Re: [PATCH] Mutilated form of Andi Kleen's AMD prefetch errata patch
From: Andi Kleen
Date: Wed Oct 01 2003 - 03:01:49 EST
On Wed, Oct 01, 2003 at 08:55:51AM +0100, Jamie Lokier wrote:
> Andi Kleen wrote:
> > Jamie Lokier <jamie@xxxxxxxxxxxxx> writes:
> > > It is easy enough to fix by making the fault handler not take
> > > mmap_sem if the fault's in the kernel address range. (With apologies
> > > to the folk running kernel mode userspace...)
> > It won't work because kernel can cause user space faults
> > (think get_user). And handling these must be protected.
> Are we mis-communicating? By "fault in the kernel address range", I
Yep, we were. I read it as "instruction faulting is in kernel range"
(aka you check the ring0 bit in the error_code), not checking cr2 >= TASK_SIZE.
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