Commit 7799e4d9 authored by Joe Stringer's avatar Joe Stringer Committed by Alexei Starovoitov

bpf: Import syscall arg documentation

These descriptions are present in the man-pages project from the
original submissions around 2015-2016. Import them so that they can be
kept up to date as developers extend the bpf syscall commands.

These descriptions follow the pattern used by scripts/bpf_helpers_doc.py
so that we can take advantage of the parser to generate more up-to-date
man page writing based upon these headers.

Some minor wording adjustments were made to make the descriptions
more consistent for the description / return format.
Signed-off-by: default avatarJoe Stringer <joe@cilium.io>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-2-joe@cilium.ioCo-authored-by: default avatarAlexei Starovoitov <ast@kernel.org>
Co-authored-by: default avatarMichael Kerrisk <mtk.manpages@gmail.com>
parent 13ec0216
......@@ -93,7 +93,127 @@ union bpf_iter_link_info {
} map;
};
/* BPF syscall commands, see bpf(2) man-page for details. */
/* BPF syscall commands, see bpf(2) man-page for more details. */
/**
* DOC: eBPF Syscall Preamble
*
* The operation to be performed by the **bpf**\ () system call is determined
* by the *cmd* argument. Each operation takes an accompanying argument,
* provided via *attr*, which is a pointer to a union of type *bpf_attr* (see
* below). The size argument is the size of the union pointed to by *attr*.
*/
/**
* DOC: eBPF Syscall Commands
*
* BPF_MAP_CREATE
* Description
* Create a map and return a file descriptor that refers to the
* map. The close-on-exec file descriptor flag (see **fcntl**\ (2))
* is automatically enabled for the new file descriptor.
*
* Applying **close**\ (2) to the file descriptor returned by
* **BPF_MAP_CREATE** will delete the map (but see NOTES).
*
* Return
* A new file descriptor (a nonnegative integer), or -1 if an
* error occurred (in which case, *errno* is set appropriately).
*
* BPF_MAP_LOOKUP_ELEM
* Description
* Look up an element with a given *key* in the map referred to
* by the file descriptor *map_fd*.
*
* Return
* Returns zero on success. On error, -1 is returned and *errno*
* is set appropriately.
*
* BPF_MAP_UPDATE_ELEM
* Description
* Create or update an element (key/value pair) in a specified map.
*
* The *flags* argument should be specified as one of the
* following:
*
* **BPF_ANY**
* Create a new element or update an existing element.
* **BPF_NOEXIST**
* Create a new element only if it did not exist.
* **BPF_EXIST**
* Update an existing element.
*
* Return
* Returns zero on success. On error, -1 is returned and *errno*
* is set appropriately.
*
* May set *errno* to **EINVAL**, **EPERM**, **ENOMEM**,
* **E2BIG**, **EEXIST**, or **ENOENT**.
*
* **E2BIG**
* The number of elements in the map reached the
* *max_entries* limit specified at map creation time.
* **EEXIST**
* If *flags* specifies **BPF_NOEXIST** and the element
* with *key* already exists in the map.
* **ENOENT**
* If *flags* specifies **BPF_EXIST** and the element with
* *key* does not exist in the map.
*
* BPF_MAP_DELETE_ELEM
* Description
* Look up and delete an element by key in a specified map.
*
* Return
* Returns zero on success. On error, -1 is returned and *errno*
* is set appropriately.
*
* BPF_MAP_GET_NEXT_KEY
* Description
* Look up an element by key in a specified map and return the key
* of the next element. Can be used to iterate over all elements
* in the map.
*
* Return
* Returns zero on success. On error, -1 is returned and *errno*
* is set appropriately.
*
* The following cases can be used to iterate over all elements of
* the map:
*
* * If *key* is not found, the operation returns zero and sets
* the *next_key* pointer to the key of the first element.
* * If *key* is found, the operation returns zero and sets the
* *next_key* pointer to the key of the next element.
* * If *key* is the last element, returns -1 and *errno* is set
* to **ENOENT**.
*
* May set *errno* to **ENOMEM**, **EFAULT**, **EPERM**, or
* **EINVAL** on error.
*
* BPF_PROG_LOAD
* Description
* Verify and load an eBPF program, returning a new file
* descriptor associated with the program.
*
* Applying **close**\ (2) to the file descriptor returned by
* **BPF_PROG_LOAD** will unload the eBPF program (but see NOTES).
*
* The close-on-exec file descriptor flag (see **fcntl**\ (2)) is
* automatically enabled for the new file descriptor.
*
* Return
* A new file descriptor (a nonnegative integer), or -1 if an
* error occurred (in which case, *errno* is set appropriately).
*
* NOTES
* eBPF objects (maps and programs) can be shared between processes.
* For example, after **fork**\ (2), the child inherits file descriptors
* referring to the same eBPF objects. In addition, file descriptors
* referring to eBPF objects can be transferred over UNIX domain sockets.
* File descriptors referring to eBPF objects can be duplicated in the
* usual way, using **dup**\ (2) and similar calls. An eBPF object is
* deallocated only after all file descriptors referring to the object
* have been closed.
*/
enum bpf_cmd {
BPF_MAP_CREATE,
BPF_MAP_LOOKUP_ELEM,
......
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