perf/x86/intel/uncore: Handle invalid event coding for free-running counter

Counting with invalid event coding for free-running counter may cause
OOPs, e.g. uncore_iio_free_running_0/event=1/.

Current code only validate the event with free-running event format,
event=0xff,umask=0xXY. Non-free-running event format never be checked
for the PMU with free-running counters.

Add generic hw_config() to check and reject the invalid event coding
for free-running PMU.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: eranian@google.com
Fixes: 0f519f03 ("perf/x86/intel/uncore: Support IIO free-running counters on SKX")
Link: https://lkml.kernel.org/r/1556672028-119221-2-git-send-email-kan.liang@linux.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/intel/uncore.h

@@ -419,6 +419,16 @@ static inline bool is_freerunning_event(struct perf_event *event)
 	       (((cfg >> 8) & 0xff) >= UNCORE_FREERUNNING_UMASK_START);
 }
 
+/* Check and reject invalid config */
+static inline int uncore_freerunning_hw_config(struct intel_uncore_box *box,
+					       struct perf_event *event)
+{
+	if (is_freerunning_event(event))
+		return 0;
+
+	return -EINVAL;
+}
+
 static inline void uncore_disable_box(struct intel_uncore_box *box)
 {
 	if (box->pmu->type->ops->disable_box)

arch/x86/events/intel/uncore_snbep.c

@@ -3585,6 +3585,7 @@ static struct uncore_event_desc skx_uncore_iio_freerunning_events[] = {
 
 static struct intel_uncore_ops skx_uncore_iio_freerunning_ops = {
 	.read_counter		= uncore_msr_read_counter,
+	.hw_config		= uncore_freerunning_hw_config,
 };
 
 static struct attribute *skx_uncore_iio_freerunning_formats_attr[] = {