bpf: Add support for kfunc set with common btf_ids

Later on, we will introduce kfuncs bpf_cast_to_kern_ctx() and
bpf_rdonly_cast() which apply to all program types. Currently kfunc set
only supports individual prog types. This patch added support for kfunc
applying to all program types.

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221120195426.3113828-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index d52054e..1c78d4d 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -199,6 +199,7 @@ DEFINE_IDR(btf_idr);
 DEFINE_SPINLOCK(btf_idr_lock);
 
 enum btf_kfunc_hook {
+       BTF_KFUNC_HOOK_COMMON,
        BTF_KFUNC_HOOK_XDP,
        BTF_KFUNC_HOOK_TC,
        BTF_KFUNC_HOOK_STRUCT_OPS,
@@ -7531,6 +7532,8 @@ static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
 static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
 {
        switch (prog_type) {
+       case BPF_PROG_TYPE_UNSPEC:
+               return BTF_KFUNC_HOOK_COMMON;
        case BPF_PROG_TYPE_XDP:
                return BTF_KFUNC_HOOK_XDP;
        case BPF_PROG_TYPE_SCHED_CLS:
@@ -7559,6 +7562,11 @@ u32 *btf_kfunc_id_set_contains(const struct btf *btf,
                               u32 kfunc_btf_id)
 {
        enum btf_kfunc_hook hook;
+       u32 *kfunc_flags;
+
+       kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, kfunc_btf_id);
+       if (kfunc_flags)
+               return kfunc_flags;
 
        hook = bpf_prog_type_to_kfunc_hook(prog_type);
        return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id);

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 3d4edd3..8e0d80b 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1901,10 +1901,19 @@ static const struct btf_kfunc_id_set generic_kfunc_set = {
        .set   = &generic_btf_ids,
 };
 
+
 BTF_ID_LIST(generic_dtor_ids)
 BTF_ID(struct, task_struct)
 BTF_ID(func, bpf_task_release)
 
+BTF_SET8_START(common_btf_ids)
+BTF_SET8_END(common_btf_ids)
+
+static const struct btf_kfunc_id_set common_kfunc_set = {
+       .owner = THIS_MODULE,
+       .set   = &common_btf_ids,
+};
+
 static int __init kfunc_init(void)
 {
        int ret;
@@ -1918,9 +1927,10 @@ static int __init kfunc_init(void)
        ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &generic_kfunc_set);
        ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &generic_kfunc_set);
        ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set);
-       return ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
+       ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
                                                  ARRAY_SIZE(generic_dtors),
                                                  THIS_MODULE);
+       return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &common_kfunc_set);
 }
 
 late_initcall(kfunc_init);