Adding bpf_program__attach_tracing_multi function for attaching
tracing program to multiple functions.
struct bpf_link *
bpf_program__attach_tracing_multi(const struct bpf_program *prog,
const char *pattern,
const struct bpf_tracing_multi_opts *opts);
User can specify functions to attach with 'pattern' argument that
allows wildcards (*?' supported) or provide BTF ids of functions
in array directly via opts argument. These options are mutually
exclusive.
When using BTF ids, user can also provide cookie value for each
provided id/function, that can be retrieved later in bpf program
with bpf_get_attach_cookie helper. Each cookie value is paired with
provided BTF id with the same array index.
Adding support to auto attach programs with following sections:
fsession.multi/<pattern>
fsession.multi.s/<pattern>
fentry.multi/<pattern>
fexit.multi/<pattern>
fentry.multi.s/<pattern>
fexit.multi.s/<pattern>
The provided <pattern> is used as 'pattern' argument in
bpf_program__attach_kprobe_multi_opts function.
The <pattern> allows to specify optional kernel module name with
following syntax:
<module>:<function_pattern>
In order to attach tracing_multi link to a module functions:
- program must be loaded with 'module' btf fd
(in attr::attach_btf_obj_fd)
- bpf_program__attach_kprobe_multi_opts must either have
pattern with module spec or BTF ids from the module
Signed-off-by: Jiri Olsa <[email protected]>
---
tools/lib/bpf/libbpf.c | 309 +++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 15 ++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 325 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 34987ce7cdc8..8842adcf8c8a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -7716,6 +7716,52 @@ static int bpf_object__sanitize_prog(struct bpf_object
*obj, struct bpf_program
static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char
*attach_name,
int *btf_obj_fd, int *btf_type_id);
+static inline bool is_tracing_multi(enum bpf_attach_type type)
+{
+ return type == BPF_TRACE_FENTRY_MULTI || type == BPF_TRACE_FEXIT_MULTI
||
+ type == BPF_TRACE_FSESSION_MULTI;
+}
+
+static int tracing_multi_mod_fd(struct bpf_program *prog, int *btf_obj_fd)
+{
+ const char *attach_name, *sep, *mod_name = NULL;
+ int i, err, mod_len = 0;
+
+ *btf_obj_fd = 0;
+ attach_name = strchr(prog->sec_name, '/');
+
+ /* Program with no details in spec, using kernel btf. */
+ if (!attach_name)
+ return 0;
+
+ attach_name++;
+ sep = strchr(attach_name, ':');
+ if (sep) {
+ mod_name = attach_name;
+ mod_len = sep - mod_name;
+ }
+
+ /* Program with no module section, using kernel btf. */
+ if (!mod_name)
+ return 0;
+
+ err = load_module_btfs(prog->obj);
+ if (err)
+ return err;
+
+ for (i = 0; i < prog->obj->btf_module_cnt; i++) {
+ const struct module_btf *mod = &prog->obj->btf_modules[i];
+
+ if (mod_name && strncmp(mod->name, mod_name, mod_len) == 0) {
+ *btf_obj_fd = mod->fd;
+ return 0;
+ }
+ }
+
+ /* Specified module was not found, let's bail out. */
+ return -EINVAL;
+}
+
/* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported
sec_defs */
static int libbpf_prepare_prog_load(struct bpf_program *prog,
struct bpf_prog_load_opts *opts, long
cookie)
@@ -7779,6 +7825,18 @@ static int libbpf_prepare_prog_load(struct bpf_program
*prog,
opts->attach_btf_obj_fd = btf_obj_fd;
opts->attach_btf_id = btf_type_id;
}
+
+ if (is_tracing_multi(prog->expected_attach_type)) {
+ int err, btf_obj_fd = 0;
+
+ err = tracing_multi_mod_fd(prog, &btf_obj_fd);
+ if (err < 0)
+ return err;
+
+ prog->attach_btf_obj_fd = btf_obj_fd;
+ opts->attach_btf_obj_fd = btf_obj_fd;
+ }
+
return 0;
}
@@ -9835,6 +9893,7 @@ static int attach_kprobe_session(const struct bpf_program
*prog, long cookie, st
static int attach_uprobe_multi(const struct bpf_program *prog, long cookie,
struct bpf_link **link);
static int attach_lsm(const struct bpf_program *prog, long cookie, struct
bpf_link **link);
static int attach_iter(const struct bpf_program *prog, long cookie, struct
bpf_link **link);
+static int attach_tracing_multi(const struct bpf_program *prog, long cookie,
struct bpf_link **link);
static const struct bpf_sec_def section_defs[] = {
SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE),
@@ -9883,6 +9942,12 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("fexit.s+", TRACING, BPF_TRACE_FEXIT,
SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("fsession+", TRACING, BPF_TRACE_FSESSION,
SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fsession.s+", TRACING, BPF_TRACE_FSESSION,
SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+ SEC_DEF("fsession.multi+", TRACING, BPF_TRACE_FSESSION_MULTI, 0,
attach_tracing_multi),
+ SEC_DEF("fsession.multi.s+", TRACING, BPF_TRACE_FSESSION_MULTI,
SEC_SLEEPABLE, attach_tracing_multi),
+ SEC_DEF("fentry.multi+", TRACING, BPF_TRACE_FENTRY_MULTI, 0,
attach_tracing_multi),
+ SEC_DEF("fexit.multi+", TRACING, BPF_TRACE_FEXIT_MULTI, 0,
attach_tracing_multi),
+ SEC_DEF("fentry.multi.s+", TRACING, BPF_TRACE_FENTRY_MULTI,
SEC_SLEEPABLE, attach_tracing_multi),
+ SEC_DEF("fexit.multi.s+", TRACING, BPF_TRACE_FEXIT_MULTI,
SEC_SLEEPABLE, attach_tracing_multi),
SEC_DEF("freplace+", EXT, 0, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("lsm+", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF,
attach_lsm),
SEC_DEF("lsm.s+", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF |
SEC_SLEEPABLE, attach_lsm),
@@ -12258,6 +12323,250 @@ static int attach_uprobe_multi(const struct
bpf_program *prog, long cookie, stru
return ret;
}
+#define MAX_BPF_FUNC_ARGS 12
+
+static bool btf_type_is_modifier(const struct btf_type *t)
+{
+ switch (BTF_INFO_KIND(t->info)) {
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_TYPE_TAG:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool is_allowed_func(const struct btf *btf, const struct btf_type *t)
+{
+ const struct btf_type *proto;
+ const struct btf_param *args;
+ __u32 i, nargs;
+ __s64 ret;
+
+ proto = btf_type_by_id(btf, t->type);
+ if (BTF_INFO_KIND(proto->info) != BTF_KIND_FUNC_PROTO)
+ return false;
+
+ args = (const struct btf_param *)(proto + 1);
+ nargs = btf_vlen(proto);
+ if (nargs > MAX_BPF_FUNC_ARGS)
+ return false;
+
+ /* No support for struct/union return argument type. */
+ t = btf__type_by_id(btf, proto->type);
+ while (t && btf_type_is_modifier(t))
+ t = btf__type_by_id(btf, t->type);
+
+ if (btf_is_struct(t) || btf_is_union(t))
+ return false;
+
+ for (i = 0; i < nargs; i++) {
+ /* No support for variable args. */
+ if (i == nargs - 1 && args[i].type == 0)
+ return false;
+
+ /* No support of struct argument size greater than 16 bytes. */
+ ret = btf__resolve_size(btf, args[i].type);
+ if (ret < 0 || ret > 16)
+ return false;
+ }
+
+ return true;
+}
+
+static int
+collect_btf_func_ids_by_glob(const struct btf *btf, const char *pattern, __u32
**ids)
+{
+ __u32 type_id, nr_types = btf__type_cnt(btf);
+ size_t cap = 0, cnt = 0;
+
+ if (!pattern)
+ return -EINVAL;
+
+ for (type_id = 1; type_id < nr_types; type_id++) {
+ const struct btf_type *t = btf__type_by_id(btf, type_id);
+ const char *name;
+ int err;
+
+ if (btf_kind(t) != BTF_KIND_FUNC)
+ continue;
+ name = btf__name_by_offset(btf, t->name_off);
+ if (!name)
+ continue;
+
+ if (!glob_match(name, pattern))
+ continue;
+ if (!is_allowed_func(btf, t))
+ continue;
+
+ err = libbpf_ensure_mem((void **) ids, &cap, sizeof(**ids), cnt
+ 1);
+ if (err) {
+ free(*ids);
+ return -ENOMEM;
+ }
+ (*ids)[cnt++] = type_id;
+ }
+
+ return cnt;
+}
+
+static int collect_func_ids_by_glob(struct bpf_object *obj, const char
*pattern, __u32 **ids)
+{
+ const char *mod_name = NULL, *sep;
+ int i, err, mod_len = 0;
+ struct btf *btf = NULL;
+
+ err = bpf_object__load_vmlinux_btf(obj, true);
+ if (err)
+ return err;
+
+ /* In case we have module specified, we will find its btf and use that.
*/
+ sep = strchr(pattern, ':');
+ if (sep) {
+ mod_name = pattern;
+ mod_len = sep - pattern;
+ pattern = sep + 1;
+
+ err = load_module_btfs(obj);
+ if (err)
+ goto cleanup;
+
+ for (i = 0; i < obj->btf_module_cnt; i++) {
+ const struct module_btf *mod = &obj->btf_modules[i];
+
+ if (!strncmp(mod->name, mod_name, mod_len)) {
+ btf = mod->btf;
+ break;
+ }
+ }
+ if (!btf) {
+ err = -EINVAL;
+ goto cleanup;
+ }
+ } else {
+ btf = obj->btf_vmlinux;
+ }
+
+ err = collect_btf_func_ids_by_glob(btf, pattern, ids);
+
+cleanup:
+ bpf_object_cleanup_btf(obj);
+ return err;
+}
+
+struct bpf_link *
+bpf_program__attach_tracing_multi(const struct bpf_program *prog, const char
*pattern,
+ const struct bpf_tracing_multi_opts *opts)
+{
+ LIBBPF_OPTS(bpf_link_create_opts, lopts);
+ __u32 *ids, *free_ids = NULL;
+ __u64 *cookies;
+ int prog_fd, link_fd, err, cnt;
+ struct bpf_link *link;
+
+ cnt = OPTS_GET(opts, cnt, 0);
+ ids = OPTS_GET(opts, ids, NULL);
+ cookies = OPTS_GET(opts, cookies, NULL);
+
+ if (!!ids != !!cnt)
+ return libbpf_err_ptr(-EINVAL);
+ if (pattern && (ids || cookies))
+ return libbpf_err_ptr(-EINVAL);
+ if (!pattern && !ids)
+ return libbpf_err_ptr(-EINVAL);
+
+ if (pattern) {
+ cnt = collect_func_ids_by_glob(prog->obj, pattern, &ids);
+ if (cnt < 0)
+ return libbpf_err_ptr(cnt);
+ if (cnt == 0)
+ return libbpf_err_ptr(-EINVAL);
+ free_ids = ids;
+ }
+
+ lopts.tracing_multi.ids = ids;
+ lopts.tracing_multi.cookies = cookies;
+ lopts.tracing_multi.cnt = cnt;
+
+ link = calloc(1, sizeof(*link));
+ if (!link) {
+ err = -ENOMEM;
+ goto error;
+ }
+ link->detach = &bpf_link__detach_fd;
+
+ prog_fd = bpf_program__fd(prog);
+ link_fd = bpf_link_create(prog_fd, 0, prog->expected_attach_type,
&lopts);
+ if (link_fd < 0) {
+ err = -errno;
+ pr_warn("prog '%s': failed to attach: %s\n", prog->name,
errstr(err));
+ goto error;
+ }
+ link->fd = link_fd;
+ free(free_ids);
+ return link;
+
+error:
+ free(link);
+ free(free_ids);
+ return libbpf_err_ptr(err);
+}
+
+static int attach_tracing_multi(const struct bpf_program *prog, long cookie,
struct bpf_link **link)
+{
+ static const char *const prefixes[] = {
+ "fentry.multi",
+ "fexit.multi",
+ "fsession.multi",
+ "fentry.multi.s",
+ "fexit.multi.s",
+ "fsession.multi.s",
+ };
+ const char *spec = NULL;
+ char *pattern;
+ size_t i;
+ int n;
+
+ *link = NULL;
+
+ for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
+ size_t pfx_len;
+
+ if (!str_has_pfx(prog->sec_name, prefixes[i]))
+ continue;
+
+ pfx_len = strlen(prefixes[i]);
+ /* no auto-attach case of, e.g., SEC("fentry.multi") */
+ if (prog->sec_name[pfx_len] == '\0')
+ return 0;
+
+ if (prog->sec_name[pfx_len] != '/')
+ continue;
+
+ spec = prog->sec_name + pfx_len + 1;
+ break;
+ }
+
+ if (!spec) {
+ pr_warn("prog '%s': invalid section name '%s'\n",
+ prog->name, prog->sec_name);
+ return -EINVAL;
+ }
+
+ n = sscanf(spec, "%m[a-zA-Z0-9_.*?:]", &pattern);
+ if (n < 1) {
+ pr_warn("tracing multi pattern is invalid: %s\n", spec);
+ return -EINVAL;
+ }
+
+ *link = bpf_program__attach_tracing_multi(prog, pattern, NULL);
+ free(pattern);
+ return libbpf_get_error(*link);
+}
+
static inline int add_uprobe_event_legacy(const char *probe_name, bool
retprobe,
const char *binary_path, size_t
offset)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index dfc37a615578..b677aea7e592 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -701,6 +701,21 @@ bpf_program__attach_ksyscall(const struct bpf_program
*prog,
const char *syscall_name,
const struct bpf_ksyscall_opts *opts);
+struct bpf_tracing_multi_opts {
+ /* size of this struct, for forward/backward compatibility */
+ size_t sz;
+ __u32 *ids;
+ __u64 *cookies;
+ size_t cnt;
+ size_t :0;
+};
+
+#define bpf_tracing_multi_opts__last_field cnt
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracing_multi(const struct bpf_program *prog, const char
*pattern,
+ const struct bpf_tracing_multi_opts *opts);
+
struct bpf_uprobe_opts {
/* size of this struct, for forward/backward compatibility */
size_t sz;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index d18fbcea7578..ff4d7b2c8a14 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -452,6 +452,7 @@ LIBBPF_1.7.0 {
bpf_map__set_exclusive_program;
bpf_map__exclusive_program;
bpf_prog_assoc_struct_ops;
+ bpf_program__attach_tracing_multi;
bpf_program__assoc_struct_ops;
btf__permute;
} LIBBPF_1.6.0;
--
2.53.0
