From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 65EA96B0005 for ; Tue, 17 Apr 2018 17:16:45 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id p12so12028876pfn.13 for ; Tue, 17 Apr 2018 14:16:45 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id r14si4469006pgt.292.2018.04.17.14.16.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Apr 2018 14:16:44 -0700 (PDT) Subject: [PATCH 2/2] x86, pti: fix boot warning from Global-bit setting From: Dave Hansen Date: Tue, 17 Apr 2018 14:13:04 -0700 References: <20180417211302.421F6442@viggo.jf.intel.com> In-Reply-To: <20180417211302.421F6442@viggo.jf.intel.com> Message-Id: <20180417211304.7B3F1FDB@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Dave Hansen , mceier@gmail.com, aaro.koskinen@nokia.com, aarcange@redhat.com, luto@kernel.org, arjan@linux.intel.com, bp@alien8.de, dan.j.williams@intel.com, dwmw2@infradead.org, gregkh@linuxfoundation.org, hughd@google.com, jpoimboe@redhat.com, jgross@suse.com, keescook@google.com, torvalds@linux-foundation.org, namit@vmware.com, peterz@infradead.org, tglx@linutronix.de These are _very_ lightly tested. I'm throwing them out there for folks are looking for a fix. --- From: Dave Hansen pageattr.c is not friendly when it encounters empty (zero) PTEs. The kernel linear map is exempt from these checks, but kernel text is not. This patch adds the code to also exempt kernel text from these checks. The proximate cause of these warnings was most likely an __init area that spanned a 2MB page boundary that resulted in a "zero" PMD. Signed-off-by: Dave Hansen Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image) Reported-by: Mariusz Ceier Reported-by: Aaro Koskinen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org --- b/arch/x86/mm/pageattr.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff -puN arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr arch/x86/mm/pageattr.c --- a/arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr 2018-04-17 14:10:22.695395554 -0700 +++ b/arch/x86/mm/pageattr.c 2018-04-17 14:10:22.721395554 -0700 @@ -1151,6 +1151,16 @@ static int populate_pgd(struct cpa_data return 0; } +bool __cpa_pfn_in_highmap(unsigned long pfn) +{ + /* + * Kernel text has an alias mapping at a high address, known + * here as "highmap". + */ + return within_inclusive(pfn, highmap_start_pfn(), + highmap_end_pfn()); +} + static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, int primary) { @@ -1183,6 +1193,10 @@ static int __cpa_process_fault(struct cp cpa->numpages = 1; cpa->pfn = __pa(vaddr) >> PAGE_SHIFT; return 0; + + } else if (__cpa_pfn_in_highmap(cpa->pfn)) { + /* Faults in the highmap are OK, so do not warn: */ + return -EFAULT; } else { WARN(1, KERN_WARNING "CPA: called for zero pte. " "vaddr = %lx cpa->vaddr = %lx\n", vaddr, @@ -1335,8 +1349,7 @@ static int cpa_process_alias(struct cpa_ * to touch the high mapped kernel as well: */ if (!within(vaddr, (unsigned long)_text, _brk_end) && - within_inclusive(cpa->pfn, highmap_start_pfn(), - highmap_end_pfn())) { + __cpa_pfn_in_highmap(cpa->pfn)) { unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) + __START_KERNEL_map - phys_base; alias_cpa = *cpa; _