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Subject[PATCH] m68knommu: ColdFire add support for kernel preemption
From: Sebastian Siewior <bigeasy@linutronix.de>

As the subject says this patch adds the support for kernel preemption
on m68knommu Coldfire. I thing the same changes could be applied to
68360 & 68328 but since I don't have the HW for testing, I don't touch it.

Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
---


diff -Naurp linux-2.6.25/arch/m68knommu/kernel/asm-offsets.c linux-2.6.25-uc0/arch/m68knommu/kernel/asm-offsets.c
--- linux-2.6.25/arch/m68knommu/kernel/asm-offsets.c 2008-04-17 12:49:44.000000000 +1000
+++ linux-2.6.25-uc0/arch/m68knommu/kernel/asm-offsets.c 2008-03-28 15:29:06.000000000 +1000
@@ -91,6 +91,7 @@ int main(void)
DEFINE(TI_TASK, offsetof(struct thread_info, task));
DEFINE(TI_EXECDOMAIN, offsetof(struct thread_info, exec_domain));
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
+ DEFINE(TI_PREEMPTCOUNT, offsetof(struct thread_info, preempt_count));
DEFINE(TI_CPU, offsetof(struct thread_info, cpu));

return 0;
diff -Naurp linux-2.6.25/arch/m68knommu/platform/coldfire/entry.S linux-2.6.25-uc0/arch/m68knommu/platform/coldfire/entry.S
--- linux-2.6.25/arch/m68knommu/platform/coldfire/entry.S 2008-04-17 12:49:44.000000000 +1000
+++ linux-2.6.25-uc0/arch/m68knommu/platform/coldfire/entry.S 2008-05-01 11:58:21.000000000 +1000
@@ -106,6 +106,22 @@ ret_from_exception:
btst #5,%sp@(PT_SR) /* check if returning to kernel */
jeq Luser_return /* if so, skip resched, signals */

+#ifdef CONFIG_PREEMPT
+ movel %sp,%d1 /* get thread_info pointer */
+ andl #-THREAD_SIZE,%d1 /* at base of kernel stack */
+ movel %d1,%a0
+ movel %a0@(TI_FLAGS),%d1 /* get thread_info->flags */
+ andl #_TIF_NEED_RESCHED,%d1
+ jeq Lkernel_return
+
+ movel %a0@(TI_PREEMPTCOUNT),%d1
+ cmpl #0,%d1
+ jne Lkernel_return
+
+ pea Lkernel_return
+ jmp preempt_schedule_irq /* preempt the kernel */
+#endif
+
Lkernel_return:
moveml %sp@,%d1-%d5/%a0-%a2
lea %sp@(32),%sp /* space for 8 regs */

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