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Diffstat (limited to 'Documentation/bpf/map_devmap.rst')
| -rw-r--r-- | Documentation/bpf/map_devmap.rst | 68 |
1 files changed, 42 insertions, 26 deletions
diff --git a/Documentation/bpf/map_devmap.rst b/Documentation/bpf/map_devmap.rst index f64da348dbfe..927312c7b8c8 100644 --- a/Documentation/bpf/map_devmap.rst +++ b/Documentation/bpf/map_devmap.rst @@ -29,8 +29,11 @@ Usage ===== Kernel BPF ---------- -.. c:function:: - long bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags) +bpf_redirect_map() +^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags) Redirect the packet to the endpoint referenced by ``map`` at index ``key``. For ``BPF_MAP_TYPE_DEVMAP`` and ``BPF_MAP_TYPE_DEVMAP_HASH`` this map contains @@ -56,26 +59,32 @@ lower bits of the ``flags`` argument if the map lookup fails. More information about redirection can be found :doc:`redirect` -.. c:function:: +bpf_map_lookup_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + void *bpf_map_lookup_elem(struct bpf_map *map, const void *key) Net device entries can be retrieved using the ``bpf_map_lookup_elem()`` helper. -Userspace ---------- +User space +---------- .. note:: DEVMAP entries can only be updated/deleted from user space and not from an eBPF program. Trying to call these functions from a kernel eBPF program will result in the program failing to load and a verifier warning. -.. c:function:: +bpf_map_update_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + int bpf_map_update_elem(int fd, const void *key, const void *value, __u64 flags); - Net device entries can be added or updated using the ``bpf_map_update_elem()`` - helper. This helper replaces existing elements atomically. The ``value`` parameter - can be ``struct bpf_devmap_val`` or a simple ``int ifindex`` for backwards - compatibility. +Net device entries can be added or updated using the ``bpf_map_update_elem()`` +helper. This helper replaces existing elements atomically. The ``value`` parameter +can be ``struct bpf_devmap_val`` or a simple ``int ifindex`` for backwards +compatibility. .. code-block:: c @@ -87,35 +96,42 @@ Userspace } bpf_prog; }; - The ``flags`` argument can be one of the following: - +The ``flags`` argument can be 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. - DEVMAPs can associate a program with a device entry by adding a ``bpf_prog.fd`` - to ``struct bpf_devmap_val``. Programs are run after ``XDP_REDIRECT`` and have - access to both Rx device and Tx device. The program associated with the ``fd`` - must have type XDP with expected attach type ``xdp_devmap``. - When a program is associated with a device index, the program is run on an - ``XDP_REDIRECT`` and before the buffer is added to the per-cpu queue. Examples - of how to attach/use xdp_devmap progs can be found in the kernel selftests: +DEVMAPs can associate a program with a device entry by adding a ``bpf_prog.fd`` +to ``struct bpf_devmap_val``. Programs are run after ``XDP_REDIRECT`` and have +access to both Rx device and Tx device. The program associated with the ``fd`` +must have type XDP with expected attach type ``xdp_devmap``. +When a program is associated with a device index, the program is run on an +``XDP_REDIRECT`` and before the buffer is added to the per-cpu queue. Examples +of how to attach/use xdp_devmap progs can be found in the kernel selftests: - - ``tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c`` - - ``tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c`` +- ``tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c`` +- ``tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c`` + +bpf_map_lookup_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c .. c:function:: int bpf_map_lookup_elem(int fd, const void *key, void *value); - Net device entries can be retrieved using the ``bpf_map_lookup_elem()`` - helper. +Net device entries can be retrieved using the ``bpf_map_lookup_elem()`` +helper. + +bpf_map_delete_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c .. c:function:: int bpf_map_delete_elem(int fd, const void *key); - Net device entries can be deleted using the ``bpf_map_delete_elem()`` - helper. This helper will return 0 on success, or negative error in case of - failure. +Net device entries can be deleted using the ``bpf_map_delete_elem()`` +helper. This helper will return 0 on success, or negative error in case of +failure. Examples ======== |