diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c
index 38993e09ef03ef371932707058c57bd15dd2d875..deb9eba3a43ddc081fd051976c5904026b0261ee 100644
--- a/arch/sh/kernel/ftrace.c
+++ b/arch/sh/kernel/ftrace.c
@@ -139,7 +139,7 @@ static void ftrace_mod_code(void)
clear_mod_flag();
}
-void ftrace_nmi_enter(void)
+void arch_ftrace_nmi_enter(void)
{
if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
smp_rmb();
@@ -150,7 +150,7 @@ void ftrace_nmi_enter(void)
smp_mb();
}
-void ftrace_nmi_exit(void)
+void arch_ftrace_nmi_exit(void)
{
/* Finish all executions before clearing nmi_running */
smp_mb();
diff --git a/include/linux/ftrace_irq.h b/include/linux/ftrace_irq.h
index dca7bf8cffe2f48f0d9f91be301013ca45a709b2..4ec2c9b205f2138fb1239c9580da866b753ffbc4 100644
--- a/include/linux/ftrace_irq.h
+++ b/include/linux/ftrace_irq.h
@@ -3,11 +3,34 @@
#ifdef CONFIG_FTRACE_NMI_ENTER
-extern void ftrace_nmi_enter(void);
-extern void ftrace_nmi_exit(void);
+extern void arch_ftrace_nmi_enter(void);
+extern void arch_ftrace_nmi_exit(void);
#else
-static inline void ftrace_nmi_enter(void) { }
-static inline void ftrace_nmi_exit(void) { }
+static inline void arch_ftrace_nmi_enter(void) { }
+static inline void arch_ftrace_nmi_exit(void) { }
#endif
+#ifdef CONFIG_HWLAT_TRACER
+extern bool trace_hwlat_callback_enabled;
+extern void trace_hwlat_callback(bool enter);
+#endif
+
+static inline void ftrace_nmi_enter(void)
+{
+#ifdef CONFIG_HWLAT_TRACER
+ if (trace_hwlat_callback_enabled)
+ trace_hwlat_callback(true);
+#endif
+ arch_ftrace_nmi_enter();
+}
+
+static inline void ftrace_nmi_exit(void)
+{
+ arch_ftrace_nmi_exit();
+#ifdef CONFIG_HWLAT_TRACER
+ if (trace_hwlat_callback_enabled)
+ trace_hwlat_callback(false);
+#endif
+}
+
#endif /* _LINUX_FTRACE_IRQ_H */
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index 70d47dd993591b235a9dc7ef453dc30231be5256..d1cc37e78f9975ca38c48635b3bd377065685e32 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -330,18 +330,22 @@ FTRACE_ENTRY(hwlat, hwlat_entry,
F_STRUCT(
__field( u64, duration )
__field( u64, outer_duration )
+ __field( u64, nmi_total_ts )
__field_struct( struct timespec, timestamp )
__field_desc( long, timestamp, tv_sec )
__field_desc( long, timestamp, tv_nsec )
+ __field( unsigned int, nmi_count )
__field( unsigned int, seqnum )
),
- F_printk("cnt:%u\tts:%010lu.%010lu\tinner:%llu\touter:%llu\n",
+ F_printk("cnt:%u\tts:%010lu.%010lu\tinner:%llu\touter:%llunmi-ts:%llu\tnmi-count:%u\n",
__entry->seqnum,
__entry->tv_sec,
__entry->tv_nsec,
__entry->duration,
- __entry->outer_duration),
+ __entry->outer_duration,
+ __entry->nmi_total_ts,
+ __entry->nmi_count),
FILTER_OTHER
);
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 65aab3914a561be97fa15f8d7d92c59c472957ca..b97286c48735b898957d7951e0b536f0209cdad2 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -64,6 +64,15 @@ static struct dentry *hwlat_sample_window; /* sample window us */
/* Save the previous tracing_thresh value */
static unsigned long save_tracing_thresh;
+/* NMI timestamp counters */
+static u64 nmi_ts_start;
+static u64 nmi_total_ts;
+static int nmi_count;
+static int nmi_cpu;
+
+/* Tells NMIs to call back to the hwlat tracer to record timestamps */
+bool trace_hwlat_callback_enabled;
+
/* If the user changed threshold, remember it */
static u64 last_tracing_thresh = DEFAULT_LAT_THRESHOLD * NSEC_PER_USEC;
@@ -72,7 +81,9 @@ struct hwlat_sample {
u64 seqnum; /* unique sequence */
u64 duration; /* delta */
u64 outer_duration; /* delta (outer loop) */
+ u64 nmi_total_ts; /* Total time spent in NMIs */
struct timespec timestamp; /* wall time */
+ int nmi_count; /* # NMIs during this sample */
};
/* keep the global state somewhere. */
@@ -112,6 +123,8 @@ static void trace_hwlat_sample(struct hwlat_sample *sample)
entry->duration = sample->duration;
entry->outer_duration = sample->outer_duration;
entry->timestamp = sample->timestamp;
+ entry->nmi_total_ts = sample->nmi_total_ts;
+ entry->nmi_count = sample->nmi_count;
if (!call_filter_check_discard(call, entry, buffer, event))
__buffer_unlock_commit(buffer, event);
@@ -125,6 +138,26 @@ static void trace_hwlat_sample(struct hwlat_sample *sample)
#define init_time(a, b) (a = b)
#define time_u64(a) a
+void trace_hwlat_callback(bool enter)
+{
+ if (smp_processor_id() != nmi_cpu)
+ return;
+
+ /*
+ * Currently trace_clock_local() calls sched_clock() and the
+ * generic version is not NMI safe.
+ */
+ if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
+ if (enter)
+ nmi_ts_start = time_get();
+ else
+ nmi_total_ts = time_get() - nmi_ts_start;
+ }
+
+ if (enter)
+ nmi_count++;
+}
+
/**
* get_sample - sample the CPU TSC and look for likely hardware latencies
*
@@ -144,6 +177,14 @@ static int get_sample(void)
do_div(thresh, NSEC_PER_USEC); /* modifies interval value */
+ nmi_cpu = smp_processor_id();
+ nmi_total_ts = 0;
+ nmi_count = 0;
+ /* Make sure NMIs see this first */
+ barrier();
+
+ trace_hwlat_callback_enabled = true;
+
init_time(last_t2, 0);
start = time_get(); /* start timestamp */
@@ -188,6 +229,10 @@ static int get_sample(void)
} while (total <= hwlat_data.sample_width);
+ barrier(); /* finish the above in the view for NMIs */
+ trace_hwlat_callback_enabled = false;
+ barrier(); /* Make sure nmi_total_ts is no longer updated */
+
ret = 0;
/* If we exceed the threshold value, we have found a hardware latency */
@@ -196,11 +241,17 @@ static int get_sample(void)
ret = 1;
+ /* We read in microseconds */
+ if (nmi_total_ts)
+ do_div(nmi_total_ts, NSEC_PER_USEC);
+
hwlat_data.count++;
s.seqnum = hwlat_data.count;
s.duration = sample;
s.outer_duration = outer_sample;
s.timestamp = CURRENT_TIME;
+ s.nmi_total_ts = nmi_total_ts;
+ s.nmi_count = nmi_count;
trace_hwlat_sample(&s);
/* Keep a running maximum ever recorded hardware latency */
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index d67a562df259f6fe7546053d3d420a518cdbc21e..3fc20422c166969324e53ffd8e48f5c3e3183395 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1109,13 +1109,27 @@ trace_hwlat_print(struct trace_iterator *iter, int flags,
trace_assign_type(field, entry);
- trace_seq_printf(s, "#%-5u inner/outer(us): %4llu/%-5llu ts:%ld.%09ld\n",
+ trace_seq_printf(s, "#%-5u inner/outer(us): %4llu/%-5llu ts:%ld.%09ld",
field->seqnum,
field->duration,
field->outer_duration,
field->timestamp.tv_sec,
field->timestamp.tv_nsec);
+ if (field->nmi_count) {
+ /*
+ * The generic sched_clock() is not NMI safe, thus
+ * we only record the count and not the time.
+ */
+ if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK))
+ trace_seq_printf(s, " nmi-total:%llu",
+ field->nmi_total_ts);
+ trace_seq_printf(s, " nmi-count:%u",
+ field->nmi_count);
+ }
+
+ trace_seq_putc(s, '\n');
+
return trace_handle_return(s);
}