lkml.org 
[lkml]   [2008]   [Jan]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] x86: mmiotrace - trace memory mapped IO
On Sun, 27 Jan 2008 19:55:36 +0200
Pekka Paalanen <pq@iki.fi> wrote:

> The following is a copy of the patch description:
...
> Mmiotrace works by wrapping the ioremap family of kernel functions and
> marking the returned pages as not present. Access to the IO memory
> triggers a page fault, which will be handled by mmiotrace's custom page
> fault handler. This will single-step the faulted instruction with the
> MMIO page marked as present. Access logs are directed to user space via
> relay and debug_fs.

Hi,

a test user found a problem with mmiotrace (ported to x86/mm git tree).
The symbol 'init_mm' is undefined, but required when building the 32-bit
mmiotrace kernel module.

commit 3abf024d2abb79614d8c4cb25a70d5596f77d0ad
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Wed Jan 30 13:30:28 2008 +0100

x86: nuke a ton of unused exports

This commit removes EXPORT_SYMBOL(init_mm). Apparently mmiotrace requires
this symbol, but I do not know why. I do not use init_mm myself, so
apparently some function I call is inlined and requires it. Page table or
attribute handling stuff maybe?

Is it possible to simply put back this export or should I dig deeper into
why it seems to be required?
I can provide the simple patch to put it back in my next patch set, if
this is the right solution.

I will post the patch set after this issue is solved. In the mean time,
for the interested, the current patches are here:
http://jumi.lut.fi/~paalanen/scratch/mmio25/


Ps. I tested x86/mm version of mmiotrace on my 64-bit system and it seems
to work ok. I had to write a simple test module because I did not have any
drivers that a) called ioremap, b) were not broken on x86/mm, and c) I
had the hardware to actually use it. So this testing is very light.

--
Pekka Paalanen
http://www.iki.fi/pq/


\
 
 \ /
  Last update: 2008-01-30 23:43    [W:0.114 / U:1.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site