samples/bpf: add example to test reading address

This commit adds additional test in the trace_event example, by
attaching the bpf program to MEM_UOPS_RETIRED.LOCK_LOADS event with
PERF_SAMPLE_ADDR requested, and print the lock address value read from
the bpf program to trace_pipe.
Signed-off-by: Teng Qin <qinteng@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/bpf/trace_event_kern.c

@@ -39,6 +39,7 @@ int bpf_prog1(struct bpf_perf_event_data *ctx)
 {
 	char time_fmt1[] = "Time Enabled: %llu, Time Running: %llu";
 	char time_fmt2[] = "Get Time Failed, ErrCode: %d";
+	char addr_fmt[] = "Address recorded on event: %llx";
 	char fmt[] = "CPU-%d period %lld ip %llx";
 	u32 cpu = bpf_get_smp_processor_id();
 	struct bpf_perf_event_value value_buf;
@@ -64,6 +65,9 @@ int bpf_prog1(struct bpf_perf_event_data *ctx)
 	else
 	  bpf_trace_printk(time_fmt2, sizeof(time_fmt2), ret);
 
+	if (ctx->addr != 0)
+	  bpf_trace_printk(addr_fmt, sizeof(addr_fmt), ctx->addr);
+
 	val = bpf_map_lookup_elem(&counts, &key);
 	if (val)
 		(*val)++;

samples/bpf/trace_event_user.c

@@ -215,6 +215,17 @@ static void test_bpf_perf_event(void)
 		/* Intel Instruction Retired */
 		.config = 0xc0,
 	};
+	struct perf_event_attr attr_type_raw_lock_load = {
+		.sample_freq = SAMPLE_FREQ,
+		.freq = 1,
+		.type = PERF_TYPE_RAW,
+		/* Intel MEM_UOPS_RETIRED.LOCK_LOADS */
+		.config = 0x21d0,
+		/* Request to record lock address from PEBS */
+		.sample_type = PERF_SAMPLE_ADDR,
+		/* Record address value requires precise event */
+		.precise_ip = 2,
+	};
 
 	printf("Test HW_CPU_CYCLES\n");
 	test_perf_event_all_cpu(&attr_type_hw);
@@ -236,6 +247,10 @@ static void test_bpf_perf_event(void)
 	test_perf_event_all_cpu(&attr_type_raw);
 	test_perf_event_task(&attr_type_raw);
 
+	printf("Test Lock Load\n");
+	test_perf_event_all_cpu(&attr_type_raw_lock_load);
+	test_perf_event_task(&attr_type_raw_lock_load);
+
 	printf("*** PASS ***\n");
 }