Register/unregister a custom BPF program SEC() handler

[insearchoflosttime]

Implement the ability to register + unregister a prog handler. This should be a wrapper around the libbpf library's

/**
 * @brief **libbpf_register_prog_handler()** registers a custom BPF program
 * SEC() handler.
 * @param sec section prefix for which custom handler is registered
 * @param prog_type BPF program type associated with specified section
 * @param exp_attach_type Expected BPF attach type associated with specified section
 * @param opts optional cookie, callbacks, and other extra options
 * @return Non-negative handler ID is returned on success. This handler ID has
 * to be passed to *libbpf_unregister_prog_handler()* to unregister such
 * custom handler. Negative error code is returned on error.
 *
 * *sec* defines which SEC() definitions are handled by this custom handler
 * registration. *sec* can have few different forms:
 *   - if *sec* is just a plain string (e.g., "abc"), it will match only
 *   SEC("abc"). If BPF program specifies SEC("abc/whatever") it will result
 *   in an error;
 *   - if *sec* is of the form "abc/", proper SEC() form is
 *   SEC("abc/something"), where acceptable "something" should be checked by
 *   *prog_init_fn* callback, if there are additional restrictions;
 *   - if *sec* is of the form "abc+", it will successfully match both
 *   SEC("abc") and SEC("abc/whatever") forms;
 *   - if *sec* is NULL, custom handler is registered for any BPF program that
 *   doesn't match any of the registered (custom or libbpf's own) SEC()
 *   handlers. There could be only one such generic custom handler registered
 *   at any given time.
 *
 * All custom handlers (except the one with *sec* == NULL) are processed
 * before libbpf's own SEC() handlers. It is allowed to "override" libbpf's
 * SEC() handlers by registering custom ones for the same section prefix
 * (i.e., it's possible to have custom SEC("perf_event/LLC-load-misses")
 * handler).
 *
 * Note, like much of global libbpf APIs (e.g., libbpf_set_print(),
 * libbpf_set_strict_mode(), etc)) these APIs are not thread-safe. User needs
 * to ensure synchronization if there is a risk of running this API from
 * multiple threads simultaneously.
 */
LIBBPF_API int libbpf_register_prog_handler(const char *sec,
					    enum bpf_prog_type prog_type,
					    enum bpf_attach_type exp_attach_type,
					    const struct libbpf_prog_handler_opts *opts);
/**
 * @brief *libbpf_unregister_prog_handler()* unregisters previously registered
 * custom BPF program SEC() handler.
 * @param handler_id handler ID returned by *libbpf_register_prog_handler()*
 * after successful registration
 * @return 0 on success, negative error code if handler isn't found
 *
 * Note, like much of global libbpf APIs (e.g., libbpf_set_print(),
 * libbpf_set_strict_mode(), etc)) these APIs are not thread-safe. User needs
 * to ensure synchronization if there is a risk of running this API from
 * multiple threads simultaneously.
 */
LIBBPF_API int libbpf_unregister_prog_handler(int handler_id);

(https://github.com/libbpf/libbpf/blob/3591deb9bc6b0848721f831790b78ae0a593b4c5/src/libbpf.h#L1385-L1438)

[chenhengqi]

Please assign this to me :)

[rlaisqls]

@chenhengqi Is there any progress on this issue?