From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49lxkXwgjmIKvVBD52S2DvF+8XGn2od02xM8qUNgBZ6GB1hbHMRNhLGre7ePBmNBP3iaTfI ARC-Seal: i=1; a=rsa-sha256; t=1523999804; cv=none; d=google.com; s=arc-20160816; b=WF/wGVGaDvUeWOxFiXY4STHvEcMTP+NfivciAG3vPRY0HAGMKFhvrw+ekMjFupZ0T7 o4C8g7GlJzDJGr7JzQtpppR0Z6xZKaaoQlz82Vyj5/XExYcGYQ1y+niCUkyldA9jX3Gs GzJTXTE95U2F467oqzpIoiT6aAOa7Qn0t3Ede1wHPwCRwvT3d7w+yoIfNrDyb/t7GOWE Cu+iyLN0pFj2utptFFgcWqc8qHim+d/iRmruxRb7kVEbjoJ0pWINUxAe4AAIPbogGZ+N 4nVy1WBiuWBhQPjSD9FIY6N3otFuut444SqIVxmuzQkqAf8tOpBAeK7gxhBuXvtEocs9 U3CQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:in-reply-to:references:date:from:cc:to:subject :arc-authentication-results; bh=bgafNeYO9tAFeWzFFeayw1cHgbUfjT8N1srNhCRwlUE=; b=vvJHreuzAsK79omJZGzeTPhVG6Bs4Ffty+QruWjlxeX0eucc4CMf4xBHH5Juo6v5HA EikgkKi69bLr85F7XMrxAM9AK+0eHQaFimtD6iYqqOlUhg1Cc3pOAstGzAO7rjO3XJ1O Ptl4D38g3kf43ep6q85JUjTf5nCB4SpB/5fcvQk1J5H38YaeAg4YHwlxfAH7/TGiufJC jOsxYfNus3tmQb6q7TjVxWF50gFdGIzIznzDhccctmAH0FT0XHzBpO9f5jF9pCa+h/Vt ph7EOOuKWoGwXCwv28JQAqFthJ77YpE2DLmNF9SzubBSW+qeW//EPez3cGOXH7eqoUBD FSJQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of dave.hansen@linux.intel.com designates 134.134.136.20 as permitted sender) smtp.mailfrom=dave.hansen@linux.intel.com Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of dave.hansen@linux.intel.com designates 134.134.136.20 as permitted sender) smtp.mailfrom=dave.hansen@linux.intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,464,1517904000"; d="scan'208";a="34416197" Subject: [PATCH 2/2] x86, pti: fix boot warning from Global-bit setting 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 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> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598029619129049046?= X-GMAIL-MSGID: =?utf-8?q?1598029619129049046?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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; _