csky: add page fault perf event support

This patch add support for page fault count, major fault count
and minorfault count. Without this patch page faults are not
sampled for perf event.

Performance counter stats for '/usr/lib/perf-test/callchain_test':
	0      page-faults               #    0.000 K/sec
Signed-off-by: Mao Han <han_mao@c-sky.com>
Signed-off-by: Guo Ren <ren_guo@c-sky.com>

arch/csky/mm/fault.c

@@ -17,6 +17,7 @@
 #include <linux/vt_kern.h>
 #include <linux/extable.h>
 #include <linux/uaccess.h>
+#include <linux/perf_event.h>
 
 #include <asm/hardirq.h>
 #include <asm/mmu_context.h>
@@ -106,6 +107,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
 		return;
 	}
 #endif
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 	/*
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
@@ -153,10 +156,15 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
 			goto bad_area;
 		BUG();
 	}
-	if (fault & VM_FAULT_MAJOR)
+	if (fault & VM_FAULT_MAJOR) {
 		tsk->maj_flt++;
-	else
+		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
+			      address);
+	} else {
 		tsk->min_flt++;
+		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
+			      address);
+	}
 
 	up_read(&mm->mmap_sem);
 	return;