Commit 8f8a0242 authored by Viktor Malik's avatar Viktor Malik Committed by Andrii Nakryiko
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libbpf: support "module: Function" syntax for tracing programs 



In some situations, it is useful to explicitly specify a kernel module
to search for a tracing program target (e.g. when a function of the same
name exists in multiple modules or in vmlinux).

This patch enables that by allowing the "module:function" syntax for the
find_kernel_btf_id function. Thanks to this, the syntax can be used both
from a SEC macro (i.e. `SEC(fentry/module:function)`) and via the
bpf_program__set_attach_target API call.

Signed-off-by: default avatarViktor Malik <vmalik@redhat.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/9085a8cb9a552de98e554deb22ff7e977d025440.1714469650.git.vmalik@redhat.com
parent 9a1a2cb5

tools/lib/bpf/libbpf.c

+26 −9
Original line number Diff line number Diff line
@@ -9862,9 +9862,20 @@ static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name, 
			      enum bpf_attach_type attach_type,

			      int *btf_obj_fd, int *btf_type_id)

{

	int ret, i;

	int ret, i, mod_len;

	const char *fn_name, *mod_name = NULL;



	ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);

	fn_name = strchr(attach_name, ':');

	if (fn_name) {

		mod_name = attach_name;

		mod_len = fn_name - mod_name;

		fn_name++;

	}



	if (!mod_name || strncmp(mod_name, "vmlinux", mod_len) == 0) {

		ret = find_attach_btf_id(obj->btf_vmlinux,

					 mod_name ? fn_name : attach_name,

					 attach_type);

		if (ret > 0) {

			*btf_obj_fd = 0; /* vmlinux BTF */

			*btf_type_id = ret;
@@ -9872,6 +9883,7 @@ static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name, 
		}

		if (ret != -ENOENT)

			return ret;

	}



	ret = load_module_btfs(obj);

	if (ret)
@@ -9880,7 +9892,12 @@ static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name, 
	for (i = 0; i < obj->btf_module_cnt; i++) {

		const struct module_btf *mod = &obj->btf_modules[i];



		ret = find_attach_btf_id(mod->btf, attach_name, attach_type);

		if (mod_name && strncmp(mod->name, mod_name, mod_len) != 0)

			continue;



		ret = find_attach_btf_id(mod->btf,

					 mod_name ? fn_name : attach_name,

					 attach_type);

		if (ret > 0) {

			*btf_obj_fd = mod->fd;

			*btf_type_id = ret;