On Sat, 2023-10-21 at 22:03 -0700, thinker.li@xxxxxxxxx wrote:
> From: Kui-Feng Lee <thinker.li@xxxxxxxxx>
>
> Replace the static list of struct_ops types with per-btf struct_ops_tab to
> enable dynamic registration.
>
> Both bpf_dummy_ops and bpf_tcp_ca now utilize the registration function
> instead of being listed in bpf_struct_ops_types.h.
>
> Cc: netdev@xxxxxxxxxxxxxxx
> Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>
Hello,
I left two nitpicks below, feel free to ignore if you think is good as-is.
> ---
> include/linux/bpf.h | 36 +++++++--
> include/linux/btf.h | 5 +-
> kernel/bpf/bpf_struct_ops.c | 123 ++++++++----------------------
> kernel/bpf/bpf_struct_ops_types.h | 12 ---
> kernel/bpf/btf.c | 41 +++++++++-
> net/bpf/bpf_dummy_struct_ops.c | 14 +++-
> net/ipv4/bpf_tcp_ca.c | 16 +++-
> 7 files changed, 130 insertions(+), 117 deletions(-)
> delete mode 100644 kernel/bpf/bpf_struct_ops_types.h
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 26feb8a2da4f..a53b2181c845 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1644,7 +1644,6 @@ struct bpf_struct_ops_desc {
> #if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL)
> #define BPF_MODULE_OWNER ((void *)((0xeB9FUL << 2) + POISON_POINTER_DELTA))
> const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *btf, u32 type_id);
> -void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log);
> bool bpf_struct_ops_get(const void *kdata);
> void bpf_struct_ops_put(const void *kdata);
> int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key,
> @@ -1690,10 +1689,6 @@ static inline const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *
> {
> return NULL;
> }
> -static inline void bpf_struct_ops_init(struct btf *btf,
> - struct bpf_verifier_log *log)
> -{
> -}
> static inline bool bpf_try_module_get(const void *data, struct module *owner)
> {
> return try_module_get(owner);
> @@ -3212,4 +3207,35 @@ static inline bool bpf_is_subprog(const struct bpf_prog *prog)
> return prog->aux->func_idx != 0;
> }
>
> +int register_bpf_struct_ops(struct bpf_struct_ops *st_ops);
> +
> +enum bpf_struct_ops_state {
> + BPF_STRUCT_OPS_STATE_INIT,
> + BPF_STRUCT_OPS_STATE_INUSE,
> + BPF_STRUCT_OPS_STATE_TOBEFREE,
> + BPF_STRUCT_OPS_STATE_READY,
> +};
> +
> +struct bpf_struct_ops_common_value {
> + refcount_t refcnt;
> + enum bpf_struct_ops_state state;
> +};
> +
> +/* bpf_struct_ops_##_name (e.g. bpf_struct_ops_tcp_congestion_ops) is
> + * the map's value exposed to the userspace and its btf-type-id is
> + * stored at the map->btf_vmlinux_value_type_id.
> + *
> + */
> +#define DEFINE_STRUCT_OPS_VALUE_TYPE(_name) \
> +extern struct bpf_struct_ops bpf_##_name; \
> + \
> +struct bpf_struct_ops_##_name { \
> + struct bpf_struct_ops_common_value common; \
> + struct _name data ____cacheline_aligned_in_smp; \
> +}
> +
> +extern void bpf_struct_ops_init(struct bpf_struct_ops_desc *st_ops_desc,
> + struct btf *btf,
> + struct bpf_verifier_log *log);
> +
> #endif /* _LINUX_BPF_H */
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index 6a64b372b7a0..533db3f406b3 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -12,6 +12,8 @@
> #include <uapi/linux/bpf.h>
>
> #define BTF_TYPE_EMIT(type) ((void)(type *)0)
> +#define BTF_STRUCT_OPS_TYPE_EMIT(type) {((void)(struct type *)0); \
> + ((void)(struct bpf_struct_ops_##type *)0); }
> #define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val)
>
> /* These need to be macros, as the expressions are used in assembler input */
> @@ -200,6 +202,7 @@ u32 btf_obj_id(const struct btf *btf);
> bool btf_is_kernel(const struct btf *btf);
> bool btf_is_module(const struct btf *btf);
> struct module *btf_try_get_module(const struct btf *btf);
> +struct btf *btf_get_module_btf(const struct module *module);
> u32 btf_nr_types(const struct btf *btf);
> bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
> const struct btf_member *m,
> @@ -574,8 +577,6 @@ static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type
> struct bpf_struct_ops;
> struct bpf_struct_ops_desc;
>
> -struct bpf_struct_ops_desc *
> -btf_add_struct_ops(struct btf *btf, struct bpf_struct_ops *st_ops);
> const struct bpf_struct_ops_desc *
> btf_get_struct_ops(struct btf *btf, u32 *ret_cnt);
>
> diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
> index 99ab61cc6cad..44412f95bc32 100644
> --- a/kernel/bpf/bpf_struct_ops.c
> +++ b/kernel/bpf/bpf_struct_ops.c
> @@ -13,21 +13,8 @@
> #include <linux/btf_ids.h>
> #include <linux/rcupdate_wait.h>
>
> -enum bpf_struct_ops_state {
> - BPF_STRUCT_OPS_STATE_INIT,
> - BPF_STRUCT_OPS_STATE_INUSE,
> - BPF_STRUCT_OPS_STATE_TOBEFREE,
> - BPF_STRUCT_OPS_STATE_READY,
> -};
> -
> -struct bpf_struct_ops_common_value {
> - refcount_t refcnt;
> - enum bpf_struct_ops_state state;
> -};
> -#define BPF_STRUCT_OPS_COMMON_VALUE struct bpf_struct_ops_common_value common
> -
> struct bpf_struct_ops_value {
> - BPF_STRUCT_OPS_COMMON_VALUE;
> + struct bpf_struct_ops_common_value common;
> char data[] ____cacheline_aligned_in_smp;
> };
>
> @@ -72,35 +59,6 @@ static DEFINE_MUTEX(update_mutex);
> #define VALUE_PREFIX "bpf_struct_ops_"
> #define VALUE_PREFIX_LEN (sizeof(VALUE_PREFIX) - 1)
>
> -/* bpf_struct_ops_##_name (e.g. bpf_struct_ops_tcp_congestion_ops) is
> - * the map's value exposed to the userspace and its btf-type-id is
> - * stored at the map->btf_vmlinux_value_type_id.
> - *
> - */
> -#define BPF_STRUCT_OPS_TYPE(_name) \
> -extern struct bpf_struct_ops bpf_##_name; \
> - \
> -struct bpf_struct_ops_##_name { \
> - BPF_STRUCT_OPS_COMMON_VALUE; \
> - struct _name data ____cacheline_aligned_in_smp; \
> -};
> -#include "bpf_struct_ops_types.h"
> -#undef BPF_STRUCT_OPS_TYPE
> -
> -enum {
> -#define BPF_STRUCT_OPS_TYPE(_name) BPF_STRUCT_OPS_TYPE_##_name,
> -#include "bpf_struct_ops_types.h"
> -#undef BPF_STRUCT_OPS_TYPE
> - __NR_BPF_STRUCT_OPS_TYPE,
> -};
> -
> -static struct bpf_struct_ops_desc bpf_struct_ops[] = {
> -#define BPF_STRUCT_OPS_TYPE(_name) \
> - [BPF_STRUCT_OPS_TYPE_##_name] = { .st_ops = &bpf_##_name },
> -#include "bpf_struct_ops_types.h"
> -#undef BPF_STRUCT_OPS_TYPE
> -};
> -
> const struct bpf_verifier_ops bpf_struct_ops_verifier_ops = {
> };
>
> @@ -110,13 +68,22 @@ const struct bpf_prog_ops bpf_struct_ops_prog_ops = {
> #endif
> };
>
> -static const struct btf_type *module_type;
> -static const struct btf_type *common_value_type;
> +BTF_ID_LIST(st_ops_ids)
> +BTF_ID(struct, module)
> +BTF_ID(struct, bpf_struct_ops_common_value)
> +
> +enum {
> + idx_module_id,
> + idx_st_ops_common_value_id,
> +};
> +
> +extern struct btf *btf_vmlinux;
>
> static bool is_valid_value_type(struct btf *btf, s32 value_id,
> const struct btf_type *type,
> const char *value_name)
> {
> + const struct btf_type *common_value_type;
> const struct btf_member *member;
> const struct btf_type *vt, *mt;
>
> @@ -128,6 +95,8 @@ static bool is_valid_value_type(struct btf *btf, s32 value_id,
> }
> member = btf_type_member(vt);
> mt = btf_type_by_id(btf, member->type);
> + common_value_type = btf_type_by_id(btf_vmlinux,
> + st_ops_ids[idx_st_ops_common_value_id]);
> if (mt != common_value_type) {
> pr_warn("The first member of %s should be bpf_struct_ops_common_value\n",
> value_name);
> @@ -144,9 +113,9 @@ static bool is_valid_value_type(struct btf *btf, s32 value_id,
> return true;
> }
>
> -static void bpf_struct_ops_init_one(struct bpf_struct_ops_desc *st_ops_desc,
> - struct btf *btf,
> - struct bpf_verifier_log *log)
> +void bpf_struct_ops_init(struct bpf_struct_ops_desc *st_ops_desc,
> + struct btf *btf,
> + struct bpf_verifier_log *log)
> {
> struct bpf_struct_ops *st_ops = st_ops_desc->st_ops;
> const struct btf_member *member;
> @@ -232,51 +201,20 @@ static void bpf_struct_ops_init_one(struct bpf_struct_ops_desc *st_ops_desc,
> }
> }
>
> -void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
> -{
> - struct bpf_struct_ops_desc *st_ops_desc;
> - s32 module_id, common_value_id;
> - u32 i;
> -
> - /* Ensure BTF type is emitted for "struct bpf_struct_ops_##_name" */
> -#define BPF_STRUCT_OPS_TYPE(_name) BTF_TYPE_EMIT(struct bpf_struct_ops_##_name);
> -#include "bpf_struct_ops_types.h"
> -#undef BPF_STRUCT_OPS_TYPE
> -
> - module_id = btf_find_by_name_kind(btf, "module", BTF_KIND_STRUCT);
> - if (module_id < 0) {
> - pr_warn("Cannot find struct module in btf_vmlinux\n");
> - return;
> - }
> - module_type = btf_type_by_id(btf, module_id);
> - common_value_id = btf_find_by_name_kind(btf,
> - "bpf_struct_ops_common_value",
> - BTF_KIND_STRUCT);
> - if (common_value_id < 0) {
> - pr_warn("Cannot find struct common_value in btf_vmlinux\n");
> - return;
> - }
> - common_value_type = btf_type_by_id(btf, common_value_id);
> -
> - for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
> - st_ops_desc = &bpf_struct_ops[i];
> - bpf_struct_ops_init_one(st_ops_desc, btf, log);
> - }
> -}
> -
> -extern struct btf *btf_vmlinux;
> -
> static const struct bpf_struct_ops_desc *
> bpf_struct_ops_find_value(struct btf *btf, u32 value_id)
> {
> + const struct bpf_struct_ops_desc *st_ops_list;
> unsigned int i;
> + u32 cnt = 0;
>
> - if (!value_id || !btf_vmlinux)
> + if (!value_id)
> return NULL;
>
> - for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
> - if (bpf_struct_ops[i].value_id == value_id)
> - return &bpf_struct_ops[i];
> + st_ops_list = btf_get_struct_ops(btf, &cnt);
> + for (i = 0; i < cnt; i++) {
> + if (st_ops_list[i].value_id == value_id)
> + return &st_ops_list[i];
> }
>
> return NULL;
> @@ -285,14 +223,17 @@ bpf_struct_ops_find_value(struct btf *btf, u32 value_id)
> const struct bpf_struct_ops_desc *
> bpf_struct_ops_find(struct btf *btf, u32 type_id)
> {
> + const struct bpf_struct_ops_desc *st_ops_list;
> unsigned int i;
> + u32 cnt;
>
> - if (!type_id || !btf_vmlinux)
> + if (!type_id)
> return NULL;
>
> - for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
> - if (bpf_struct_ops[i].type_id == type_id)
> - return &bpf_struct_ops[i];
> + st_ops_list = btf_get_struct_ops(btf, &cnt);
> + for (i = 0; i < cnt; i++) {
> + if (st_ops_list[i].type_id == type_id)
> + return &st_ops_list[i];
> }
>
> return NULL;
> @@ -429,6 +370,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
> const struct bpf_struct_ops_desc *st_ops_desc = st_map->st_ops_desc;
> const struct bpf_struct_ops *st_ops = st_ops_desc->st_ops;
> struct bpf_struct_ops_value *uvalue, *kvalue;
> + const struct btf_type *module_type;
> const struct btf_member *member;
> const struct btf_type *t = st_ops_desc->type;
> struct bpf_tramp_links *tlinks;
> @@ -485,6 +427,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
> image = st_map->image;
> image_end = st_map->image + PAGE_SIZE;
>
> + module_type = btf_type_by_id(btf_vmlinux, st_ops_ids[idx_module_id]);
> for_each_member(i, t, member) {
> const struct btf_type *mtype, *ptype;
> struct bpf_prog *prog;
> diff --git a/kernel/bpf/bpf_struct_ops_types.h b/kernel/bpf/bpf_struct_ops_types.h
> deleted file mode 100644
> index 5678a9ddf817..000000000000
> --- a/kernel/bpf/bpf_struct_ops_types.h
> +++ /dev/null
> @@ -1,12 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -/* internal file - do not include directly */
> -
> -#ifdef CONFIG_BPF_JIT
> -#ifdef CONFIG_NET
> -BPF_STRUCT_OPS_TYPE(bpf_dummy_ops)
> -#endif
> -#ifdef CONFIG_INET
> -#include <net/tcp.h>
> -BPF_STRUCT_OPS_TYPE(tcp_congestion_ops)
> -#endif
> -#endif
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index c1e2ed6c972e..c53888e8dddb 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -5790,8 +5790,6 @@ struct btf *btf_parse_vmlinux(void)
> /* btf_parse_vmlinux() runs under bpf_verifier_lock */
> bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
>
> - bpf_struct_ops_init(btf, log);
> -
> refcount_set(&btf->refcnt, 1);
>
> err = btf_alloc_id(btf);
> @@ -7532,7 +7530,7 @@ struct module *btf_try_get_module(const struct btf *btf)
> /* Returns struct btf corresponding to the struct module.
> * This function can return NULL or ERR_PTR.
> */
> -static struct btf *btf_get_module_btf(const struct module *module)
> +struct btf *btf_get_module_btf(const struct module *module)
> {
> #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> struct btf_module *btf_mod, *tmp;
> @@ -8672,3 +8670,40 @@ const struct bpf_struct_ops_desc *btf_get_struct_ops(struct btf *btf, u32 *ret_c
> return (const struct bpf_struct_ops_desc *)btf->struct_ops_tab->ops;
> }
>
> +int register_bpf_struct_ops(struct bpf_struct_ops *st_ops)
> +{
> + struct bpf_struct_ops_desc *desc;
> + struct bpf_verifier_log *log;
> + struct btf *btf;
> + int err = 0;
> +
> + if (st_ops == NULL)
> + return -EINVAL;
> +
> + btf = btf_get_module_btf(st_ops->owner);
> + if (!btf)
> + return -EINVAL;
> +
> + log = kzalloc(sizeof(*log), GFP_KERNEL | __GFP_NOWARN);
> + if (!log) {
> + err = -ENOMEM;
> + goto errout;
> + }
> +
> + log->level = BPF_LOG_KERNEL;
Nit: maybe use bpf_vlog_init() here to avoid breaking encapsulation?
> +
> + desc = btf_add_struct_ops(btf, st_ops);
> + if (IS_ERR(desc)) {
> + err = PTR_ERR(desc);
> + goto errout;
> + }
> +
> + bpf_struct_ops_init(desc, btf, log);
Nit: I think bpf_struct_ops_init() could be changed to return 'int',
then register_bpf_struct_ops() could report to calling module if
something went wrong on the last phase, wdyt?
> +
> +errout:
> + kfree(log);
> + btf_put(btf);
> +
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(register_bpf_struct_ops);
> diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
> index ffa224053a6c..148a5851c4fa 100644
> --- a/net/bpf/bpf_dummy_struct_ops.c
> +++ b/net/bpf/bpf_dummy_struct_ops.c
> @@ -7,7 +7,7 @@
> #include <linux/bpf.h>
> #include <linux/btf.h>
>
> -extern struct bpf_struct_ops bpf_bpf_dummy_ops;
> +static struct bpf_struct_ops bpf_bpf_dummy_ops;
>
> /* A common type for test_N with return value in bpf_dummy_ops */
> typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
> @@ -223,11 +223,13 @@ static int bpf_dummy_reg(void *kdata)
> return -EOPNOTSUPP;
> }
>
> +DEFINE_STRUCT_OPS_VALUE_TYPE(bpf_dummy_ops);
> +
> static void bpf_dummy_unreg(void *kdata)
> {
> }
>
> -struct bpf_struct_ops bpf_bpf_dummy_ops = {
> +static struct bpf_struct_ops bpf_bpf_dummy_ops = {
> .verifier_ops = &bpf_dummy_verifier_ops,
> .init = bpf_dummy_init,
> .check_member = bpf_dummy_ops_check_member,
> @@ -235,4 +237,12 @@ struct bpf_struct_ops bpf_bpf_dummy_ops = {
> .reg = bpf_dummy_reg,
> .unreg = bpf_dummy_unreg,
> .name = "bpf_dummy_ops",
> + .owner = THIS_MODULE,
> };
> +
> +static int __init bpf_dummy_struct_ops_init(void)
> +{
> + BTF_STRUCT_OPS_TYPE_EMIT(bpf_dummy_ops);
> + return register_bpf_struct_ops(&bpf_bpf_dummy_ops);
> +}
> +late_initcall(bpf_dummy_struct_ops_init);
> diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
> index 3c8b76578a2a..b36a19274e5b 100644
> --- a/net/ipv4/bpf_tcp_ca.c
> +++ b/net/ipv4/bpf_tcp_ca.c
> @@ -12,7 +12,7 @@
> #include <net/bpf_sk_storage.h>
>
> /* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */
> -extern struct bpf_struct_ops bpf_tcp_congestion_ops;
> +static struct bpf_struct_ops bpf_tcp_congestion_ops;
>
> static u32 unsupported_ops[] = {
> offsetof(struct tcp_congestion_ops, get_info),
> @@ -277,7 +277,9 @@ static int bpf_tcp_ca_validate(void *kdata)
> return tcp_validate_congestion_control(kdata);
> }
>
> -struct bpf_struct_ops bpf_tcp_congestion_ops = {
> +DEFINE_STRUCT_OPS_VALUE_TYPE(tcp_congestion_ops);
> +
> +static struct bpf_struct_ops bpf_tcp_congestion_ops = {
> .verifier_ops = &bpf_tcp_ca_verifier_ops,
> .reg = bpf_tcp_ca_reg,
> .unreg = bpf_tcp_ca_unreg,
> @@ -287,10 +289,18 @@ struct bpf_struct_ops bpf_tcp_congestion_ops = {
> .init = bpf_tcp_ca_init,
> .validate = bpf_tcp_ca_validate,
> .name = "tcp_congestion_ops",
> + .owner = THIS_MODULE,
> };
>
> static int __init bpf_tcp_ca_kfunc_init(void)
> {
> - return register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set);
> + int ret;
> +
> + BTF_STRUCT_OPS_TYPE_EMIT(tcp_congestion_ops);
> +
> + ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set);
> + ret = ret ?: register_bpf_struct_ops(&bpf_tcp_congestion_ops);
> +
> + return ret;
> }
> late_initcall(bpf_tcp_ca_kfunc_init);
