sparc64: Implement a real set_perf_counter_pending().

When the perf counter subsystem needs to reschedule work out
from an NMI, it invokes set_perf_counter_pending().

This triggers a non-NMI irq which should invoke
perf_counter_do_pending().

Currently this won't trigger because sparc64 won't trigger
the perf counter subsystem from NMIs, but when the HW counter
support is added it will.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/include/asm/perf_counter.h

 #ifndef __ASM_SPARC_PERF_COUNTER_H
 #define __ASM_SPARC_PERF_COUNTER_H
 
-static inline void set_perf_counter_pending(void) { }
+extern void set_perf_counter_pending(void);
 
 #define	PERF_COUNTER_INDEX_OFFSET	0
 

arch/sparc/kernel/pcr.c

@@ -7,6 +7,8 @@
 #include <linux/init.h>
 #include <linux/irq.h>
 
+#include <linux/perf_counter.h>
+
 #include <asm/pil.h>
 #include <asm/pcr.h>
 #include <asm/nmi.h>
@@ -34,10 +36,20 @@ unsigned int picl_shift;
  */
 void deferred_pcr_work_irq(int irq, struct pt_regs *regs)
 {
+	struct pt_regs *old_regs;
+
 	clear_softint(1 << PIL_DEFERRED_PCR_WORK);
+
+	old_regs = set_irq_regs(regs);
+	irq_enter();
+#ifdef CONFIG_PERF_COUNTERS
+	perf_counter_do_pending();
+#endif
+	irq_exit();
+	set_irq_regs(old_regs);
 }
 
-void schedule_deferred_pcr_work(void)
+void set_perf_counter_pending(void)
 {
 	set_softint(1 << PIL_DEFERRED_PCR_WORK);
 }