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-rw-r--r--tools/lib/bpf/libbpf.c179
1 files changed, 169 insertions, 10 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2e4fa3ce6b94..ca20e493726d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -176,6 +176,8 @@ enum kern_feature_id {
FEAT_PROBE_READ_KERN,
/* BPF_PROG_BIND_MAP is supported */
FEAT_PROG_BIND_MAP,
+ /* Kernel support for module BTFs */
+ FEAT_MODULE_BTF,
__FEAT_CNT,
};
@@ -402,6 +404,12 @@ struct extern_desc {
static LIST_HEAD(bpf_objects_list);
+struct module_btf {
+ struct btf *btf;
+ char *name;
+ __u32 id;
+};
+
struct bpf_object {
char name[BPF_OBJ_NAME_LEN];
char license[64];
@@ -470,6 +478,11 @@ struct bpf_object {
struct btf *btf_vmlinux;
/* vmlinux BTF override for CO-RE relocations */
struct btf *btf_vmlinux_override;
+ /* Lazily initialized kernel module BTFs */
+ struct module_btf *btf_modules;
+ bool btf_modules_loaded;
+ size_t btf_module_cnt;
+ size_t btf_module_cap;
void *priv;
bpf_object_clear_priv_t clear_priv;
@@ -3960,6 +3973,35 @@ static int probe_prog_bind_map(void)
return ret >= 0;
}
+static int probe_module_btf(void)
+{
+ static const char strs[] = "\0int";
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+ };
+ struct bpf_btf_info info;
+ __u32 len = sizeof(info);
+ char name[16];
+ int fd, err;
+
+ fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
+ if (fd < 0)
+ return 0; /* BTF not supported at all */
+
+ memset(&info, 0, sizeof(info));
+ info.name = ptr_to_u64(name);
+ info.name_len = sizeof(name);
+
+ /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
+ * kernel's module BTF support coincides with support for
+ * name/name_len fields in struct bpf_btf_info.
+ */
+ err = bpf_obj_get_info_by_fd(fd, &info, &len);
+ close(fd);
+ return !err;
+}
+
enum kern_feature_result {
FEAT_UNKNOWN = 0,
FEAT_SUPPORTED = 1,
@@ -4003,7 +4045,10 @@ static struct kern_feature_desc {
},
[FEAT_PROG_BIND_MAP] = {
"BPF_PROG_BIND_MAP support", probe_prog_bind_map,
- }
+ },
+ [FEAT_MODULE_BTF] = {
+ "module BTF support", probe_module_btf,
+ },
};
static bool kernel_supports(enum kern_feature_id feat_id)
@@ -4674,13 +4719,96 @@ static int bpf_core_add_cands(struct core_cand *local_cand,
return 0;
}
+static int load_module_btfs(struct bpf_object *obj)
+{
+ struct bpf_btf_info info;
+ struct module_btf *mod_btf;
+ struct btf *btf;
+ char name[64];
+ __u32 id = 0, len;
+ int err, fd;
+
+ if (obj->btf_modules_loaded)
+ return 0;
+
+ /* don't do this again, even if we find no module BTFs */
+ obj->btf_modules_loaded = true;
+
+ /* kernel too old to support module BTFs */
+ if (!kernel_supports(FEAT_MODULE_BTF))
+ return 0;
+
+ while (true) {
+ err = bpf_btf_get_next_id(id, &id);
+ if (err && errno == ENOENT)
+ return 0;
+ if (err) {
+ err = -errno;
+ pr_warn("failed to iterate BTF objects: %d\n", err);
+ return err;
+ }
+
+ fd = bpf_btf_get_fd_by_id(id);
+ if (fd < 0) {
+ if (errno == ENOENT)
+ continue; /* expected race: BTF was unloaded */
+ err = -errno;
+ pr_warn("failed to get BTF object #%d FD: %d\n", id, err);
+ return err;
+ }
+
+ len = sizeof(info);
+ memset(&info, 0, sizeof(info));
+ info.name = ptr_to_u64(name);
+ info.name_len = sizeof(name);
+
+ err = bpf_obj_get_info_by_fd(fd, &info, &len);
+ if (err) {
+ err = -errno;
+ pr_warn("failed to get BTF object #%d info: %d\n", id, err);
+ close(fd);
+ return err;
+ }
+
+ /* ignore non-module BTFs */
+ if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
+ close(fd);
+ continue;
+ }
+
+ btf = btf_get_from_fd(fd, obj->btf_vmlinux);
+ close(fd);
+ if (IS_ERR(btf)) {
+ pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n",
+ name, id, PTR_ERR(btf));
+ return PTR_ERR(btf);
+ }
+
+ err = btf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
+ sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
+ if (err)
+ return err;
+
+ mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
+
+ mod_btf->btf = btf;
+ mod_btf->id = id;
+ mod_btf->name = strdup(name);
+ if (!mod_btf->name)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
static struct core_cand_list *
bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
{
struct core_cand local_cand = {};
struct core_cand_list *cands;
+ const struct btf *main_btf;
size_t local_essent_len;
- int err;
+ int err, i;
local_cand.btf = local_btf;
local_cand.t = btf__type_by_id(local_btf, local_type_id);
@@ -4697,15 +4825,38 @@ bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 l
return ERR_PTR(-ENOMEM);
/* Attempt to find target candidates in vmlinux BTF first */
- err = bpf_core_add_cands(&local_cand, local_essent_len,
- obj->btf_vmlinux_override ?: obj->btf_vmlinux,
- "vmlinux", 1, cands);
- if (err) {
- bpf_core_free_cands(cands);
- return ERR_PTR(err);
+ main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
+ err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
+ if (err)
+ goto err_out;
+
+ /* if vmlinux BTF has any candidate, don't got for module BTFs */
+ if (cands->len)
+ return cands;
+
+ /* if vmlinux BTF was overridden, don't attempt to load module BTFs */
+ if (obj->btf_vmlinux_override)
+ return cands;
+
+ /* now look through module BTFs, trying to still find candidates */
+ err = load_module_btfs(obj);
+ if (err)
+ goto err_out;
+
+ for (i = 0; i < obj->btf_module_cnt; i++) {
+ err = bpf_core_add_cands(&local_cand, local_essent_len,
+ obj->btf_modules[i].btf,
+ obj->btf_modules[i].name,
+ btf__get_nr_types(obj->btf_vmlinux) + 1,
+ cands);
+ if (err)
+ goto err_out;
}
return cands;
+err_out:
+ bpf_core_free_cands(cands);
+ return ERR_PTR(err);
}
/* Check two types for compatibility for the purpose of field access
@@ -5756,7 +5907,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
if (!hashmap__find(cand_cache, type_key, (void **)&cands)) {
cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
if (IS_ERR(cands)) {
- pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld",
+ pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
prog->name, relo_idx, local_id, btf_kind_str(local_type),
local_name, PTR_ERR(cands));
return PTR_ERR(cands);
@@ -5944,7 +6095,7 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
}
out:
- /* obj->btf_vmlinux is freed at the end of object load phase */
+ /* obj->btf_vmlinux and module BTFs are freed after object load */
btf__free(obj->btf_vmlinux_override);
obj->btf_vmlinux_override = NULL;
@@ -7316,6 +7467,14 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
err = err ? : bpf_object__load_progs(obj, attr->log_level);
+ /* clean up module BTFs */
+ for (i = 0; i < obj->btf_module_cnt; i++) {
+ btf__free(obj->btf_modules[i].btf);
+ free(obj->btf_modules[i].name);
+ }
+ free(obj->btf_modules);
+
+ /* clean up vmlinux BTF */
btf__free(obj->btf_vmlinux);
obj->btf_vmlinux = NULL;
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-18 05:22:01 +0000