diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 1da4a438ba00..43161fdd44bb 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -201,13 +201,6 @@ struct reloc_desc { }; }; -typedef int (*libbpf_prog_setup_fn_t)(struct bpf_program *prog, long cookie); -typedef int (*libbpf_prog_prepare_load_fn_t)(struct bpf_program *prog, - struct bpf_prog_load_opts *opts, long cookie); -/* If auto-attach is not supported, callback should return 0 and set link to NULL */ -typedef int (*libbpf_prog_attach_fn_t)(const struct bpf_program *prog, long cookie, - struct bpf_link **link); - /* stored as sec_def->cookie for all libbpf-supported SEC()s */ enum sec_def_flags { SEC_NONE = 0, @@ -235,10 +228,11 @@ enum sec_def_flags { }; struct bpf_sec_def { - const char *sec; + char *sec; enum bpf_prog_type prog_type; enum bpf_attach_type expected_attach_type; long cookie; + int handler_id; libbpf_prog_setup_fn_t prog_setup_fn; libbpf_prog_prepare_load_fn_t prog_prepare_load_fn; @@ -8590,7 +8584,7 @@ int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log } #define SEC_DEF(sec_pfx, ptype, atype, flags, ...) { \ - .sec = sec_pfx, \ + .sec = (char *)sec_pfx, \ .prog_type = BPF_PROG_TYPE_##ptype, \ .expected_attach_type = atype, \ .cookie = (long)(flags), \ @@ -8683,61 +8677,167 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("sk_lookup", SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE | SEC_SLOPPY_PFX), }; -#define MAX_TYPE_NAME_SIZE 32 +static size_t custom_sec_def_cnt; +static struct bpf_sec_def *custom_sec_defs; +static struct bpf_sec_def custom_fallback_def; +static bool has_custom_fallback_def; + +static int last_custom_sec_def_handler_id; + +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) +{ + struct bpf_sec_def *sec_def; + + if (!OPTS_VALID(opts, libbpf_prog_handler_opts)) + return libbpf_err(-EINVAL); + + if (last_custom_sec_def_handler_id == INT_MAX) /* prevent overflow */ + return libbpf_err(-E2BIG); + + if (sec) { + sec_def = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt + 1, + sizeof(*sec_def)); + if (!sec_def) + return libbpf_err(-ENOMEM); + + custom_sec_defs = sec_def; + sec_def = &custom_sec_defs[custom_sec_def_cnt]; + } else { + if (has_custom_fallback_def) + return libbpf_err(-EBUSY); + + sec_def = &custom_fallback_def; + } + + sec_def->sec = sec ? strdup(sec) : NULL; + if (sec && !sec_def->sec) + return libbpf_err(-ENOMEM); + + sec_def->prog_type = prog_type; + sec_def->expected_attach_type = exp_attach_type; + sec_def->cookie = OPTS_GET(opts, cookie, 0); + + sec_def->prog_setup_fn = OPTS_GET(opts, prog_setup_fn, NULL); + sec_def->prog_prepare_load_fn = OPTS_GET(opts, prog_prepare_load_fn, NULL); + sec_def->prog_attach_fn = OPTS_GET(opts, prog_attach_fn, NULL); + + sec_def->handler_id = ++last_custom_sec_def_handler_id; + + if (sec) + custom_sec_def_cnt++; + else + has_custom_fallback_def = true; + + return sec_def->handler_id; +} + +int libbpf_unregister_prog_handler(int handler_id) +{ + struct bpf_sec_def *sec_defs; + int i; + + if (handler_id <= 0) + return libbpf_err(-EINVAL); + + if (has_custom_fallback_def && custom_fallback_def.handler_id == handler_id) { + memset(&custom_fallback_def, 0, sizeof(custom_fallback_def)); + has_custom_fallback_def = false; + return 0; + } + + for (i = 0; i < custom_sec_def_cnt; i++) { + if (custom_sec_defs[i].handler_id == handler_id) + break; + } + + if (i == custom_sec_def_cnt) + return libbpf_err(-ENOENT); + + free(custom_sec_defs[i].sec); + for (i = i + 1; i < custom_sec_def_cnt; i++) + custom_sec_defs[i - 1] = custom_sec_defs[i]; + custom_sec_def_cnt--; + + /* try to shrink the array, but it's ok if we couldn't */ + sec_defs = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt, sizeof(*sec_defs)); + if (sec_defs) + custom_sec_defs = sec_defs; + + return 0; +} + +static bool sec_def_matches(const struct bpf_sec_def *sec_def, const char *sec_name, + bool allow_sloppy) +{ + size_t len = strlen(sec_def->sec); + + /* "type/" always has to have proper SEC("type/extras") form */ + if (sec_def->sec[len - 1] == '/') { + if (str_has_pfx(sec_name, sec_def->sec)) + return true; + return false; + } + + /* "type+" means it can be either exact SEC("type") or + * well-formed SEC("type/extras") with proper '/' separator + */ + if (sec_def->sec[len - 1] == '+') { + len--; + /* not even a prefix */ + if (strncmp(sec_name, sec_def->sec, len) != 0) + return false; + /* exact match or has '/' separator */ + if (sec_name[len] == '\0' || sec_name[len] == '/') + return true; + return false; + } + + /* SEC_SLOPPY_PFX definitions are allowed to be just prefix + * matches, unless strict section name mode + * (LIBBPF_STRICT_SEC_NAME) is enabled, in which case the + * match has to be exact. + */ + if (allow_sloppy && str_has_pfx(sec_name, sec_def->sec)) + return true; + + /* Definitions not marked SEC_SLOPPY_PFX (e.g., + * SEC("syscall")) are exact matches in both modes. + */ + return strcmp(sec_name, sec_def->sec) == 0; +} static const struct bpf_sec_def *find_sec_def(const char *sec_name) { const struct bpf_sec_def *sec_def; - enum sec_def_flags sec_flags; - int i, n = ARRAY_SIZE(section_defs), len; - bool strict = libbpf_mode & LIBBPF_STRICT_SEC_NAME; + int i, n; + bool strict = libbpf_mode & LIBBPF_STRICT_SEC_NAME, allow_sloppy; + n = custom_sec_def_cnt; for (i = 0; i < n; i++) { - sec_def = §ion_defs[i]; - sec_flags = sec_def->cookie; - len = strlen(sec_def->sec); - - /* "type/" always has to have proper SEC("type/extras") form */ - if (sec_def->sec[len - 1] == '/') { - if (str_has_pfx(sec_name, sec_def->sec)) - return sec_def; - continue; - } - - /* "type+" means it can be either exact SEC("type") or - * well-formed SEC("type/extras") with proper '/' separator - */ - if (sec_def->sec[len - 1] == '+') { - len--; - /* not even a prefix */ - if (strncmp(sec_name, sec_def->sec, len) != 0) - continue; - /* exact match or has '/' separator */ - if (sec_name[len] == '\0' || sec_name[len] == '/') - return sec_def; - continue; - } - - /* SEC_SLOPPY_PFX definitions are allowed to be just prefix - * matches, unless strict section name mode - * (LIBBPF_STRICT_SEC_NAME) is enabled, in which case the - * match has to be exact. - */ - if ((sec_flags & SEC_SLOPPY_PFX) && !strict) { - if (str_has_pfx(sec_name, sec_def->sec)) - return sec_def; - continue; - } - - /* Definitions not marked SEC_SLOPPY_PFX (e.g., - * SEC("syscall")) are exact matches in both modes. - */ - if (strcmp(sec_name, sec_def->sec) == 0) + sec_def = &custom_sec_defs[i]; + if (sec_def_matches(sec_def, sec_name, false)) return sec_def; } + + n = ARRAY_SIZE(section_defs); + for (i = 0; i < n; i++) { + sec_def = §ion_defs[i]; + allow_sloppy = (sec_def->cookie & SEC_SLOPPY_PFX) && !strict; + if (sec_def_matches(sec_def, sec_name, allow_sloppy)) + return sec_def; + } + + if (has_custom_fallback_def) + return &custom_fallback_def; + return NULL; } +#define MAX_TYPE_NAME_SIZE 32 + static char *libbpf_get_type_names(bool attach_type) { int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index c8d8daad212e..c1b0c2ef14d8 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -1328,6 +1328,115 @@ LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker, LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker); LIBBPF_API void bpf_linker__free(struct bpf_linker *linker); +/* + * Custom handling of BPF program's SEC() definitions + */ + +struct bpf_prog_load_opts; /* defined in bpf.h */ + +/* Called during bpf_object__open() for each recognized BPF program. Callback + * can use various bpf_program__set_*() setters to adjust whatever properties + * are necessary. + */ +typedef int (*libbpf_prog_setup_fn_t)(struct bpf_program *prog, long cookie); + +/* Called right before libbpf performs bpf_prog_load() to load BPF program + * into the kernel. Callback can adjust opts as necessary. + */ +typedef int (*libbpf_prog_prepare_load_fn_t)(struct bpf_program *prog, + struct bpf_prog_load_opts *opts, long cookie); + +/* Called during skeleton attach or through bpf_program__attach(). If + * auto-attach is not supported, callback should return 0 and set link to + * NULL (it's not considered an error during skeleton attach, but it will be + * an error for bpf_program__attach() calls). On error, error should be + * returned directly and link set to NULL. On success, return 0 and set link + * to a valid struct bpf_link. + */ +typedef int (*libbpf_prog_attach_fn_t)(const struct bpf_program *prog, long cookie, + struct bpf_link **link); + +struct libbpf_prog_handler_opts { + /* size of this struct, for forward/backward compatiblity */ + size_t sz; + /* User-provided value that is passed to prog_setup_fn, + * prog_prepare_load_fn, and prog_attach_fn callbacks. Allows user to + * register one set of callbacks for multiple SEC() definitions and + * still be able to distinguish them, if necessary. For example, + * libbpf itself is using this to pass necessary flags (e.g., + * sleepable flag) to a common internal SEC() handler. + */ + long cookie; + /* BPF program initialization callback (see libbpf_prog_setup_fn_t). + * Callback is optional, pass NULL if it's not necessary. + */ + libbpf_prog_setup_fn_t prog_setup_fn; + /* BPF program loading callback (see libbpf_prog_prepare_load_fn_t). + * Callback is optional, pass NULL if it's not necessary. + */ + libbpf_prog_prepare_load_fn_t prog_prepare_load_fn; + /* BPF program attach callback (see libbpf_prog_attach_fn_t). + * Callback is optional, pass NULL if it's not necessary. + */ + libbpf_prog_attach_fn_t prog_attach_fn; +}; +#define libbpf_prog_handler_opts__last_field prog_attach_fn + +/** + * @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); + #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 47e70c9058d9..df1b947792c8 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -439,3 +439,9 @@ LIBBPF_0.7.0 { libbpf_probe_bpf_prog_type; libbpf_set_memlock_rlim_max; } LIBBPF_0.6.0; + +LIBBPF_0.8.0 { + global: + libbpf_register_prog_handler; + libbpf_unregister_prog_handler; +} LIBBPF_0.7.0; diff --git a/tools/lib/bpf/libbpf_version.h b/tools/lib/bpf/libbpf_version.h index 0fefefc3500b..61f2039404b6 100644 --- a/tools/lib/bpf/libbpf_version.h +++ b/tools/lib/bpf/libbpf_version.h @@ -4,6 +4,6 @@ #define __LIBBPF_VERSION_H #define LIBBPF_MAJOR_VERSION 0 -#define LIBBPF_MINOR_VERSION 7 +#define LIBBPF_MINOR_VERSION 8 #endif /* __LIBBPF_VERSION_H */