Commit 89538398 authored by Alexei Starovoitov's avatar Alexei Starovoitov

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
......@@ -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.
* Return
* 1 if set, 0 if not set.
* Description
* 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 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) \
......
......@@ -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.
* Return
* 1 if set, 0 if not set.
* Description
* 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 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) \
......
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