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-rw-r--r--tools/lib/bpf/libbpf.c112
1 files changed, 99 insertions, 13 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a4f55f8a460d..9b36c52b8511 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -390,6 +390,12 @@ struct extern_desc {
} kcfg;
struct {
unsigned long long addr;
+
+ /* target btf_id of the corresponding kernel var. */
+ int vmlinux_btf_id;
+
+ /* local btf_id of the ksym extern's type. */
+ __u32 type_id;
} ksym;
};
};
@@ -2522,12 +2528,23 @@ static int bpf_object__load_vmlinux_btf(struct bpf_object *obj)
{
bool need_vmlinux_btf = false;
struct bpf_program *prog;
- int err;
+ int i, err;
/* CO-RE relocations need kernel BTF */
if (obj->btf_ext && obj->btf_ext->core_relo_info.len)
need_vmlinux_btf = 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;
+ }
+ }
+
bpf_object__for_each_program(prog, obj) {
if (!prog->load)
continue;
@@ -3156,16 +3173,10 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
return -ENOTSUP;
}
} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
- const struct btf_type *vt;
-
ksym_sec = sec;
ext->type = EXT_KSYM;
-
- vt = skip_mods_and_typedefs(obj->btf, t->type, NULL);
- if (!btf_is_void(vt)) {
- pr_warn("extern (ksym) '%s' is not typeless (void)\n", ext_name);
- return -ENOTSUP;
- }
+ skip_mods_and_typedefs(obj->btf, t->type,
+ &ext->ksym.type_id);
} else {
pr_warn("unrecognized extern section '%s'\n", sec_name);
return -ENOTSUP;
@@ -5800,8 +5811,13 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
insn[1].imm = ext->kcfg.data_off;
} else /* EXT_KSYM */ {
- insn[0].imm = (__u32)ext->ksym.addr;
- insn[1].imm = ext->ksym.addr >> 32;
+ if (ext->ksym.type_id) { /* typed ksyms */
+ insn[0].src_reg = BPF_PSEUDO_BTF_ID;
+ insn[0].imm = ext->ksym.vmlinux_btf_id;
+ } else { /* typeless ksyms */
+ insn[0].imm = (__u32)ext->ksym.addr;
+ insn[1].imm = ext->ksym.addr >> 32;
+ }
}
relo->processed = true;
break;
@@ -6933,10 +6949,72 @@ out:
return err;
}
+static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
+{
+ struct extern_desc *ext;
+ int i, id;
+
+ for (i = 0; i < obj->nr_extern; i++) {
+ const struct btf_type *targ_var, *targ_type;
+ __u32 targ_type_id, local_type_id;
+ const char *targ_var_name;
+ int ret;
+
+ ext = &obj->externs[i];
+ if (ext->type != EXT_KSYM || !ext->ksym.type_id)
+ continue;
+
+ id = btf__find_by_name_kind(obj->btf_vmlinux, ext->name,
+ BTF_KIND_VAR);
+ if (id <= 0) {
+ pr_warn("extern (ksym) '%s': failed to find BTF ID in vmlinux BTF.\n",
+ ext->name);
+ return -ESRCH;
+ }
+
+ /* find local type_id */
+ local_type_id = ext->ksym.type_id;
+
+ /* find target type_id */
+ targ_var = btf__type_by_id(obj->btf_vmlinux, id);
+ targ_var_name = btf__name_by_offset(obj->btf_vmlinux,
+ targ_var->name_off);
+ targ_type = skip_mods_and_typedefs(obj->btf_vmlinux,
+ targ_var->type,
+ &targ_type_id);
+
+ ret = bpf_core_types_are_compat(obj->btf, local_type_id,
+ obj->btf_vmlinux, targ_type_id);
+ if (ret <= 0) {
+ const struct btf_type *local_type;
+ const char *targ_name, *local_name;
+
+ local_type = btf__type_by_id(obj->btf, local_type_id);
+ local_name = btf__name_by_offset(obj->btf,
+ local_type->name_off);
+ targ_name = btf__name_by_offset(obj->btf_vmlinux,
+ targ_type->name_off);
+
+ pr_warn("extern (ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
+ ext->name, local_type_id,
+ btf_kind_str(local_type), local_name, targ_type_id,
+ btf_kind_str(targ_type), targ_name);
+ return -EINVAL;
+ }
+
+ ext->is_set = true;
+ ext->ksym.vmlinux_btf_id = id;
+ pr_debug("extern (ksym) '%s': resolved to [%d] %s %s\n",
+ ext->name, id, btf_kind_str(targ_var), targ_var_name);
+ }
+ return 0;
+}
+
static int bpf_object__resolve_externs(struct bpf_object *obj,
const char *extra_kconfig)
{
bool need_config = false, need_kallsyms = false;
+ bool need_vmlinux_btf = false;
struct extern_desc *ext;
void *kcfg_data = NULL;
int err, i;
@@ -6967,7 +7045,10 @@ static int bpf_object__resolve_externs(struct bpf_object *obj,
strncmp(ext->name, "CONFIG_", 7) == 0) {
need_config = true;
} else if (ext->type == EXT_KSYM) {
- need_kallsyms = true;
+ if (ext->ksym.type_id)
+ need_vmlinux_btf = true;
+ else
+ need_kallsyms = true;
} else {
pr_warn("unrecognized extern '%s'\n", ext->name);
return -EINVAL;
@@ -6996,6 +7077,11 @@ static int bpf_object__resolve_externs(struct bpf_object *obj,
if (err)
return -EINVAL;
}
+ if (need_vmlinux_btf) {
+ err = bpf_object__resolve_ksyms_btf_id(obj);
+ if (err)
+ return -EINVAL;
+ }
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
@@ -7028,10 +7114,10 @@ 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__resolve_externs(obj, obj->kconfig);
err = err ? : bpf_object__sanitize_and_load_btf(obj);
err = err ? : bpf_object__sanitize_maps(obj);
- err = err ? : bpf_object__load_vmlinux_btf(obj);
err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
err = err ? : bpf_object__create_maps(obj);
err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-28 17:14:41 +0000