s390/diag: add tracepoint for diagnose calls

To be able to analyse problems in regard to hypervisor overhead
add a tracepoing for diagnose calls. It reports the number of
the diagnose issued, e.g.

            sshd-1385  [002] ....    42.701431: diagnose: nr=0x9c
          <idle>-0     [001] ..s.    43.587528: diagnose: nr=0x9c

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

4 files changed, 53 insertions, 4 deletions

diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index b756c6348ac6..dc167a23b920 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -66,6 +66,8 @@ obj-$(CONFIG_UPROBES)		+= uprobes.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf.o perf_cpum_sf.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf_events.o
 
+obj-$(CONFIG_TRACEPOINTS)	+= trace.o
+
 # vdso
 obj-y				+= vdso64/
 obj-$(CONFIG_COMPAT)		+= vdso32/
diff --git a/arch/s390/kernel/diag.c b/arch/s390/kernel/diag.c
index 4ddb5200ddf0..f98766ede4e1 100644
--- a/arch/s390/kernel/diag.c
+++ b/arch/s390/kernel/diag.c
@@ -10,9 +10,13 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <asm/diag.h>
+#include <asm/trace/diag.h>
 
-DEFINE_PER_CPU(struct diag_stat, diag_stat);
-EXPORT_PER_CPU_SYMBOL(diag_stat);
+struct diag_stat {
+	unsigned int counter[NR_DIAG_STAT];
+};
+
+static DEFINE_PER_CPU(struct diag_stat, diag_stat);
 
 struct diag_desc {
 	int code;
@@ -114,6 +118,20 @@ static int __init show_diag_stat_init(void)
 
 device_initcall(show_diag_stat_init);
 
+void diag_stat_inc(enum diag_stat_enum nr)
+{
+	this_cpu_inc(diag_stat.counter[nr]);
+	trace_diagnose(diag_map[nr].code);
+}
+EXPORT_SYMBOL(diag_stat_inc);
+
+void diag_stat_inc_norecursion(enum diag_stat_enum nr)
+{
+	this_cpu_inc(diag_stat.counter[nr]);
+	trace_diagnose_norecursion(diag_map[nr].code);
+}
+EXPORT_SYMBOL(diag_stat_inc_norecursion);
+
 /*
  * Diagnose 14: Input spool file manipulation
  */
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index f7db48b61dcf..dbd40d448294 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -377,11 +377,11 @@ int smp_vcpu_scheduled(int cpu)
 void smp_yield_cpu(int cpu)
 {
 	if (MACHINE_HAS_DIAG9C) {
-		diag_stat_inc(DIAG_STAT_X09C);
+		diag_stat_inc_norecursion(DIAG_STAT_X09C);
 		asm volatile("diag %0,0,0x9c"
 			     : : "d" (pcpu_devices[cpu].address));
 	} else if (MACHINE_HAS_DIAG44) {
-		diag_stat_inc(DIAG_STAT_X044);
+		diag_stat_inc_norecursion(DIAG_STAT_X044);
 		asm volatile("diag 0,0,0x44");
 	}
 }
diff --git a/arch/s390/kernel/trace.c b/arch/s390/kernel/trace.c
new file mode 100644
index 000000000000..73239bb576c4
--- /dev/null
+++ b/arch/s390/kernel/trace.c
@@ -0,0 +1,29 @@
+/*
+ * Tracepoint definitions for s390
+ *
+ * Copyright IBM Corp. 2015
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/percpu.h>
+#define CREATE_TRACE_POINTS
+#include <asm/trace/diag.h>
+
+EXPORT_TRACEPOINT_SYMBOL(diagnose);
+
+static DEFINE_PER_CPU(unsigned int, diagnose_trace_depth);
+
+void trace_diagnose_norecursion(int diag_nr)
+{
+	unsigned long flags;
+	unsigned int *depth;
+
+	local_irq_save(flags);
+	depth = this_cpu_ptr(&diagnose_trace_depth);
+	if (*depth == 0) {
+		(*depth)++;
+		trace_diagnose(diag_nr);
+		(*depth)--;
+	}
+	local_irq_restore(flags);
+}