Messages in this thread | | | Date | Fri, 8 Apr 2016 14:54:28 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 4/4] perf bpf: Automatically create bpf-output event __bpf_stdout__ |
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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
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