From: Matt Fleming <matt@codeblueprint.co.uk>
To: Ingo Molnar <mingo@kernel.org>
Cc: Scott Ashcroft <scott.ashcroft@talk21.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Borislav Petkov <bp@alien8.de>,
Ben Hutchings <ben@decadent.org.uk>,
Raphael Hertzog <hertzog@debian.org>,
Roger Shimizu <rogershimizu@gmail.com>,
Alexis Murzeau <amurzeau@gmail.com>,
Julia Lawall <julia.lawall@lip6.fr>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH] x86/efi: Always map boot service regions into new EFI page tables
Date: Tue, 15 Mar 2016 15:54:18 +0000 [thread overview]
Message-ID: <20160315155418.GH2619@codeblueprint.co.uk> (raw)
In-Reply-To: <20160314164700.GA21726@gmail.com>
On Mon, 14 Mar, at 05:47:00PM, Ingo Molnar wrote:
>
> * Matt Fleming <matt@codeblueprint.co.uk> 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.
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?
next prev parent reply other threads:[~2016-03-15 15:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 11:19 [GIT PULL] EFI urgent fix for v4.6 queue Matt Fleming
2016-03-11 11:19 ` [PATCH] x86/efi: Always map boot service regions into new EFI page tables Matt Fleming
2016-03-12 18:57 ` [tip:x86/urgent] x86/efi: Fix boot crash by always mapping " tip-bot for Matt Fleming
2016-03-12 23:02 ` Matt Fleming
2016-03-13 17:56 ` Ingo Molnar
2016-03-13 17:09 ` [PATCH] x86/efi: Always map " Scott Ashcroft
2016-03-13 21:58 ` Matt Fleming
2016-03-13 23:07 ` Matt Fleming
2016-03-13 23:44 ` Scott Ashcroft
2016-03-14 1:09 ` Scott Ashcroft
2016-03-14 10:30 ` Ingo Molnar
2016-03-14 11:35 ` Matt Fleming
2016-03-14 12:05 ` Ingo Molnar
2016-03-14 14:27 ` Matt Fleming
2016-03-14 16:47 ` Ingo Molnar
2016-03-15 15:54 ` Matt Fleming [this message]
2016-03-15 16:05 ` Borislav Petkov
2016-03-15 16:25 ` Julia Lawall
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