From 138b9a0511c789f2451ff1d80e7fd3f9eef3a9e3 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sat, 11 Jul 2020 23:53:25 +0200 Subject: [PATCH] bpf: Remove btf_id helpers resolving 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 Signed-off-by: Alexei Starovoitov Tested-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200711215329.41165-6-jolsa@kernel.org --- kernel/bpf/btf.c | 89 +++--------------------------------------------- 1 file changed, 5 insertions(+), 84 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 4c3007f428b1..71140b73ae3c 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4079,96 +4079,17 @@ error: 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, -- 2.20.1