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bpf: Remove btf_id helpers resolving

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Now when we moved the helpers btf_id arrays into .BTF_ids section,
we can remove the code that resolve those IDs in runtime.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-6-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2020-07-11 23:53:25 +02:00 committed by Alexei Starovoitov
parent c9a0f3b85e
commit 138b9a0511
1 changed files with 5 additions and 84 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

89
kernel/bpf/btf.c
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@ -4079,96 +4079,17 @@ int btf_struct_access(struct bpf_verifier_log *log,
return -EINVAL;
}
static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn,
int arg)
{
char fnname[KSYM_SYMBOL_LEN + 4] = "btf_";
const struct btf_param *args;
const struct btf_type *t;
const char *tname, *sym;
u32 btf_id, i;
if (IS_ERR(btf_vmlinux)) {
bpf_log(log, "btf_vmlinux is malformed\n");
return -EINVAL;
}
sym = kallsyms_lookup((long)fn, NULL, NULL, NULL, fnname + 4);
if (!sym) {
bpf_log(log, "kernel doesn't have kallsyms\n");
return -EFAULT;
}
for (i = 1; i <= btf_vmlinux->nr_types; i++) {
t = btf_type_by_id(btf_vmlinux, i);
if (BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF)
continue;
tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
if (!strcmp(tname, fnname))
break;
}
if (i > btf_vmlinux->nr_types) {
bpf_log(log, "helper %s type is not found\n", fnname);
return -ENOENT;
}
t = btf_type_by_id(btf_vmlinux, t->type);
if (!btf_type_is_ptr(t))
return -EFAULT;
t = btf_type_by_id(btf_vmlinux, t->type);
if (!btf_type_is_func_proto(t))
return -EFAULT;
args = (const struct btf_param *)(t + 1);
if (arg >= btf_type_vlen(t)) {
bpf_log(log, "bpf helper %s doesn't have %d-th argument\n",
fnname, arg);
return -EINVAL;
}
t = btf_type_by_id(btf_vmlinux, args[arg].type);
if (!btf_type_is_ptr(t) || !t->type) {
/* anything but the pointer to struct is a helper config bug */
bpf_log(log, "ARG_PTR_TO_BTF is misconfigured\n");
return -EFAULT;
}
btf_id = t->type;
t = btf_type_by_id(btf_vmlinux, t->type);
/* skip modifiers */
while (btf_type_is_modifier(t)) {
btf_id = t->type;
t = btf_type_by_id(btf_vmlinux, t->type);
}
if (!btf_type_is_struct(t)) {
bpf_log(log, "ARG_PTR_TO_BTF is not a struct\n");
return -EFAULT;
}
bpf_log(log, "helper %s arg%d has btf_id %d struct %s\n", fnname + 4,
arg, btf_id, __btf_name_by_offset(btf_vmlinux, t->name_off));
return btf_id;
}
int btf_resolve_helper_id(struct bpf_verifier_log *log,
const struct bpf_func_proto *fn, int arg)
{
int *btf_id = &fn->btf_id[arg];
int ret;
int id;
if (fn->arg_type[arg] != ARG_PTR_TO_BTF_ID)
return -EINVAL;
ret = READ_ONCE(*btf_id);
if (ret)
return ret;
/* ok to race the search. The result is the same */
ret = __btf_resolve_helper_id(log, fn->func, arg);
if (!ret) {
/* Function argument cannot be type 'void' */
bpf_log(log, "BTF resolution bug\n");
return -EFAULT;
}
WRITE_ONCE(*btf_id, ret);
return ret;
id = fn->btf_id[arg];
if (!id || id > btf_vmlinux->nr_types)
return -EINVAL;
return id;
}
static int __get_type_size(struct btf *btf, u32 btf_id,