From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Cc: Scott Wood <scottwood@freescale.com>,
"linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>,
Rex Feany <RFeany@mrv.com>
Subject: Re: [PATCH 0/6] PowerPc 8xx TLB/MMU fixes
Date: Tue, 06 Oct 2009 17:44:46 +1100 [thread overview]
Message-ID: <1254811486.6035.2.camel@pasglop> (raw)
In-Reply-To: <OFDFE80DD9.19502D87-ONC1257647.0022C31E-C1257647.00235079@transmode.se>
> > I assumed it was NIP because ... I'm not sure why. TRAP() above
> > dereferences regs, and that didn't fail, but I didn't see that until
> > now.
>
> Yes, it is a bit strange though that the kernel isn't allowed to read from
> NULL. Is that expected?
Yes, that's absolutely expected :-) You really want any NULL deref to
blow up asap.
0 is actually part of the address space assigned to user processes. By
default they don't have anything there neither though, but if the
current process do have something mapped there, then the kernel would
read that when doing a NULL deref.
Cheers,
Ben.
prev parent reply other threads:[~2009-10-06 6:44 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-05 12:16 [PATCH 0/6] PowerPc 8xx TLB/MMU fixes Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 1/6] 8xx: DTLB Error must check for more errors Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 2/6] 8xx, fault: Add some debug code to do_page_fault() Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 3/6] 8xx: get rid of _PAGE_HWWRITE dependency in MMU Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 4/6] 8xx: Tag DAR with 0x00f0 to catch buggy instructions Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 5/6] 8xx: Fixup DAR from buggy dcbX instructions Joakim Tjernlund
2009-10-05 12:16 ` [PATCH 6/6] 8xx: start using dcbX instructions in various copy routines Joakim Tjernlund
2009-10-05 20:17 ` [PATCH 3/6] 8xx: get rid of _PAGE_HWWRITE dependency in MMU Benjamin Herrenschmidt
2009-10-05 21:25 ` Joakim Tjernlund
2009-10-05 21:37 ` Benjamin Herrenschmidt
2009-10-05 22:00 ` Joakim Tjernlund
2009-10-05 22:09 ` Benjamin Herrenschmidt
2009-10-05 22:55 ` Joakim Tjernlund
2009-10-05 23:15 ` Benjamin Herrenschmidt
2009-10-05 23:35 ` Joakim Tjernlund
2009-10-06 0:34 ` Benjamin Herrenschmidt
2009-10-06 6:15 ` Joakim Tjernlund
2009-10-06 6:45 ` Benjamin Herrenschmidt
2009-10-06 7:54 ` Joakim Tjernlund
2009-10-06 15:40 ` Joakim Tjernlund
2009-10-06 17:28 ` Joakim Tjernlund
2009-10-06 22:05 ` Joakim Tjernlund
2009-10-06 23:25 ` Benjamin Herrenschmidt
2009-10-07 1:07 ` Benjamin Herrenschmidt
2009-10-07 7:47 ` Joakim Tjernlund
2009-10-05 18:12 ` [PATCH 0/6] PowerPc 8xx TLB/MMU fixes Scott Wood
2009-10-05 18:27 ` Joakim Tjernlund
2009-10-05 20:09 ` Scott Wood
2009-10-05 21:04 ` Joakim Tjernlund
2009-10-05 21:31 ` Benjamin Herrenschmidt
2009-10-05 21:41 ` Joakim Tjernlund
2009-10-05 21:46 ` Scott Wood
2009-10-05 21:31 ` Scott Wood
2009-10-05 22:04 ` Rex Feany
2009-10-05 22:31 ` Joakim Tjernlund
2009-10-05 22:37 ` Benjamin Herrenschmidt
2009-10-05 22:58 ` Joakim Tjernlund
2009-10-05 23:49 ` Joakim Tjernlund
2009-10-06 1:52 ` Benjamin Herrenschmidt
2009-10-06 8:06 ` Joakim Tjernlund
2009-10-06 8:32 ` Benjamin Herrenschmidt
2009-10-06 10:58 ` Joakim Tjernlund
2009-10-06 11:06 ` Benjamin Herrenschmidt
2009-10-06 11:39 ` Joakim Tjernlund
2009-10-06 13:18 ` Joakim Tjernlund
2009-10-05 22:42 ` Rex Feany
2009-10-05 23:00 ` Joakim Tjernlund
2009-10-06 6:25 ` Joakim Tjernlund
2009-10-06 6:44 ` Benjamin Herrenschmidt [this message]
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