Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 89538398 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'fix-bpf-docs' 



Quentin Monnet says:

====================
Hi,
This set is an update to the documentation for the BPF helper functions in
the UAPI header bpf.h, used to generate the bpf-helpers(7) man page.

First patch contains fixes to the current documentation. The second patch
adds documentation for the two helpers bpf_spin_lock() and
bpf_spin_unlock(). The last patch simply reports the changes to the version
of that header in tools/.
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents cd70182e ea6eced0

include/uapi/linux/bpf.h

+120 −63
Original line number Diff line number Diff line
@@ -502,16 +502,6 @@ union bpf_attr { 
 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)

 * 	Description

 * 		Push an element *value* in *map*. *flags* is one of:

 *

 * 		**BPF_EXIST**

 * 		If the queue/stack is full, the oldest element is removed to

 * 		make room for this.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_probe_read(void *dst, u32 size, const void *src)

 * 	Description

 * 		For tracing programs, safely attempt to read *size* bytes from
@@ -1435,14 +1425,14 @@ union bpf_attr { 
 * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)

 * 	Description

 * 		Equivalent to bpf_get_socket_cookie() helper that accepts

 * 		*skb*, but gets socket from **struct bpf_sock_addr** contex.

 * 		*skb*, but gets socket from **struct bpf_sock_addr** context.

 * 	Return

 * 		A 8-byte long non-decreasing number.

 *

 * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)

 * 	Description

 * 		Equivalent to bpf_get_socket_cookie() helper that accepts

 * 		*skb*, but gets socket from **struct bpf_sock_ops** contex.

 * 		*skb*, but gets socket from **struct bpf_sock_ops** context.

 * 	Return

 * 		A 8-byte long non-decreasing number.

 *
@@ -2098,52 +2088,52 @@ union bpf_attr { 
 *	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)

 * int bpf_rc_repeat(void *ctx)

 *	Description

 *		This helper is used in programs implementing IR decoding, to

 *		report a successfully decoded key press with *scancode*,

 *		*toggle* value in the given *protocol*. The scancode will be

 *		translated to a keycode using the rc keymap, and reported as

 *		an input key down event. After a period a key up event is

 *		generated. This period can be extended by calling either

 *		**bpf_rc_keydown**\ () again with the same values, or calling

 *		**bpf_rc_repeat**\ ().

 *		report a successfully decoded repeat key message. This delays

 *		the generation of a key up event for previously generated

 *		key down event.

 *

 *		Some protocols include a toggle bit, in case the button	was

 *		released and pressed again between consecutive scancodes.

 *		Some IR protocols like NEC have a special IR message for

 *		repeating last button, for when a button is held down.

 *

 *		The *ctx* should point to the lirc sample as passed into

 *		the program.

 *

 *		The *protocol* is the decoded protocol number (see

 *		**enum rc_proto** for some predefined values).

 *

 *		This helper is only available is the kernel was compiled with

 *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to

 *		"**y**".

 *	Return

 *		0

 *

 * int bpf_rc_repeat(void *ctx)

 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)

 *	Description

 *		This helper is used in programs implementing IR decoding, to

 *		report a successfully decoded repeat key message. This delays

 *		the generation of a key up event for previously generated

 *		key down event.

 *		report a successfully decoded key press with *scancode*,

 *		*toggle* value in the given *protocol*. The scancode will be

 *		translated to a keycode using the rc keymap, and reported as

 *		an input key down event. After a period a key up event is

 *		generated. This period can be extended by calling either

 *		**bpf_rc_keydown**\ () again with the same values, or calling

 *		**bpf_rc_repeat**\ ().

 *

 *		Some IR protocols like NEC have a special IR message for

 *		repeating last button, for when a button is held down.

 *		Some protocols include a toggle bit, in case the button	was

 *		released and pressed again between consecutive scancodes.

 *

 *		The *ctx* should point to the lirc sample as passed into

 *		the program.

 *

 *		The *protocol* is the decoded protocol number (see

 *		**enum rc_proto** for some predefined values).

 *

 *		This helper is only available is the kernel was compiled with

 *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to

 *		"**y**".

 *	Return

 *		0

 *

 * uint64_t bpf_skb_cgroup_id(struct sk_buff *skb)

 * u64 bpf_skb_cgroup_id(struct sk_buff *skb)

 * 	Description

 * 		Return the cgroup v2 id of the socket associated with the *skb*.

 * 		This is roughly similar to the **bpf_get_cgroup_classid**\ ()
@@ -2159,30 +2149,12 @@ union bpf_attr { 
 * 	Return

 * 		The id is returned or 0 in case the id could not be retrieved.

 *

 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)

 *	Description

 *		Return id of cgroup v2 that is ancestor of cgroup associated

 *		with the *skb* at the *ancestor_level*.  The root cgroup is at

 *		*ancestor_level* zero and each step down the hierarchy

 *		increments the level. If *ancestor_level* == level of cgroup

 *		associated with *skb*, then return value will be same as that

 *		of **bpf_skb_cgroup_id**\ ().

 *

 *		The helper is useful to implement policies based on cgroups

 *		that are upper in hierarchy than immediate cgroup associated

 *		with *skb*.

 *

 *		The format of returned id and helper limitations are same as in

 *		**bpf_skb_cgroup_id**\ ().

 *	Return

 *		The id is returned or 0 in case the id could not be retrieved.

 *

 * u64 bpf_get_current_cgroup_id(void)

 * 	Return

 * 		A 64-bit integer containing the current cgroup id based

 * 		on the cgroup within which the current task is running.

 *

 * void* get_local_storage(void *map, u64 flags)

 * void *bpf_get_local_storage(void *map, u64 flags)

 *	Description

 *		Get the pointer to the local storage area.

 *		The type and the size of the local storage is defined
@@ -2209,6 +2181,24 @@ union bpf_attr { 
 *	Return

 *		0 on success, or a negative error in case of failure.

 *

 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)

 *	Description

 *		Return id of cgroup v2 that is ancestor of cgroup associated

 *		with the *skb* at the *ancestor_level*.  The root cgroup is at

 *		*ancestor_level* zero and each step down the hierarchy

 *		increments the level. If *ancestor_level* == level of cgroup

 *		associated with *skb*, then return value will be same as that

 *		of **bpf_skb_cgroup_id**\ ().

 *

 *		The helper is useful to implement policies based on cgroups

 *		that are upper in hierarchy than immediate cgroup associated

 *		with *skb*.

 *

 *		The format of returned id and helper limitations are same as in

 *		**bpf_skb_cgroup_id**\ ().

 *	Return

 *		The id is returned or 0 in case the id could not be retrieved.

 *

 * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)

 *	Description

 *		Look for TCP socket matching *tuple*, optionally in a child
@@ -2289,6 +2279,16 @@ union bpf_attr { 
 *	Return

 *		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)

 * 	Description

 * 		Push an element *value* in *map*. *flags* is one of:

 *

 * 		**BPF_EXIST**

 * 			If the queue/stack is full, the oldest element is

 * 			removed to make room for this.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_pop_elem(struct bpf_map *map, void *value)

 * 	Description

 * 		Pop an element from *map*.
@@ -2343,36 +2343,93 @@ union bpf_attr { 
 *	Return

 *		0

 *

 * int bpf_spin_lock(struct bpf_spin_lock *lock)

 *	Description

 *		Acquire a spinlock represented by the pointer *lock*, which is

 *		stored as part of a value of a map. Taking the lock allows to

 *		safely update the rest of the fields in that value. The

 *		spinlock can (and must) later be released with a call to

 *		**bpf_spin_unlock**\ (\ *lock*\ ).

 *

 *		Spinlocks in BPF programs come with a number of restrictions

 *		and constraints:

 *

 *		* **bpf_spin_lock** objects are only allowed inside maps of

 *		  types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this

 *		  list could be extended in the future).

 *		* BTF description of the map is mandatory.

 *		* The BPF program can take ONE lock at a time, since taking two

 *		  or more could cause dead locks.

 *		* Only one **struct bpf_spin_lock** is allowed per map element.

 *		* When the lock is taken, calls (either BPF to BPF or helpers)

 *		  are not allowed.

 *		* The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not

 *		  allowed inside a spinlock-ed region.

 *		* The BPF program MUST call **bpf_spin_unlock**\ () to release

 *		  the lock, on all execution paths, before it returns.

 *		* The BPF program can access **struct bpf_spin_lock** only via

 *		  the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()

 *		  helpers. Loading or storing data into the **struct

 *		  bpf_spin_lock** *lock*\ **;** field of a map is not allowed.

 *		* To use the **bpf_spin_lock**\ () helper, the BTF description

 *		  of the map value must be a struct and have **struct

 *		  bpf_spin_lock** *anyname*\ **;** field at the top level.

 *		  Nested lock inside another struct is not allowed.

 *		* The **struct bpf_spin_lock** *lock* field in a map value must

 *		  be aligned on a multiple of 4 bytes in that value.

 *		* Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy

 *		  the **bpf_spin_lock** field to user space.

 *		* Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from

 *		  a BPF program, do not update the **bpf_spin_lock** field.

 *		* **bpf_spin_lock** cannot be on the stack or inside a

 *		  networking packet (it can only be inside of a map values).

 *		* **bpf_spin_lock** is available to root only.

 *		* Tracing programs and socket filter programs cannot use

 *		  **bpf_spin_lock**\ () due to insufficient preemption checks

 *		  (but this may change in the future).

 *		* **bpf_spin_lock** is not allowed in inner maps of map-in-map.

 *	Return

 *		0

 *

 * int bpf_spin_unlock(struct bpf_spin_lock *lock)

 *	Description

 *		Release the *lock* previously locked by a call to

 *		**bpf_spin_lock**\ (\ *lock*\ ).

 *	Return

 *		0

 *

 * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)

 *	Description

 *		This helper gets a **struct bpf_sock** pointer such

 *		that all the fields in bpf_sock can be accessed.

 *		that all the fields in this **bpf_sock** can be accessed.

 *	Return

 *		A **struct bpf_sock** pointer on success, or NULL in

 *		A **struct bpf_sock** pointer on success, or **NULL** in

 *		case of failure.

 *

 * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)

 *	Description

 *		This helper gets a **struct bpf_tcp_sock** pointer from a

 *		**struct bpf_sock** pointer.

 *

 *	Return

 *		A **struct bpf_tcp_sock** pointer on success, or NULL in

 *		A **struct bpf_tcp_sock** pointer on success, or **NULL** in

 *		case of failure.

 *

 * int bpf_skb_ecn_set_ce(struct sk_buf *skb)

 *	Description

 *             Sets ECN of IP header to ce (congestion encountered) if

 *             current value is ect (ECN capable). Works with IPv6 and IPv4.

 *		Set ECN (Explicit Congestion Notification) field of IP header

 *		to **CE** (Congestion Encountered) if current value is **ECT**

 *		(ECN Capable Transport). Otherwise, do nothing. Works with IPv6

 *		and IPv4.

 *	Return

 *             1 if set, 0 if not set.

 *		1 if the **CE** flag is set (either by the current helper call

 *		or because it was already present), 0 if it is not set.

 *

 * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)

 *	Description

 *		Return a **struct bpf_sock** pointer in TCP_LISTEN state.

 *		bpf_sk_release() is unnecessary and not allowed.

 *		Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.

 *		**bpf_sk_release**\ () is unnecessary and not allowed.

 *	Return

 *		A **struct bpf_sock** pointer on success, or NULL in

 *		A **struct bpf_sock** pointer on success, or **NULL** in

 *		case of failure.

 */

#define __BPF_FUNC_MAPPER(FN)		\

tools/include/uapi/linux/bpf.h

+120 −63
Original line number Diff line number Diff line
@@ -502,16 +502,6 @@ union bpf_attr { 
 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)

 * 	Description

 * 		Push an element *value* in *map*. *flags* is one of:

 *

 * 		**BPF_EXIST**

 * 		If the queue/stack is full, the oldest element is removed to

 * 		make room for this.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_probe_read(void *dst, u32 size, const void *src)

 * 	Description

 * 		For tracing programs, safely attempt to read *size* bytes from
@@ -1435,14 +1425,14 @@ union bpf_attr { 
 * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)

 * 	Description

 * 		Equivalent to bpf_get_socket_cookie() helper that accepts

 * 		*skb*, but gets socket from **struct bpf_sock_addr** contex.

 * 		*skb*, but gets socket from **struct bpf_sock_addr** context.

 * 	Return

 * 		A 8-byte long non-decreasing number.

 *

 * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)

 * 	Description

 * 		Equivalent to bpf_get_socket_cookie() helper that accepts

 * 		*skb*, but gets socket from **struct bpf_sock_ops** contex.

 * 		*skb*, but gets socket from **struct bpf_sock_ops** context.

 * 	Return

 * 		A 8-byte long non-decreasing number.

 *
@@ -2098,52 +2088,52 @@ union bpf_attr { 
 *	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)

 * int bpf_rc_repeat(void *ctx)

 *	Description

 *		This helper is used in programs implementing IR decoding, to

 *		report a successfully decoded key press with *scancode*,

 *		*toggle* value in the given *protocol*. The scancode will be

 *		translated to a keycode using the rc keymap, and reported as

 *		an input key down event. After a period a key up event is

 *		generated. This period can be extended by calling either

 *		**bpf_rc_keydown**\ () again with the same values, or calling

 *		**bpf_rc_repeat**\ ().

 *		report a successfully decoded repeat key message. This delays

 *		the generation of a key up event for previously generated

 *		key down event.

 *

 *		Some protocols include a toggle bit, in case the button	was

 *		released and pressed again between consecutive scancodes.

 *		Some IR protocols like NEC have a special IR message for

 *		repeating last button, for when a button is held down.

 *

 *		The *ctx* should point to the lirc sample as passed into

 *		the program.

 *

 *		The *protocol* is the decoded protocol number (see

 *		**enum rc_proto** for some predefined values).

 *

 *		This helper is only available is the kernel was compiled with

 *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to

 *		"**y**".

 *	Return

 *		0

 *

 * int bpf_rc_repeat(void *ctx)

 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)

 *	Description

 *		This helper is used in programs implementing IR decoding, to

 *		report a successfully decoded repeat key message. This delays

 *		the generation of a key up event for previously generated

 *		key down event.

 *		report a successfully decoded key press with *scancode*,

 *		*toggle* value in the given *protocol*. The scancode will be

 *		translated to a keycode using the rc keymap, and reported as

 *		an input key down event. After a period a key up event is

 *		generated. This period can be extended by calling either

 *		**bpf_rc_keydown**\ () again with the same values, or calling

 *		**bpf_rc_repeat**\ ().

 *

 *		Some IR protocols like NEC have a special IR message for

 *		repeating last button, for when a button is held down.

 *		Some protocols include a toggle bit, in case the button	was

 *		released and pressed again between consecutive scancodes.

 *

 *		The *ctx* should point to the lirc sample as passed into

 *		the program.

 *

 *		The *protocol* is the decoded protocol number (see

 *		**enum rc_proto** for some predefined values).

 *

 *		This helper is only available is the kernel was compiled with

 *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to

 *		"**y**".

 *	Return

 *		0

 *

 * uint64_t bpf_skb_cgroup_id(struct sk_buff *skb)

 * u64 bpf_skb_cgroup_id(struct sk_buff *skb)

 * 	Description

 * 		Return the cgroup v2 id of the socket associated with the *skb*.

 * 		This is roughly similar to the **bpf_get_cgroup_classid**\ ()
@@ -2159,30 +2149,12 @@ union bpf_attr { 
 * 	Return

 * 		The id is returned or 0 in case the id could not be retrieved.

 *

 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)

 *	Description

 *		Return id of cgroup v2 that is ancestor of cgroup associated

 *		with the *skb* at the *ancestor_level*.  The root cgroup is at

 *		*ancestor_level* zero and each step down the hierarchy

 *		increments the level. If *ancestor_level* == level of cgroup

 *		associated with *skb*, then return value will be same as that

 *		of **bpf_skb_cgroup_id**\ ().

 *

 *		The helper is useful to implement policies based on cgroups

 *		that are upper in hierarchy than immediate cgroup associated

 *		with *skb*.

 *

 *		The format of returned id and helper limitations are same as in

 *		**bpf_skb_cgroup_id**\ ().

 *	Return

 *		The id is returned or 0 in case the id could not be retrieved.

 *

 * u64 bpf_get_current_cgroup_id(void)

 * 	Return

 * 		A 64-bit integer containing the current cgroup id based

 * 		on the cgroup within which the current task is running.

 *

 * void* get_local_storage(void *map, u64 flags)

 * void *bpf_get_local_storage(void *map, u64 flags)

 *	Description

 *		Get the pointer to the local storage area.

 *		The type and the size of the local storage is defined
@@ -2209,6 +2181,24 @@ union bpf_attr { 
 *	Return

 *		0 on success, or a negative error in case of failure.

 *

 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)

 *	Description

 *		Return id of cgroup v2 that is ancestor of cgroup associated

 *		with the *skb* at the *ancestor_level*.  The root cgroup is at

 *		*ancestor_level* zero and each step down the hierarchy

 *		increments the level. If *ancestor_level* == level of cgroup

 *		associated with *skb*, then return value will be same as that

 *		of **bpf_skb_cgroup_id**\ ().

 *

 *		The helper is useful to implement policies based on cgroups

 *		that are upper in hierarchy than immediate cgroup associated

 *		with *skb*.

 *

 *		The format of returned id and helper limitations are same as in

 *		**bpf_skb_cgroup_id**\ ().

 *	Return

 *		The id is returned or 0 in case the id could not be retrieved.

 *

 * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)

 *	Description

 *		Look for TCP socket matching *tuple*, optionally in a child
@@ -2289,6 +2279,16 @@ union bpf_attr { 
 *	Return

 *		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)

 * 	Description

 * 		Push an element *value* in *map*. *flags* is one of:

 *

 * 		**BPF_EXIST**

 * 			If the queue/stack is full, the oldest element is

 * 			removed to make room for this.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * int bpf_map_pop_elem(struct bpf_map *map, void *value)

 * 	Description

 * 		Pop an element from *map*.
@@ -2343,36 +2343,93 @@ union bpf_attr { 
 *	Return

 *		0

 *

 * int bpf_spin_lock(struct bpf_spin_lock *lock)

 *	Description

 *		Acquire a spinlock represented by the pointer *lock*, which is

 *		stored as part of a value of a map. Taking the lock allows to

 *		safely update the rest of the fields in that value. The

 *		spinlock can (and must) later be released with a call to

 *		**bpf_spin_unlock**\ (\ *lock*\ ).

 *

 *		Spinlocks in BPF programs come with a number of restrictions

 *		and constraints:

 *

 *		* **bpf_spin_lock** objects are only allowed inside maps of

 *		  types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this

 *		  list could be extended in the future).

 *		* BTF description of the map is mandatory.

 *		* The BPF program can take ONE lock at a time, since taking two

 *		  or more could cause dead locks.

 *		* Only one **struct bpf_spin_lock** is allowed per map element.

 *		* When the lock is taken, calls (either BPF to BPF or helpers)

 *		  are not allowed.

 *		* The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not

 *		  allowed inside a spinlock-ed region.

 *		* The BPF program MUST call **bpf_spin_unlock**\ () to release

 *		  the lock, on all execution paths, before it returns.

 *		* The BPF program can access **struct bpf_spin_lock** only via

 *		  the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()

 *		  helpers. Loading or storing data into the **struct

 *		  bpf_spin_lock** *lock*\ **;** field of a map is not allowed.

 *		* To use the **bpf_spin_lock**\ () helper, the BTF description

 *		  of the map value must be a struct and have **struct

 *		  bpf_spin_lock** *anyname*\ **;** field at the top level.

 *		  Nested lock inside another struct is not allowed.

 *		* The **struct bpf_spin_lock** *lock* field in a map value must

 *		  be aligned on a multiple of 4 bytes in that value.

 *		* Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy

 *		  the **bpf_spin_lock** field to user space.

 *		* Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from

 *		  a BPF program, do not update the **bpf_spin_lock** field.

 *		* **bpf_spin_lock** cannot be on the stack or inside a

 *		  networking packet (it can only be inside of a map values).

 *		* **bpf_spin_lock** is available to root only.

 *		* Tracing programs and socket filter programs cannot use

 *		  **bpf_spin_lock**\ () due to insufficient preemption checks

 *		  (but this may change in the future).

 *		* **bpf_spin_lock** is not allowed in inner maps of map-in-map.

 *	Return

 *		0

 *

 * int bpf_spin_unlock(struct bpf_spin_lock *lock)

 *	Description

 *		Release the *lock* previously locked by a call to

 *		**bpf_spin_lock**\ (\ *lock*\ ).

 *	Return

 *		0

 *

 * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)

 *	Description

 *		This helper gets a **struct bpf_sock** pointer such

 *		that all the fields in bpf_sock can be accessed.

 *		that all the fields in this **bpf_sock** can be accessed.

 *	Return

 *		A **struct bpf_sock** pointer on success, or NULL in

 *		A **struct bpf_sock** pointer on success, or **NULL** in

 *		case of failure.

 *

 * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)

 *	Description

 *		This helper gets a **struct bpf_tcp_sock** pointer from a

 *		**struct bpf_sock** pointer.

 *

 *	Return

 *		A **struct bpf_tcp_sock** pointer on success, or NULL in

 *		A **struct bpf_tcp_sock** pointer on success, or **NULL** in

 *		case of failure.

 *

 * int bpf_skb_ecn_set_ce(struct sk_buf *skb)

 *	Description

 *             Sets ECN of IP header to ce (congestion encountered) if

 *             current value is ect (ECN capable). Works with IPv6 and IPv4.

 *		Set ECN (Explicit Congestion Notification) field of IP header

 *		to **CE** (Congestion Encountered) if current value is **ECT**

 *		(ECN Capable Transport). Otherwise, do nothing. Works with IPv6

 *		and IPv4.

 *	Return

 *             1 if set, 0 if not set.

 *		1 if the **CE** flag is set (either by the current helper call

 *		or because it was already present), 0 if it is not set.

 *

 * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)

 *	Description

 *		Return a **struct bpf_sock** pointer in TCP_LISTEN state.

 *		bpf_sk_release() is unnecessary and not allowed.

 *		Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.

 *		**bpf_sk_release**\ () is unnecessary and not allowed.

 *	Return

 *		A **struct bpf_sock** pointer on success, or NULL in

 *		A **struct bpf_sock** pointer on success, or **NULL** in

 *		case of failure.

 */

#define __BPF_FUNC_MAPPER(FN)		\