uapi/linux/bpf.h

1016 /* Note that tracing related programs such as
1020  * therefore break existing tracing BPF programs. Tracing BPF
1742 			} tracing;
1872  * 		For tracing programs, safely attempt to read *size* bytes from
1892  * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
1898  * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
1899  * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
1902  * 		*\/sys/kernel/tracing/trace_options* (see also the
2381  * 		Note that this helper is not restricted to tracing use cases
2413  * 		on which the tracing program is executed, and a pointer to a
3298  * 		to the context on which the tracing program is executed.
4182  * 		tracing programs for reading strings, and more importantly to
5250  * 		Get address of the traced function (for tracing and kprobe programs).
5388  *		Get **n**-th argument register (zero based) of the traced function (for tracing programs)
5397  *		Get return value of the traced function (for tracing programs)
5402  *		**-EOPNOTSUPP** for tracing programs other than BPF_TRACE_FEXIT or BPF_MODIFY_RETURN.
5406  *		Get number of registers of the traced function (for tracing programs) where
6619 		} tracing;