[IA64] Schedule fp-clearing insns at least 6 cycles after reading ar.bsp.

Decreases syscall overhead by approximately 6 cycles.

Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 15 insertions, 10 deletions

diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index c0f28339d58..0c84bed1bda 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -705,15 +705,15 @@ ENTRY(ia64_leave_syscall)
         // start restoring the state saved on the kernel stack (struct pt_regs):
         ld8 r9=[r2],PT(CR_IPSR)-PT(R9)
         ld8 r11=[r3],PT(CR_IIP)-PT(R11)
-        mov f6=f0               // clear f6
+        nop.i 0
         ;;
         invala                  // M0|1 invalidate ALAT
         rsm psr.i | psr.ic      // M2 initiate turning off of interrupt and interruption collection
-        mov f9=f0               // clear f9
+        nop.i 0
 
         ld8 r29=[r2],16         // load cr.ipsr
         ld8 r28=[r3],16                 // load cr.iip
-        mov f8=f0               // clear f8
+        mov r22=r0              // clear r22
         ;;
         ld8 r30=[r2],16         // M0|1 load cr.ifs
         ld8 r25=[r3],16         // M0|1 load ar.unat
@@ -721,15 +721,15 @@ ENTRY(ia64_leave_syscall)
         ;;
         ld8 r26=[r2],PT(B0)-PT(AR_PFS)  // M0|1 load ar.pfs
 (pKStk) mov r22=psr             // M2 read PSR now that interrupts are disabled
-        mov f10=f0              // clear f10
+(pUStk) add r14=IA64_TASK_THREAD_ON_USTACK_OFFSET,r13
         ;;
         ld8 r21=[r2],PT(AR_RNAT)-PT(B0) // load b0
         ld8 r27=[r3],PT(PR)-PT(AR_RSC)  // load ar.rsc
-        mov f11=f0              // clear f11
+        mov f6=f0               // clear f6
         ;;
         ld8 r24=[r2],PT(AR_FPSR)-PT(AR_RNAT)    // load ar.rnat (may be garbage)
         ld8 r31=[r3],PT(R1)-PT(PR)              // load predicates
-(pUStk) add r14=IA64_TASK_THREAD_ON_USTACK_OFFSET,r13
+        mov f7=f0               // clear f7
         ;;
         ld8 r20=[r2],PT(R12)-PT(AR_FPSR)        // load ar.fpsr
         ld8.fill r1=[r3],16     // load r1
@@ -737,24 +737,29 @@ ENTRY(ia64_leave_syscall)
         ;;
         srlz.d                  // M0  ensure interruption collection is off
         ld8.fill r13=[r3],16
-        mov f7=f0               // clear f7
+        mov f8=f0               // clear f8
         ;;
         ld8.fill r12=[r2]       // restore r12 (sp)
         mov.m ar.ssd=r0         // M2 clear ar.ssd
-        mov r22=r0              // clear r22
+        mov b6=r18              // I0  restore b6
 
+        nop.m 0
+        mov f9=f0               // clear f9
+        shr.u r18=r19,16        // I0|1 get byte size of existing "dirty" partition
+        ;;
         ld8.fill r15=[r3]       // restore r15
 (pUStk) st1 [r14]=r17
         addl r3=THIS_CPU(ia64_phys_stacked_size_p8),r0
         ;;
 (pUStk) ld4 r17=[r3]            // r17 = cpu_data->phys_stacked_size_p8
         mov.m ar.csd=r0         // M2 clear ar.csd
-        mov b6=r18              // I0  restore b6
+        mov f10=f0              // clear f10
         ;;
         mov r14=r0              // clear r14
-        shr.u r18=r19,16        // I0|1 get byte size of existing "dirty" partition
+        mov f11=f0              // clear f11
 (pKStk) br.cond.dpnt.many skip_rbs_switch
 
+
         mov.m ar.ccv=r0         // clear ar.ccv
 (pNonSys) br.cond.dpnt.many dont_preserve_current_frame
         br.cond.sptk.many rbs_switch