[Xen-changelog] [xen-unstable] [IA64] Fix ia64_switch_to() so that it checks overlap with xenheap.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Alex Williamson <alex.williamson@xxxxxx>
# Date 1200596743 25200
# Node ID fb47d7f0d84b1b1fdb1ef344130e2b7cd4a6a09b
# Parent  ed7d55e8cd34d99a79cba597a964784498bf5d1f
[IA64] Fix ia64_switch_to() so that it checks overlap with xenheap.

- Remove unncessary movl if possible
- Fix overlapping check
- re-add #ifdef XEN.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 xen/arch/ia64/linux-xen/entry.S |   66 ++++++++++++++++++++++++++--------------
 1 files changed, 43 insertions(+), 23 deletions(-)

diff -r ed7d55e8cd34 -r fb47d7f0d84b xen/arch/ia64/linux-xen/entry.S
--- a/xen/arch/ia64/linux-xen/entry.S   Thu Jan 17 12:05:43 2008 -0700
+++ b/xen/arch/ia64/linux-xen/entry.S   Thu Jan 17 12:05:43 2008 -0700
@@ -195,8 +195,8 @@ GLOBAL_ENTRY(ia64_switch_to)
 
        adds r22=IA64_TASK_THREAD_KSP_OFFSET,r13
 #ifdef XEN
-       movl r27=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET;;
-       ld8 r27=[r27]
+       movl r24=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET;;
+       ld8 r27=[r24]
        adds r21=IA64_TASK_THREAD_KSP_OFFSET,in0
        dep r20=0,in0,60,4              // physical address of "next"
 #else
@@ -231,12 +231,9 @@ GLOBAL_ENTRY(ia64_switch_to)
 (p6)   srlz.d
        ld8 sp=[r21]                    // load kernel stack pointer of new task
 #ifdef XEN
-       movl r8=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_OFFSET;;
-       st8 [r8]=in0
-#else
-       mov IA64_KR(CURRENT)=in0        // update "current" application register
-#endif
-#ifdef XEN          //for VTI domain current is save to 21 of bank0
+       add r25=IA64_KR_CURRENT_OFFSET-IA64_KR_CURRENT_STACK_OFFSET,r24
+       ;;
+       st8 [r25]=in0                   // update "current" application register
        ;;
        bsw.0
        ;;
@@ -247,6 +244,7 @@ GLOBAL_ENTRY(ia64_switch_to)
        bsw.1
        ;;
 #else
+       mov IA64_KR(CURRENT)=in0        // update "current" application register
        mov r8=r13          // return pointer to previously running task
        mov r13=in0         // set "current" pointer
 #endif
@@ -259,33 +257,55 @@ GLOBAL_ENTRY(ia64_switch_to)
 
 .map:
 #ifdef XEN
-       // avoid overlapping with kernel TR
-       movl r25=KERNEL_START
-       dep  r23=0,in0,0,KERNEL_TR_PAGE_SHIFT
-       ;;
-       cmp.eq p7,p0=r25,r23
-       ;;
-(p7)   movl r8=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET;;
-(p7)   st8 [r8]=r26
+       // in0: next in virtual address which must be in 
+       //      the xen identity mapping area.
+       // r20: physical address of next
+       // r22: ksp offset: used: don't overwrite. will be used later
+       // r24: = THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET
+       // r26: (physical address of next) >> IA64_GRANULE_SHIFT
+       //
+       // r8: return value
+       // r13:  thread pointer
+       // r21:  thread pointer for VTi domain ??? can be removed?
+       
+       // avoid overlapping with xenheap TR
+       mov r28=ip                      // get kernel tr area
+       ;;
+       tpa r27=r28                     // convert to physical address
+       ;;
+       dep r25=0,r27,0,KERNEL_TR_PAGE_SHIFT
+       dep r23=0,r20,0,KERNEL_TR_PAGE_SHIFT
+       ;;
+       cmp.eq p7,p6=r25,r23
+       mov r28=-1
+       ;;
+(p7)   st8 [r24]=r28                   // remember we don't map stack.
 (p7)   br.cond.sptk .done
+       ;;
 #endif
        rsm psr.ic                      // interrupts (psr.i) are already 
disabled here
        movl r25=PAGE_KERNEL
-       movl r26 = IA64_GRANULE_SHIFT << 2
+#ifdef XEN     
+       movl r27=IA64_GRANULE_SHIFT << 2
+#endif
        ;;
        srlz.d
        or r23=r25,r20                  // construct PA | page properties
-       ptr.d in0, r26                  // to purge dtr[IA64_TR_VHPT]
-       ;;
-       mov cr.itir=r26
+#ifdef XEN
+       ptr.d in0,r27                   // to purge dtr[IA64_TR_VHPT]
+#else
+       movl r27=IA64_GRANULE_SHIFT << 2        
+#endif
+       ;;
+       mov cr.itir=r27
        mov cr.ifa=in0                  // VA of next task...
+#ifdef XEN
        srlz.d
+#endif
        ;;
        mov r25=IA64_TR_CURRENT_STACK
 #ifdef XEN
-       movl r8=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET;;
-       st8 [r8]=r26
-       
+       st8 [r24]=r26                   // remember last page we mapped...
 #else
        mov IA64_KR(CURRENT_STACK)=r26  // remember last page we mapped...
 #endif

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