1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2
3 /*
4 * AF_XDP user-space access library.
5 *
6 * Copyright (c) 2018 - 2019 Intel Corporation.
7 * Copyright (c) 2019 Facebook
8 *
9 * Author(s): Magnus Karlsson <magnus.karlsson@intel.com>
10 */
11
12 #ifndef __XSK_H
13 #define __XSK_H
14
15 #include <stdio.h>
16 #include <stdint.h>
17 #include <stdbool.h>
18 #include <linux/if_xdp.h>
19
20 #include <bpf/libbpf.h>
21
22 #ifdef __cplusplus
23 extern "C" {
24 #endif
25
26 /* Do not access these members directly. Use the functions below. */
27 #define DEFINE_XSK_RING(name) \
28 struct name { \
29 __u32 cached_prod; \
30 __u32 cached_cons; \
31 __u32 mask; \
32 __u32 size; \
33 __u32 *producer; \
34 __u32 *consumer; \
35 void *ring; \
36 __u32 *flags; \
37 }
38
39 DEFINE_XSK_RING(xsk_ring_prod);
40 DEFINE_XSK_RING(xsk_ring_cons);
41
42 /* For a detailed explanation on the memory barriers associated with the
43 * ring, please take a look at net/xdp/xsk_queue.h.
44 */
45
46 struct xsk_umem;
47 struct xsk_socket;
48
49 static inline __u64 *xsk_ring_prod__fill_addr(struct xsk_ring_prod *fill,
50 __u32 idx)
51 {
52 __u64 *addrs = (__u64 *)fill->ring;
53
54 return &addrs[idx & fill->mask];
55 }
56
57 static inline const __u64 *
58 xsk_ring_cons__comp_addr(const struct xsk_ring_cons *comp, __u32 idx)
59 {
60 const __u64 *addrs = (const __u64 *)comp->ring;
61
62 return &addrs[idx & comp->mask];
63 }
64
65 static inline struct xdp_desc *xsk_ring_prod__tx_desc(struct xsk_ring_prod *tx,
66 __u32 idx)
67 {
68 struct xdp_desc *descs = (struct xdp_desc *)tx->ring;
69
70 return &descs[idx & tx->mask];
71 }
72
73 static inline const struct xdp_desc *
74 xsk_ring_cons__rx_desc(const struct xsk_ring_cons *rx, __u32 idx)
75 {
76 const struct xdp_desc *descs = (const struct xdp_desc *)rx->ring;
77
78 return &descs[idx & rx->mask];
79 }
80
81 static inline int xsk_ring_prod__needs_wakeup(const struct xsk_ring_prod *r)
82 {
83 return *r->flags & XDP_RING_NEED_WAKEUP;
84 }
85
86 static inline __u32 xsk_prod_nb_free(struct xsk_ring_prod *r, __u32 nb)
87 {
88 __u32 free_entries = r->cached_cons - r->cached_prod;
89
90 if (free_entries >= nb)
91 return free_entries;
92
93 /* Refresh the local tail pointer.
94 * cached_cons is r->size bigger than the real consumer pointer so
95 * that this addition can be avoided in the more frequently
96 * executed code that computs free_entries in the beginning of
97 * this function. Without this optimization it whould have been
98 * free_entries = r->cached_prod - r->cached_cons + r->size.
99 */
100 r->cached_cons = __atomic_load_n(r->consumer, __ATOMIC_ACQUIRE);
101 r->cached_cons += r->size;
102
103 return r->cached_cons - r->cached_prod;
104 }
105
106 static inline __u32 xsk_cons_nb_avail(struct xsk_ring_cons *r, __u32 nb)
107 {
108 __u32 entries = r->cached_prod - r->cached_cons;
109
110 if (entries == 0) {
111 r->cached_prod = __atomic_load_n(r->producer, __ATOMIC_ACQUIRE);
112 entries = r->cached_prod - r->cached_cons;
113 }
114
115 return (entries > nb) ? nb : entries;
116 }
117
118 static inline __u32 xsk_ring_prod__reserve(struct xsk_ring_prod *prod, __u32 nb, __u32 *idx)
119 {
120 if (xsk_prod_nb_free(prod, nb) < nb)
121 return 0;
122
123 *idx = prod->cached_prod;
124 prod->cached_prod += nb;
125
126 return nb;
127 }
128
129 static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, __u32 nb)
130 {
131 /* Make sure everything has been written to the ring before indicating
132 * this to the kernel by writing the producer pointer.
133 */
134 __atomic_store_n(prod->producer, *prod->producer + nb, __ATOMIC_RELEASE);
135 }
136
137 static inline void xsk_ring_prod__cancel(struct xsk_ring_prod *prod, __u32 nb)
138 {
139 prod->cached_prod -= nb;
140 }
141
142 static inline __u32 xsk_ring_cons__peek(struct xsk_ring_cons *cons, __u32 nb, __u32 *idx)
143 {
144 __u32 entries = xsk_cons_nb_avail(cons, nb);
145
146 if (entries > 0) {
147 *idx = cons->cached_cons;
148 cons->cached_cons += entries;
149 }
150
151 return entries;
152 }
153
154 static inline void xsk_ring_cons__cancel(struct xsk_ring_cons *cons, __u32 nb)
155 {
156 cons->cached_cons -= nb;
157 }
158
159 static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, __u32 nb)
160 {
161 /* Make sure data has been read before indicating we are done
162 * with the entries by updating the consumer pointer.
163 */
164 __atomic_store_n(cons->consumer, *cons->consumer + nb, __ATOMIC_RELEASE);
165 }
166
167 static inline void *xsk_umem__get_data(void *umem_area, __u64 addr)
168 {
169 return &((char *)umem_area)[addr];
170 }
171
172 static inline __u64 xsk_umem__extract_addr(__u64 addr)
173 {
174 return addr & XSK_UNALIGNED_BUF_ADDR_MASK;
175 }
176
177 static inline __u64 xsk_umem__extract_offset(__u64 addr)
178 {
179 return addr >> XSK_UNALIGNED_BUF_OFFSET_SHIFT;
180 }
181
182 static inline __u64 xsk_umem__add_offset_to_addr(__u64 addr)
183 {
184 return xsk_umem__extract_addr(addr) + xsk_umem__extract_offset(addr);
185 }
186
187 int xsk_umem__fd(const struct xsk_umem *umem);
188 int xsk_socket__fd(const struct xsk_socket *xsk);
189
190 #define XSK_RING_CONS__DEFAULT_NUM_DESCS 2048
191 #define XSK_RING_PROD__DEFAULT_NUM_DESCS 2048
192 #define XSK_UMEM__DEFAULT_FRAME_SHIFT 12 /* 4096 bytes */
193 #define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
194 #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
195 #define XSK_UMEM__DEFAULT_FLAGS 0
196
197 struct xsk_umem_config {
198 __u32 fill_size;
199 __u32 comp_size;
200 __u32 frame_size;
201 __u32 frame_headroom;
202 __u32 flags;
203 __u32 tx_metadata_len;
204 };
205
206 int xsk_attach_xdp_program(struct bpf_program *prog, int ifindex, u32 xdp_flags);
207 void xsk_detach_xdp_program(int ifindex, u32 xdp_flags);
208 int xsk_update_xskmap(struct bpf_map *map, struct xsk_socket *xsk, u32 index);
209 void xsk_clear_xskmap(struct bpf_map *map);
210 bool xsk_is_in_mode(u32 ifindex, int mode);
211
212 struct xsk_socket_config {
213 __u32 rx_size;
214 __u32 tx_size;
215 __u16 bind_flags;
216 };
217
218 /* Set config to NULL to get the default configuration. */
219 int xsk_umem__create(struct xsk_umem **umem,
220 void *umem_area, __u64 size,
221 struct xsk_ring_prod *fill,
222 struct xsk_ring_cons *comp,
223 const struct xsk_umem_config *config);
224 int xsk_socket__create(struct xsk_socket **xsk,
225 int ifindex, __u32 queue_id,
226 struct xsk_umem *umem,
227 struct xsk_ring_cons *rx,
228 struct xsk_ring_prod *tx,
229 const struct xsk_socket_config *config);
230 int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
231 int ifindex,
232 __u32 queue_id, struct xsk_umem *umem,
233 struct xsk_ring_cons *rx,
234 struct xsk_ring_prod *tx,
235 struct xsk_ring_prod *fill,
236 struct xsk_ring_cons *comp,
237 const struct xsk_socket_config *config);
238
239 /* Returns 0 for success and -EBUSY if the umem is still in use. */
240 int xsk_umem__delete(struct xsk_umem *umem);
241 void xsk_socket__delete(struct xsk_socket *xsk);
242
243 int xsk_set_mtu(int ifindex, int mtu);
244
245 #ifdef __cplusplus
246 } /* extern "C" */
247 #endif
248
249 #endif /* __XSK_H */
250
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