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} ____cacheline_aligned; /* perf critical, avoid false-sharing */
 63
 64struct xdp_txq_info {
 65	struct net_device *dev;
 66};
 67
 68struct xdp_buff {
 69	void *data;
 70	void *data_end;
 71	void *data_meta;
 72	void *data_hard_start;
 73	struct xdp_rxq_info *rxq;
 74	struct xdp_txq_info *txq;
 75	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
 76};
 77
 78/* Reserve memory area at end-of data area.
 79 *
 80 * This macro reserves tailroom in the XDP buffer by limiting the
 81 * XDP/BPF data access to data_hard_end.  Notice same area (and size)
 82 * is used for XDP_PASS, when constructing the SKB via build_skb().
 83 */
 84#define xdp_data_hard_end(xdp)				\
 85	((xdp)->data_hard_start + (xdp)->frame_sz -	\
 86	 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 87
 88static inline struct skb_shared_info *
 89xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
 90{
 91	return (struct skb_shared_info *)xdp_data_hard_end(xdp);
 92}
 93
 94struct xdp_frame {
 95	void *data;
 96	u16 len;
 97	u16 headroom;
 98	u32 metasize:8;
 99	u32 frame_sz:24;
100	/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
101	 * while mem info is valid on remote CPU.
102	 */
103	struct xdp_mem_info mem;
104	struct net_device *dev_rx; /* used by cpumap */
105};
106
107
108static inline struct skb_shared_info *
109xdp_get_shared_info_from_frame(struct xdp_frame *frame)
110{
111	void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
112
113	return (struct skb_shared_info *)(data_hard_start + frame->frame_sz -
114				SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
115}
116
117struct xdp_cpumap_stats {
118	unsigned int redirect;
119	unsigned int pass;
120	unsigned int drop;
121};
122
123/* Clear kernel pointers in xdp_frame */
124static inline void xdp_scrub_frame(struct xdp_frame *frame)
125{
126	frame->data = NULL;
127	frame->dev_rx = NULL;
128}
129
130/* Avoids inlining WARN macro in fast-path */
131void xdp_warn(const char *msg, const char *func, const int line);
132#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
133
134struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
135
136static inline
137void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
138{
139	xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
140	xdp->data = frame->data;
141	xdp->data_end = frame->data + frame->len;
142	xdp->data_meta = frame->data - frame->metasize;
143	xdp->frame_sz = frame->frame_sz;
144}
145
146static inline
147int xdp_update_frame_from_buff(struct xdp_buff *xdp,
148			       struct xdp_frame *xdp_frame)
149{
150	int metasize, headroom;
151
152	/* Assure headroom is available for storing info */
153	headroom = xdp->data - xdp->data_hard_start;
154	metasize = xdp->data - xdp->data_meta;
155	metasize = metasize > 0 ? metasize : 0;
156	if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
157		return -ENOSPC;
158
159	/* Catch if driver didn't reserve tailroom for skb_shared_info */
160	if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
161		XDP_WARN("Driver BUG: missing reserved tailroom");
162		return -ENOSPC;
163	}
164
165	xdp_frame->data = xdp->data;
166	xdp_frame->len  = xdp->data_end - xdp->data;
167	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
168	xdp_frame->metasize = metasize;
169	xdp_frame->frame_sz = xdp->frame_sz;
170
171	return 0;
172}
173
174/* Convert xdp_buff to xdp_frame */
175static inline
176struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
177{
178	struct xdp_frame *xdp_frame;
179
180	if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
181		return xdp_convert_zc_to_xdp_frame(xdp);
182
183	/* Store info in top of packet */
184	xdp_frame = xdp->data_hard_start;
185	if (unlikely(xdp_update_frame_from_buff(xdp, xdp_frame) < 0))
186		return NULL;
187
188	/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
189	xdp_frame->mem = xdp->rxq->mem;
190
191	return xdp_frame;
192}
193
194void xdp_return_frame(struct xdp_frame *xdpf);
195void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
196void xdp_return_buff(struct xdp_buff *xdp);
197
198/* When sending xdp_frame into the network stack, then there is no
199 * return point callback, which is needed to release e.g. DMA-mapping
200 * resources with page_pool.  Thus, have explicit function to release
201 * frame resources.
202 */
203void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
204static inline void xdp_release_frame(struct xdp_frame *xdpf)
205{
206	struct xdp_mem_info *mem = &xdpf->mem;
207
208	/* Curr only page_pool needs this */
209	if (mem->type == MEM_TYPE_PAGE_POOL)
210		__xdp_release_frame(xdpf->data, mem);
211}
212
213int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
214		     struct net_device *dev, u32 queue_index);
215void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
216void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
217bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
218int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
219			       enum xdp_mem_type type, void *allocator);
220void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
221
222/* Drivers not supporting XDP metadata can use this helper, which
223 * rejects any room expansion for metadata as a result.
224 */
225static __always_inline void
226xdp_set_data_meta_invalid(struct xdp_buff *xdp)
227{
228	xdp->data_meta = xdp->data + 1;
229}
230
231static __always_inline bool
232xdp_data_meta_unsupported(const struct xdp_buff *xdp)
233{
234	return unlikely(xdp->data_meta > xdp->data);
235}
236
237struct xdp_attachment_info {
238	struct bpf_prog *prog;
239	u32 flags;
240};
241
242struct netdev_bpf;
243bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
244			     struct netdev_bpf *bpf);
245void xdp_attachment_setup(struct xdp_attachment_info *info,
246			  struct netdev_bpf *bpf);
247
248#define DEV_MAP_BULK_SIZE 16
249
250#endif /* __LINUX_NET_XDP_H__ */