Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934636AbcCOQZc (ORCPT ); Tue, 15 Mar 2016 12:25:32 -0400 Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:23826 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751048AbcCOQZa (ORCPT ); Tue, 15 Mar 2016 12:25:30 -0400 X-IronPort-AV: E=Sophos;i="5.24,340,1454972400"; d="scan'208";a="168776915" Date: Tue, 15 Mar 2016 17:25:25 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Matt Fleming cc: Ingo Molnar , Scott Ashcroft , "H . Peter Anvin" , Thomas Gleixner , Ard Biesheuvel , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Maarten Lankhorst , Matthew Garrett , Borislav Petkov , Ben Hutchings , Raphael Hertzog , Roger Shimizu , Alexis Murzeau , Julia Lawall , Linus Torvalds , Andrew Morton , Peter Zijlstra , Josh Poimboeuf , Fengguang Wu Subject: Re: [PATCH] x86/efi: Always map boot service regions into new EFI page tables In-Reply-To: <20160315155418.GH2619@codeblueprint.co.uk> Message-ID: References: <1457695163-29632-1-git-send-email-matt@codeblueprint.co.uk> <1457695163-29632-2-git-send-email-matt@codeblueprint.co.uk> <1457888975.3884.9.camel@talk21.com> <20160313215847.GA2619@codeblueprint.co.uk> <20160313230736.GB2619@codeblueprint.co.uk> <20160314103019.GA32573@gmail.com> <20160314113502.GC2619@codeblueprint.co.uk> <20160314120502.GA17388@gmail.com> <20160314142734.GE2619@codeblueprint.co.uk> <20160314164700.GA21726@gmail.com> <20160315155418.GH2619@codeblueprint.co.uk> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5682 Lines: 85 On Tue, 15 Mar 2016, Matt Fleming wrote: > On Mon, 14 Mar, at 05:47:00PM, Ingo Molnar wrote: > > > > * Matt Fleming wrote: > > > > > Running the attached semantic patch across arch/x86/mm yields a few > > > more places where we get the data type wrong for PAE, > > > > Very nice! > > > > > * file: arch/x86/mm/mmap.c:43 shifting int '( ( - 1UL ) & STACK_RND_MASK )' by PAGE_SHIFT is truncated to 32-bits > > > * file: arch/x86/mm/pageattr-test.c:57 shifting long 'i' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr-test.c:138 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/gup.c:422 shifting int 'nr' by PAGE_SHIFT is truncated to 32-bits > > > * file: arch/x86/mm/gup.c:303 shifting unsigned long '( unsigned long ) nr_pages' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/gup.c:370 shifting unsigned long '( unsigned long ) nr_pages' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pat.c:751 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr-test.c:57 shifting long 'i' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:947 shifting unsigned 'num_pages' by PAGE_SHIFT is truncated to 32-bits > > > * file: arch/x86/mm/pageattr.c:1995 shifting unsigned 'numpages' by PAGE_SHIFT is truncated to 32-bits > > > * file: arch/x86/mm/pageattr-test.c:138 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:1117 shifting unsigned long 'cpa -> numpages' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:1017 shifting unsigned long 'cpa -> numpages' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:1277 shifting unsigned long 'cpa -> pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:1318 shifting unsigned long 'cpa -> pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:986 shifting unsigned long 'cpa -> pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/pageattr.c:1059 shifting unsigned long 'cpa -> pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:197 shifting unsigned long 'end_pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:100 shifting unsigned long 'min_pfn_mapped' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:641 shifting unsigned long 'pagenr' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:111 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:121 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:111 shifting unsigned long __initdata 'pgt_buf_end' by PAGE_SHIFT is truncated to 32-bits > > > * file: arch/x86/mm/init.c:196 shifting unsigned long 'start_pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:91 shifting unsigned long '( unsigned long ) num' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init.c:117 shifting unsigned long '( pfn + i )' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init_32.c:293 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init_32.c:301 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init_32.c:344 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init_32.c:361 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > * file: arch/x86/mm/init_32.c:471 shifting unsigned long 'pfn' by PAGE_SHIFT is truncated to 32-bits for PAE > > > > > > The coccinelle script isn't perfect, and there are a number of false > > > positives. For example, the first hit is bogus and looks like a > > > coccinelle bug, but the results do show some things that need to be > > > investigated. > > > > So I checked a few random examples in your list, and the false positive rate looks > > rather low. > > > > The current Kbuild integration of Cocci scripts is pretty user-hostile. I'd love > > to make this Cocci check part of the regular build process in some fashion (if a > > Kconfig option is enabled), similarly to how we run objtool for example. We could > > emit the Cocci warnings as a regular compiler 'warning: ' message, so people will > > notice them as part of the build? > > For this type of cocci script where architecture knowledge of bug > idioms is required (you need to know shifting by "PAGE_SHIFT" is > usually done to build an address or size of some kind) I think the > first step would be to automatically lookup scripts to be run on a > per-directory basis. > > For example, running make(1) in arch/x86/kernel should map to > scripts/coccinelle/arch/x86/kernel, etc. Considering the current organization of make coccicheck, I think it would be easier for Coccinelle to just abort on files not in the desired directories. This is possible to encode, although perhaps a little bit awkward. julia > And yes, I agree, turning this on via a CONFIG_* symbol would be nice. > > > The false positive(s) could either be worked around or annotated away. > > > > Obviously we'd only use Cocci scripts that are known to be reliable. > > Fengguang, do you run coccinelle scripts currently as part of the > 0-day lkp build machinery? >