-----Original Message-----
From: Wood Scott-B07421
Sent: Thursday, March 14, 2013 12:38 AM
To: David Laight
Cc: Jia Hongtao-B38951; Wood Scott-B07421; linuxppc-dev@lists.ozlabs.org;
Stuart Yoder
Subject: Re: [PATCH V4] powerpc/85xx: Add machine check handler to fix
PCIe erratum on mpc85xx
=20
On 03/13/2013 04:40:40 AM, David Laight wrote:

quoted

quoted

Hmm, seems there's no probe_user_address() -- for userspace we
basically want the same thing minus the KERNEL_DS.  See
arch/powerpc/perf/callchain.c for an example.

Isn't that just copy_from_user() ?

=20
Plus pagefault_disable/enable().
=20
-Scott

pagefault_disable() is identical to preempt_disable(). So I think this
could not avoid other cpu to swap out the instruction we want to read back.
probe_kernel_address() also have the same issue.

Does this mean we can't just use pagefault_disable() to prevent from gettin=
g
the wrong instruction?

-Hongtao.