Date: Wed, 22 Jan 2003 14:23:09 -0800 From: Arun Sharma <adsharma@unix-os.sc.intel.com> To: Doug Rabson <dfr@nlsystems.com> Cc: freebsd-ia64@FreeBSD.ORG Subject: Re: cat /proc/pid/map == panic Message-ID: <20030122142309.A15191@unix-os.sc.intel.com> In-Reply-To: <200301221021.29297.dfr@nlsystems.com>; from dfr@nlsystems.com on Wed, Jan 22, 2003 at 10:21:29AM %2B0000 References: <200301220302.h0M323r01126@unix-os.sc.intel.com> <200301221021.29297.dfr@nlsystems.com>
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On Wed, Jan 22, 2003 at 10:21:29AM +0000, Doug Rabson wrote:
> On Wednesday 22 January 2003 3:02 am, Arun Sharma wrote:
> > cat /proc/pid/map results in a page not present fault. The attached
> > patch fixed it for me.
>
> This is going to find the wrong pte, I think. Without the
> pmap_install(pmap), your pmap_find_vhpt will look in the current
> process instead of the target.
That's right. An updated patch is attached.
> Does it work if you just add the check
> for pmap==0 to the old code, i.e. still use pmap_install and tpa to get
> the mapping?
I haven't tried it, but I think in my case pmap was almost certainly
non-zero (the process in question is sshd). Further, cr.iip was pointing
to the tpa instruction when the page not present fault happened. The
problem with ia64_tpa is that it will result in faults. The code in
procfs is trying to count the number of resident pages - so you may not
want to fault more pages in.
A further optimization of this patch may be to just load one region
register instead of loading all of them.
-Arun
--- src/sys/ia64/ia64/pmap.c- Tue Jan 21 17:46:59 2003
+++ src/sys/ia64/ia64/pmap.c Wed Jan 22 11:37:30 2003
@@ -1164,13 +1164,20 @@
register pmap_t pmap;
vm_offset_t va;
{
+ struct ia64_lpte *pte;
pmap_t oldpmap;
- vm_offset_t pa;
+
+ if (!pmap)
+ return 0;
oldpmap = pmap_install(pmap);
- pa = ia64_tpa(va);
+ pte = pmap_find_vhpt(va);
pmap_install(oldpmap);
- return pa;
+
+ if (!pte)
+ return 0;
+
+ return pmap_pte_pa(pte);
}
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