From: Ian Munsie <imunsie@au1.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: "andrew.donnellan" <andrew.donnellan@au1.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: cxl: fix setting of _PAGE_USER bit when handling page faults
Date: Fri, 25 Mar 2016 12:15:49 -0500 [thread overview]
Message-ID: <1458925788-sup-2032@x230.ozlabs.ibm.com> (raw)
In-Reply-To: <3qWf364wYxz9sDG@ozlabs.org>
Excerpts from Michael Ellerman's message of 2016-03-25 05:01:38 -0500:
> I think you can (should) use is_kernel_addr() for the DAR check.
>
> I'm also slightly worried by that logic in the case of a non-kernel context.
>
> ie. if ctx->kernel is false, we get:
>
> if (true || !is_kernel_addr(dar))
> access |= _PAGE_USER;
>
> Which means we just add _PAGE_USER for any address. What am I missing here?
It's been ages since I did a deep dive on the related mm code, so I
don't recall the precise details so take this with a grain of salt, but
if memory serves the call to copro_handle_mm_fault will fail if a user
is trying to access a kernel region since it won't be mapped in the mm.
-Ian
next prev parent reply other threads:[~2016-03-25 17:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-18 4:01 [PATCH] cxl: fix setting of _PAGE_USER bit when handling page faults Andrew Donnellan
2016-03-18 6:30 ` Ian Munsie
2016-03-21 4:38 ` Andrew Donnellan
2016-03-25 10:01 ` Michael Ellerman
2016-03-25 17:15 ` Ian Munsie [this message]
2016-03-28 13:42 ` Aneesh Kumar K.V
2016-03-28 18:00 ` Aneesh Kumar K.V
2016-04-11 4:10 ` Andrew Donnellan
2016-04-11 4:27 ` Michael Ellerman
2016-04-11 4:31 ` Aneesh Kumar K.V
2016-04-11 11:14 ` Michael Ellerman
2016-04-11 13:42 ` Aneesh Kumar K.V
2016-04-12 11:42 ` Michael Ellerman
2016-03-29 22:08 ` [PATCH] " Matthew R. Ochs
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