From: Scott Wood <scottwood@freescale•com>
To: Jia Hongtao-B38951 <B38951@freescale•com>
Cc: Wood Scott-B07421 <B07421@freescale•com>,
David Laight <David.Laight@ACULAB•COM>,
"linuxppc-dev@lists•ozlabs.org" <linuxppc-dev@lists•ozlabs.org>,
Stuart Yoder <b08248@gmail•com>
Subject: Re: [PATCH V4] powerpc/85xx: Add machine check handler to fix PCIe erratum on mpc85xx
Date: Thu, 7 Mar 2013 10:37:47 -0600 [thread overview]
Message-ID: <1362674267.23227.1@snotra> (raw)
In-Reply-To: <412C8208B4A0464FA894C5F0C278CD5D01BFA1D0@039-SN1MPN1-002.039d.mgd.msft.net> (from B38951@freescale.com on Thu Mar 7 02:06:05 2013)
On 03/07/2013 02:06:05 AM, Jia Hongtao-B38951 wrote:
> Here is the ideas from Scott:
> "
> > + if (is_in_pci_mem_space(addr)) {
> > + inst =3D *(unsigned int *)regs->nip;
>=20
> Be careful about taking a fault here. A simple TLB miss should be =20
> safe
> given that we shouldn't be accessing PCIe in the middle of exception
> code, but what if the mapping has gone away (e.g. a userspace driver =20
> had
> its code munmap()ed or swapped out)? What if permissions allow =20
> execute
> but not read (not sure if Linux will allow this, but the hardware =20
> does)?
>=20
> What if it happened in a KVM guest? You can't access guest addresses
> directly.
> "
That means you need to be careful about how you read the instruction, =20
not that you shouldn't do it at all.
-Scott=
next prev parent reply other threads:[~2013-03-07 16:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-04 8:40 [PATCH V4] powerpc/85xx: Add machine check handler to fix PCIe erratum on mpc85xx Jia Hongtao
2013-03-04 16:16 ` Stuart Yoder
2013-03-04 23:45 ` Scott Wood
2013-03-05 10:12 ` Jia Hongtao-B38951
2013-03-05 18:47 ` Scott Wood
2013-03-06 8:28 ` Jia Hongtao-B38951
2013-03-06 10:24 ` David Laight
2013-03-07 8:06 ` Jia Hongtao-B38951
2013-03-07 10:04 ` David Laight
2013-03-07 16:37 ` Scott Wood [this message]
2013-03-08 8:01 ` Jia Hongtao-B38951
2013-03-09 0:49 ` Scott Wood
2013-03-12 7:40 ` Jia Hongtao-B38951
2013-03-12 9:47 ` David Laight
2013-03-12 21:24 ` Scott Wood
2013-03-13 9:40 ` David Laight
2013-03-13 16:37 ` Scott Wood
2013-03-15 2:47 ` Jia Hongtao-B38951
2013-03-15 16:34 ` Scott Wood
2013-03-29 8:03 ` Jia Hongtao-B38951
2013-03-29 16:33 ` Scott Wood
2013-04-02 9:28 ` Jia Hongtao-B38951
2013-04-02 19:46 ` Scott Wood
2013-03-04 17:15 ` David Laight
2013-03-05 10:12 ` Jia Hongtao-B38951
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