bpf: add lookup/update/delete/iterate methods to BPF maps

'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map

Alexei Starovoitov committed 12 years ago

Commit db20fd21 parent 749730c3 files · +281 −0Browse files

Showing the changes to include/uapi/linux (1 of 3 files). Show all

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include/uapi/linux/bpf.h+38−0

@@ -70,6 +70,35 @@ enum bpf_cmd { · 69 unmodified lines
70	70	* map is deleted when fd is closed
71	71	*/
72	72	BPF_MAP_CREATE,
	73	+
	74	+ /* lookup key in a given map
	75	+ * err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)
	76	+ * Using attr->map_fd, attr->key, attr->value
	77	+ * returns zero and stores found elem into value
	78	+ * or negative error
	79	+ */
	80	+ BPF_MAP_LOOKUP_ELEM,
	81	+
	82	+ /* create or update key/value pair in a given map
	83	+ * err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)
	84	+ * Using attr->map_fd, attr->key, attr->value
	85	+ * returns zero or negative error
	86	+ */
	87	+ BPF_MAP_UPDATE_ELEM,
	88	+
	89	+ /* find and delete elem by key in a given map
	90	+ * err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)
	91	+ * Using attr->map_fd, attr->key
	92	+ * returns zero or negative error
	93	+ */
	94	+ BPF_MAP_DELETE_ELEM,
	95	+
	96	+ /* lookup key in a given map and return next key
	97	+ * err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size)
	98	+ * Using attr->map_fd, attr->key, attr->next_key
	99	+ * returns zero and stores next key or negative error
	100	+ */
	101	+ BPF_MAP_GET_NEXT_KEY,
73	102	};
74	103
75	104	enum bpf_map_type {
@@ -83,6 +112,15 @@ union bpf_attr { · 7 unmodified lines
83	112	__u32 value_size; /* size of value in bytes */
84	113	__u32 max_entries; /* max number of entries in a map */
85	114	};
	115	+
	116	+ struct { /* anonymous struct used by BPF_MAP__ELEM commands /
	117	+ __u32 map_fd;
	118	+ __aligned_u64 key;
	119	+ union {
	120	+ __aligned_u64 value;
	121	+ __aligned_u64 next_key;
	122	+ };
	123	+ };
86	124	} __attribute__((aligned(8)));
87	125
88	126	#endif /* _UAPI__LINUX_BPF_H__ */