[PATCH] ARM SMP: reallocate main IRQ handler code registers

By changing r9 -> r8 and r8 to 'tsk' (r9) we are able to remove
one instruction from the preempt path.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

1 files changed, 16 insertions, 19 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index b0efbf98d832..8ff82bc75eb1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -144,20 +144,20 @@ __dabt_svc:
 __irq_svc:
         svc_entry irq
 #ifdef CONFIG_PREEMPT
-        get_thread_info r8
-        ldr     r9, [r8, #TI_PREEMPT]           @ get preempt count
-        add     r7, r9, #1                      @ increment it
-        str     r7, [r8, #TI_PREEMPT]
+        get_thread_info tsk
+        ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
+        add     r7, r8, #1                      @ increment it
+        str     r7, [tsk, #TI_PREEMPT]
 #endif
         irq_handler
 #ifdef CONFIG_PREEMPT
-        ldr     r0, [r8, #TI_FLAGS]             @ get flags
+        ldr     r0, [tsk, #TI_FLAGS]            @ get flags
         tst     r0, #_TIF_NEED_RESCHED
         blne    svc_preempt
 preempt_return:
-        ldr     r0, [r8, #TI_PREEMPT]           @ read preempt value
+        ldr     r0, [tsk, #TI_PREEMPT]          @ read preempt value
+        str     r8, [tsk, #TI_PREEMPT]          @ restore preempt count
         teq     r0, r7
-        str     r9, [r8, #TI_PREEMPT]           @ restore preempt count
         strne   r0, [r0, -r0]                   @ bug()
 #endif
         ldr     r0, [sp, #S_PSR]                @ irqs are already disabled
@@ -168,7 +168,7 @@ preempt_return:
 
 #ifdef CONFIG_PREEMPT
 svc_preempt:
-        teq     r9, #0                          @ was preempt count = 0
+        teq     r8, #0                          @ was preempt count = 0
         ldreq   r6, .LCirq_stat
         movne   pc, lr                          @ no
         ldr     r0, [r6, #4]                    @ local_irq_count
@@ -176,9 +176,9 @@ svc_preempt:
         adds    r0, r0, r1
         movne   pc, lr
         mov     r7, #0                          @ preempt_schedule_irq
-        str     r7, [r8, #TI_PREEMPT]           @ expects preempt_count == 0
+        str     r7, [tsk, #TI_PREEMPT]          @ expects preempt_count == 0
 1:      bl      preempt_schedule_irq            @ irq en/disable is done inside
-        ldr     r0, [r8, #TI_FLAGS]             @ get new tasks TI_FLAGS
+        ldr     r0, [tsk, #TI_FLAGS]            @ get new tasks TI_FLAGS
         tst     r0, #_TIF_NEED_RESCHED
         beq     preempt_return                  @ go again
         b       1b
@@ -338,21 +338,18 @@ __dabt_usr:
 __irq_usr:
         usr_entry irq
 
+        get_thread_info tsk
 #ifdef CONFIG_PREEMPT
-        get_thread_info r8
-        ldr     r9, [r8, #TI_PREEMPT]           @ get preempt count
-        add     r7, r9, #1                      @ increment it
-        str     r7, [r8, #TI_PREEMPT]
+        ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
+        add     r7, r8, #1                      @ increment it
+        str     r7, [tsk, #TI_PREEMPT]
 #endif
         irq_handler
 #ifdef CONFIG_PREEMPT
-        ldr     r0, [r8, #TI_PREEMPT]
+        ldr     r0, [tsk, #TI_PREEMPT]
+        str     r8, [tsk, #TI_PREEMPT]
         teq     r0, r7
-        str     r9, [r8, #TI_PREEMPT]
         strne   r0, [r0, -r0]
-        mov     tsk, r8
-#else
-        get_thread_info tsk
 #endif
         mov     why, #0
         b       ret_to_user