cpp examples: use a raw tracepoint for RandomRead

examples/cpp/RandomRead.cc

@@ -24,14 +24,6 @@ const std::string BPF_PROGRAM = R"(
 #define CGROUP_FILTER 0
 #endif
 
-struct urandom_read_args {
- // See /sys/kernel/debug/tracing/events/random/urandom_read/format
- uint64_t common__unused;
- int got_bits;
- int pool_left;
- int input_left;
-};
-
 struct event_t {
  int pid;
  char comm[16];
@@ -42,17 +34,19 @@ struct event_t {
 BPF_PERF_OUTPUT(events);
 BPF_CGROUP_ARRAY(cgroup, 1);
 
-int on_urandom_read(struct urandom_read_args* attr) {
+int on_urandom_read(struct bpf_raw_tracepoint_args *ctx) {
  if (CGROUP_FILTER && (cgroup.check_current_task(0) != 1))
  return 0;
 
  struct event_t event = {};
  event.pid = bpf_get_current_pid_tgid();
  bpf_get_current_comm(&event.comm, sizeof(event.comm));
  event.cpu = bpf_get_smp_processor_id();
- event.got_bits = attr->got_bits;
+ // from include/trace/events/random.h:
+ // TP_PROTO(int got_bits, int pool_left, int input_left)
+ event.got_bits = ctx->args[0];
 
- events.perf_submit(attr, &event, sizeof(event));
+ events.perf_submit(ctx, &event, sizeof(event));
  return 0;
 }
 )";
@@ -126,7 +120,7 @@ int main(int argc, char** argv) {
  }
 
  auto attach_res =
- bpf->attach_tracepoint("random:urandom_read", "on_urandom_read");
+ bpf->attach_raw_tracepoint("urandom_read", "on_urandom_read");
  if (attach_res.code() != 0) {
  std::cerr << attach_res.msg() << std::endl;
  return 1;