xref: /linux/net/core/xdp.c (revision 3f0a50f345f78183f6e9b39c2f45ca5dcaa511ca) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* net/core/xdp.c
3  *
4  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
5  */
6 #include <linux/bpf.h>
7 #include <linux/filter.h>
8 #include <linux/types.h>
9 #include <linux/mm.h>
10 #include <linux/netdevice.h>
11 #include <linux/slab.h>
12 #include <linux/idr.h>
13 #include <linux/rhashtable.h>
14 #include <linux/bug.h>
15 #include <net/page_pool.h>
16 
17 #include <net/xdp.h>
18 #include <net/xdp_priv.h> /* struct xdp_mem_allocator */
19 #include <trace/events/xdp.h>
20 #include <net/xdp_sock_drv.h>
21 
22 #define REG_STATE_NEW		0x0
23 #define REG_STATE_REGISTERED	0x1
24 #define REG_STATE_UNREGISTERED	0x2
25 #define REG_STATE_UNUSED	0x3
26 
27 static DEFINE_IDA(mem_id_pool);
28 static DEFINE_MUTEX(mem_id_lock);
29 #define MEM_ID_MAX 0xFFFE
30 #define MEM_ID_MIN 1
31 static int mem_id_next = MEM_ID_MIN;
32 
33 static bool mem_id_init; /* false */
34 static struct rhashtable *mem_id_ht;
35 
36 static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
37 {
38 	const u32 *k = data;
39 	const u32 key = *k;
40 
41 	BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
42 		     != sizeof(u32));
43 
44 	/* Use cyclic increasing ID as direct hash key */
45 	return key;
46 }
47 
48 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
49 			  const void *ptr)
50 {
51 	const struct xdp_mem_allocator *xa = ptr;
52 	u32 mem_id = *(u32 *)arg->key;
53 
54 	return xa->mem.id != mem_id;
55 }
56 
57 static const struct rhashtable_params mem_id_rht_params = {
58 	.nelem_hint = 64,
59 	.head_offset = offsetof(struct xdp_mem_allocator, node),
60 	.key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
61 	.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
62 	.max_size = MEM_ID_MAX,
63 	.min_size = 8,
64 	.automatic_shrinking = true,
65 	.hashfn    = xdp_mem_id_hashfn,
66 	.obj_cmpfn = xdp_mem_id_cmp,
67 };
68 
69 static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
70 {
71 	struct xdp_mem_allocator *xa;
72 
73 	xa = container_of(rcu, struct xdp_mem_allocator, rcu);
74 
75 	/* Allow this ID to be reused */
76 	ida_simple_remove(&mem_id_pool, xa->mem.id);
77 
78 	kfree(xa);
79 }
80 
81 static void mem_xa_remove(struct xdp_mem_allocator *xa)
82 {
83 	trace_mem_disconnect(xa);
84 
85 	if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
86 		call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
87 }
88 
89 static void mem_allocator_disconnect(void *allocator)
90 {
91 	struct xdp_mem_allocator *xa;
92 	struct rhashtable_iter iter;
93 
94 	mutex_lock(&mem_id_lock);
95 
96 	rhashtable_walk_enter(mem_id_ht, &iter);
97 	do {
98 		rhashtable_walk_start(&iter);
99 
100 		while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
101 			if (xa->allocator == allocator)
102 				mem_xa_remove(xa);
103 		}
104 
105 		rhashtable_walk_stop(&iter);
106 
107 	} while (xa == ERR_PTR(-EAGAIN));
108 	rhashtable_walk_exit(&iter);
109 
110 	mutex_unlock(&mem_id_lock);
111 }
112 
113 void xdp_unreg_mem_model(struct xdp_mem_info *mem)
114 {
115 	struct xdp_mem_allocator *xa;
116 	int type = mem->type;
117 	int id = mem->id;
118 
119 	/* Reset mem info to defaults */
120 	mem->id = 0;
121 	mem->type = 0;
122 
123 	if (id == 0)
124 		return;
125 
126 	if (type == MEM_TYPE_PAGE_POOL) {
127 		rcu_read_lock();
128 		xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
129 		page_pool_destroy(xa->page_pool);
130 		rcu_read_unlock();
131 	}
132 }
133 EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);
134 
135 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
136 {
137 	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
138 		WARN(1, "Missing register, driver bug");
139 		return;
140 	}
141 
142 	xdp_unreg_mem_model(&xdp_rxq->mem);
143 }
144 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
145 
146 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
147 {
148 	/* Simplify driver cleanup code paths, allow unreg "unused" */
149 	if (xdp_rxq->reg_state == REG_STATE_UNUSED)
150 		return;
151 
152 	xdp_rxq_info_unreg_mem_model(xdp_rxq);
153 
154 	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
155 	xdp_rxq->dev = NULL;
156 }
157 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
158 
159 static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
160 {
161 	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
162 }
163 
164 /* Returns 0 on success, negative on failure */
165 int __xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
166 		       struct net_device *dev, u32 queue_index,
167 		       unsigned int napi_id, u32 frag_size)
168 {
169 	if (!dev) {
170 		WARN(1, "Missing net_device from driver");
171 		return -ENODEV;
172 	}
173 
174 	if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
175 		WARN(1, "Driver promised not to register this");
176 		return -EINVAL;
177 	}
178 
179 	if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
180 		WARN(1, "Missing unregister, handled but fix driver");
181 		xdp_rxq_info_unreg(xdp_rxq);
182 	}
183 
184 	/* State either UNREGISTERED or NEW */
185 	xdp_rxq_info_init(xdp_rxq);
186 	xdp_rxq->dev = dev;
187 	xdp_rxq->queue_index = queue_index;
188 	xdp_rxq->napi_id = napi_id;
189 	xdp_rxq->frag_size = frag_size;
190 
191 	xdp_rxq->reg_state = REG_STATE_REGISTERED;
192 	return 0;
193 }
194 EXPORT_SYMBOL_GPL(__xdp_rxq_info_reg);
195 
196 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
197 {
198 	xdp_rxq->reg_state = REG_STATE_UNUSED;
199 }
200 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
201 
202 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
203 {
204 	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
205 }
206 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
207 
208 static int __mem_id_init_hash_table(void)
209 {
210 	struct rhashtable *rht;
211 	int ret;
212 
213 	if (unlikely(mem_id_init))
214 		return 0;
215 
216 	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
217 	if (!rht)
218 		return -ENOMEM;
219 
220 	ret = rhashtable_init(rht, &mem_id_rht_params);
221 	if (ret < 0) {
222 		kfree(rht);
223 		return ret;
224 	}
225 	mem_id_ht = rht;
226 	smp_mb(); /* mutex lock should provide enough pairing */
227 	mem_id_init = true;
228 
229 	return 0;
230 }
231 
232 /* Allocate a cyclic ID that maps to allocator pointer.
233  * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
234  *
235  * Caller must lock mem_id_lock.
236  */
237 static int __mem_id_cyclic_get(gfp_t gfp)
238 {
239 	int retries = 1;
240 	int id;
241 
242 again:
243 	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
244 	if (id < 0) {
245 		if (id == -ENOSPC) {
246 			/* Cyclic allocator, reset next id */
247 			if (retries--) {
248 				mem_id_next = MEM_ID_MIN;
249 				goto again;
250 			}
251 		}
252 		return id; /* errno */
253 	}
254 	mem_id_next = id + 1;
255 
256 	return id;
257 }
258 
259 static bool __is_supported_mem_type(enum xdp_mem_type type)
260 {
261 	if (type == MEM_TYPE_PAGE_POOL)
262 		return is_page_pool_compiled_in();
263 
264 	if (type >= MEM_TYPE_MAX)
265 		return false;
266 
267 	return true;
268 }
269 
270 static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
271 						     enum xdp_mem_type type,
272 						     void *allocator)
273 {
274 	struct xdp_mem_allocator *xdp_alloc;
275 	gfp_t gfp = GFP_KERNEL;
276 	int id, errno, ret;
277 	void *ptr;
278 
279 	if (!__is_supported_mem_type(type))
280 		return ERR_PTR(-EOPNOTSUPP);
281 
282 	mem->type = type;
283 
284 	if (!allocator) {
285 		if (type == MEM_TYPE_PAGE_POOL)
286 			return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
287 		return NULL;
288 	}
289 
290 	/* Delay init of rhashtable to save memory if feature isn't used */
291 	if (!mem_id_init) {
292 		mutex_lock(&mem_id_lock);
293 		ret = __mem_id_init_hash_table();
294 		mutex_unlock(&mem_id_lock);
295 		if (ret < 0) {
296 			WARN_ON(1);
297 			return ERR_PTR(ret);
298 		}
299 	}
300 
301 	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
302 	if (!xdp_alloc)
303 		return ERR_PTR(-ENOMEM);
304 
305 	mutex_lock(&mem_id_lock);
306 	id = __mem_id_cyclic_get(gfp);
307 	if (id < 0) {
308 		errno = id;
309 		goto err;
310 	}
311 	mem->id = id;
312 	xdp_alloc->mem = *mem;
313 	xdp_alloc->allocator = allocator;
314 
315 	/* Insert allocator into ID lookup table */
316 	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
317 	if (IS_ERR(ptr)) {
318 		ida_simple_remove(&mem_id_pool, mem->id);
319 		mem->id = 0;
320 		errno = PTR_ERR(ptr);
321 		goto err;
322 	}
323 
324 	if (type == MEM_TYPE_PAGE_POOL)
325 		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect, mem);
326 
327 	mutex_unlock(&mem_id_lock);
328 
329 	return xdp_alloc;
330 err:
331 	mutex_unlock(&mem_id_lock);
332 	kfree(xdp_alloc);
333 	return ERR_PTR(errno);
334 }
335 
336 int xdp_reg_mem_model(struct xdp_mem_info *mem,
337 		      enum xdp_mem_type type, void *allocator)
338 {
339 	struct xdp_mem_allocator *xdp_alloc;
340 
341 	xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
342 	if (IS_ERR(xdp_alloc))
343 		return PTR_ERR(xdp_alloc);
344 	return 0;
345 }
346 EXPORT_SYMBOL_GPL(xdp_reg_mem_model);
347 
348 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
349 			       enum xdp_mem_type type, void *allocator)
350 {
351 	struct xdp_mem_allocator *xdp_alloc;
352 
353 	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
354 		WARN(1, "Missing register, driver bug");
355 		return -EFAULT;
356 	}
357 
358 	xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
359 	if (IS_ERR(xdp_alloc))
360 		return PTR_ERR(xdp_alloc);
361 
362 	if (trace_mem_connect_enabled() && xdp_alloc)
363 		trace_mem_connect(xdp_alloc, xdp_rxq);
364 	return 0;
365 }
366 
367 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
368 
369 /* XDP RX runs under NAPI protection, and in different delivery error
370  * scenarios (e.g. queue full), it is possible to return the xdp_frame
371  * while still leveraging this protection.  The @napi_direct boolean
372  * is used for those calls sites.  Thus, allowing for faster recycling
373  * of xdp_frames/pages in those cases.
374  */
375 void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
376 		  struct xdp_buff *xdp)
377 {
378 	struct xdp_mem_allocator *xa;
379 	struct page *page;
380 
381 	switch (mem->type) {
382 	case MEM_TYPE_PAGE_POOL:
383 		rcu_read_lock();
384 		/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
385 		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
386 		page = virt_to_head_page(data);
387 		if (napi_direct && xdp_return_frame_no_direct())
388 			napi_direct = false;
389 		page_pool_put_full_page(xa->page_pool, page, napi_direct);
390 		rcu_read_unlock();
391 		break;
392 	case MEM_TYPE_PAGE_SHARED:
393 		page_frag_free(data);
394 		break;
395 	case MEM_TYPE_PAGE_ORDER0:
396 		page = virt_to_page(data); /* Assumes order0 page*/
397 		put_page(page);
398 		break;
399 	case MEM_TYPE_XSK_BUFF_POOL:
400 		/* NB! Only valid from an xdp_buff! */
401 		xsk_buff_free(xdp);
402 		break;
403 	default:
404 		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
405 		WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
406 		break;
407 	}
408 }
409 
410 void xdp_return_frame(struct xdp_frame *xdpf)
411 {
412 	struct skb_shared_info *sinfo;
413 	int i;
414 
415 	if (likely(!xdp_frame_has_frags(xdpf)))
416 		goto out;
417 
418 	sinfo = xdp_get_shared_info_from_frame(xdpf);
419 	for (i = 0; i < sinfo->nr_frags; i++) {
420 		struct page *page = skb_frag_page(&sinfo->frags[i]);
421 
422 		__xdp_return(page_address(page), &xdpf->mem, false, NULL);
423 	}
424 out:
425 	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
426 }
427 EXPORT_SYMBOL_GPL(xdp_return_frame);
428 
429 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
430 {
431 	struct skb_shared_info *sinfo;
432 	int i;
433 
434 	if (likely(!xdp_frame_has_frags(xdpf)))
435 		goto out;
436 
437 	sinfo = xdp_get_shared_info_from_frame(xdpf);
438 	for (i = 0; i < sinfo->nr_frags; i++) {
439 		struct page *page = skb_frag_page(&sinfo->frags[i]);
440 
441 		__xdp_return(page_address(page), &xdpf->mem, true, NULL);
442 	}
443 out:
444 	__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
445 }
446 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
447 
448 /* XDP bulk APIs introduce a defer/flush mechanism to return
449  * pages belonging to the same xdp_mem_allocator object
450  * (identified via the mem.id field) in bulk to optimize
451  * I-cache and D-cache.
452  * The bulk queue size is set to 16 to be aligned to how
453  * XDP_REDIRECT bulking works. The bulk is flushed when
454  * it is full or when mem.id changes.
455  * xdp_frame_bulk is usually stored/allocated on the function
456  * call-stack to avoid locking penalties.
457  */
458 void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
459 {
460 	struct xdp_mem_allocator *xa = bq->xa;
461 
462 	if (unlikely(!xa || !bq->count))
463 		return;
464 
465 	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
466 	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
467 	bq->count = 0;
468 }
469 EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
470 
471 /* Must be called with rcu_read_lock held */
472 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
473 			   struct xdp_frame_bulk *bq)
474 {
475 	struct xdp_mem_info *mem = &xdpf->mem;
476 	struct xdp_mem_allocator *xa;
477 
478 	if (mem->type != MEM_TYPE_PAGE_POOL) {
479 		xdp_return_frame(xdpf);
480 		return;
481 	}
482 
483 	xa = bq->xa;
484 	if (unlikely(!xa)) {
485 		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
486 		bq->count = 0;
487 		bq->xa = xa;
488 	}
489 
490 	if (bq->count == XDP_BULK_QUEUE_SIZE)
491 		xdp_flush_frame_bulk(bq);
492 
493 	if (unlikely(mem->id != xa->mem.id)) {
494 		xdp_flush_frame_bulk(bq);
495 		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
496 	}
497 
498 	if (unlikely(xdp_frame_has_frags(xdpf))) {
499 		struct skb_shared_info *sinfo;
500 		int i;
501 
502 		sinfo = xdp_get_shared_info_from_frame(xdpf);
503 		for (i = 0; i < sinfo->nr_frags; i++) {
504 			skb_frag_t *frag = &sinfo->frags[i];
505 
506 			bq->q[bq->count++] = skb_frag_address(frag);
507 			if (bq->count == XDP_BULK_QUEUE_SIZE)
508 				xdp_flush_frame_bulk(bq);
509 		}
510 	}
511 	bq->q[bq->count++] = xdpf->data;
512 }
513 EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
514 
515 void xdp_return_buff(struct xdp_buff *xdp)
516 {
517 	struct skb_shared_info *sinfo;
518 	int i;
519 
520 	if (likely(!xdp_buff_has_frags(xdp)))
521 		goto out;
522 
523 	sinfo = xdp_get_shared_info_from_buff(xdp);
524 	for (i = 0; i < sinfo->nr_frags; i++) {
525 		struct page *page = skb_frag_page(&sinfo->frags[i]);
526 
527 		__xdp_return(page_address(page), &xdp->rxq->mem, true, xdp);
528 	}
529 out:
530 	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
531 }
532 EXPORT_SYMBOL_GPL(xdp_return_buff);
533 
534 /* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
535 void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
536 {
537 	struct xdp_mem_allocator *xa;
538 	struct page *page;
539 
540 	rcu_read_lock();
541 	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
542 	page = virt_to_head_page(data);
543 	if (xa)
544 		page_pool_release_page(xa->page_pool, page);
545 	rcu_read_unlock();
546 }
547 EXPORT_SYMBOL_GPL(__xdp_release_frame);
548 
549 void xdp_attachment_setup(struct xdp_attachment_info *info,
550 			  struct netdev_bpf *bpf)
551 {
552 	if (info->prog)
553 		bpf_prog_put(info->prog);
554 	info->prog = bpf->prog;
555 	info->flags = bpf->flags;
556 }
557 EXPORT_SYMBOL_GPL(xdp_attachment_setup);
558 
559 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
560 {
561 	unsigned int metasize, totsize;
562 	void *addr, *data_to_copy;
563 	struct xdp_frame *xdpf;
564 	struct page *page;
565 
566 	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
567 	metasize = xdp_data_meta_unsupported(xdp) ? 0 :
568 		   xdp->data - xdp->data_meta;
569 	totsize = xdp->data_end - xdp->data + metasize;
570 
571 	if (sizeof(*xdpf) + totsize > PAGE_SIZE)
572 		return NULL;
573 
574 	page = dev_alloc_page();
575 	if (!page)
576 		return NULL;
577 
578 	addr = page_to_virt(page);
579 	xdpf = addr;
580 	memset(xdpf, 0, sizeof(*xdpf));
581 
582 	addr += sizeof(*xdpf);
583 	data_to_copy = metasize ? xdp->data_meta : xdp->data;
584 	memcpy(addr, data_to_copy, totsize);
585 
586 	xdpf->data = addr + metasize;
587 	xdpf->len = totsize - metasize;
588 	xdpf->headroom = 0;
589 	xdpf->metasize = metasize;
590 	xdpf->frame_sz = PAGE_SIZE;
591 	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
592 
593 	xsk_buff_free(xdp);
594 	return xdpf;
595 }
596 EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);
597 
598 /* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
599 void xdp_warn(const char *msg, const char *func, const int line)
600 {
601 	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
602 };
603 EXPORT_SYMBOL_GPL(xdp_warn);
604 
605 int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
606 {
607 	n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
608 				      n_skb, skbs);
609 	if (unlikely(!n_skb))
610 		return -ENOMEM;
611 
612 	return 0;
613 }
614 EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);
615 
616 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
617 					   struct sk_buff *skb,
618 					   struct net_device *dev)
619 {
620 	struct skb_shared_info *sinfo = xdp_get_shared_info_from_frame(xdpf);
621 	unsigned int headroom, frame_size;
622 	void *hard_start;
623 	u8 nr_frags;
624 
625 	/* xdp frags frame */
626 	if (unlikely(xdp_frame_has_frags(xdpf)))
627 		nr_frags = sinfo->nr_frags;
628 
629 	/* Part of headroom was reserved to xdpf */
630 	headroom = sizeof(*xdpf) + xdpf->headroom;
631 
632 	/* Memory size backing xdp_frame data already have reserved
633 	 * room for build_skb to place skb_shared_info in tailroom.
634 	 */
635 	frame_size = xdpf->frame_sz;
636 
637 	hard_start = xdpf->data - headroom;
638 	skb = build_skb_around(skb, hard_start, frame_size);
639 	if (unlikely(!skb))
640 		return NULL;
641 
642 	skb_reserve(skb, headroom);
643 	__skb_put(skb, xdpf->len);
644 	if (xdpf->metasize)
645 		skb_metadata_set(skb, xdpf->metasize);
646 
647 	if (unlikely(xdp_frame_has_frags(xdpf)))
648 		xdp_update_skb_shared_info(skb, nr_frags,
649 					   sinfo->xdp_frags_size,
650 					   nr_frags * xdpf->frame_sz,
651 					   xdp_frame_is_frag_pfmemalloc(xdpf));
652 
653 	/* Essential SKB info: protocol and skb->dev */
654 	skb->protocol = eth_type_trans(skb, dev);
655 
656 	/* Optional SKB info, currently missing:
657 	 * - HW checksum info		(skb->ip_summed)
658 	 * - HW RX hash			(skb_set_hash)
659 	 * - RX ring dev queue index	(skb_record_rx_queue)
660 	 */
661 
662 	/* Until page_pool get SKB return path, release DMA here */
663 	xdp_release_frame(xdpf);
664 
665 	/* Allow SKB to reuse area used by xdp_frame */
666 	xdp_scrub_frame(xdpf);
667 
668 	return skb;
669 }
670 EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
671 
672 struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
673 					 struct net_device *dev)
674 {
675 	struct sk_buff *skb;
676 
677 	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
678 	if (unlikely(!skb))
679 		return NULL;
680 
681 	memset(skb, 0, offsetof(struct sk_buff, tail));
682 
683 	return __xdp_build_skb_from_frame(xdpf, skb, dev);
684 }
685 EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
686 
687 struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf)
688 {
689 	unsigned int headroom, totalsize;
690 	struct xdp_frame *nxdpf;
691 	struct page *page;
692 	void *addr;
693 
694 	headroom = xdpf->headroom + sizeof(*xdpf);
695 	totalsize = headroom + xdpf->len;
696 
697 	if (unlikely(totalsize > PAGE_SIZE))
698 		return NULL;
699 	page = dev_alloc_page();
700 	if (!page)
701 		return NULL;
702 	addr = page_to_virt(page);
703 
704 	memcpy(addr, xdpf, totalsize);
705 
706 	nxdpf = addr;
707 	nxdpf->data = addr + headroom;
708 	nxdpf->frame_sz = PAGE_SIZE;
709 	nxdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
710 	nxdpf->mem.id = 0;
711 
712 	return nxdpf;
713 }
714