud_t pud) > #define pmd_set_fixmap_offset(pudp, addr) ((pmd_t *)pudp) > #define pmd_clear_fixmap() > > +#define pmd_offset_kimg(dir,addr) ((pmd_t *)dir) > + > #endif /* CONFIG_PGTABLE_LEVELS > 2 */ > > #if CONFIG_PGTABLE_LEVELS > 3 > @@ -540,6 +548,9 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd) > > #define pgd_page(pgd) pfn_to_page(__phys_to_pfn(pgd_val(pgd) & PHYS_MASK)) > > +/* use ONLY for statically allocated translation tables */ > +#define pud_offset_kimg(dir,addr) ((pud_t *)__phys_to_kimg(pud_offset_phys((dir), (addr)))) > + > #else > > #define pgd_page_paddr(pgd) ({ BUILD_BUG(); 0;}) > @@ -550,6 +561,8 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd) > #define pud_set_fixmap_offset(pgdp, addr) ((pud_t *)pgdp) > #define pud_clear_fixmap() > > +#define pud_offset_kimg(dir,addr) ((pud_t *)dir) > + > #endif /* CONFIG_PGTABLE_LEVELS > 3 */ > > #define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd)) > -- > 2.5.0 >