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Date: Wed, 02 Jul 2014 14:32:45 +0900 From: Namhyung Kim <namhyung@...il.com> To: Alexei Starovoitov <ast@...mgrid.com> Cc: "David S. Miller" <davem@...emloft.net>, Ingo Molnar <mingo@...nel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Steven Rostedt <rostedt@...dmis.org>, Daniel Borkmann <dborkman@...hat.com>, Chema Gonzalez <chema@...gle.com>, Eric Dumazet <edumazet@...gle.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Arnaldo Carvalho de Melo <acme@...radead.org>, Jiri Olsa <jolsa@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...or.com>, Andrew Morton <akpm@...ux-foundation.org>, Kees Cook <keescook@...omium.org>, linux-api@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH RFC net-next 11/14] tracing: allow eBPF programs to be attached to events On Fri, 27 Jun 2014 17:06:03 -0700, Alexei Starovoitov wrote: > User interface: > cat bpf_123 > /sys/kernel/debug/tracing/__event__/filter > > where 123 is an id of the eBPF program priorly loaded. > __event__ is static tracepoint event. > (kprobe events will be supported in the future patches) > > eBPF programs can call in-kernel helper functions to: > - lookup/update/delete elements in maps > - memcmp > - trace_printk ISTR Steve doesn't like to use trace_printk() (at least for production kernels) anymore. And I'm not sure it'd work if there's no existing trace_printk() on a system. > - load_pointer > - dump_stack [SNIP] > @@ -634,6 +635,15 @@ ftrace_raw_event_##call(void *__data, proto) \ > if (ftrace_trigger_soft_disabled(ftrace_file)) \ > return; \ > \ > + if (unlikely(ftrace_file->flags & FTRACE_EVENT_FL_FILTERED) && \ > + unlikely(ftrace_file->event_call->flags & TRACE_EVENT_FL_BPF)) { \ > + struct bpf_context __ctx; \ > + \ > + populate_bpf_context(&__ctx, args, 0, 0, 0, 0, 0); \ > + trace_filter_call_bpf(ftrace_file->filter, &__ctx); \ > + return; \ > + } \ > + \ Hmm.. But it seems the eBPF prog is not a filter - it'd always drop the event. And I think it's better to use a recorded entry rather then args as a bpf_context so that tools like perf can manipulate it at compile time based on the event format. Thanks, Namhyung > __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \ > \ > entry = ftrace_event_buffer_reserve(&fbuffer, ftrace_file, \ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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