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libbpf: Refactor bpf_object__resolve_ksyms_btf_id 

This patch refactors most of the logic from
bpf_object__resolve_ksyms_btf_id() into a new function
bpf_object__resolve_ksym_var_btf_id().
It is to get ready for a later patch adding
bpf_object__resolve_ksym_func_btf_id() which resolves
a kernel function to the running kernel btf_id.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015207.1546749-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2021-03-24 18:52:07 -07:00 committed by Alexei Starovoitov
parent e78aea8b21
commit 933d1aa324
1 changed files with 70 additions and 60 deletions
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130
tools/lib/bpf/libbpf.c
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@ -7395,75 +7395,85 @@ out:
return err; return err;
} }
static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
struct extern_desc *ext)
{
const struct btf_type *targ_var, *targ_type;
__u32 targ_type_id, local_type_id;
const char *targ_var_name;
int i, id, btf_fd, err;
struct btf *btf;
btf = obj->btf_vmlinux;
btf_fd = 0;
id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR);
if (id == -ENOENT) {
err = load_module_btfs(obj);
if (err)
return err;
for (i = 0; i < obj->btf_module_cnt; i++) {
btf = obj->btf_modules[i].btf;
/* we assume module BTF FD is always >0 */
btf_fd = obj->btf_modules[i].fd;
id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR);
if (id != -ENOENT)
break;
}
}
if (id <= 0) {
pr_warn("extern (var ksym) '%s': failed to find BTF ID in kernel BTF(s).\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(btf, id);
targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
err = bpf_core_types_are_compat(obj->btf, local_type_id,
btf, targ_type_id);
if (err <= 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(btf, targ_type->name_off);
pr_warn("extern (var 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.kernel_btf_obj_fd = btf_fd;
ext->ksym.kernel_btf_id = id;
pr_debug("extern (var 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_ksyms_btf_id(struct bpf_object *obj) static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
{ {
struct extern_desc *ext; struct extern_desc *ext;
struct btf *btf; int i, err;
int i, j, id, btf_fd, err;
for (i = 0; i < obj->nr_extern; i++) { 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]; ext = &obj->externs[i];
if (ext->type != EXT_KSYM || !ext->ksym.type_id) if (ext->type != EXT_KSYM || !ext->ksym.type_id)
continue; continue;
btf = obj->btf_vmlinux; err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
btf_fd = 0; if (err)
id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); return err;
if (id == -ENOENT) {
err = load_module_btfs(obj);
if (err)
return err;
for (j = 0; j < obj->btf_module_cnt; j++) {
btf = obj->btf_modules[j].btf;
/* we assume module BTF FD is always >0 */
btf_fd = obj->btf_modules[j].fd;
id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR);
if (id != -ENOENT)
break;
}
}
if (id <= 0) {
pr_warn("extern (ksym) '%s': failed to find BTF ID in kernel BTF(s).\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(btf, id);
targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
ret = bpf_core_types_are_compat(obj->btf, local_type_id,
btf, 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(btf, 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.kernel_btf_obj_fd = btf_fd;
ext->ksym.kernel_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; return 0;
} }