From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 6487D6B0005 for ; Fri, 20 Apr 2018 18:24:15 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id y22-v6so5701627pll.12 for ; Fri, 20 Apr 2018 15:24:15 -0700 (PDT) Received: from mga18.intel.com (mga18.intel.com. [134.134.136.126]) by mx.google.com with ESMTPS id p14-v6si787066pli.250.2018.04.20.15.24.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Apr 2018 15:24:14 -0700 (PDT) Subject: [PATCH 2/5] x86, pti: fix boot warning from Global-bit setting From: Dave Hansen Date: Fri, 20 Apr 2018 15:20:21 -0700 References: <20180420222018.E7646EE1@viggo.jf.intel.com> In-Reply-To: <20180420222018.E7646EE1@viggo.jf.intel.com> Message-Id: <20180420222021.1C7D2B3F@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 From: Dave Hansen The pageattr.c code attempts to process "faults" when it goes looking for PTEs to change and finds non-present entries. It allows these faults in the linear map which is "expected to have holes", but WARN()s about them elsewhere, like when called on the kernel image. However, we are now calling change_page_attr_clear() on the kernel image in the process of trying to clear the Global bit. This trips the warning in __cpa_process_fault() if a non-present PTE is encountered in the kernel image. The "holes" in the kernel image result from free_init_pages()'s use of set_memory_np(). These holes are totally fine, and result from normal operation, just as they would be in the kernel linear map. Just silence the warning when holes in the kernel image are encountered. 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 | 41 +++++++++++++++++++++++++++++++---------- 1 file changed, 31 insertions(+), 10 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 2018-04-20 14:10:01.619749168 -0700 +++ b/arch/x86/mm/pageattr.c 2018-04-20 14:10:01.623749168 -0700 @@ -93,6 +93,18 @@ void arch_report_meminfo(struct seq_file static inline void split_page_count(int level) { } #endif +static inline int +within(unsigned long addr, unsigned long start, unsigned long end) +{ + return addr >= start && addr < end; +} + +static inline int +within_inclusive(unsigned long addr, unsigned long start, unsigned long end) +{ + return addr >= start && addr <= end; +} + #ifdef CONFIG_X86_64 static inline unsigned long highmap_start_pfn(void) @@ -106,20 +118,26 @@ static inline unsigned long highmap_end_ return __pa_symbol(roundup(_brk_end, PMD_SIZE) - 1) >> PAGE_SHIFT; } -#endif - -static inline int -within(unsigned long addr, unsigned long start, unsigned long end) +static bool __cpa_pfn_in_highmap(unsigned long pfn) { - return addr >= start && addr < end; + /* + * 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 inline int -within_inclusive(unsigned long addr, unsigned long start, unsigned long end) +#else + +static bool __cpa_pfn_in_highmap(unsigned long pfn) { - return addr >= start && addr <= end; + /* There is no highmap on 32-bit */ + return false; } +#endif + /* * Flushing functions */ @@ -1183,6 +1201,10 @@ 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 +1357,7 @@ 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; _