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>

diff --git a/samples/bpf/trace_event_kern.c b/samples/bpf/trace_event_kern.c
index a77a583..7068fbd 100644 (file)
--- a/samples/bpf/trace_event_kern.c
+++ b/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)++;

diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index bf4f1b6..56f7a25 100644 (file)
--- a/samples/bpf/trace_event_user.c
+++ b/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");
 }