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Date: Fri, 16 Apr 2004 01:04:13 -0500
From: "Alan L. Cox" <alc@imimic.com>
Organization: iMimic Networking, Inc.
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To: Kris Kennaway <kris@obsecurity.org>
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cc: alc@FreeBSD.org
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cc: Alan Cox <alc@cs.rice.edu>
cc: Andrew Gallatin <gallatin@cs.duke.edu>
Subject: Re: Another alpha panic
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Kris Kennaway wrote:
> 
> Dump of assembler code for function pmap_activate:
> 0xfffffc00005cf0b0 <pmap_activate>:     ldah    gp,14(t12)
...
> 0xfffffc00005cf160 <pmap_activate+176>: srl     t1,0xd,t1
> 0xfffffc00005cf164 <pmap_activate+180>: stq     t1,16(t2)
...
I believe that the shift right is the "... >> PAGE_SHIFT" in

     td->td_pcb->pcb_hw.apcb_ptbr =
         ALPHA_K0SEG_TO_PHYS((vm_offset_t) pmap->pm_lev1) >> PAGE_SHIFT;

and the store quad is dereferencing "td->td_pcb".  In other words, 
td->td_pcb points to never-never land.

Alan