From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 28ECF6B025F for ; Fri, 11 Aug 2017 14:01:52 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id d136so20916878qkg.11 for ; Fri, 11 Aug 2017 11:01:52 -0700 (PDT) Received: from mail-qt0-f179.google.com (mail-qt0-f179.google.com. [209.85.216.179]) by mx.google.com with ESMTPS id v4si1278041qtb.16.2017.08.11.11.01.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Aug 2017 11:01:51 -0700 (PDT) Received: by mail-qt0-f179.google.com with SMTP id 16so25262592qtz.4 for ; Fri, 11 Aug 2017 11:01:50 -0700 (PDT) Subject: Re: [kernel-hardening] [PATCH v5 05/10] arm64/mm: Add support for XPFO References: <20170809200755.11234-1-tycho@docker.com> <20170809200755.11234-6-tycho@docker.com> From: Laura Abbott Message-ID: Date: Fri, 11 Aug 2017 11:01:46 -0700 MIME-Version: 1.0 In-Reply-To: <20170809200755.11234-6-tycho@docker.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Tycho Andersen , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, kernel-hardening@lists.openwall.com, Marco Benatto , Juerg Haefliger , Juerg Haefliger On 08/09/2017 01:07 PM, Tycho Andersen wrote: > From: Juerg Haefliger > > Enable support for eXclusive Page Frame Ownership (XPFO) for arm64 and > provide a hook for updating a single kernel page table entry (which is > required by the generic XPFO code). > > At the moment, only 64k page sizes are supported. > Can you add a note somewhere explaining this limitation or what's on the TODO list? > Signed-off-by: Juerg Haefliger > Tested-by: Tycho Andersen > --- > arch/arm64/Kconfig | 1 + > arch/arm64/mm/Makefile | 2 ++ > arch/arm64/mm/xpfo.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 67 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index dfd908630631..2ddae41e0793 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -121,6 +121,7 @@ config ARM64 > select SPARSE_IRQ > select SYSCTL_EXCEPTION_TRACE > select THREAD_INFO_IN_TASK > + select ARCH_SUPPORTS_XPFO if ARM64_64K_PAGES > help > ARM 64-bit (AArch64) Linux support. > > diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile > index 9b0ba191e48e..22e5cab543d8 100644 > --- a/arch/arm64/mm/Makefile > +++ b/arch/arm64/mm/Makefile > @@ -11,3 +11,5 @@ KASAN_SANITIZE_physaddr.o += n > > obj-$(CONFIG_KASAN) += kasan_init.o > KASAN_SANITIZE_kasan_init.o := n > + > +obj-$(CONFIG_XPFO) += xpfo.o > diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c > new file mode 100644 > index 000000000000..de03a652d48a > --- /dev/null > +++ b/arch/arm64/mm/xpfo.c > @@ -0,0 +1,64 @@ > +/* > + * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P. > + * Copyright (C) 2016 Brown University. All rights reserved. > + * > + * Authors: > + * Juerg Haefliger > + * Vasileios P. Kemerlis > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License version 2 as published by > + * the Free Software Foundation. > + */ > + > +#include > +#include > + > +#include > + > +/* > + * Lookup the page table entry for a virtual address and return a pointer to > + * the entry. Based on x86 tree. > + */ > +static pte_t *lookup_address(unsigned long addr) > +{ > + pgd_t *pgd; > + pud_t *pud; > + pmd_t *pmd; > + > + pgd = pgd_offset_k(addr); > + if (pgd_none(*pgd)) > + return NULL; > + > + BUG_ON(pgd_bad(*pgd)); > + > + pud = pud_offset(pgd, addr); > + if (pud_none(*pud)) > + return NULL; > + > + BUG_ON(pud_bad(*pud)); > + > + pmd = pmd_offset(pud, addr); > + if (pmd_none(*pmd)) > + return NULL; > + > + BUG_ON(pmd_bad(*pmd)); > + > + return pte_offset_kernel(pmd, addr); > +} We already have much of this logic implemented for kernel_page_present in arch/arm64/mm/pageattr.c, we should move this into there and make this common, similar to x86 > + > +/* Update a single kernel page table entry */ > +inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot) > +{ > + pte_t *pte = lookup_address((unsigned long)kaddr); > + > + set_pte(pte, pfn_pte(page_to_pfn(page), prot)); > +} > + > +inline void xpfo_flush_kernel_page(struct page *page, int order) > +{ > + unsigned long kaddr = (unsigned long)page_address(page); > + unsigned long size = PAGE_SIZE; > + > + flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size); > +} > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org