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authorAndrii Nakryiko <andrii@kernel.org>2020-12-11 13:58:24 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2020-12-14 16:39:42 +0100
commitfe62de310e2b563c0d303a09d06b020077fe86b4 (patch)
tree3e8eda78ac61c7590a9b2544b61e19961b67f3bf /tools/lib
parentb4fe9fec51ef48011f11c2da4099f0b530449c92 (diff)
libbpf: Support modules in bpf_program__set_attach_target() API
Support finding kernel targets in kernel modules when using bpf_program__set_attach_target() API. This brings it up to par with what libbpf supports when doing declarative SEC()-based target determination. Some minor internal refactoring was needed to make sure vmlinux BTF can be loaded before bpf_object's load phase. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20201211215825.3646154-2-andrii@kernel.org
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c64
1 files changed, 40 insertions, 24 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 9be88a90a4aa..6ae748f6ea11 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2518,7 +2518,7 @@ static int bpf_object__finalize_btf(struct bpf_object *obj)
return 0;
}
-static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog)
+static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
{
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
prog->type == BPF_PROG_TYPE_LSM)
@@ -2533,37 +2533,43 @@ static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog)
return false;
}
-static int bpf_object__load_vmlinux_btf(struct bpf_object *obj)
+static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
{
- bool need_vmlinux_btf = false;
struct bpf_program *prog;
- int i, err;
+ int i;
/* CO-RE relocations need kernel BTF */
if (obj->btf_ext && obj->btf_ext->core_relo_info.len)
- need_vmlinux_btf = true;
+ return true;
/* Support for typed ksyms needs kernel BTF */
for (i = 0; i < obj->nr_extern; i++) {
const struct extern_desc *ext;
ext = &obj->externs[i];
- if (ext->type == EXT_KSYM && ext->ksym.type_id) {
- need_vmlinux_btf = true;
- break;
- }
+ if (ext->type == EXT_KSYM && ext->ksym.type_id)
+ return true;
}
bpf_object__for_each_program(prog, obj) {
if (!prog->load)
continue;
- if (libbpf_prog_needs_vmlinux_btf(prog)) {
- need_vmlinux_btf = true;
- break;
- }
+ if (prog_needs_vmlinux_btf(prog))
+ return true;
}
- if (!need_vmlinux_btf)
+ return false;
+}
+
+static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
+{
+ int err;
+
+ /* btf_vmlinux could be loaded earlier */
+ if (obj->btf_vmlinux)
+ return 0;
+
+ if (!force && !obj_needs_vmlinux_btf(obj))
return 0;
obj->btf_vmlinux = libbpf_find_kernel_btf();
@@ -7475,7 +7481,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
}
err = bpf_object__probe_loading(obj);
- err = err ? : bpf_object__load_vmlinux_btf(obj);
+ err = err ? : bpf_object__load_vmlinux_btf(obj, false);
err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
err = err ? : bpf_object__sanitize_and_load_btf(obj);
err = err ? : bpf_object__sanitize_maps(obj);
@@ -10870,23 +10876,33 @@ int bpf_program__set_attach_target(struct bpf_program *prog,
int attach_prog_fd,
const char *attach_func_name)
{
- int btf_id;
+ int btf_obj_fd = 0, btf_id = 0, err;
if (!prog || attach_prog_fd < 0 || !attach_func_name)
return -EINVAL;
- if (attach_prog_fd)
+ if (prog->obj->loaded)
+ return -EINVAL;
+
+ if (attach_prog_fd) {
btf_id = libbpf_find_prog_btf_id(attach_func_name,
attach_prog_fd);
- else
- btf_id = libbpf_find_vmlinux_btf_id(attach_func_name,
- prog->expected_attach_type);
-
- if (btf_id < 0)
- return btf_id;
+ if (btf_id < 0)
+ return btf_id;
+ } else {
+ /* load btf_vmlinux, if not yet */
+ err = bpf_object__load_vmlinux_btf(prog->obj, true);
+ if (err)
+ return err;
+ err = find_kernel_btf_id(prog->obj, attach_func_name,
+ prog->expected_attach_type,
+ &btf_obj_fd, &btf_id);
+ if (err)
+ return err;
+ }
prog->attach_btf_id = btf_id;
- prog->attach_btf_obj_fd = 0;
+ prog->attach_btf_obj_fd = btf_obj_fd;
prog->attach_prog_fd = attach_prog_fd;
return 0;
}