tools, bpf: Synchronise BPF UAPI header with tools

Synchronise the bpf.h header under tools, to report the fixes recently
brought to the documentation for the BPF helpers.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904161454.31135-4-quentin@isovalent.com

tools/include/uapi/linux/bpf.h

@@ -3349,37 +3349,37 @@ union bpf_attr {
  *	Description
  *		Dynamically cast a *sk* pointer to a *tcp6_sock* pointer.
  *	Return
- *		*sk* if casting is valid, or NULL otherwise.
+ *		*sk* if casting is valid, or **NULL** otherwise.
  *
  * struct tcp_sock *bpf_skc_to_tcp_sock(void *sk)
  *	Description
  *		Dynamically cast a *sk* pointer to a *tcp_sock* pointer.
  *	Return
- *		*sk* if casting is valid, or NULL otherwise.
+ *		*sk* if casting is valid, or **NULL** otherwise.
  *
  * struct tcp_timewait_sock *bpf_skc_to_tcp_timewait_sock(void *sk)
  * 	Description
  *		Dynamically cast a *sk* pointer to a *tcp_timewait_sock* pointer.
  *	Return
- *		*sk* if casting is valid, or NULL otherwise.
+ *		*sk* if casting is valid, or **NULL** otherwise.
  *
  * struct tcp_request_sock *bpf_skc_to_tcp_request_sock(void *sk)
  * 	Description
  *		Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
  *	Return
- *		*sk* if casting is valid, or NULL otherwise.
+ *		*sk* if casting is valid, or **NULL** otherwise.
  *
  * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk)
  * 	Description
  *		Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
  *	Return
- *		*sk* if casting is valid, or NULL otherwise.
+ *		*sk* if casting is valid, or **NULL** otherwise.
  *
  * long bpf_get_task_stack(struct task_struct *task, void *buf, u32 size, u64 flags)
  *	Description
  *		Return a user or a kernel stack in bpf program provided buffer.
  *		To achieve this, the helper needs *task*, which is a valid
- *		pointer to struct task_struct. To store the stacktrace, the
+ *		pointer to **struct task_struct**. To store the stacktrace, the
  *		bpf program provides *buf* with a nonnegative *size*.
  *
  *		The last argument, *flags*, holds the number of stack frames to
@@ -3410,12 +3410,12 @@ union bpf_attr {
  * long bpf_load_hdr_opt(struct bpf_sock_ops *skops, void *searchby_res, u32 len, u64 flags)
  *	Description
  *		Load header option.  Support reading a particular TCP header
- *		option for bpf program (BPF_PROG_TYPE_SOCK_OPS).
+ *		option for bpf program (**BPF_PROG_TYPE_SOCK_OPS**).
  *
  *		If *flags* is 0, it will search the option from the
- *		sock_ops->skb_data.  The comment in "struct bpf_sock_ops"
+ *		*skops*\ **->skb_data**.  The comment in **struct bpf_sock_ops**
  *		has details on what skb_data contains under different
- *		sock_ops->op.
+ *		*skops*\ **->op**.
  *
  *		The first byte of the *searchby_res* specifies the
  *		kind that it wants to search.
@@ -3435,7 +3435,7 @@ union bpf_attr {
  *		[ 254, 4, 0xeB, 0x9F, 0, 0, .... 0 ].
  *
  *		To search for the standard window scale option (3),
- *		the searchby_res should be [ 3, 0, 0, .... 0 ].
+ *		the *searchby_res* should be [ 3, 0, 0, .... 0 ].
  *		Note, kind-length must be 0 for regular option.
  *
  *		Searching for No-Op (0) and End-of-Option-List (1) are
@@ -3445,27 +3445,30 @@ union bpf_attr {
  *		of a header option.
  *
  *		Supported flags:
+ *
  *		* **BPF_LOAD_HDR_OPT_TCP_SYN** to search from the
  *		  saved_syn packet or the just-received syn packet.
  *
  *	Return
- *		>0 when found, the header option is copied to *searchby_res*.
- *		The return value is the total length copied.
+ *		> 0 when found, the header option is copied to *searchby_res*.
+ *		The return value is the total length copied. On failure, a
+ *		negative error code is returned:
  *
- *		**-EINVAL** If param is invalid
+ *		**-EINVAL** if a parameter is invalid.
  *
- *		**-ENOMSG** The option is not found
+ *		**-ENOMSG** if the option is not found.
  *
- *		**-ENOENT** No syn packet available when
- *			    **BPF_LOAD_HDR_OPT_TCP_SYN** is used
+ *		**-ENOENT** if no syn packet is available when
+ *		**BPF_LOAD_HDR_OPT_TCP_SYN** is used.
  *
- *		**-ENOSPC** Not enough space.  Only *len* number of
+ *		**-ENOSPC** if there is not enough space.  Only *len* number of
  *		bytes are copied.
  *
- *		**-EFAULT** Cannot parse the header options in the packet
+ *		**-EFAULT** on failure to parse the header options in the
+ *		packet.
  *
- *		**-EPERM** This helper cannot be used under the
- *			   current sock_ops->op.
+ *		**-EPERM** if the helper cannot be used under the current
+ *		*skops*\ **->op**.
  *
  * long bpf_store_hdr_opt(struct bpf_sock_ops *skops, const void *from, u32 len, u64 flags)
  *	Description
@@ -3483,44 +3486,44 @@ union bpf_attr {
  *		by searching the same option in the outgoing skb.
  *
  *		This helper can only be called during
- *		BPF_SOCK_OPS_WRITE_HDR_OPT_CB.
+ *		**BPF_SOCK_OPS_WRITE_HDR_OPT_CB**.
  *
  *	Return
  *		0 on success, or negative error in case of failure:
  *
- *		**-EINVAL** If param is invalid
+ *		**-EINVAL** If param is invalid.
  *
- *		**-ENOSPC** Not enough space in the header.
+ *		**-ENOSPC** if there is not enough space in the header.
  *		Nothing has been written
  *
- *		**-EEXIST** The option has already existed
+ *		**-EEXIST** if the option already exists.
  *
- *		**-EFAULT** Cannot parse the existing header options
+ *		**-EFAULT** on failrue to parse the existing header options.
  *
- *		**-EPERM** This helper cannot be used under the
- *			   current sock_ops->op.
+ *		**-EPERM** if the helper cannot be used under the current
+ *		*skops*\ **->op**.
  *
  * long bpf_reserve_hdr_opt(struct bpf_sock_ops *skops, u32 len, u64 flags)
  *	Description
  *		Reserve *len* bytes for the bpf header option.  The
- *		space will be used by bpf_store_hdr_opt() later in
- *		BPF_SOCK_OPS_WRITE_HDR_OPT_CB.
+ *		space will be used by **bpf_store_hdr_opt**\ () later in
+ *		**BPF_SOCK_OPS_WRITE_HDR_OPT_CB**.
  *
- *		If bpf_reserve_hdr_opt() is called multiple times,
+ *		If **bpf_reserve_hdr_opt**\ () is called multiple times,
  *		the total number of bytes will be reserved.
  *
  *		This helper can only be called during
- *		BPF_SOCK_OPS_HDR_OPT_LEN_CB.
+ *		**BPF_SOCK_OPS_HDR_OPT_LEN_CB**.
  *
  *	Return
  *		0 on success, or negative error in case of failure:
  *
- *		**-EINVAL** if param is invalid
+ *		**-EINVAL** if a parameter is invalid.
  *
- *		**-ENOSPC** Not enough space in the header.
+ *		**-ENOSPC** if there is not enough space in the header.
  *
- *		**-EPERM** This helper cannot be used under the
- *			   current sock_ops->op.
+ *		**-EPERM** if the helper cannot be used under the current
+ *		*skops*\ **->op**.
  *
  * void *bpf_inode_storage_get(struct bpf_map *map, void *inode, void *value, u64 flags)
  *	Description
@@ -3560,9 +3563,9 @@ union bpf_attr {
  *
  * long bpf_d_path(struct path *path, char *buf, u32 sz)
  *	Description
- *		Return full path for given 'struct path' object, which
- *		needs to be the kernel BTF 'path' object. The path is
- *		returned in the provided buffer 'buf' of size 'sz' and
+ *		Return full path for given **struct path** object, which
+ *		needs to be the kernel BTF *path* object. The path is
+ *		returned in the provided buffer *buf* of size *sz* and
  *		is zero terminated.
  *
  *	Return
@@ -3573,7 +3576,7 @@ union bpf_attr {
  * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)
  * 	Description
  * 		Read *size* bytes from user space address *user_ptr* and store
- * 		the data in *dst*. This is a wrapper of copy_from_user().
+ * 		the data in *dst*. This is a wrapper of **copy_from_user**\ ().
  * 	Return
  * 		0 on success, or a negative error in case of failure.
  */