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: Viktor Malik <vmalik@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 898d5d34ecea..88adc989dbe9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9859,16 +9859,28 @@ 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);
- if (ret > 0) {
- *btf_obj_fd = 0; /* vmlinux BTF */
- *btf_type_id = ret;
- return 0;
+ 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;
+ return 0;
+ }
+ if (ret != -ENOENT)
+ return ret;
}
- if (ret != -ENOENT)
- return ret;
ret = load_module_btfs(obj);
if (ret)
@@ -9877,7 +9889,12 @@ 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;
--
2.44.0
