[Xen-changelog] [xen-unstable] [IA64] Fix ia64_swith_to() so that it doesn't check with init_task

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

# HG changeset patch
# User Alex Williamson <alex.williamson@xxxxxx>
# Date 1200596743 25200
# Node ID ed7d55e8cd34d99a79cba597a964784498bf5d1f
# Parent  8909a5717cd7eca27b36b7dd54b1cb10e59cd0c2
[IA64] Fix ia64_swith_to() so that it doesn't check with init_task

init_task isn't used directly so that comparison with init_task in
ia64_switch_to() is pointless. Remove the comparison.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 xen/arch/ia64/linux-xen/entry.S |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletion(-)

diff -r 8909a5717cd7 -r ed7d55e8cd34 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
@@ -194,13 +194,13 @@ GLOBAL_ENTRY(ia64_switch_to)
        .body
 
        adds r22=IA64_TASK_THREAD_KSP_OFFSET,r13
-       movl r25=init_task
 #ifdef XEN
        movl r27=THIS_CPU(cpu_kr)+IA64_KR_CURRENT_STACK_OFFSET;;
        ld8 r27=[r27]
        adds r21=IA64_TASK_THREAD_KSP_OFFSET,in0
        dep r20=0,in0,60,4              // physical address of "next"
 #else
+       movl r25=init_task
        mov r27=IA64_KR(CURRENT_STACK)
        adds r21=IA64_TASK_THREAD_KSP_OFFSET,in0
        dep r20=0,in0,61,3              // physical address of "next"
@@ -208,6 +208,14 @@ GLOBAL_ENTRY(ia64_switch_to)
        ;;
        st8 [r22]=sp                    // save kernel stack pointer of old task
        shr.u r26=r20,IA64_GRANULE_SHIFT
+#ifdef XEN
+       ;;
+       /*
+        * If we've already mapped this task's page, we can skip doing it again.
+        */
+       cmp.eq p7,p6=r26,r27
+       br.cond.dpnt .map
+#else  
        cmp.eq p7,p6=r25,in0
        ;;
        /*
@@ -215,6 +223,7 @@ GLOBAL_ENTRY(ia64_switch_to)
         */
 (p6)   cmp.eq p7,p6=r26,r27
 (p6)   br.cond.dpnt .map
+#endif 
        ;;
 .done:
 (p6)   ssm psr.ic                      // if we had to map, reenable the 
psr.ic bit FIRST!!!

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