From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Jamie Lokier <jamie@shareable.org>
Cc: Ian Molton <spyro@f2s.com>,
linux-arm-kernel@lists.arm.linux.org.uk,
linux-kernel@vger.kernel.org
Subject: Re: A question about PROT_NONE on ARM and ARM26
Date: Wed, 30 Jun 2004 09:16:21 +0100 [thread overview]
Message-ID: <20040630091621.A8576@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20040630024434.GA25064@mail.shareable.org>; from jamie@shareable.org on Wed, Jun 30, 2004 at 03:44:34AM +0100
On Wed, Jun 30, 2004 at 03:44:34AM +0100, Jamie Lokier wrote:
> My question is: if the _kernel_ reads a PROT_NONE page, will it fault?
> It looks likely to me.
There are two different types of privileged accesses on ARM. One is the
standard load/store instruction, which checks the permissions for the
current processor mode. The other is one which simulates a user mode
access to the address.
We use the latter for get_user/put_user/copy_to_user/copy_from_user.
> This means that calling write() with a PROT_NONE region would succeed,
> wouldn't it?
No, because the uaccess.h function will fault, and we'll end up returning
-EFAULT.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
next prev parent reply other threads:[~2004-06-30 8:16 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-30 2:44 A question about PROT_NONE on ARM and ARM26 Jamie Lokier
2004-06-30 3:38 ` William Lee Irwin III
2004-07-01 3:26 ` Testing PROT_NONE and other protections, and a surprise Jamie Lokier
2004-07-01 3:35 ` William Lee Irwin III
2004-07-01 4:01 ` Jamie Lokier
2004-07-01 3:44 ` Kyle Moffett
2004-07-01 4:11 ` Jamie Lokier
2004-07-01 4:59 ` Kyle Moffett
2004-07-01 12:39 ` Jamie Lokier
2004-07-01 14:43 ` [OT] " Kyle Moffett
2004-07-01 14:50 ` Jamie Lokier
2004-07-01 15:01 ` Kyle Moffett
2004-07-01 16:37 ` Matt Mackall
2004-07-01 17:26 ` Michael Driscoll
2004-07-02 7:37 ` Gabriel Paubert
2004-07-01 12:52 ` Russell King
2004-07-01 14:26 ` Richard Curnow
2004-06-30 8:16 ` Russell King [this message]
2004-06-30 14:59 ` A question about PROT_NONE on ARM and ARM26 Jamie Lokier
2004-06-30 15:22 ` Ian Molton
2004-06-30 18:26 ` Russell King
2004-06-30 19:14 ` Jamie Lokier
2004-06-30 19:23 ` Russell King
2004-06-30 20:15 ` Jamie Lokier
2004-06-30 22:59 ` Russell King
2004-06-30 23:30 ` Jamie Lokier
2004-06-30 23:48 ` Ian Molton
2004-07-01 1:59 ` Jamie Lokier
2004-07-01 1:05 ` Nicolas Pitre
2004-07-01 1:50 ` Jamie Lokier
2004-07-02 18:39 ` Russell King
2004-07-01 15:27 ` Scott Wood
2004-07-01 23:53 ` Jamie Lokier
2004-07-02 14:36 ` Scott Wood
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