linux-kernel - Re: [PATCH v2 03/20] ARM: LPAE: use u32 instead of unsigned long for 32-bit ptes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20101115233517.GH31421@n2100.arm.linux.org.uk>
Date:	Mon, 15 Nov 2010 23:35:17 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Nicolas Pitre <nico@...xnic.net>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v2 03/20] ARM: LPAE: use u32 instead of unsigned long
	for 32-bit ptes

On Mon, Nov 15, 2010 at 05:11:50PM -0500, Nicolas Pitre wrote:
> On Mon, 15 Nov 2010, Catalin Marinas wrote:
> 
> > On 15 November 2010 09:47, Arnd Bergmann <arnd@...db.de> wrote:
> > > On Monday 15 November 2010 10:39:30 Catalin Marinas wrote:
> > >> > There will be compiler warnings because u32 is unsigned int, and we
> > >> > print it as %08lx.  Generic code cases pte values to (long long) and
> > >> > prints them using %08llx.  We should do the same.
> > >>
> > >> We still need some kind of macro because with LPAE we need %016llx
> > >> since the phys address can go to 40-bit and there are some additional
> > >> bits in the top word. Unless you'd like to always print 16 characters
> > >> even for 32-bit ptes (or if there is some other printk magic I'm not
> > >> aware of).
> > >
> > > Why not just %010llx? That would just be two extra characters.
> > 
> > We still have attributes (like XN, bit 54) stored in the top part of
> > the pte. This may be of interest when debugging.
> 
> They will be printed if they exist. The %010 in front of llx only means 
> to have a minimum of 10 zero-paded digits if the value is smaller than 
> that.
> 
> However, not having aligned values will be confusing.  A macro for the 
> format might be the best compromize.

It's what is done in the generic kernel code for page table entries.

        printk(KERN_ALERT
                "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
                current->comm,
                (long long)pte_val(pte), (long long)pmd_val(*pmd));

The places where this matters, there isn't any alignment between
lines to worry about:

	printk(", *pmd=%08lx", pmd_val(*pmd));
	printk(", *pte=%08lx", pte_val(*pte));
	printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));

in show_pte() are examples of what need changing.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/