From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753298AbbJYKtb (ORCPT ); Sun, 25 Oct 2015 06:49:31 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:34423 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753244AbbJYKtL (ORCPT ); Sun, 25 Oct 2015 06:49:11 -0400 From: Matt Fleming To: Ingo Molnar , Thomas Gleixner , "H . Peter Anvin" Cc: Sai Praneeth , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Ricardo Neri , Glenn P Williamson , Ravi Shankar , Matt Fleming , Borislav Petkov , Dave Hansen Subject: [PATCH] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled Date: Sun, 25 Oct 2015 10:49:04 +0000 Message-Id: <1445770144-22280-2-git-send-email-matt@codeblueprint.co.uk> X-Mailer: git-send-email 2.6.0 In-Reply-To: <1445770144-22280-1-git-send-email-matt@codeblueprint.co.uk> References: <1445770144-22280-1-git-send-email-matt@codeblueprint.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sai Praneeth When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are monitored to see whether address falls in direct mapping or kernel text mapping (see Documentation/x86/x86_64/mm.txt for details), if it does not, the kernel panics. During 1:1 mapping of EFI runtime services we access virtual addresses which are == physical addresses, thus the 1:1 mapping and these addresses do not fall in either of the above two regions and hence when passed as arguments to __pa() kernel panics as reported by Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@intel.com. So, before calling __pa() virtual addresses should be validated which results in skipping call to split_page_count() and that should be fine because it is used to keep track of everything *but* 1:1 mappings. Signed-off-by: Sai Praneeth Prakhya Reported-by: Dave Hansen Reviewed-by: Borislav Petkov Cc: Ricardo Neri Cc: Glenn P Williamson Cc: Ravi Shankar Signed-off-by: Matt Fleming --- arch/x86/mm/pageattr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 727158cb3b3c..9abe0c9b1098 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); - if (pfn_range_is_mapped(PFN_DOWN(__pa(address)), - PFN_DOWN(__pa(address)) + 1)) - split_page_count(level); + if (virt_addr_valid(address)) { + unsigned long pfn = PFN_DOWN(__pa(address)); + + if (pfn_range_is_mapped(pfn, pfn + 1)) + split_page_count(level); + } /* * Install the new, split up pagetable. -- 2.6.0