Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752095AbbKPUT5 (ORCPT ); Mon, 16 Nov 2015 15:19:57 -0500 Received: from www.linutronix.de ([62.245.132.108]:42912 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509AbbKPUTx (ORCPT ); Mon, 16 Nov 2015 15:19:53 -0500 Date: Mon, 16 Nov 2015 21:19:01 +0100 (CET) From: Thomas Gleixner To: Matt Fleming cc: Ingo Molnar , "H . Peter Anvin" , Toshi Kani , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Sai Praneeth Prakhya , Dave Hansen , Borislav Petkov Subject: Re: [PATCH v2 1/5] x86/mm/pageattr: Ensure cpa->pfn only contains page frame numbers In-Reply-To: <1447538451-5793-2-git-send-email-matt@codeblueprint.co.uk> Message-ID: References: <1447538451-5793-1-git-send-email-matt@codeblueprint.co.uk> <1447538451-5793-2-git-send-email-matt@codeblueprint.co.uk> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3610 Lines: 106 On Sat, 14 Nov 2015, Matt Fleming wrote: > The x86 pageattr code is confused about the data that is stored > cpa->pfn, sometimes it's treated as a page frame number, sometimes > it's treated as an unshifted physical address, and in one place it's > treated as a pte. Yuck. > The result of this is that the mapping functions do not map the > intended physical address. > > This isn't a problem in practice because most of the addresses we're > mapping in the EFI code paths are already mapped in 'trampoline_pgd' > and so the pageattr mappings functions don't actually do anything in > this case. But when we move to using a separate page table for the EFI > runtime this will be an issue. Are you sure that this does not affect existing kernel versions? > while (num_pages-- && start < end) { > - > - /* deal with the NX bit */ > - if (!(pgprot_val(pgprot) & _PAGE_NX)) > - cpa->pfn &= ~_PAGE_NX; That should be a seperate patch because this is just bogus code and has nothing to do with the pfn confusion. > - > - set_pte(pte, pfn_pte(cpa->pfn >> PAGE_SHIFT, pgprot)); > + set_pte(pte, pfn_pte(cpa->pfn, pgprot)); > diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c > index a0ac0f9c307f..c8b58ac47b77 100644 > --- a/arch/x86/platform/efi/efi_64.c > +++ b/arch/x86/platform/efi/efi_64.c > @@ -143,7 +143,7 @@ void efi_sync_low_kernel_mappings(void) > > int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) > { > - unsigned long text; > + unsigned long pfn, text; > struct page *page; > unsigned npages; > pgd_t *pgd; > @@ -160,7 +160,8 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) > * and ident-map those pages containing the map before calling > * phys_efi_set_virtual_address_map(). > */ > - if (kernel_map_pages_in_pgd(pgd, pa_memmap, pa_memmap, num_pages, _PAGE_NX)) { > + pfn = pa_memmap >> PAGE_SHIFT; > + if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX)) { > pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap); > return 1; > } > @@ -176,21 +177,29 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) > if (!IS_ENABLED(CONFIG_EFI_MIXED)) > return 0; > > + npages = (_end - _text) >> PAGE_SHIFT; You really need to PFN_ALIGN _end and _text. Has been wrong in the existing code as well. > + text = __pa(_text); > + pfn = text >> PAGE_SHIFT; > + > + if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) { > + pr_err("Failed to map kernel text 1:1\n"); > + return 1; > + } > + > page = alloc_page(GFP_KERNEL|__GFP_DMA32); > if (!page) > panic("Unable to allocate EFI runtime stack < 4GB\n"); > > efi_scratch.phys_stack = virt_to_phys(page_address(page)); > - efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */ > - > - npages = (_end - _text) >> PAGE_SHIFT; > - text = __pa(_text); > + pfn = page_to_pfn(page); > > - if (kernel_map_pages_in_pgd(pgd, text >> PAGE_SHIFT, text, npages, 0)) { > - pr_err("Failed to map kernel text 1:1\n"); > + if (kernel_map_pages_in_pgd(pgd, pfn, efi_scratch.phys_stack, 1, 0)) { This looks like an unrelated change, hmm? > + pr_err("Failed to map mixed mode stack\n"); > return 1; > } > > + efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */ > + > return 0; > } Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/