4 files changed, 21 insertions, 4 deletions

diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
index b0872c801866..3bb75c1f25e8 100644
--- a/tools/perf/Documentation/perf-config.txt
+++ b/tools/perf/Documentation/perf-config.txt
@@ -706,6 +706,12 @@ intel-pt.*::
 		If set, Intel PT decoder will set the mispred flag on all
 		branches.
 
+	intel-pt.max-loops::
+		If set and non-zero, the maximum number of unconditional
+		branches decoded without consuming any trace packets. If
+		the maximum is exceeded there will be a "Never-ending loop"
+		error. The default is 100000.
+
 auxtrace.*::
 
 	auxtrace.dumpdir::
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index cb2520abf261..5ab631702769 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -41,8 +41,11 @@
 
 #define INTEL_PT_RETURN 1
 
-/* Maximum number of loops with no packets consumed i.e. stuck in a loop */
-#define INTEL_PT_MAX_LOOPS 10000
+/*
+ * Default maximum number of loops with no packets consumed i.e. stuck in a
+ * loop.
+ */
+#define INTEL_PT_MAX_LOOPS 100000
 
 struct intel_pt_blk {
 	struct intel_pt_blk *prev;
@@ -220,6 +223,7 @@ struct intel_pt_decoder {
 	uint64_t timestamp_insn_cnt;
 	uint64_t sample_insn_cnt;
 	uint64_t stuck_ip;
+	int max_loops;
 	int no_progress;
 	int stuck_ip_prd;
 	int stuck_ip_cnt;
@@ -315,6 +319,7 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
 	decoder->vm_tm_corr_dry_run = params->vm_tm_corr_dry_run;
 	decoder->first_timestamp    = params->first_timestamp;
 	decoder->last_reliable_timestamp = params->first_timestamp;
+	decoder->max_loops          = params->max_loops ? params->max_loops : INTEL_PT_MAX_LOOPS;
 
 	decoder->flags              = params->flags;
 
@@ -483,7 +488,7 @@ static const char *intel_pt_err_msgs[] = {
 	[INTEL_PT_ERR_OVR]    = "Overflow packet",
 	[INTEL_PT_ERR_LOST]   = "Lost trace data",
 	[INTEL_PT_ERR_UNK]    = "Unknown error!",
-	[INTEL_PT_ERR_NELOOP] = "Never-ending loop",
+	[INTEL_PT_ERR_NELOOP] = "Never-ending loop (refer perf config intel-pt.max-loops)",
 };
 
 int intel_pt__strerror(int code, char *buf, size_t buflen)
@@ -1168,7 +1173,7 @@ static int intel_pt_walk_insn(struct intel_pt_decoder *decoder,
 				decoder->stuck_ip = decoder->state.to_ip;
 				decoder->stuck_ip_prd = 1;
 				decoder->stuck_ip_cnt = 1;
-			} else if (cnt > INTEL_PT_MAX_LOOPS ||
+			} else if (cnt > decoder->max_loops ||
 				   decoder->state.to_ip == decoder->stuck_ip) {
 				intel_pt_log_at("ERROR: Never-ending loop",
 						decoder->state.to_ip);
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
index 714c475808c0..4b5e79fcf557 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.h
@@ -270,6 +270,7 @@ struct intel_pt_params {
 	uint32_t tsc_ctc_ratio_d;
 	enum intel_pt_param_flags flags;
 	unsigned int quick;
+	int max_loops;
 };
 
 struct intel_pt_decoder;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 154a1077f22e..6f852b305e92 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -123,6 +123,7 @@ struct intel_pt {
 	u64 noretcomp_bit;
 	unsigned max_non_turbo_ratio;
 	unsigned cbr2khz;
+	int max_loops;
 
 	unsigned long num_events;
 
@@ -1200,6 +1201,7 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
 	params.vm_time_correlation = pt->synth_opts.vm_time_correlation;
 	params.vm_tm_corr_dry_run = pt->synth_opts.vm_tm_corr_dry_run;
 	params.first_timestamp = pt->first_timestamp;
+	params.max_loops = pt->max_loops;
 
 	if (pt->filts.cnt > 0)
 		params.pgd_ip = intel_pt_pgd_ip;
@@ -3431,6 +3433,9 @@ static int intel_pt_perf_config(const char *var, const char *value, void *data)
 	if (!strcmp(var, "intel-pt.mispred-all"))
 		pt->mispred_all = perf_config_bool(var, value);
 
+	if (!strcmp(var, "intel-pt.max-loops"))
+		perf_config_int(&pt->max_loops, var, value);
+
 	return 0;
 }