RE: [Linux-ia64] Kernel panic in dtlb_fault

["Mallick, Asit K" <asit.k.mallick@intel.com>]

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This is a patch that fixes the VHPT disabled kernel problems. Uros has
verified this and it is at the same level as VHPT enabled kernel on B3.

Thanks,
Asit


> -----Original Message-----
> From: Uros Prestor [mailto:uros@turbolinux.com]
> Sent: Friday, January 12, 2001 11:37 AM
> To: Mallick, Asit K
> Cc: linux-ia64@linuxia64.org
> Subject: Re: [Linux-ia64] Kernel panic in dtlb_fault
> 
> 
> "Mallick, Asit K" wrote:
> 
> > Attached is a patch to fix the problem. Uros and Jenna were 
> able to boot
> > with this patch. Sorry for sending the early version.
> 
> Something is still not kosher if you enable 
> CONFIG_DISABLE_VHPT=y.  If I try
> recompiling the gnupro RPM the compilation breaks down 
> immediately after the
> config stage With the following error:
> 
>      # rpm -ba /usr/src/turbo/SPECS/gnupro.spec
>      ...
>      creating ./config.status
>      creating Makefile
>      Configuring utils...
>      Created "Makefile" in /work/BUILD/gnupro-2.96/build/utils
>      Configuring spu...
>      Created "Makefile" in /work/BUILD/gnupro-2.96/build/utils/spu
>      ++ perl -e 'if( -x "/usr/bin/getconf" &&  ( ($p=`/usr/bin/getconf
>      _NPROCESSORS_ONLN`) >= 0 ) ){ print "$p"} else { print "1"; }'
>      + make -j 2
>      /bin/sh: SHELL: command not found
>      /bin/sh: -c: command not found
>      make: *** [all-libiberty] Error 127
>      make: *** Waiting for unfinished jobs....
>      Bad exit status from /var/tmp/rpm-tmp.82077 (%build)
> 
> Things become very bizarre if you try to compile by hand, ranging from
> reports of missing /lib/libc.so.6.1 to internal compiler 
> errors...  This
> happens both on 2xB3 BigSur and 4xB3 Lion.  If I revert to 
> the kernel which
> enables VHPT the compilation goes just fine.
> 
> Uros
> 
> --
> Uros Prestor
> uros@turbolinux.com
> 
> 
> 
> 
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> Linux-IA64 mailing list
> Linux-IA64@linuxia64.org
> http://lists.linuxia64.org/lists/listinfo/linux-ia64
> 


[-- Attachment #2: ivt.diff --]
[-- Type: application/octet-stream, Size: 2207 bytes --]

--- linux-2.4.0/arch/ia64/kernel/ivt.S	Tue Jan  9 03:48:36 2001
+++ linux/arch/ia64/kernel/ivt.S	Fri Jan 12 04:47:05 2001
@@ -184,15 +184,16 @@
 	 * mode, walk the page table, and then re-execute the L3 PTE read
 	 * and go on normally after that.
 	 */
-itlb_fault:
 	mov r16=cr.ifa				// get virtual address
 	mov r29=b0				// save b0
 	mov r31=pr				// save predicates
+itlb_fault:
 	mov r17=cr.iha				// get virtual address of L3 PTE
 	movl r30=1f				// load nested fault continuation point
 	;;
 1:	ld8 r18=[r17]				// read L3 PTE
 	;;
+	mov b0=r29
 	tbit.z p6,p0=r18,_PAGE_P_BIT		// page present bit cleared?
 (p6)	br.cond.spnt.many page_fault
 	;;
@@ -219,15 +220,16 @@
 	 * mode, walk the page table, and then re-execute the L3 PTE read
 	 * and go on normally after that.
 	 */
-dtlb_fault:
 	mov r16=cr.ifa				// get virtual address
 	mov r29=b0				// save b0
 	mov r31=pr				// save predicates
+dtlb_fault:
 	mov r17=cr.iha				// get virtual address of L3 PTE
 	movl r30=1f				// load nested fault continuation point
 	;;
 1:	ld8 r18=[r17]				// read L3 PTE
 	;;
+	mov b0=r29
 	tbit.z p6,p0=r18,_PAGE_P_BIT		// page present bit cleared?
 (p6)	br.cond.spnt.many page_fault
 	;;
@@ -261,6 +263,7 @@
 (p8)	thash r17=r16
 	;;
 (p8)	mov cr.iha=r17
+(p8)	mov r29=b0				// save b0
 (p8)	br.cond.dptk.many itlb_fault
 #endif
 	extr.u r23=r21,IA64_PSR_CPL0_BIT,2	// extract psr.cpl
@@ -296,6 +299,7 @@
 (p8)	thash r17=r16
 	;;
 (p8)	mov cr.iha=r17
+(p8)	mov r29=b0				// save b0
 (p8)	br.cond.dptk.many dtlb_fault
 #endif
 	extr.u r23=r21,IA64_PSR_CPL0_BIT,2	// extract psr.cpl
@@ -399,7 +403,6 @@
 	shr.u r18=r16,PMD_SHIFT			// shift L2 index into position
 	;;
 	ld8 r17=[r17]				// fetch the L1 entry (may be 0)
-	mov b0=r30
 	;;
 (p7)	cmp.eq p6,p7=r17,r0			// was L1 entry NULL?
 	dep r17=r18,r17,3,(PAGE_SHIFT-3)	// compute address of L2 page table entry
@@ -409,8 +412,8 @@
 	;;
 (p7)	cmp.eq.or.andcm p6,p7=r17,r0		// was L2 entry NULL?
 	dep r17=r19,r17,3,(PAGE_SHIFT-3)	// compute address of L3 page table entry
-	;;
 (p6)	br.cond.spnt.many page_fault
+	mov b0=r30
 	br.sptk.many b0				// return to continuation point
 	;;