powerpc/mm: Add trace point for tracking hash pte fault

This enables us to understand how many hash fault we are taking
when running benchmarks.

For ex:
-bash-4.2# ./perf stat -e  powerpc:hash_fault -e page-faults /tmp/ebizzy.ppc64 -S 30  -P -n 1000
...

 Performance counter stats for '/tmp/ebizzy.ppc64 -S 30 -P -n 1000':

       1,10,04,075      powerpc:hash_fault
       1,10,03,429      page-faults

      30.865978991 seconds time elapsed

NOTE:
The impact of the tracepoint was not noticeable when running test. It was
within the run-time variance of the test. For ex:

without-patch:
--------------

 Performance counter stats for './a.out 3000 300':

	       643      page-faults               #    0.089 M/sec
	  7.236562      task-clock (msec)         #    0.928 CPUs utilized
	 2,179,213      stalled-cycles-frontend   #    0.00% frontend cycles idle
	17,174,367      stalled-cycles-backend    #    0.00% backend  cycles idle
		 0      context-switches          #    0.000 K/sec

       0.007794658 seconds time elapsed

And with-patch:
---------------

 Performance counter stats for './a.out 3000 300':

	       643      page-faults               #    0.089 M/sec
	  7.233746      task-clock (msec)         #    0.921 CPUs utilized
		 0      context-switches          #    0.000 K/sec

       0.007854876 seconds time elapsed

 Performance counter stats for './a.out 3000 300':

	       643      page-faults               #    0.087 M/sec
	       649      powerpc:hash_fault        #    0.087 M/sec
	  7.430376      task-clock (msec)         #    0.938 CPUs utilized
	 2,347,174      stalled-cycles-frontend   #    0.00% frontend cycles idle
	17,524,282      stalled-cycles-backend    #    0.00% backend  cycles idle
		 0      context-switches          #    0.000 K/sec

       0.007920284 seconds time elapsed

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h
index c15da6073cb8b..8e86b48d03699 100644
--- a/arch/powerpc/include/asm/trace.h
+++ b/arch/powerpc/include/asm/trace.h
@@ -144,6 +144,26 @@ TRACE_EVENT_FN(opal_exit,
 );
 #endif
 
+TRACE_EVENT(hash_fault,
+
+	    TP_PROTO(unsigned long addr, unsigned long access, unsigned long trap),
+	    TP_ARGS(addr, access, trap),
+	    TP_STRUCT__entry(
+		    __field(unsigned long, addr)
+		    __field(unsigned long, access)
+		    __field(unsigned long, trap)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->addr = addr;
+		    __entry->access = access;
+		    __entry->trap = trap;
+		    ),
+
+	    TP_printk("hash fault with addr 0x%lx and access = 0x%lx trap = 0x%lx",
+		      __entry->addr, __entry->access, __entry->trap)
+);
+
 #endif /* _TRACE_POWERPC_H */
 
 #undef TRACE_INCLUDE_PATH