Em Fri, Apr 08, 2016 at 03:07:25PM +0000, Wang Nan escreveu:
> struct bpf_map_def SEC("maps") __bpf_stdout__ = {
> .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
> .key_size = sizeof(int),
> .value_size = sizeof(u32),
> .max_entries = __NR_CPUS__,
> };
>
> static inline int __attribute__((always_inline))
> func(void *ctx, int type)
> {
> char output_str[] = "Raise a BPF event!";
> char err_str[] = "BAD %d\n";
> int err;
>
> err = perf_event_output(ctx, &channel, get_smp_processor_id(),
I had to change channel here to __bpf_stdout__, then it works :-)
> &output_str, sizeof(output_str));
> if (err)
> trace_printk(err_str, sizeof(err_str), err);
> return 1;
Asking for strace-like output for 'nanosleep', the function hooked:
[root@jouet bpf]# trace -e nanosleep --ev test_bpf_stdout.c usleep 1
0.007 ( 0.007 ms): usleep/729 nanosleep(rqtp: 0x7ffc5bbc5fe0) ...
0.007 ( ): __bpf_stdout__:Raise a BPF event!..)
0.008 ( ): perf_bpf_probe:func_begin:(ffffffff81112460))
0.069 ( ): __bpf_stdout__:Raise a BPF event!..)
0.070 ( ): perf_bpf_probe:func_end:(ffffffff81112460 <-
ffffffff81003d92))
0.072 ( 0.072 ms): usleep/729 ... [continued]: nanosleep()) = 0
[root@jouet bpf]#
Ok, merged those, now lets see how all this mixes with callchains...
- Arnaldo
