general protection fault on boot.

[Kostik Belousov]

On Wed, Sep 09, 2009 at 01:38:59PM -0400, John Baldwin wrote:
> On Wednesday 09 September 2009 12:32:51 pm Vincent Hoffman wrote:
> > Hi all,
> >           I've been running the 8.0-BETAs in a xen virtual machine
> > (hvm/fully virtualised) for testing and something between r196730 and
> > r196746 causes a general protection fault on boot. I'll try and narrow
> > it down if i get a chance but I'm a a bit busy at the moment.
> >  
> > backtrace is available at
> > http://unsane.co.uk/~jhary/freebsd/GPF-09-09-09.gif 
> > Xen dom0 is a centos5.3 box using the xen-3.3.1 rpms from
> > http://www.gitco.de/linux/i386/centos/5/rpms/  if thats of any use.
> > 
> > Let me know if I need to provide any more info.
> 
> Hmm, can you try reverting 196737?  Or actually, can you print out the value 
> of %ebx ('p $ebx' in ddb will work I think)?  I wonder if this patch would 
> fix it:
> 
> Index: pmap.c
> ===================================================================
> --- pmap.c	(revision 196974)
> +++ pmap.c	(working copy)
> @@ -999,7 +999,7 @@
>  		 * coherence domain.
>  		 */
>  		mfence();
> -		for (; sva < eva; sva += cpu_clflush_line_size)
> +		for (; sva <= eva; sva += cpu_clflush_line_size)
>  			clflush(sva);
>  		mfence();
>  	} else {

Oh, no, another pointy hat to me :(.

Please, try this patch instead.

diff --git a/sys/i386/xen/pmap.c b/sys/i386/xen/pmap.c
index 4b81aae..122318c 100644
--- a/sys/i386/xen/pmap.c
+++ b/sys/i386/xen/pmap.c
@@ -1004,8 +1004,8 @@ pmap_invalidate_cache_range(vm_offset_t sva, vm_offset_t eva)
 		 * coherence domain.
 		 */
 		mfence();
-		for (; eva < sva; eva += cpu_clflush_line_size)
-			clflush(eva);
+		for (; sva < eva; sva += cpu_clflush_line_size)
+			clflush(sva);
 		mfence();
 	} else {
 
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