From: jamie@shareable.org (Jamie Lokier)
To: linux-arm-kernel@lists.infradead.org
Subject: kernel virtual memory access (from app) does not generate segfault
Date: Wed, 21 Apr 2010 01:33:06 +0100 [thread overview]
Message-ID: <20100421003306.GU11723@shareable.org> (raw)
In-Reply-To: <20100420224108.GA1432@n2100.arm.linux.org.uk>
Russell King - ARM Linux wrote:
> On Tue, Apr 20, 2010 at 11:31:06PM +0100, Jamie Lokier wrote:
> > But a possible NAK: What happens when the kernel does get/put_user()
> > on an address > TASK_SIZE with kernel-only mapping? user_mode()
> > returns 0, so the LDRT will loop in the kernel, won't it?
>
> No - the first data fault will cause the pgd entry to be copied, and then
> the subsequent data fault will be a permission fault.
>
> The difference between instruction faults and data faults is that we
> always interpret instruction faults on pre-ARMv6 CPUs as a 'translation
> fault' rather than a permission fault since they can't tell us what the
> problem was.
Subtle, but nice.
So are the ifar_info and ifsr_info tables completely redundant
pre-ARMv6, or is it just ifsr_info?
-- Jamie
next prev parent reply other threads:[~2010-04-21 0:33 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-20 9:14 kernel virtual memory access (from app) does not generate segfault Sasha Sirotkin
2010-04-20 9:34 ` Ben Dooks
2010-04-20 10:27 ` Dave P. Martin
2010-04-20 14:20 ` anfei
2010-04-20 17:09 ` Ben Dooks
2010-04-20 19:28 ` Russell King - ARM Linux
2010-04-20 22:31 ` Jamie Lokier
2010-04-20 22:41 ` Russell King - ARM Linux
2010-04-21 0:33 ` Jamie Lokier [this message]
2010-04-21 11:17 ` kernel virtual memory access (from app) does not generatesegfault Dave P. Martin
2010-04-21 12:43 ` anfei
2010-04-21 16:07 ` Dave P. Martin
2010-04-21 19:16 ` Jamie Lokier
2010-04-21 19:40 ` Russell King - ARM Linux
2010-04-21 21:00 ` Jamie Lokier
2010-04-21 19:36 ` Russell King - ARM Linux
2010-04-21 19:35 ` Russell King - ARM Linux
2010-04-21 21:24 ` Nicolas Pitre
2010-04-21 21:44 ` Russell King - ARM Linux
2010-04-21 21:54 ` Russell King - ARM Linux
2010-04-21 22:59 ` Nicolas Pitre
2010-04-22 10:56 ` Dave P. Martin
2010-04-22 12:29 ` anfei
2010-04-22 13:18 ` Dave P. Martin
2010-04-22 15:59 ` Jamie Lokier
2010-04-21 13:11 ` kernel virtual memory access (from app) does not generate segfault anfei
2010-04-21 19:45 ` Jamie Lokier
2010-06-08 13:29 ` anfei
2010-06-08 13:36 ` Russell King - ARM Linux
2010-06-08 14:19 ` anfei
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