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98b5c2c65c
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>
98 lines
2.8 KiB
C
98 lines
2.8 KiB
C
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#undef TRACE_SYSTEM_VAR
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#ifdef CONFIG_PERF_EVENTS
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#undef __entry
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#define __entry entry
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#undef __get_dynamic_array
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#define __get_dynamic_array(field) \
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((void *)__entry + (__entry->__data_loc_##field & 0xffff))
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#undef __get_dynamic_array_len
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#define __get_dynamic_array_len(field) \
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((__entry->__data_loc_##field >> 16) & 0xffff)
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#undef __get_str
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#define __get_str(field) (char *)__get_dynamic_array(field)
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#undef __get_bitmask
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#define __get_bitmask(field) (char *)__get_dynamic_array(field)
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#undef __perf_count
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#define __perf_count(c) (__count = (c))
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#undef __perf_task
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#define __perf_task(t) (__task = (t))
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#undef DECLARE_EVENT_CLASS
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#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
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static notrace void \
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perf_trace_##call(void *__data, proto) \
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{ \
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struct trace_event_call *event_call = __data; \
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struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\
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struct trace_event_raw_##call *entry; \
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struct bpf_prog *prog = event_call->prog; \
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struct pt_regs *__regs; \
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u64 __count = 1; \
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struct task_struct *__task = NULL; \
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struct hlist_head *head; \
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int __entry_size; \
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int __data_size; \
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int rctx; \
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\
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__data_size = trace_event_get_offsets_##call(&__data_offsets, args); \
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\
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head = this_cpu_ptr(event_call->perf_events); \
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if (!prog && __builtin_constant_p(!__task) && !__task && \
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hlist_empty(head)) \
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return; \
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\
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__entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
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sizeof(u64)); \
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__entry_size -= sizeof(u32); \
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\
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entry = perf_trace_buf_alloc(__entry_size, &__regs, &rctx); \
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if (!entry) \
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return; \
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\
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perf_fetch_caller_regs(__regs); \
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\
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tstruct \
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\
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{ assign; } \
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\
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if (prog) { \
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*(struct pt_regs **)entry = __regs; \
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if (!trace_call_bpf(prog, entry) || hlist_empty(head)) { \
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perf_swevent_put_recursion_context(rctx); \
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return; \
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} \
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} \
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perf_trace_buf_submit(entry, __entry_size, rctx, \
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event_call->event.type, __count, __regs, \
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head, __task); \
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}
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/*
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* This part is compiled out, it is only here as a build time check
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* to make sure that if the tracepoint handling changes, the
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* perf probe will fail to compile unless it too is updated.
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*/
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#undef DEFINE_EVENT
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#define DEFINE_EVENT(template, call, proto, args) \
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static inline void perf_test_probe_##call(void) \
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{ \
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check_trace_callback_type_##call(perf_trace_##template); \
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}
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#undef DEFINE_EVENT_PRINT
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#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
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DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
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#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
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#endif /* CONFIG_PERF_EVENTS */
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