Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933721AbbLOU6l (ORCPT ); Tue, 15 Dec 2015 15:58:41 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:58063 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933674AbbLOU6i (ORCPT ); Tue, 15 Dec 2015 15:58:38 -0500 Date: Tue, 15 Dec 2015 21:58:35 +0100 From: Pavel Machek To: Linus Torvalds Cc: Andy Lutomirski , Arjan van de Ven , Borislav Petkov , kernel list , Stephen Smalley , Brian Gerst , Denys Vlasenko , Peter Anvin , Mike Galbraith , Peter Zijlstra , Thomas Gleixner Subject: Re: 4.4-rc5: ugly warn on: 5 W+X pages found Message-ID: <20151215205835.GA3522@amd> References: <20151214080403.GA3708@amd> <20151214085803.GA10520@pd.tnic> <20151214090726.GA6472@amd> <20151214202627.GA15104@amd> <566F3378.8070009@linux.intel.com> <20151215094015.GA3677@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3928 Lines: 103 Hi! > > I tried applying: > > > > [PATCH 1/2] x86_32/mm: Set NX in __supported_pte_mask before enabling > > paging > > > > but I still get > > > > [ 2.691897] x86/mm: Found insecure W+X mapping at address ffe69000/0xffe69000 > > This may be an insane suggestion, but how about we try to detect when > that entry gets set, rather than after the fact. > > Something really brute-force like > > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index 6ec0c8b2e9df..538c9bb239b9 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -337,6 +337,13 @@ static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd) > > #endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */ > > +static inline int kernel_write_execute_prot(pgprotval_t protval) > +{ > + return !(protval & _PAGE_USER) && > + !(protval & _PAGE_NX) && > + (protval & _PAGE_RW); > +} ... > + if (protval & _PAGE_PRESENT) { > protval &= __supported_pte_mask; > + WARN_ON_ONCE(kernel_write_execute_prot(protval)); > + } > > return protval; > } > > or similar? > > The above is entirely untested. Maybe it doesn't compile. Or > boot. Or work. Well, with two extra spaces at each line, it does not apply :-). I applied it by hand, and the output is: [ 0.000000] MTRR variable ranges enabled: [ 0.000000] 0 base 000000000 mask F80000000 write-back [ 0.000000] 1 base 080000000 mask FC0000000 write-back [ 0.000000] 2 base 0BF700000 mask FFFF00000 uncachable [ 0.000000] 3 base 0BF800000 mask FFF800000 uncachable [ 0.000000] 4 disabled [ 0.000000] 5 disabled [ 0.000000] 6 disabled [ 0.000000] 7 disabled [ 0.000000] x86/PAT: PAT not supported by CPU. [ 0.000000] initial memory mapped: [mem 0x00000000-0x05bfffff] [ 0.000000] Base memory trampoline at [c009b000] 9b000 size 16384 [ 0.000000] ------------[ cut here ]------------ [ 0.000000] WARNING: CPU: 0 PID: 0 at ./arch/x86/include/asm/pgtable.h:357 kernel_physical_mapping_init+0x 256/0x395() [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc5+ #137 [ 0.000000] Hardware name: LENOVO 17097HU/17097HU, BIOS 7BETD8WW (2.19 ) 03/31/2011 [ 0.000000] 00000000 00000000 c4e63e90 c42baaf8 00000000 c4e63eac c404066b 00000165 [ 0.000000] c4f134da 00000000 00000000 00000000 c4e63ebc c404070f 00000009 00000000 [ 0.000000] c4e63f18 c4f134da c4e63f00 00000000 00000000 00000000 00000000 00000000 [ 0.000000] Call Trace: [ 0.000000] [] dump_stack+0x41/0x59 [ 0.000000] [] warn_slowpath_common+0x6b/0xa0 [ 0.000000] [] ? kernel_physical_mapping_init+0x256/0x395 [ 0.000000] [] warn_slowpath_null+0xf/0x20 [ 0.000000] [] kernel_physical_mapping_init+0x256/0x395 [ 0.000000] [] init_memory_mapping+0x191/0x300 [ 0.000000] [] init_mem_mapping+0xe7/0x1f3 [ 0.000000] [] ? init_mem_mapping+0xe7/0x1f3 [ 0.000000] [] setup_arch+0x659/0x8ca [ 0.000000] [] start_kernel+0xbb/0x360 [ 0.000000] [] i386_start_kernel+0x82/0x86 [ 0.000000] ---[ end trace e117245cd61feaf1 ]--- [ 0.000000] BRK [0x0566a000, 0x0566afff] PGTABLE [ 0.000000] BRK [0x0566b000, 0x0566bfff] PGTABLE [ 0.000000] BRK [0x0566c000, 0x0566cfff] PGTABLE I'll take a look if I can figure out what it means... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/