bpf: Switch to new kfunc flags infrastructure

Instead of populating multiple sets to indicate some attribute and then
researching the same BTF ID in them, prepare a single unified BTF set
which indicates whether a kfunc is allowed to be called, and also its
attributes if any at the same time. Now, only one call is needed to
perform the lookup for both kfunc availability and its attributes.

Signed-off-by: Kumar Kartikeya Dwivedi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

include/linux/bpf.h

···
 				struct bpf_reg_state *regs);
 int btf_check_kfunc_arg_match(struct bpf_verifier_env *env,
 			      const struct btf *btf, u32 func_id,
-			      struct bpf_reg_state *regs);
+			      struct bpf_reg_state *regs,
+			      u32 kfunc_flags);
 int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
 			  struct bpf_reg_state *reg);
 int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,

include/linux/btf.h

···
 #define BTF_TYPE_EMIT(type) ((void)(type *)0)
 #define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val)
 
-enum btf_kfunc_type {
-	BTF_KFUNC_TYPE_CHECK,
-	BTF_KFUNC_TYPE_ACQUIRE,
-	BTF_KFUNC_TYPE_RELEASE,
-	BTF_KFUNC_TYPE_RET_NULL,
-	BTF_KFUNC_TYPE_KPTR_ACQUIRE,
-	BTF_KFUNC_TYPE_MAX,
-};
+/* These need to be macros, as the expressions are used in assembler input */
+#define KF_ACQUIRE	(1 << 0) /* kfunc is an acquire function */
+#define KF_RELEASE	(1 << 1) /* kfunc is a release function */
+#define KF_RET_NULL	(1 << 2) /* kfunc returns a pointer that may be NULL */
+#define KF_KPTR_GET	(1 << 3) /* kfunc returns reference to a kptr */
 
 struct btf;
 struct btf_member;
···
 
 struct btf_kfunc_id_set {
 	struct module *owner;
-	union {
-		struct {
-			struct btf_id_set *check_set;
-			struct btf_id_set *acquire_set;
-			struct btf_id_set *release_set;
-			struct btf_id_set *ret_null_set;
-			struct btf_id_set *kptr_acquire_set;
-		};
-		struct btf_id_set *sets[BTF_KFUNC_TYPE_MAX];
-	};
+	struct btf_id_set8 *set;
 };
 
 struct btf_id_dtor_kfunc {
···
 const char *btf_name_by_offset(const struct btf *btf, u32 offset);
 struct btf *btf_parse_vmlinux(void);
 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
-bool btf_kfunc_id_set_contains(const struct btf *btf,
+u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 			       enum bpf_prog_type prog_type,
-			       enum btf_kfunc_type type, u32 kfunc_btf_id);
+			       u32 kfunc_btf_id);
 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 			      const struct btf_kfunc_id_set *s);
 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
···
 {
 	return NULL;
 }
-static inline bool btf_kfunc_id_set_contains(const struct btf *btf,
+static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 					     enum bpf_prog_type prog_type,
-					     enum btf_kfunc_type type,
 					     u32 kfunc_btf_id)
 {
-	return false;
+	return NULL;
 }
 static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 					    const struct btf_kfunc_id_set *s)

kernel/bpf/btf.c

···
 };
 
 struct btf_kfunc_set_tab {
-	struct btf_id_set *sets[BTF_KFUNC_HOOK_MAX][BTF_KFUNC_TYPE_MAX];
+	struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
 };
 
 struct btf_id_dtor_kfunc_tab {
···
 static void btf_free_kfunc_set_tab(struct btf *btf)
 {
 	struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
-	int hook, type;
+	int hook;
 
 	if (!tab)
 		return;
···
 	 */
 	if (btf_is_module(btf))
 		goto free_tab;
-	for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++) {
-		for (type = 0; type < ARRAY_SIZE(tab->sets[0]); type++)
-			kfree(tab->sets[hook][type]);
-	}
+	for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++)
+		kfree(tab->sets[hook]);
 free_tab:
 	kfree(tab);
 	btf->kfunc_set_tab = NULL;
···
 static int btf_check_func_arg_match(struct bpf_verifier_env *env,
 				    const struct btf *btf, u32 func_id,
 				    struct bpf_reg_state *regs,
-				    bool ptr_to_mem_ok)
+				    bool ptr_to_mem_ok,
+				    u32 kfunc_flags)
 {
 	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
 	struct bpf_verifier_log *log = &env->log;
···
 
 	if (is_kfunc) {
 		/* Only kfunc can be release func */
-		rel = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
-						BTF_KFUNC_TYPE_RELEASE, func_id);
-		kptr_get = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
-						     BTF_KFUNC_TYPE_KPTR_ACQUIRE, func_id);
+		rel = kfunc_flags & KF_RELEASE;
+		kptr_get = kfunc_flags & KF_KPTR_GET;
 	}
 
 	/* check that BTF function arguments match actual types that the
···
 		return -EINVAL;
 
 	is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
-	err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global);
+	err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, 0);
 
 	/* Compiler optimizations can remove arguments from static functions
 	 * or mismatched type can be passed into a global function.
···
 
 int btf_check_kfunc_arg_match(struct bpf_verifier_env *env,
 			      const struct btf *btf, u32 func_id,
-			      struct bpf_reg_state *regs)
+			      struct bpf_reg_state *regs,
+			      u32 kfunc_flags)
 {
-	return btf_check_func_arg_match(env, btf, func_id, regs, true);
+	return btf_check_func_arg_match(env, btf, func_id, regs, true, kfunc_flags);
 }
 
 /* Convert BTF of a function into bpf_reg_state if possible
···
 	return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
 }
 
+static void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
+{
+	return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
+}
+
 enum {
 	BTF_MODULE_F_LIVE = (1 << 0),
 };
···
 
 /* Kernel Function (kfunc) BTF ID set registration API */
 
-static int __btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
-				    enum btf_kfunc_type type,
-				    struct btf_id_set *add_set, bool vmlinux_set)
+static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
+				  struct btf_id_set8 *add_set)
 {
+	bool vmlinux_set = !btf_is_module(btf);
 	struct btf_kfunc_set_tab *tab;
-	struct btf_id_set *set;
+	struct btf_id_set8 *set;
 	u32 set_cnt;
 	int ret;
 
-	if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX) {
+	if (hook >= BTF_KFUNC_HOOK_MAX) {
 		ret = -EINVAL;
 		goto end;
 	}
···
 		btf->kfunc_set_tab = tab;
 	}
 
-	set = tab->sets[hook][type];
+	set = tab->sets[hook];
 	/* Warn when register_btf_kfunc_id_set is called twice for the same hook
 	 * for module sets.
 	 */
···
 	 * pointer and return.
 	 */
 	if (!vmlinux_set) {
-		tab->sets[hook][type] = add_set;
+		tab->sets[hook] = add_set;
 		return 0;
 	}
 
···
 	 * and concatenate all individual sets being registered. While each set
 	 * is individually sorted, they may become unsorted when concatenated,
 	 * hence re-sorting the final set again is required to make binary
-	 * searching the set using btf_id_set_contains function work.
+	 * searching the set using btf_id_set8_contains function work.
 	 */
 	set_cnt = set ? set->cnt : 0;
 
···
 	}
 
 	/* Grow set */
-	set = krealloc(tab->sets[hook][type],
-		       offsetof(struct btf_id_set, ids[set_cnt + add_set->cnt]),
+	set = krealloc(tab->sets[hook],
+		       offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]),
 		       GFP_KERNEL | __GFP_NOWARN);
 	if (!set) {
 		ret = -ENOMEM;
···
 	}
 
 	/* For newly allocated set, initialize set->cnt to 0 */
-	if (!tab->sets[hook][type])
+	if (!tab->sets[hook])
 		set->cnt = 0;
-	tab->sets[hook][type] = set;
+	tab->sets[hook] = set;
 
 	/* Concatenate the two sets */
-	memcpy(set->ids + set->cnt, add_set->ids, add_set->cnt * sizeof(set->ids[0]));
+	memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0]));
 	set->cnt += add_set->cnt;
 
-	sort(set->ids, set->cnt, sizeof(set->ids[0]), btf_id_cmp_func, NULL);
+	sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);
 
 	return 0;
 end:
···
 	return ret;
 }
 
-static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
-				  const struct btf_kfunc_id_set *kset)
-{
-	bool vmlinux_set = !btf_is_module(btf);
-	int type, ret = 0;
-
-	for (type = 0; type < ARRAY_SIZE(kset->sets); type++) {
-		if (!kset->sets[type])
-			continue;
-
-		ret = __btf_populate_kfunc_set(btf, hook, type, kset->sets[type], vmlinux_set);
-		if (ret)
-			break;
-	}
-	return ret;
-}
-
-static bool __btf_kfunc_id_set_contains(const struct btf *btf,
+static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
 					enum btf_kfunc_hook hook,
-					enum btf_kfunc_type type,
 					u32 kfunc_btf_id)
 {
-	struct btf_id_set *set;
+	struct btf_id_set8 *set;
+	u32 *id;
 
-	if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX)
-		return false;
+	if (hook >= BTF_KFUNC_HOOK_MAX)
+		return NULL;
 	if (!btf->kfunc_set_tab)
-		return false;
-	set = btf->kfunc_set_tab->sets[hook][type];
+		return NULL;
+	set = btf->kfunc_set_tab->sets[hook];
 	if (!set)
-		return false;
-	return btf_id_set_contains(set, kfunc_btf_id);
+		return NULL;
+	id = btf_id_set8_contains(set, kfunc_btf_id);
+	if (!id)
+		return NULL;
+	/* The flags for BTF ID are located next to it */
+	return id + 1;
 }
 
 static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
···
  * keeping the reference for the duration of the call provides the necessary
  * protection for looking up a well-formed btf->kfunc_set_tab.
  */
-bool btf_kfunc_id_set_contains(const struct btf *btf,
+u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 			       enum bpf_prog_type prog_type,
-			       enum btf_kfunc_type type, u32 kfunc_btf_id)
+			       u32 kfunc_btf_id)
 {
 	enum btf_kfunc_hook hook;
 
 	hook = bpf_prog_type_to_kfunc_hook(prog_type);
-	return __btf_kfunc_id_set_contains(btf, hook, type, kfunc_btf_id);
+	return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id);
 }
 
 /* This function must be invoked only from initcalls/module init functions */
···
 		return PTR_ERR(btf);
 
 	hook = bpf_prog_type_to_kfunc_hook(prog_type);
-	ret = btf_populate_kfunc_set(btf, hook, kset);
+	ret = btf_populate_kfunc_set(btf, hook, kset->set);
 	btf_put(btf);
 	return ret;
 }

kernel/bpf/verifier.c

···
 	int err, insn_idx = *insn_idx_p;
 	const struct btf_param *args;
 	struct btf *desc_btf;
+	u32 *kfunc_flags;
 	bool acq;
 
 	/* skip for now, but return error when we find this in fixup_kfunc_call */
···
 	func_name = btf_name_by_offset(desc_btf, func->name_off);
 	func_proto = btf_type_by_id(desc_btf, func->type);
 
-	if (!btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
-				      BTF_KFUNC_TYPE_CHECK, func_id)) {
+	kfunc_flags = btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog), func_id);
+	if (!kfunc_flags) {
 		verbose(env, "calling kernel function %s is not allowed\n",
 			func_name);
 		return -EACCES;
 	}
-
-	acq = btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
-					BTF_KFUNC_TYPE_ACQUIRE, func_id);
+	acq = *kfunc_flags & KF_ACQUIRE;
 
 	/* Check the arguments */
-	err = btf_check_kfunc_arg_match(env, desc_btf, func_id, regs);
+	err = btf_check_kfunc_arg_match(env, desc_btf, func_id, regs, *kfunc_flags);
 	if (err < 0)
 		return err;
 	/* In case of release function, we get register number of refcounted
···
 		regs[BPF_REG_0].btf = desc_btf;
 		regs[BPF_REG_0].type = PTR_TO_BTF_ID;
 		regs[BPF_REG_0].btf_id = ptr_type_id;
-		if (btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
-					      BTF_KFUNC_TYPE_RET_NULL, func_id)) {
+		if (*kfunc_flags & KF_RET_NULL) {
 			regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
 			/* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
 			regs[BPF_REG_0].id = ++env->id_gen;

net/bpf/test_run.c

···
 
 ALLOW_ERROR_INJECTION(bpf_modify_return_test, ERRNO);
 
-BTF_SET_START(test_sk_check_kfunc_ids)
-BTF_ID(func, bpf_kfunc_call_test1)
-BTF_ID(func, bpf_kfunc_call_test2)
-BTF_ID(func, bpf_kfunc_call_test3)
-BTF_ID(func, bpf_kfunc_call_test_acquire)
-BTF_ID(func, bpf_kfunc_call_memb_acquire)
-BTF_ID(func, bpf_kfunc_call_test_release)
-BTF_ID(func, bpf_kfunc_call_memb_release)
-BTF_ID(func, bpf_kfunc_call_memb1_release)
-BTF_ID(func, bpf_kfunc_call_test_kptr_get)
-BTF_ID(func, bpf_kfunc_call_test_pass_ctx)
-BTF_ID(func, bpf_kfunc_call_test_pass1)
-BTF_ID(func, bpf_kfunc_call_test_pass2)
-BTF_ID(func, bpf_kfunc_call_test_fail1)
-BTF_ID(func, bpf_kfunc_call_test_fail2)
-BTF_ID(func, bpf_kfunc_call_test_fail3)
-BTF_ID(func, bpf_kfunc_call_test_mem_len_pass1)
-BTF_ID(func, bpf_kfunc_call_test_mem_len_fail1)
-BTF_ID(func, bpf_kfunc_call_test_mem_len_fail2)
-BTF_SET_END(test_sk_check_kfunc_ids)
-
-BTF_SET_START(test_sk_acquire_kfunc_ids)
-BTF_ID(func, bpf_kfunc_call_test_acquire)
-BTF_ID(func, bpf_kfunc_call_memb_acquire)
-BTF_ID(func, bpf_kfunc_call_test_kptr_get)
-BTF_SET_END(test_sk_acquire_kfunc_ids)
-
-BTF_SET_START(test_sk_release_kfunc_ids)
-BTF_ID(func, bpf_kfunc_call_test_release)
-BTF_ID(func, bpf_kfunc_call_memb_release)
-BTF_ID(func, bpf_kfunc_call_memb1_release)
-BTF_SET_END(test_sk_release_kfunc_ids)
-
-BTF_SET_START(test_sk_ret_null_kfunc_ids)
-BTF_ID(func, bpf_kfunc_call_test_acquire)
-BTF_ID(func, bpf_kfunc_call_memb_acquire)
-BTF_ID(func, bpf_kfunc_call_test_kptr_get)
-BTF_SET_END(test_sk_ret_null_kfunc_ids)
-
-BTF_SET_START(test_sk_kptr_acquire_kfunc_ids)
-BTF_ID(func, bpf_kfunc_call_test_kptr_get)
-BTF_SET_END(test_sk_kptr_acquire_kfunc_ids)
+BTF_SET8_START(test_sk_check_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test2)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test3)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_acquire, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_kfunc_call_memb_acquire, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_release, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_kfunc_call_memb_release, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_kfunc_call_memb1_release, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_kptr_get, KF_ACQUIRE | KF_RET_NULL | KF_KPTR_GET)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_pass_ctx)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_pass1)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_pass2)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_fail1)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_fail2)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_fail3)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_pass1)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
+BTF_SET8_END(test_sk_check_kfunc_ids)
 
 static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
 			   u32 size, u32 headroom, u32 tailroom)
···
 }
 
 static const struct btf_kfunc_id_set bpf_prog_test_kfunc_set = {
-	.owner        = THIS_MODULE,
-	.check_set        = &test_sk_check_kfunc_ids,
-	.acquire_set      = &test_sk_acquire_kfunc_ids,
-	.release_set      = &test_sk_release_kfunc_ids,
-	.ret_null_set     = &test_sk_ret_null_kfunc_ids,
-	.kptr_acquire_set = &test_sk_kptr_acquire_kfunc_ids
+	.owner = THIS_MODULE,
+	.set   = &test_sk_check_kfunc_ids,
 };
 
 BTF_ID_LIST(bpf_prog_test_dtor_kfunc_ids)

net/ipv4/bpf_tcp_ca.c

···
 	}
 }
 
-BTF_SET_START(bpf_tcp_ca_check_kfunc_ids)
-BTF_ID(func, tcp_reno_ssthresh)
-BTF_ID(func, tcp_reno_cong_avoid)
-BTF_ID(func, tcp_reno_undo_cwnd)
-BTF_ID(func, tcp_slow_start)
-BTF_ID(func, tcp_cong_avoid_ai)
-BTF_SET_END(bpf_tcp_ca_check_kfunc_ids)
+BTF_SET8_START(bpf_tcp_ca_check_kfunc_ids)
+BTF_ID_FLAGS(func, tcp_reno_ssthresh)
+BTF_ID_FLAGS(func, tcp_reno_cong_avoid)
+BTF_ID_FLAGS(func, tcp_reno_undo_cwnd)
+BTF_ID_FLAGS(func, tcp_slow_start)
+BTF_ID_FLAGS(func, tcp_cong_avoid_ai)
+BTF_SET8_END(bpf_tcp_ca_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = {
-	.owner     = THIS_MODULE,
-	.check_set = &bpf_tcp_ca_check_kfunc_ids,
+	.owner = THIS_MODULE,
+	.set   = &bpf_tcp_ca_check_kfunc_ids,
 };
 
 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {

net/ipv4/tcp_bbr.c

···
 	.set_state	= bbr_set_state,
 };
 
-BTF_SET_START(tcp_bbr_check_kfunc_ids)
+BTF_SET8_START(tcp_bbr_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
-BTF_ID(func, bbr_init)
-BTF_ID(func, bbr_main)
-BTF_ID(func, bbr_sndbuf_expand)
-BTF_ID(func, bbr_undo_cwnd)
-BTF_ID(func, bbr_cwnd_event)
-BTF_ID(func, bbr_ssthresh)
-BTF_ID(func, bbr_min_tso_segs)
-BTF_ID(func, bbr_set_state)
+BTF_ID_FLAGS(func, bbr_init)
+BTF_ID_FLAGS(func, bbr_main)
+BTF_ID_FLAGS(func, bbr_sndbuf_expand)
+BTF_ID_FLAGS(func, bbr_undo_cwnd)
+BTF_ID_FLAGS(func, bbr_cwnd_event)
+BTF_ID_FLAGS(func, bbr_ssthresh)
+BTF_ID_FLAGS(func, bbr_min_tso_segs)
+BTF_ID_FLAGS(func, bbr_set_state)
 #endif
 #endif
-BTF_SET_END(tcp_bbr_check_kfunc_ids)
+BTF_SET8_END(tcp_bbr_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_bbr_kfunc_set = {
-	.owner     = THIS_MODULE,
-	.check_set = &tcp_bbr_check_kfunc_ids,
+	.owner = THIS_MODULE,
+	.set   = &tcp_bbr_check_kfunc_ids,
 };
 
 static int __init bbr_register(void)

net/ipv4/tcp_cubic.c

···
 	.name		= "cubic",
 };
 
-BTF_SET_START(tcp_cubic_check_kfunc_ids)
+BTF_SET8_START(tcp_cubic_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
-BTF_ID(func, cubictcp_init)
-BTF_ID(func, cubictcp_recalc_ssthresh)
-BTF_ID(func, cubictcp_cong_avoid)
-BTF_ID(func, cubictcp_state)
-BTF_ID(func, cubictcp_cwnd_event)
-BTF_ID(func, cubictcp_acked)
+BTF_ID_FLAGS(func, cubictcp_init)
+BTF_ID_FLAGS(func, cubictcp_recalc_ssthresh)
+BTF_ID_FLAGS(func, cubictcp_cong_avoid)
+BTF_ID_FLAGS(func, cubictcp_state)
+BTF_ID_FLAGS(func, cubictcp_cwnd_event)
+BTF_ID_FLAGS(func, cubictcp_acked)
 #endif
 #endif
-BTF_SET_END(tcp_cubic_check_kfunc_ids)
+BTF_SET8_END(tcp_cubic_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_cubic_kfunc_set = {
-	.owner     = THIS_MODULE,
-	.check_set = &tcp_cubic_check_kfunc_ids,
+	.owner = THIS_MODULE,
+	.set   = &tcp_cubic_check_kfunc_ids,
 };
 
 static int __init cubictcp_register(void)

net/ipv4/tcp_dctcp.c

···
 	.name		= "dctcp-reno",
 };
 
-BTF_SET_START(tcp_dctcp_check_kfunc_ids)
+BTF_SET8_START(tcp_dctcp_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
-BTF_ID(func, dctcp_init)
-BTF_ID(func, dctcp_update_alpha)
-BTF_ID(func, dctcp_cwnd_event)
-BTF_ID(func, dctcp_ssthresh)
-BTF_ID(func, dctcp_cwnd_undo)
-BTF_ID(func, dctcp_state)
+BTF_ID_FLAGS(func, dctcp_init)
+BTF_ID_FLAGS(func, dctcp_update_alpha)
+BTF_ID_FLAGS(func, dctcp_cwnd_event)
+BTF_ID_FLAGS(func, dctcp_ssthresh)
+BTF_ID_FLAGS(func, dctcp_cwnd_undo)
+BTF_ID_FLAGS(func, dctcp_state)
 #endif
 #endif
-BTF_SET_END(tcp_dctcp_check_kfunc_ids)
+BTF_SET8_END(tcp_dctcp_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_dctcp_kfunc_set = {
-	.owner     = THIS_MODULE,
-	.check_set = &tcp_dctcp_check_kfunc_ids,
+	.owner = THIS_MODULE,
+	.set   = &tcp_dctcp_check_kfunc_ids,
 };
 
 static int __init dctcp_register(void)

net/netfilter/nf_conntrack_bpf.c

···
 
 __diag_pop()
 
-BTF_SET_START(nf_ct_xdp_check_kfunc_ids)
-BTF_ID(func, bpf_xdp_ct_lookup)
-BTF_ID(func, bpf_ct_release)
-BTF_SET_END(nf_ct_xdp_check_kfunc_ids)
+BTF_SET8_START(nf_ct_kfunc_set)
+BTF_ID_FLAGS(func, bpf_xdp_ct_lookup, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_skb_ct_lookup, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_ct_release, KF_RELEASE)
+BTF_SET8_END(nf_ct_kfunc_set)
 
-BTF_SET_START(nf_ct_tc_check_kfunc_ids)
-BTF_ID(func, bpf_skb_ct_lookup)
-BTF_ID(func, bpf_ct_release)
-BTF_SET_END(nf_ct_tc_check_kfunc_ids)
-
-BTF_SET_START(nf_ct_acquire_kfunc_ids)
-BTF_ID(func, bpf_xdp_ct_lookup)
-BTF_ID(func, bpf_skb_ct_lookup)
-BTF_SET_END(nf_ct_acquire_kfunc_ids)
-
-BTF_SET_START(nf_ct_release_kfunc_ids)
-BTF_ID(func, bpf_ct_release)
-BTF_SET_END(nf_ct_release_kfunc_ids)
-
-/* Both sets are identical */
-#define nf_ct_ret_null_kfunc_ids nf_ct_acquire_kfunc_ids
-
-static const struct btf_kfunc_id_set nf_conntrack_xdp_kfunc_set = {
-	.owner        = THIS_MODULE,
-	.check_set    = &nf_ct_xdp_check_kfunc_ids,
-	.acquire_set  = &nf_ct_acquire_kfunc_ids,
-	.release_set  = &nf_ct_release_kfunc_ids,
-	.ret_null_set = &nf_ct_ret_null_kfunc_ids,
-};
-
-static const struct btf_kfunc_id_set nf_conntrack_tc_kfunc_set = {
-	.owner        = THIS_MODULE,
-	.check_set    = &nf_ct_tc_check_kfunc_ids,
-	.acquire_set  = &nf_ct_acquire_kfunc_ids,
-	.release_set  = &nf_ct_release_kfunc_ids,
-	.ret_null_set = &nf_ct_ret_null_kfunc_ids,
+static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &nf_ct_kfunc_set,
 };
 
 int register_nf_conntrack_bpf(void)
 {
 	int ret;
 
-	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_xdp_kfunc_set);
-	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_tc_kfunc_set);
+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_kfunc_set);
+	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_kfunc_set);
 }

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

···
 	.write = bpf_testmod_test_write,
 };
 
-BTF_SET_START(bpf_testmod_check_kfunc_ids)
-BTF_ID(func, bpf_testmod_test_mod_kfunc)
-BTF_SET_END(bpf_testmod_check_kfunc_ids)
+BTF_SET8_START(bpf_testmod_check_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
+BTF_SET8_END(bpf_testmod_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set bpf_testmod_kfunc_set = {
-	.owner     = THIS_MODULE,
-	.check_set = &bpf_testmod_check_kfunc_ids,
+	.owner = THIS_MODULE,
+	.set   = &bpf_testmod_check_kfunc_ids,
 };
 
 extern int bpf_fentry_test1(int a);