1/* SPDX-License-Identifier: GPL-2.0-only */
  2/* include/net/xdp.h
  3 *
  4 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
  5 */
  6#ifndef __LINUX_NET_XDP_H__
  7#define __LINUX_NET_XDP_H__
  8
  9#include <linux/skbuff.h> /* skb_shared_info */
 10
 11/**
 12 * DOC: XDP RX-queue information
 13 *
 14 * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
 15 * level RX-ring queues.  It is information that is specific to how
 16 * the driver have configured a given RX-ring queue.
 17 *
 18 * Each xdp_buff frame received in the driver carry a (pointer)
 19 * reference to this xdp_rxq_info structure.  This provides the XDP
 20 * data-path read-access to RX-info for both kernel and bpf-side
 21 * (limited subset).
 22 *
 23 * For now, direct access is only safe while running in NAPI/softirq
 24 * context.  Contents is read-mostly and must not be updated during
 25 * driver NAPI/softirq poll.
 26 *
 27 * The driver usage API is a register and unregister API.
 28 *
 29 * The struct is not directly tied to the XDP prog.  A new XDP prog
 30 * can be attached as long as it doesn't change the underlying
 31 * RX-ring.  If the RX-ring does change significantly, the NIC driver
 32 * naturally need to stop the RX-ring before purging and reallocating
 33 * memory.  In that process the driver MUST call unregistor (which
 34 * also apply for driver shutdown and unload).  The register API is
 35 * also mandatory during RX-ring setup.
 36 */
 37
 38enum xdp_mem_type {
 39	MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
 40	MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
 41	MEM_TYPE_PAGE_POOL,
 42	MEM_TYPE_XSK_BUFF_POOL,
 43	MEM_TYPE_MAX,
 44};
 45
 46/* XDP flags for ndo_xdp_xmit */
 47#define XDP_XMIT_FLUSH		(1U << 0)	/* doorbell signal consumer */
 48#define XDP_XMIT_FLAGS_MASK	XDP_XMIT_FLUSH
 49
 50struct xdp_mem_info {
 51	u32 type; /* enum xdp_mem_type, but known size type */
 52	u32 id;
 53};
 54
 55struct page_pool;
 56
 57struct xdp_rxq_info {
 58	struct net_device *dev;
 59	u32 queue_index;
 60	u32 reg_state;
 61	struct xdp_mem_info mem;
 62	unsigned int napi_id;
 63} ____cacheline_aligned; /* perf critical, avoid false-sharing */
 64
 65struct xdp_txq_info {
 66	struct net_device *dev;
 67};
 68
 69struct xdp_buff {
 70	void *data;
 71	void *data_end;
 72	void *data_meta;
 73	void *data_hard_start;
 74	struct xdp_rxq_info *rxq;
 75	struct xdp_txq_info *txq;
 76	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
 77};
 78
 79static __always_inline void
 80xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)
 81{
 82	xdp->frame_sz = frame_sz;
 83	xdp->rxq = rxq;
 84}
 85
 86static __always_inline void
 87xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,
 88		 int headroom, int data_len, const bool meta_valid)
 89{
 90	unsigned char *data = hard_start + headroom;
 91
 92	xdp->data_hard_start = hard_start;
 93	xdp->data = data;
 94	xdp->data_end = data + data_len;
 95	xdp->data_meta = meta_valid ? data : data + 1;
 96}
 97
 98/* Reserve memory area at end-of data area.
 99 *
100 * This macro reserves tailroom in the XDP buffer by limiting the
101 * XDP/BPF data access to data_hard_end.  Notice same area (and size)
102 * is used for XDP_PASS, when constructing the SKB via build_skb().
103 */
104#define xdp_data_hard_end(xdp)				\
105	((xdp)->data_hard_start + (xdp)->frame_sz -	\
106	 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
107
108static inline struct skb_shared_info *
109xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
110{
111	return (struct skb_shared_info *)xdp_data_hard_end(xdp);
112}
113
114struct xdp_frame {
115	void *data;
116	u16 len;
117	u16 headroom;
118	u32 metasize:8;
119	u32 frame_sz:24;
120	/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
121	 * while mem info is valid on remote CPU.
122	 */
123	struct xdp_mem_info mem;
124	struct net_device *dev_rx; /* used by cpumap */
125};
126
127#define XDP_BULK_QUEUE_SIZE	16
128struct xdp_frame_bulk {
129	int count;
130	void *xa;
131	void *q[XDP_BULK_QUEUE_SIZE];
132};
133
134static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
135{
136	/* bq->count will be zero'ed when bq->xa gets updated */
137	bq->xa = NULL;
138}
139
140static inline struct skb_shared_info *
141xdp_get_shared_info_from_frame(struct xdp_frame *frame)
142{
143	void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
144
145	return (struct skb_shared_info *)(data_hard_start + frame->frame_sz -
146				SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
147}
148
149struct xdp_cpumap_stats {
150	unsigned int redirect;
151	unsigned int pass;
152	unsigned int drop;
153};
154
155/* Clear kernel pointers in xdp_frame */
156static inline void xdp_scrub_frame(struct xdp_frame *frame)
157{
158	frame->data = NULL;
159	frame->dev_rx = NULL;
160}
161
162/* Avoids inlining WARN macro in fast-path */
163void xdp_warn(const char *msg, const char *func, const int line);
164#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
165
166struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
167struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
168					   struct sk_buff *skb,
169					   struct net_device *dev);
170struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
171					 struct net_device *dev);
172int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp);
173struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
174
175static inline
176void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
177{
178	xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
179	xdp->data = frame->data;
180	xdp->data_end = frame->data + frame->len;
181	xdp->data_meta = frame->data - frame->metasize;
182	xdp->frame_sz = frame->frame_sz;
183}
184
185static inline
186int xdp_update_frame_from_buff(struct xdp_buff *xdp,
187			       struct xdp_frame *xdp_frame)
188{
189	int metasize, headroom;
190
191	/* Assure headroom is available for storing info */
192	headroom = xdp->data - xdp->data_hard_start;
193	metasize = xdp->data - xdp->data_meta;
194	metasize = metasize > 0 ? metasize : 0;
195	if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
196		return -ENOSPC;
197
198	/* Catch if driver didn't reserve tailroom for skb_shared_info */
199	if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
200		XDP_WARN("Driver BUG: missing reserved tailroom");
201		return -ENOSPC;
202	}
203
204	xdp_frame->data = xdp->data;
205	xdp_frame->len  = xdp->data_end - xdp->data;
206	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
207	xdp_frame->metasize = metasize;
208	xdp_frame->frame_sz = xdp->frame_sz;
209
210	return 0;
211}
212
213/* Convert xdp_buff to xdp_frame */
214static inline
215struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
216{
217	struct xdp_frame *xdp_frame;
218
219	if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
220		return xdp_convert_zc_to_xdp_frame(xdp);
221
222	/* Store info in top of packet */
223	xdp_frame = xdp->data_hard_start;
224	if (unlikely(xdp_update_frame_from_buff(xdp, xdp_frame) < 0))
225		return NULL;
226
227	/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
228	xdp_frame->mem = xdp->rxq->mem;
229
230	return xdp_frame;
231}
232
233void xdp_return_frame(struct xdp_frame *xdpf);
234void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
235void xdp_return_buff(struct xdp_buff *xdp);
236void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
237void xdp_return_frame_bulk(struct xdp_frame *xdpf,
238			   struct xdp_frame_bulk *bq);
239
240/* When sending xdp_frame into the network stack, then there is no
241 * return point callback, which is needed to release e.g. DMA-mapping
242 * resources with page_pool.  Thus, have explicit function to release
243 * frame resources.
244 */
245void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
246static inline void xdp_release_frame(struct xdp_frame *xdpf)
247{
248	struct xdp_mem_info *mem = &xdpf->mem;
249
250	/* Curr only page_pool needs this */
251	if (mem->type == MEM_TYPE_PAGE_POOL)
252		__xdp_release_frame(xdpf->data, mem);
253}
254
255int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
256		     struct net_device *dev, u32 queue_index, unsigned int napi_id);
257void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
258void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
259bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
260int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
261			       enum xdp_mem_type type, void *allocator);
262void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
263
264/* Drivers not supporting XDP metadata can use this helper, which
265 * rejects any room expansion for metadata as a result.
266 */
267static __always_inline void
268xdp_set_data_meta_invalid(struct xdp_buff *xdp)
269{
270	xdp->data_meta = xdp->data + 1;
271}
272
273static __always_inline bool
274xdp_data_meta_unsupported(const struct xdp_buff *xdp)
275{
276	return unlikely(xdp->data_meta > xdp->data);
277}
278
279struct xdp_attachment_info {
280	struct bpf_prog *prog;
281	u32 flags;
282};
283
284struct netdev_bpf;
285void xdp_attachment_setup(struct xdp_attachment_info *info,
286			  struct netdev_bpf *bpf);
287
288#define DEV_MAP_BULK_SIZE XDP_BULK_QUEUE_SIZE
289
290#endif /* __LINUX_NET_XDP_H__ */