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| author | Alexei Starovoitov <ast@fb.com> | 2016-04-07 03:43:25 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-08 03:04:26 +0200 |
| commit | 98b5c2c65c2951772a8fc661f50d675e450e8bce (patch) | |
| tree | a72f04b6056a18b50d6244e8f4b6f41e95f9e0c5 /include/trace | |
| parent | perf: split perf_trace_buf_prepare into alloc and update parts (diff) | |
| download | linux-98b5c2c65c2951772a8fc661f50d675e450e8bce.tar.xz linux-98b5c2c65c2951772a8fc661f50d675e450e8bce.zip | |
perf, bpf: allow bpf programs attach to tracepoints
introduce BPF_PROG_TYPE_TRACEPOINT program type and allow it to be attached
to the perf tracepoint handler, which will copy the arguments into
the per-cpu buffer and pass it to the bpf program as its first argument.
The layout of the fields can be discovered by doing
'cat /sys/kernel/debug/tracing/events/sched/sched_switch/format'
prior to the compilation of the program with exception that first 8 bytes
are reserved and not accessible to the program. This area is used to store
the pointer to 'struct pt_regs' which some of the bpf helpers will use:
+---------+
| 8 bytes | hidden 'struct pt_regs *' (inaccessible to bpf program)
+---------+
| N bytes | static tracepoint fields defined in tracepoint/format (bpf readonly)
+---------+
| dynamic | __dynamic_array bytes of tracepoint (inaccessible to bpf yet)
+---------+
Not that all of the fields are already dumped to user space via perf ring buffer
and broken application access it directly without consulting tracepoint/format.
Same rule applies here: static tracepoint fields should only be accessed
in a format defined in tracepoint/format. The order of fields and
field sizes are not an ABI.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/perf.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/trace/perf.h b/include/trace/perf.h index 77cd9043b7e4..a182306eefd7 100644 --- a/include/trace/perf.h +++ b/include/trace/perf.h @@ -34,6 +34,7 @@ perf_trace_##call(void *__data, proto) \ struct trace_event_call *event_call = __data; \ struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\ struct trace_event_raw_##call *entry; \ + struct bpf_prog *prog = event_call->prog; \ struct pt_regs *__regs; \ u64 __count = 1; \ struct task_struct *__task = NULL; \ @@ -45,7 +46,7 @@ perf_trace_##call(void *__data, proto) \ __data_size = trace_event_get_offsets_##call(&__data_offsets, args); \ \ head = this_cpu_ptr(event_call->perf_events); \ - if (__builtin_constant_p(!__task) && !__task && \ + if (!prog && __builtin_constant_p(!__task) && !__task && \ hlist_empty(head)) \ return; \ \ @@ -63,6 +64,13 @@ perf_trace_##call(void *__data, proto) \ \ { assign; } \ \ + if (prog) { \ + *(struct pt_regs **)entry = __regs; \ + if (!trace_call_bpf(prog, entry) || hlist_empty(head)) { \ + perf_swevent_put_recursion_context(rctx); \ + return; \ + } \ + } \ perf_trace_buf_submit(entry, __entry_size, rctx, \ event_call->event.type, __count, __regs, \ head, __task); \ |