Re: __copy_user exception handling

From: Matt Chapman <matthewc_at_hp.com>
Date: 2005-07-30 09:33:58
On Fri, Jul 29, 2005 at 04:23:33PM -0700, Chen, Kenneth W wrote:
> 
> Because exception handler use to work at instruction bundle granularity.
> The first EX would automatically catch the 2nd ld8 or st8, with a caveat
> that this code is assuming gcc 2.x tool chain.  With moving to gcc 3.x
> assembler where it understand local tag support, the exception handler
> works at instruction granularity and then all the sudden, it falls flat
> on its face.

Ah right.

> Are you sure you want to use this code?  It's for first incarnation of
> Itanium.  The kernel has an optimized version of copy_user for Itanium2.
> See memcpy_mck.S

Aha, thank you!  That explains why I can't trigger that bug in Linux
on Itanium 2.  I'll make Xen use the memcpy_mck.S version.

Matt
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Received on Fri Jul 29 19:40:45 2005

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