On 10/30/23 12:28 PM, 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>
---
include/linux/bpf.h | 36 ++++++--
include/linux/btf.h | 5 +-
kernel/bpf/bpf_struct_ops.c | 140 +++++++++---------------------
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, 140 insertions(+), 124 deletions(-)
delete mode 100644 kernel/bpf/bpf_struct_ops_types.h
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c993df3cf699..9d7105ff06db 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);
@@ -3232,4 +3227,35 @@ 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 int 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 a8813605f2f6..954536431e0b 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 type *)0); is new. Why is it needed?
+ ((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 */
@@ -201,6 +203,7 @@ 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,
@@ -575,8 +578,6 @@ 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 db2bbba50e38..f3ec72be9c63 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;
This cleanup is good. It should have been done together in patch 5 instead when
refcnt and state were grouped into a new 'struct bpf_struct_ops_common_value'.
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)
This should have been done in a separated patch immediately after patch 1. The
patch 7 has unrelated changes/cleanups like this and the above
BPF_STRUCT_OPS_COMMON_VALUE which could have been done earlier as preparation
patches instead of packing them together with the main change here: "switch to
dynamic registration". The commit message for the BTF_ID_LIST changes could be
like: "A preparation to completely retire the bpf_struct_ops_init() function in
the latter patch...".
+
+enum {
+ idx_module_id,
+ idx_st_ops_common_value_id,
nit. upper case to stay consistent with other similar usages.
+};
+
[ ... ]
+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)
NULL check is not needed. caller will never do that. If it really wanted to try,
other values would have similar effect.
+ 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;
+
+ desc = btf_add_struct_ops(btf, st_ops);
+ if (IS_ERR(desc)) {
+ err = PTR_ERR(desc);
+ goto errout;
+ }
+
+ err = bpf_struct_ops_init(desc, btf, log);
When bpf_struct_ops_init() returns err, desc is in btf_struct_ops_tab but it is
in an uninitialized state. May be do the bpf_struct_ops_init() in
btf_add_struct_ops() and only increment struct_ops_tab->cnt when everything is
correct.
+
+errout:
+ kfree(log);
+ btf_put(btf);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(register_bpf_struct_ops);
