xref: /freebsd/sys/netinet/in_fib_dxr.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2012-2022 Marko Zec
5  * Copyright (c) 2005, 2018 University of Zagreb
6  * Copyright (c) 2005 International Computer Science Institute
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 /*
31  * An implementation of DXR, a simple IPv4 LPM scheme with compact lookup
32  * structures and a trivial search procedure.  More significant bits of
33  * the search key are used to directly index a two-stage trie, while the
34  * remaining bits are used for finding the next hop in a sorted array.
35  * More details in:
36  *
37  * M. Zec, L. Rizzo, M. Mikuc, DXR: towards a billion routing lookups per
38  * second in software, ACM SIGCOMM Computer Communication Review, September
39  * 2012
40  *
41  * M. Zec, M. Mikuc, Pushing the envelope: beyond two billion IP routing
42  * lookups per second on commodity CPUs, IEEE SoftCOM, September 2017, Split
43  */
44 
45 #include <sys/cdefs.h>
46 #include "opt_inet.h"
47 
48 #include <sys/param.h>
49 #include <sys/kernel.h>
50 #include <sys/ctype.h>
51 #include <sys/epoch.h>
52 #include <sys/malloc.h>
53 #include <sys/module.h>
54 #include <sys/socket.h>
55 #include <sys/sysctl.h>
56 #include <sys/syslog.h>
57 
58 #include <vm/uma.h>
59 
60 #include <netinet/in.h>
61 #include <netinet/in_fib.h>
62 
63 #include <net/route.h>
64 #include <net/route/route_ctl.h>
65 #include <net/route/fib_algo.h>
66 
67 #define	DXR_TRIE_BITS		20
68 
69 CTASSERT(DXR_TRIE_BITS >= 16 && DXR_TRIE_BITS <= 24);
70 
71 /* DXR2: two-stage primary trie, instead of a single direct lookup table */
72 #define	DXR2
73 
74 #if DXR_TRIE_BITS > 16
75 #define	DXR_D			16
76 #else
77 #define	DXR_D			(DXR_TRIE_BITS - 1)
78 #endif
79 
80 #define	D_TBL_SIZE		(1 << DXR_D)
81 #define	DIRECT_TBL_SIZE		(1 << DXR_TRIE_BITS)
82 #define	DXR_RANGE_MASK		(0xffffffffU >> DXR_TRIE_BITS)
83 #define	DXR_RANGE_SHIFT		(32 - DXR_TRIE_BITS)
84 
85 #define	DESC_BASE_BITS		22
86 #define	DESC_FRAGMENTS_BITS	(32 - DESC_BASE_BITS)
87 #define	BASE_MAX		((1 << DESC_BASE_BITS) - 1)
88 #define	RTBL_SIZE_INCR		(BASE_MAX / 64)
89 
90 #if DXR_TRIE_BITS < 24
91 #define	FRAGS_MASK_SHORT	((1 << (23 - DXR_TRIE_BITS)) - 1)
92 #else
93 #define	FRAGS_MASK_SHORT	0
94 #endif
95 #define	FRAGS_PREF_SHORT	(((1 << DESC_FRAGMENTS_BITS) - 1) & \
96 				 ~FRAGS_MASK_SHORT)
97 #define	FRAGS_MARK_XL		(FRAGS_PREF_SHORT - 1)
98 #define	FRAGS_MARK_HIT		(FRAGS_PREF_SHORT - 2)
99 
100 #define	IS_SHORT_FORMAT(x)	((x & FRAGS_PREF_SHORT) == FRAGS_PREF_SHORT)
101 #define	IS_LONG_FORMAT(x)	((x & FRAGS_PREF_SHORT) != FRAGS_PREF_SHORT)
102 #define	IS_XL_FORMAT(x)		(x == FRAGS_MARK_XL)
103 
104 #define	RE_SHORT_MAX_NH		((1 << (DXR_TRIE_BITS - 8)) - 1)
105 
106 #define	CHUNK_HASH_BITS		16
107 #define	CHUNK_HASH_SIZE		(1 << CHUNK_HASH_BITS)
108 #define	CHUNK_HASH_MASK		(CHUNK_HASH_SIZE - 1)
109 
110 #define	TRIE_HASH_BITS		16
111 #define	TRIE_HASH_SIZE		(1 << TRIE_HASH_BITS)
112 #define	TRIE_HASH_MASK		(TRIE_HASH_SIZE - 1)
113 
114 #define	XTBL_SIZE_INCR		(DIRECT_TBL_SIZE / 16)
115 
116 #define	UNUSED_BUCKETS		8
117 
118 /* Lookup structure elements */
119 
120 struct direct_entry {
121 	uint32_t		fragments: DESC_FRAGMENTS_BITS,
122 				base: DESC_BASE_BITS;
123 };
124 
125 struct range_entry_long {
126 	uint32_t		start: DXR_RANGE_SHIFT,
127 				nexthop: DXR_TRIE_BITS;
128 };
129 
130 #if DXR_TRIE_BITS < 24
131 struct range_entry_short {
132 	uint16_t		start: DXR_RANGE_SHIFT - 8,
133 				nexthop: DXR_TRIE_BITS - 8;
134 };
135 #endif
136 
137 /* Auxiliary structures */
138 
139 struct heap_entry {
140 	uint32_t		start;
141 	uint32_t		end;
142 	uint32_t		preflen;
143 	uint32_t		nexthop;
144 };
145 
146 struct chunk_desc {
147 	LIST_ENTRY(chunk_desc)	cd_all_le;
148 	LIST_ENTRY(chunk_desc)	cd_hash_le;
149 	uint32_t		cd_hash;
150 	uint32_t		cd_refcnt;
151 	uint32_t		cd_base;
152 	uint32_t		cd_cur_size;
153 	uint32_t		cd_max_size;
154 };
155 
156 struct trie_desc {
157 	LIST_ENTRY(trie_desc)	td_all_le;
158 	LIST_ENTRY(trie_desc)	td_hash_le;
159 	uint32_t		td_hash;
160 	uint32_t		td_index;
161 	uint32_t		td_refcnt;
162 };
163 
164 struct dxr_aux {
165 	/* Glue to external state */
166 	struct fib_data		*fd;
167 	uint32_t		fibnum;
168 	int			refcnt;
169 
170 	/* Auxiliary build-time tables */
171 	struct direct_entry	direct_tbl[DIRECT_TBL_SIZE];
172 	uint16_t		d_tbl[D_TBL_SIZE];
173 	struct direct_entry	*x_tbl;
174 	union {
175 		struct range_entry_long	re;
176 		uint32_t	fragments;
177 	}			*range_tbl;
178 
179 	/* Auxiliary internal state */
180 	uint32_t		updates_mask[DIRECT_TBL_SIZE / 32];
181 	struct trie_desc	*trietbl[D_TBL_SIZE];
182 	LIST_HEAD(, chunk_desc)	chunk_hashtbl[CHUNK_HASH_SIZE];
183 	LIST_HEAD(, chunk_desc)	all_chunks;
184 	LIST_HEAD(, chunk_desc) unused_chunks[UNUSED_BUCKETS];
185 	LIST_HEAD(, trie_desc)	trie_hashtbl[TRIE_HASH_SIZE];
186 	LIST_HEAD(, trie_desc)	all_trie;
187 	LIST_HEAD(, trie_desc)	unused_trie; /* abuses hash link entry */
188 	struct sockaddr_in	dst;
189 	struct sockaddr_in	mask;
190 	struct heap_entry	heap[33];
191 	uint32_t		prefixes;
192 	uint32_t		updates_low;
193 	uint32_t		updates_high;
194 	uint32_t		unused_chunks_size;
195 	uint32_t		xtbl_size;
196 	uint32_t		all_trie_cnt;
197 	uint32_t		unused_trie_cnt;
198 	uint32_t		trie_rebuilt_prefixes;
199 	uint32_t		heap_index;
200 	uint32_t		d_bits;
201 	uint32_t		rtbl_size;
202 	uint32_t		rtbl_top;
203 	uint32_t		rtbl_work_frags;
204 	uint32_t		work_chunk;
205 };
206 
207 /* Main lookup structure container */
208 
209 struct dxr {
210 	/* Lookup tables */
211 	void			*d;
212 	void			*x;
213 	void			*r;
214 	struct nhop_object	**nh_tbl;
215 
216 	/* Glue to external state */
217 	struct dxr_aux		*aux;
218 	struct fib_data		*fd;
219 	struct epoch_context	epoch_ctx;
220 	uint32_t		fibnum;
221 	uint16_t		d_shift;
222 	uint16_t		x_shift;
223 	uint32_t		x_mask;
224 };
225 
226 static MALLOC_DEFINE(M_DXRLPM, "dxr", "DXR LPM");
227 static MALLOC_DEFINE(M_DXRAUX, "dxr aux", "DXR auxiliary");
228 
229 uma_zone_t chunk_zone;
230 uma_zone_t trie_zone;
231 
232 VNET_DEFINE_STATIC(int, frag_limit) = 100;
233 #define	V_frag_limit	VNET(frag_limit)
234 
235 /* Binary search for a matching address range */
236 #define	DXR_LOOKUP_STAGE					\
237 	if (masked_dst < range[middle].start) {			\
238 		upperbound = middle;				\
239 		middle = (middle + lowerbound) / 2;		\
240 	} else if (masked_dst < range[middle + 1].start)	\
241 		return (range[middle].nexthop);			\
242 	else {							\
243 		lowerbound = middle + 1;			\
244 		middle = (upperbound + middle + 1) / 2;		\
245 	}							\
246 	if (upperbound == lowerbound)				\
247 		return (range[lowerbound].nexthop);
248 
249 static int
250 range_lookup(struct range_entry_long *rt, struct direct_entry de, uint32_t dst)
251 {
252 	uint32_t base;
253 	uint32_t upperbound;
254 	uint32_t middle;
255 	uint32_t lowerbound;
256 	uint32_t masked_dst;
257 
258 	base = de.base;
259 	lowerbound = 0;
260 	masked_dst = dst & DXR_RANGE_MASK;
261 
262 #if DXR_TRIE_BITS < 24
263 	if (__predict_true(IS_SHORT_FORMAT(de.fragments))) {
264 		upperbound = de.fragments & FRAGS_MASK_SHORT;
265 		struct range_entry_short *range =
266 		    (struct range_entry_short *) &rt[base];
267 
268 		masked_dst >>= 8;
269 		middle = upperbound;
270 		upperbound = upperbound * 2 + 1;
271 
272 		for (;;) {
273 			DXR_LOOKUP_STAGE
274 			DXR_LOOKUP_STAGE
275 		}
276 	}
277 #endif
278 
279 	upperbound = de.fragments;
280 	middle = upperbound / 2;
281 	struct range_entry_long *range = &rt[base];
282 	if (__predict_false(IS_XL_FORMAT(de.fragments))) {
283 		upperbound = *((uint32_t *) range);
284 		range++;
285 		middle = upperbound / 2;
286 	}
287 
288 	for (;;) {
289 		DXR_LOOKUP_STAGE
290 		DXR_LOOKUP_STAGE
291 	}
292 }
293 
294 #define DXR_LOOKUP_DEFINE(D)						\
295 	static int inline						\
296 	dxr_lookup_##D(struct dxr *dxr, uint32_t dst)			\
297 	{								\
298 		struct direct_entry de;					\
299 		uint16_t *dt = dxr->d;					\
300 		struct direct_entry *xt = dxr->x;			\
301 									\
302 		de = xt[(dt[dst >> (32 - (D))] << (DXR_TRIE_BITS - (D))) \
303 		    + ((dst >> DXR_RANGE_SHIFT) &			\
304 		    (0xffffffffU >> (32 - DXR_TRIE_BITS + (D))))];	\
305 		if (__predict_true(de.fragments == FRAGS_MARK_HIT))	\
306 			return (de.base);				\
307 		return (range_lookup(dxr->r, de, dst));			\
308 	}								\
309 									\
310 	static struct nhop_object *					\
311 	dxr_fib_lookup_##D(void *algo_data,				\
312 	    const struct flm_lookup_key key, uint32_t scopeid __unused)	\
313 	{								\
314 		struct dxr *dxr = algo_data;				\
315 									\
316 		return (dxr->nh_tbl[dxr_lookup_##D(dxr,			\
317 		    ntohl(key.addr4.s_addr))]);				\
318 	}
319 
320 #ifdef DXR2
321 #if DXR_TRIE_BITS > 16
322 DXR_LOOKUP_DEFINE(16)
323 #endif
324 DXR_LOOKUP_DEFINE(15)
325 DXR_LOOKUP_DEFINE(14)
326 DXR_LOOKUP_DEFINE(13)
327 DXR_LOOKUP_DEFINE(12)
328 DXR_LOOKUP_DEFINE(11)
329 DXR_LOOKUP_DEFINE(10)
330 DXR_LOOKUP_DEFINE(9)
331 #endif /* DXR2 */
332 
333 static int inline
334 dxr_lookup(struct dxr *dxr, uint32_t dst)
335 {
336 	struct direct_entry de;
337 #ifdef DXR2
338 	uint16_t *dt = dxr->d;
339 	struct direct_entry *xt = dxr->x;
340 
341 	de = xt[(dt[dst >> dxr->d_shift] << dxr->x_shift) +
342 	    ((dst >> DXR_RANGE_SHIFT) & dxr->x_mask)];
343 #else /* !DXR2 */
344 	struct direct_entry *dt = dxr->d;
345 
346 	de = dt[dst >> DXR_RANGE_SHIFT];
347 #endif /* !DXR2 */
348 	if (__predict_true(de.fragments == FRAGS_MARK_HIT))
349 		return (de.base);
350 	return (range_lookup(dxr->r, de, dst));
351 }
352 
353 static void
354 initheap(struct dxr_aux *da, uint32_t dst_u32, uint32_t chunk)
355 {
356 	struct heap_entry *fhp = &da->heap[0];
357 	struct rtentry *rt;
358 	struct route_nhop_data rnd;
359 
360 	da->heap_index = 0;
361 	da->dst.sin_addr.s_addr = htonl(dst_u32);
362 	rt = fib4_lookup_rt(da->fibnum, da->dst.sin_addr, 0, NHR_UNLOCKED,
363 	    &rnd);
364 	if (rt != NULL) {
365 		struct in_addr addr;
366 		uint32_t scopeid;
367 
368 		rt_get_inet_prefix_plen(rt, &addr, &fhp->preflen, &scopeid);
369 		fhp->start = ntohl(addr.s_addr);
370 		fhp->end = fhp->start;
371 		if (fhp->preflen < 32)
372 			fhp->end |= (0xffffffffU >> fhp->preflen);
373 		fhp->nexthop = fib_get_nhop_idx(da->fd, rnd.rnd_nhop);
374 	} else {
375 		fhp->preflen = fhp->nexthop = fhp->start = 0;
376 		fhp->end = 0xffffffffU;
377 	}
378 }
379 
380 static uint32_t
381 chunk_size(struct dxr_aux *da, struct direct_entry *fdesc)
382 {
383 
384 	if (IS_SHORT_FORMAT(fdesc->fragments))
385 		return ((fdesc->fragments & FRAGS_MASK_SHORT) + 1);
386 	else if (IS_XL_FORMAT(fdesc->fragments))
387 		return (da->range_tbl[fdesc->base].fragments + 2);
388 	else /* if (IS_LONG_FORMAT(fdesc->fragments)) */
389 		return (fdesc->fragments + 1);
390 }
391 
392 static uint32_t
393 chunk_hash(struct dxr_aux *da, struct direct_entry *fdesc)
394 {
395 	uint32_t size = chunk_size(da, fdesc);
396 	uint32_t *p = (uint32_t *) &da->range_tbl[fdesc->base];
397 	uint32_t *l = (uint32_t *) &da->range_tbl[fdesc->base + size];
398 	uint32_t hash = fdesc->fragments;
399 
400 	for (; p < l; p++)
401 		hash = (hash << 7) + (hash >> 13) + *p;
402 
403 	return (hash + (hash >> 16));
404 }
405 
406 static int
407 chunk_ref(struct dxr_aux *da, uint32_t chunk)
408 {
409 	struct direct_entry *fdesc = &da->direct_tbl[chunk];
410 	struct chunk_desc *cdp, *empty_cdp;
411 	uint32_t base = fdesc->base;
412 	uint32_t size = chunk_size(da, fdesc);
413 	uint32_t hash = chunk_hash(da, fdesc);
414 	int i;
415 
416 	/* Find an existing descriptor */
417 	LIST_FOREACH(cdp, &da->chunk_hashtbl[hash & CHUNK_HASH_MASK],
418 	    cd_hash_le) {
419 		if (cdp->cd_hash != hash || cdp->cd_cur_size != size ||
420 		    memcmp(&da->range_tbl[base], &da->range_tbl[cdp->cd_base],
421 		    sizeof(struct range_entry_long) * size))
422 			continue;
423 		da->rtbl_top = fdesc->base;
424 		fdesc->base = cdp->cd_base;
425 		cdp->cd_refcnt++;
426 		return (0);
427 	}
428 
429 	/* No matching chunks found. Find an empty one to recycle. */
430 	for (cdp = NULL, i = size; cdp == NULL && i < UNUSED_BUCKETS; i++)
431 		cdp = LIST_FIRST(&da->unused_chunks[i]);
432 
433 	if (cdp == NULL)
434 		LIST_FOREACH(empty_cdp, &da->unused_chunks[0], cd_hash_le)
435 			if (empty_cdp->cd_max_size >= size && (cdp == NULL ||
436 			    empty_cdp->cd_max_size < cdp->cd_max_size)) {
437 				cdp = empty_cdp;
438 				if (empty_cdp->cd_max_size == size)
439 					break;
440 			}
441 
442 	if (cdp != NULL) {
443 		/* Copy from heap into the recycled chunk */
444 		bcopy(&da->range_tbl[fdesc->base], &da->range_tbl[cdp->cd_base],
445 		    size * sizeof(struct range_entry_long));
446 		fdesc->base = cdp->cd_base;
447 		da->rtbl_top -= size;
448 		da->unused_chunks_size -= cdp->cd_max_size;
449 		if (cdp->cd_max_size > size) {
450 			/* Split the range in two, need a new descriptor */
451 			empty_cdp = uma_zalloc(chunk_zone, M_NOWAIT);
452 			if (empty_cdp == NULL)
453 				return (1);
454 			LIST_INSERT_BEFORE(cdp, empty_cdp, cd_all_le);
455 			empty_cdp->cd_base = cdp->cd_base + size;
456 			empty_cdp->cd_cur_size = 0;
457 			empty_cdp->cd_max_size = cdp->cd_max_size - size;
458 
459 			i = empty_cdp->cd_max_size;
460 			if (i >= UNUSED_BUCKETS)
461 				i = 0;
462 			LIST_INSERT_HEAD(&da->unused_chunks[i], empty_cdp,
463 			    cd_hash_le);
464 
465 			da->unused_chunks_size += empty_cdp->cd_max_size;
466 			cdp->cd_max_size = size;
467 		}
468 		LIST_REMOVE(cdp, cd_hash_le);
469 	} else {
470 		/* Alloc a new descriptor at the top of the heap*/
471 		cdp = uma_zalloc(chunk_zone, M_NOWAIT);
472 		if (cdp == NULL)
473 			return (1);
474 		cdp->cd_max_size = size;
475 		cdp->cd_base = fdesc->base;
476 		LIST_INSERT_HEAD(&da->all_chunks, cdp, cd_all_le);
477 		KASSERT(cdp->cd_base + cdp->cd_max_size == da->rtbl_top,
478 		    ("dxr: %s %d", __FUNCTION__, __LINE__));
479 	}
480 
481 	cdp->cd_hash = hash;
482 	cdp->cd_refcnt = 1;
483 	cdp->cd_cur_size = size;
484 	LIST_INSERT_HEAD(&da->chunk_hashtbl[hash & CHUNK_HASH_MASK], cdp,
485 	    cd_hash_le);
486 	if (da->rtbl_top >= da->rtbl_size) {
487 		if (da->rtbl_top >= BASE_MAX) {
488 			FIB_PRINTF(LOG_ERR, da->fd,
489 			    "structural limit exceeded at %d "
490 			    "range table elements", da->rtbl_top);
491 			return (1);
492 		}
493 		da->rtbl_size += RTBL_SIZE_INCR;
494 		i = (BASE_MAX - da->rtbl_top) * LOG_DEBUG / BASE_MAX;
495 		FIB_PRINTF(i, da->fd, "range table at %d%% structural limit",
496 		    da->rtbl_top * 100 / BASE_MAX);
497 		da->range_tbl = realloc(da->range_tbl,
498 		    sizeof(*da->range_tbl) * da->rtbl_size + FRAGS_PREF_SHORT,
499 		    M_DXRAUX, M_NOWAIT);
500 		if (da->range_tbl == NULL)
501 			return (1);
502 	}
503 
504 	return (0);
505 }
506 
507 static void
508 chunk_unref(struct dxr_aux *da, uint32_t chunk)
509 {
510 	struct direct_entry *fdesc = &da->direct_tbl[chunk];
511 	struct chunk_desc *cdp, *cdp2;
512 	uint32_t base = fdesc->base;
513 	uint32_t size = chunk_size(da, fdesc);
514 	uint32_t hash = chunk_hash(da, fdesc);
515 	int i;
516 
517 	/* Find the corresponding descriptor */
518 	LIST_FOREACH(cdp, &da->chunk_hashtbl[hash & CHUNK_HASH_MASK],
519 	    cd_hash_le)
520 		if (cdp->cd_hash == hash && cdp->cd_cur_size == size &&
521 		    memcmp(&da->range_tbl[base], &da->range_tbl[cdp->cd_base],
522 		    sizeof(struct range_entry_long) * size) == 0)
523 			break;
524 
525 	KASSERT(cdp != NULL, ("dxr: dangling chunk"));
526 	if (--cdp->cd_refcnt > 0)
527 		return;
528 
529 	LIST_REMOVE(cdp, cd_hash_le);
530 	da->unused_chunks_size += cdp->cd_max_size;
531 	cdp->cd_cur_size = 0;
532 
533 	/* Attempt to merge with the preceding chunk, if empty */
534 	cdp2 = LIST_NEXT(cdp, cd_all_le);
535 	if (cdp2 != NULL && cdp2->cd_cur_size == 0) {
536 		KASSERT(cdp2->cd_base + cdp2->cd_max_size == cdp->cd_base,
537 		    ("dxr: %s %d", __FUNCTION__, __LINE__));
538 		LIST_REMOVE(cdp, cd_all_le);
539 		LIST_REMOVE(cdp2, cd_hash_le);
540 		cdp2->cd_max_size += cdp->cd_max_size;
541 		uma_zfree(chunk_zone, cdp);
542 		cdp = cdp2;
543 	}
544 
545 	/* Attempt to merge with the subsequent chunk, if empty */
546 	cdp2 = LIST_PREV(cdp, &da->all_chunks, chunk_desc, cd_all_le);
547 	if (cdp2 != NULL && cdp2->cd_cur_size == 0) {
548 		KASSERT(cdp->cd_base + cdp->cd_max_size == cdp2->cd_base,
549 		    ("dxr: %s %d", __FUNCTION__, __LINE__));
550 		LIST_REMOVE(cdp, cd_all_le);
551 		LIST_REMOVE(cdp2, cd_hash_le);
552 		cdp2->cd_max_size += cdp->cd_max_size;
553 		cdp2->cd_base = cdp->cd_base;
554 		uma_zfree(chunk_zone, cdp);
555 		cdp = cdp2;
556 	}
557 
558 	if (cdp->cd_base + cdp->cd_max_size == da->rtbl_top) {
559 		/* Free the chunk on the top of the range heap, trim the heap */
560 		KASSERT(cdp == LIST_FIRST(&da->all_chunks),
561 		    ("dxr: %s %d", __FUNCTION__, __LINE__));
562 		da->rtbl_top -= cdp->cd_max_size;
563 		da->unused_chunks_size -= cdp->cd_max_size;
564 		LIST_REMOVE(cdp, cd_all_le);
565 		uma_zfree(chunk_zone, cdp);
566 		return;
567 	}
568 
569 	i = cdp->cd_max_size;
570 	if (i >= UNUSED_BUCKETS)
571 		i = 0;
572 	LIST_INSERT_HEAD(&da->unused_chunks[i], cdp, cd_hash_le);
573 }
574 
575 #ifdef DXR2
576 static uint32_t
577 trie_hash(struct dxr_aux *da, uint32_t dxr_x, uint32_t index)
578 {
579 	uint32_t i, *val;
580 	uint32_t hash = 0;
581 
582 	for (i = 0; i < (1 << dxr_x); i++) {
583 		hash = (hash << 3) ^ (hash >> 3);
584 		val = (uint32_t *)
585 		    (void *) &da->direct_tbl[(index << dxr_x) + i];
586 		hash += (*val << 5);
587 		hash += (*val >> 5);
588 	}
589 
590 	return (hash + (hash >> 16));
591 }
592 
593 static int
594 trie_ref(struct dxr_aux *da, uint32_t index)
595 {
596 	struct trie_desc *tp;
597 	uint32_t dxr_d = da->d_bits;
598 	uint32_t dxr_x = DXR_TRIE_BITS - dxr_d;
599 	uint32_t hash = trie_hash(da, dxr_x, index);
600 
601 	/* Find an existing descriptor */
602 	LIST_FOREACH(tp, &da->trie_hashtbl[hash & TRIE_HASH_MASK], td_hash_le)
603 		if (tp->td_hash == hash &&
604 		    memcmp(&da->direct_tbl[index << dxr_x],
605 		    &da->x_tbl[tp->td_index << dxr_x],
606 		    sizeof(*da->x_tbl) << dxr_x) == 0) {
607 			tp->td_refcnt++;
608 			da->trietbl[index] = tp;
609 			return(tp->td_index);
610 		}
611 
612 	tp = LIST_FIRST(&da->unused_trie);
613 	if (tp != NULL) {
614 		LIST_REMOVE(tp, td_hash_le);
615 		da->unused_trie_cnt--;
616 	} else {
617 		tp = uma_zalloc(trie_zone, M_NOWAIT);
618 		if (tp == NULL)
619 			return (-1);
620 		LIST_INSERT_HEAD(&da->all_trie, tp, td_all_le);
621 		tp->td_index = da->all_trie_cnt++;
622 	}
623 
624 	tp->td_hash = hash;
625 	tp->td_refcnt = 1;
626 	LIST_INSERT_HEAD(&da->trie_hashtbl[hash & TRIE_HASH_MASK], tp,
627 	   td_hash_le);
628 	memcpy(&da->x_tbl[tp->td_index << dxr_x],
629 	    &da->direct_tbl[index << dxr_x], sizeof(*da->x_tbl) << dxr_x);
630 	da->trietbl[index] = tp;
631 	if (da->all_trie_cnt >= da->xtbl_size >> dxr_x) {
632 		da->xtbl_size += XTBL_SIZE_INCR;
633 		da->x_tbl = realloc(da->x_tbl,
634 		    sizeof(*da->x_tbl) * da->xtbl_size, M_DXRAUX, M_NOWAIT);
635 		if (da->x_tbl == NULL)
636 			return (-1);
637 	}
638 	return(tp->td_index);
639 }
640 
641 static void
642 trie_unref(struct dxr_aux *da, uint32_t index)
643 {
644 	struct trie_desc *tp = da->trietbl[index];
645 
646 	if (tp == NULL)
647 		return;
648 	da->trietbl[index] = NULL;
649 	if (--tp->td_refcnt > 0)
650 		return;
651 
652 	LIST_REMOVE(tp, td_hash_le);
653 	da->unused_trie_cnt++;
654 	if (tp->td_index != da->all_trie_cnt - 1) {
655 		LIST_INSERT_HEAD(&da->unused_trie, tp, td_hash_le);
656 		return;
657 	}
658 
659 	do {
660 		da->all_trie_cnt--;
661 		da->unused_trie_cnt--;
662 		LIST_REMOVE(tp, td_all_le);
663 		uma_zfree(trie_zone, tp);
664 		LIST_FOREACH(tp, &da->unused_trie, td_hash_le)
665 			if (tp->td_index == da->all_trie_cnt - 1) {
666 				LIST_REMOVE(tp, td_hash_le);
667 				break;
668 			}
669 	} while (tp != NULL);
670 }
671 #endif
672 
673 static void
674 heap_inject(struct dxr_aux *da, uint32_t start, uint32_t end, uint32_t preflen,
675     uint32_t nh)
676 {
677 	struct heap_entry *fhp;
678 	int i;
679 
680 	for (i = da->heap_index; i >= 0; i--) {
681 		if (preflen > da->heap[i].preflen)
682 			break;
683 		else if (preflen < da->heap[i].preflen)
684 			da->heap[i + 1] = da->heap[i];
685 		else
686 			return;
687 	}
688 
689 	fhp = &da->heap[i + 1];
690 	fhp->preflen = preflen;
691 	fhp->start = start;
692 	fhp->end = end;
693 	fhp->nexthop = nh;
694 	da->heap_index++;
695 }
696 
697 static int
698 dxr_walk(struct rtentry *rt, void *arg)
699 {
700 	struct dxr_aux *da = arg;
701 	uint32_t chunk = da->work_chunk;
702 	uint32_t first = chunk << DXR_RANGE_SHIFT;
703 	uint32_t last = first | DXR_RANGE_MASK;
704 	struct range_entry_long *fp =
705 	    &da->range_tbl[da->rtbl_top + da->rtbl_work_frags].re;
706 	struct heap_entry *fhp = &da->heap[da->heap_index];
707 	uint32_t preflen, nh, start, end, scopeid;
708 	struct in_addr addr;
709 
710 	rt_get_inet_prefix_plen(rt, &addr, &preflen, &scopeid);
711 	start = ntohl(addr.s_addr);
712 	if (start > last)
713 		return (-1);	/* Beyond chunk boundaries, we are done */
714 	if (start < first)
715 		return (0);	/* Skip this route */
716 
717 	end = start;
718 	if (preflen < 32)
719 		end |= (0xffffffffU >> preflen);
720 	nh = fib_get_nhop_idx(da->fd, rt_get_raw_nhop(rt));
721 
722 	if (start == fhp->start)
723 		heap_inject(da, start, end, preflen, nh);
724 	else {
725 		/* start > fhp->start */
726 		while (start > fhp->end) {
727 			uint32_t oend = fhp->end;
728 
729 			if (da->heap_index > 0) {
730 				fhp--;
731 				da->heap_index--;
732 			} else
733 				initheap(da, fhp->end + 1, chunk);
734 			if (fhp->end > oend && fhp->nexthop != fp->nexthop) {
735 				fp++;
736 				da->rtbl_work_frags++;
737 				fp->start = (oend + 1) & DXR_RANGE_MASK;
738 				fp->nexthop = fhp->nexthop;
739 			}
740 		}
741 		if (start > ((chunk << DXR_RANGE_SHIFT) | fp->start) &&
742 		    nh != fp->nexthop) {
743 			fp++;
744 			da->rtbl_work_frags++;
745 			fp->start = start & DXR_RANGE_MASK;
746 		} else if (da->rtbl_work_frags) {
747 			if ((--fp)->nexthop == nh)
748 				da->rtbl_work_frags--;
749 			else
750 				fp++;
751 		}
752 		fp->nexthop = nh;
753 		heap_inject(da, start, end, preflen, nh);
754 	}
755 
756 	return (0);
757 }
758 
759 static int
760 update_chunk(struct dxr_aux *da, uint32_t chunk)
761 {
762 	struct range_entry_long *fp;
763 #if DXR_TRIE_BITS < 24
764 	struct range_entry_short *fps;
765 	uint32_t start, nh, i;
766 #endif
767 	struct heap_entry *fhp;
768 	uint32_t first = chunk << DXR_RANGE_SHIFT;
769 	uint32_t last = first | DXR_RANGE_MASK;
770 
771 	if (da->direct_tbl[chunk].fragments != FRAGS_MARK_HIT)
772 		chunk_unref(da, chunk);
773 
774 	initheap(da, first, chunk);
775 
776 	fp = &da->range_tbl[da->rtbl_top].re;
777 	da->rtbl_work_frags = 0;
778 	fp->start = first & DXR_RANGE_MASK;
779 	fp->nexthop = da->heap[0].nexthop;
780 
781 	da->dst.sin_addr.s_addr = htonl(first);
782 	da->mask.sin_addr.s_addr = htonl(~DXR_RANGE_MASK);
783 
784 	da->work_chunk = chunk;
785 	rib_walk_from(da->fibnum, AF_INET, RIB_FLAG_LOCKED,
786 	    (struct sockaddr *) &da->dst, (struct sockaddr *) &da->mask,
787 	    dxr_walk, da);
788 
789 	/* Flush any remaining objects on the heap */
790 	fp = &da->range_tbl[da->rtbl_top + da->rtbl_work_frags].re;
791 	fhp = &da->heap[da->heap_index];
792 	while (fhp->preflen > DXR_TRIE_BITS) {
793 		uint32_t oend = fhp->end;
794 
795 		if (da->heap_index > 0) {
796 			fhp--;
797 			da->heap_index--;
798 		} else
799 			initheap(da, fhp->end + 1, chunk);
800 		if (fhp->end > oend && fhp->nexthop != fp->nexthop) {
801 			/* Have we crossed the upper chunk boundary? */
802 			if (oend >= last)
803 				break;
804 			fp++;
805 			da->rtbl_work_frags++;
806 			fp->start = (oend + 1) & DXR_RANGE_MASK;
807 			fp->nexthop = fhp->nexthop;
808 		}
809 	}
810 
811 	/* Direct hit if the chunk contains only a single fragment */
812 	if (da->rtbl_work_frags == 0) {
813 		da->direct_tbl[chunk].base = fp->nexthop;
814 		da->direct_tbl[chunk].fragments = FRAGS_MARK_HIT;
815 		return (0);
816 	}
817 
818 	da->direct_tbl[chunk].base = da->rtbl_top;
819 	da->direct_tbl[chunk].fragments = da->rtbl_work_frags;
820 
821 #if DXR_TRIE_BITS < 24
822 	/* Check whether the chunk can be more compactly encoded */
823 	fp = &da->range_tbl[da->rtbl_top].re;
824 	for (i = 0; i <= da->rtbl_work_frags; i++, fp++)
825 		if ((fp->start & 0xff) != 0 || fp->nexthop > RE_SHORT_MAX_NH)
826 			break;
827 	if (i == da->rtbl_work_frags + 1) {
828 		fp = &da->range_tbl[da->rtbl_top].re;
829 		fps = (void *) fp;
830 		for (i = 0; i <= da->rtbl_work_frags; i++, fp++, fps++) {
831 			start = fp->start;
832 			nh = fp->nexthop;
833 			fps->start = start >> 8;
834 			fps->nexthop = nh;
835 		}
836 		fps->start = start >> 8;
837 		fps->nexthop = nh;
838 		da->rtbl_work_frags >>= 1;
839 		da->direct_tbl[chunk].fragments =
840 		    da->rtbl_work_frags | FRAGS_PREF_SHORT;
841 	} else
842 #endif
843 	if (da->rtbl_work_frags >= FRAGS_MARK_HIT) {
844 		da->direct_tbl[chunk].fragments = FRAGS_MARK_XL;
845 		memmove(&da->range_tbl[da->rtbl_top + 1],
846 		   &da->range_tbl[da->rtbl_top],
847 		   (da->rtbl_work_frags + 1) * sizeof(*da->range_tbl));
848 		da->range_tbl[da->rtbl_top].fragments = da->rtbl_work_frags;
849 		da->rtbl_work_frags++;
850 	}
851 	da->rtbl_top += (da->rtbl_work_frags + 1);
852 	return (chunk_ref(da, chunk));
853 }
854 
855 static void
856 dxr_build(struct dxr *dxr)
857 {
858 	struct dxr_aux *da = dxr->aux;
859 	struct chunk_desc *cdp;
860 	struct rib_rtable_info rinfo;
861 	struct timeval t0, t1, t2, t3;
862 	uint32_t r_size, dxr_tot_size;
863 	uint32_t i, m, range_rebuild = 0;
864 	uint32_t range_frag;
865 #ifdef DXR2
866 	struct trie_desc *tp;
867 	uint32_t d_tbl_size, dxr_x, d_size, x_size;
868 	uint32_t ti, trie_rebuild = 0, prev_size = 0;
869 	uint32_t trie_frag;
870 #endif
871 
872 	KASSERT(dxr->d == NULL, ("dxr: d not free"));
873 
874 	if (da == NULL) {
875 		da = malloc(sizeof(*dxr->aux), M_DXRAUX, M_NOWAIT);
876 		if (da == NULL)
877 			return;
878 		dxr->aux = da;
879 		da->fibnum = dxr->fibnum;
880 		da->refcnt = 1;
881 		LIST_INIT(&da->all_chunks);
882 		LIST_INIT(&da->all_trie);
883 		da->rtbl_size = RTBL_SIZE_INCR;
884 		da->range_tbl = NULL;
885 		da->xtbl_size = XTBL_SIZE_INCR;
886 		da->x_tbl = NULL;
887 		bzero(&da->dst, sizeof(da->dst));
888 		bzero(&da->mask, sizeof(da->mask));
889 		da->dst.sin_len = sizeof(da->dst);
890 		da->mask.sin_len = sizeof(da->mask);
891 		da->dst.sin_family = AF_INET;
892 		da->mask.sin_family = AF_INET;
893 	}
894 	if (da->range_tbl == NULL) {
895 		da->range_tbl = malloc(sizeof(*da->range_tbl) * da->rtbl_size
896 		    + FRAGS_PREF_SHORT, M_DXRAUX, M_NOWAIT);
897 		if (da->range_tbl == NULL)
898 			return;
899 		range_rebuild = 1;
900 	}
901 #ifdef DXR2
902 	if (da->x_tbl == NULL) {
903 		da->x_tbl = malloc(sizeof(*da->x_tbl) * da->xtbl_size,
904 		    M_DXRAUX, M_NOWAIT);
905 		if (da->x_tbl == NULL)
906 			return;
907 		trie_rebuild = 1;
908 	}
909 #endif
910 	da->fd = dxr->fd;
911 
912 	microuptime(&t0);
913 
914 	dxr->nh_tbl = fib_get_nhop_array(da->fd);
915 	fib_get_rtable_info(fib_get_rh(da->fd), &rinfo);
916 
917 	if (da->updates_low > da->updates_high)
918 		range_rebuild = 1;
919 
920 range_build:
921 	if (range_rebuild) {
922 		/* Bulk cleanup */
923 		bzero(da->chunk_hashtbl, sizeof(da->chunk_hashtbl));
924 		while ((cdp = LIST_FIRST(&da->all_chunks)) != NULL) {
925 			LIST_REMOVE(cdp, cd_all_le);
926 			uma_zfree(chunk_zone, cdp);
927 		}
928 		for (i = 0; i < UNUSED_BUCKETS; i++)
929 			LIST_INIT(&da->unused_chunks[i]);
930 		da->unused_chunks_size = 0;
931 		da->rtbl_top = 0;
932 		da->updates_low = 0;
933 		da->updates_high = DIRECT_TBL_SIZE - 1;
934 		memset(da->updates_mask, 0xff, sizeof(da->updates_mask));
935 		for (i = 0; i < DIRECT_TBL_SIZE; i++) {
936 			da->direct_tbl[i].fragments = FRAGS_MARK_HIT;
937 			da->direct_tbl[i].base = 0;
938 		}
939 	}
940 	da->prefixes = rinfo.num_prefixes;
941 
942 	/* DXR: construct direct & range table */
943 	for (i = da->updates_low; i <= da->updates_high; i++) {
944 		m = da->updates_mask[i >> 5] >> (i & 0x1f);
945 		if (m == 0)
946 			i |= 0x1f;
947 		else if (m & 1 && update_chunk(da, i) != 0)
948 			return;
949 	}
950 
951 	range_frag = 0;
952 	if (da->rtbl_top)
953 		range_frag = da->unused_chunks_size * 10000ULL / da->rtbl_top;
954 	if (range_frag > V_frag_limit) {
955 		range_rebuild = 1;
956 		goto range_build;
957 	}
958 
959 	r_size = sizeof(*da->range_tbl) * da->rtbl_top;
960 	microuptime(&t1);
961 
962 #ifdef DXR2
963 	if (range_rebuild ||
964 	    abs(fls(da->prefixes) - fls(da->trie_rebuilt_prefixes)) > 1)
965 		trie_rebuild = 1;
966 
967 trie_build:
968 	if (trie_rebuild) {
969 		da->trie_rebuilt_prefixes = da->prefixes;
970 		da->d_bits = DXR_D;
971 		da->updates_low = 0;
972 		da->updates_high = DIRECT_TBL_SIZE - 1;
973 		if (!range_rebuild)
974 			memset(da->updates_mask, 0xff,
975 			    sizeof(da->updates_mask));
976 	}
977 
978 dxr2_try_squeeze:
979 	if (trie_rebuild) {
980 		/* Bulk cleanup */
981 		bzero(da->trietbl, sizeof(da->trietbl));
982 		bzero(da->trie_hashtbl, sizeof(da->trie_hashtbl));
983 		while ((tp = LIST_FIRST(&da->all_trie)) != NULL) {
984 			LIST_REMOVE(tp, td_all_le);
985 			uma_zfree(trie_zone, tp);
986 		}
987 		LIST_INIT(&da->unused_trie);
988 		da->all_trie_cnt = da->unused_trie_cnt = 0;
989 	}
990 
991 	/* Populate d_tbl, x_tbl */
992 	dxr_x = DXR_TRIE_BITS - da->d_bits;
993 	d_tbl_size = (1 << da->d_bits);
994 
995 	for (i = da->updates_low >> dxr_x; i <= da->updates_high >> dxr_x;
996 	    i++) {
997 		if (!trie_rebuild) {
998 			m = 0;
999 			for (int j = 0; j < (1 << dxr_x); j += 32)
1000 				m |= da->updates_mask[((i << dxr_x) + j) >> 5];
1001 			if (m == 0)
1002 				continue;
1003 			trie_unref(da, i);
1004 		}
1005 		ti = trie_ref(da, i);
1006 		if (ti < 0)
1007 			return;
1008 		da->d_tbl[i] = ti;
1009 	}
1010 
1011 	trie_frag = 0;
1012 	if (da->all_trie_cnt)
1013 		trie_frag = da->unused_trie_cnt * 10000ULL / da->all_trie_cnt;
1014 	if (trie_frag > V_frag_limit) {
1015 		trie_rebuild = 1;
1016 		goto trie_build;
1017 	}
1018 
1019 	d_size = sizeof(*da->d_tbl) * d_tbl_size;
1020 	x_size = sizeof(*da->x_tbl) * DIRECT_TBL_SIZE / d_tbl_size
1021 	    * da->all_trie_cnt;
1022 	dxr_tot_size = d_size + x_size + r_size;
1023 
1024 	if (trie_rebuild == 1) {
1025 		/* Try to find a more compact D/X split */
1026 		if (prev_size == 0 || dxr_tot_size <= prev_size)
1027 			da->d_bits--;
1028 		else {
1029 			da->d_bits++;
1030 			trie_rebuild = 2;
1031 		}
1032 		prev_size = dxr_tot_size;
1033 		goto dxr2_try_squeeze;
1034 	}
1035 	microuptime(&t2);
1036 #else /* !DXR2 */
1037 	dxr_tot_size = sizeof(da->direct_tbl) + r_size;
1038 	t2 = t1;
1039 #endif
1040 
1041 	dxr->d = malloc(dxr_tot_size, M_DXRLPM, M_NOWAIT);
1042 	if (dxr->d == NULL)
1043 		return;
1044 #ifdef DXR2
1045 	memcpy(dxr->d, da->d_tbl, d_size);
1046 	dxr->x = ((char *) dxr->d) + d_size;
1047 	memcpy(dxr->x, da->x_tbl, x_size);
1048 	dxr->r = ((char *) dxr->x) + x_size;
1049 	dxr->d_shift = 32 - da->d_bits;
1050 	dxr->x_shift = dxr_x;
1051 	dxr->x_mask = 0xffffffffU >> (32 - dxr_x);
1052 #else /* !DXR2 */
1053 	memcpy(dxr->d, da->direct_tbl, sizeof(da->direct_tbl));
1054 	dxr->r = ((char *) dxr->d) + sizeof(da->direct_tbl);
1055 #endif
1056 	memcpy(dxr->r, da->range_tbl, r_size);
1057 
1058 	if (da->updates_low <= da->updates_high)
1059 		bzero(&da->updates_mask[da->updates_low / 32],
1060 		    (da->updates_high - da->updates_low) / 8 + 1);
1061 	da->updates_low = DIRECT_TBL_SIZE - 1;
1062 	da->updates_high = 0;
1063 	microuptime(&t3);
1064 
1065 #ifdef DXR2
1066 	FIB_PRINTF(LOG_INFO, da->fd, "D%dX%dR, %d prefixes, %d nhops (max)",
1067 	    da->d_bits, dxr_x, rinfo.num_prefixes, rinfo.num_nhops);
1068 #else
1069 	FIB_PRINTF(LOG_INFO, da->fd, "D%dR, %d prefixes, %d nhops (max)",
1070 	    DXR_D, rinfo.num_prefixes, rinfo.num_nhops);
1071 #endif
1072 	i = dxr_tot_size * 100;
1073 	if (rinfo.num_prefixes)
1074 		i /= rinfo.num_prefixes;
1075 	FIB_PRINTF(LOG_INFO, da->fd, "%d.%02d KBytes, %d.%02d Bytes/prefix",
1076 	    dxr_tot_size / 1024, dxr_tot_size * 100 / 1024 % 100,
1077 	    i / 100, i % 100);
1078 #ifdef DXR2
1079 	FIB_PRINTF(LOG_INFO, da->fd,
1080 	    "%d.%02d%% trie, %d.%02d%% range fragmentation",
1081 	    trie_frag / 100, trie_frag % 100,
1082 	    range_frag / 100, range_frag % 100);
1083 #else
1084 	FIB_PRINTF(LOG_INFO, da->fd, "%d.%01d%% range fragmentation",
1085 	    range_frag / 100, range_frag % 100);
1086 #endif
1087 	i = (t1.tv_sec - t0.tv_sec) * 1000000 + t1.tv_usec - t0.tv_usec;
1088 	FIB_PRINTF(LOG_INFO, da->fd, "range table %s in %u.%03u ms",
1089 	    range_rebuild ? "rebuilt" : "updated", i / 1000, i % 1000);
1090 #ifdef DXR2
1091 	i = (t2.tv_sec - t1.tv_sec) * 1000000 + t2.tv_usec - t1.tv_usec;
1092 	FIB_PRINTF(LOG_INFO, da->fd, "trie %s in %u.%03u ms",
1093 	    trie_rebuild ? "rebuilt" : "updated", i / 1000, i % 1000);
1094 #endif
1095 	i = (t3.tv_sec - t2.tv_sec) * 1000000 + t3.tv_usec - t2.tv_usec;
1096 	FIB_PRINTF(LOG_INFO, da->fd, "snapshot forked in %u.%03u ms",
1097 	    i / 1000, i % 1000);
1098 }
1099 
1100 /*
1101  * Glue functions for attaching to FreeBSD 13 fib_algo infrastructure.
1102  */
1103 
1104 static struct nhop_object *
1105 dxr_fib_lookup(void *algo_data, const struct flm_lookup_key key,
1106     uint32_t scopeid)
1107 {
1108 	struct dxr *dxr = algo_data;
1109 
1110 	return (dxr->nh_tbl[dxr_lookup(dxr, ntohl(key.addr4.s_addr))]);
1111 }
1112 
1113 static enum flm_op_result
1114 dxr_init(uint32_t fibnum, struct fib_data *fd, void *old_data, void **data)
1115 {
1116 	struct dxr *old_dxr = old_data;
1117 	struct dxr_aux *da = NULL;
1118 	struct dxr *dxr;
1119 
1120 	dxr = malloc(sizeof(*dxr), M_DXRAUX, M_NOWAIT);
1121 	if (dxr == NULL)
1122 		return (FLM_REBUILD);
1123 
1124 	/* Check whether we may reuse the old auxiliary structures */
1125 	if (old_dxr != NULL && old_dxr->aux != NULL) {
1126 		da = old_dxr->aux;
1127 		atomic_add_int(&da->refcnt, 1);
1128 	}
1129 
1130 	dxr->aux = da;
1131 	dxr->d = NULL;
1132 	dxr->fd = fd;
1133 	dxr->fibnum = fibnum;
1134 	*data = dxr;
1135 
1136 	return (FLM_SUCCESS);
1137 }
1138 
1139 static void
1140 dxr_destroy(void *data)
1141 {
1142 	struct dxr *dxr = data;
1143 	struct dxr_aux *da;
1144 	struct chunk_desc *cdp;
1145 	struct trie_desc *tp;
1146 
1147 	if (dxr->d != NULL)
1148 		free(dxr->d, M_DXRLPM);
1149 
1150 	da = dxr->aux;
1151 	free(dxr, M_DXRAUX);
1152 
1153 	if (da == NULL || atomic_fetchadd_int(&da->refcnt, -1) > 1)
1154 		return;
1155 
1156 	/* Release auxiliary structures */
1157 	while ((cdp = LIST_FIRST(&da->all_chunks)) != NULL) {
1158 		LIST_REMOVE(cdp, cd_all_le);
1159 		uma_zfree(chunk_zone, cdp);
1160 	}
1161 	while ((tp = LIST_FIRST(&da->all_trie)) != NULL) {
1162 		LIST_REMOVE(tp, td_all_le);
1163 		uma_zfree(trie_zone, tp);
1164 	}
1165 	free(da->range_tbl, M_DXRAUX);
1166 	free(da->x_tbl, M_DXRAUX);
1167 	free(da, M_DXRAUX);
1168 }
1169 
1170 static void
1171 epoch_dxr_destroy(epoch_context_t ctx)
1172 {
1173 	struct dxr *dxr = __containerof(ctx, struct dxr, epoch_ctx);
1174 
1175 	dxr_destroy(dxr);
1176 }
1177 
1178 static void *
1179 choose_lookup_fn(struct dxr_aux *da)
1180 {
1181 
1182 #ifdef DXR2
1183 	switch (da->d_bits) {
1184 #if DXR_TRIE_BITS > 16
1185 	case 16:
1186 		return (dxr_fib_lookup_16);
1187 #endif
1188 	case 15:
1189 		return (dxr_fib_lookup_15);
1190 	case 14:
1191 		return (dxr_fib_lookup_14);
1192 	case 13:
1193 		return (dxr_fib_lookup_13);
1194 	case 12:
1195 		return (dxr_fib_lookup_12);
1196 	case 11:
1197 		return (dxr_fib_lookup_11);
1198 	case 10:
1199 		return (dxr_fib_lookup_10);
1200 	case 9:
1201 		return (dxr_fib_lookup_9);
1202 	}
1203 #endif /* DXR2 */
1204 	return (dxr_fib_lookup);
1205 }
1206 
1207 static enum flm_op_result
1208 dxr_dump_end(void *data, struct fib_dp *dp)
1209 {
1210 	struct dxr *dxr = data;
1211 	struct dxr_aux *da;
1212 
1213 	dxr_build(dxr);
1214 
1215 	da = dxr->aux;
1216 	if (da == NULL)
1217 		return (FLM_REBUILD);
1218 
1219 	/* Structural limit exceeded, hard error */
1220 	if (da->rtbl_top >= BASE_MAX)
1221 		return (FLM_ERROR);
1222 
1223 	/* A malloc(,, M_NOWAIT) failed somewhere, retry later */
1224 	if (dxr->d == NULL)
1225 		return (FLM_REBUILD);
1226 
1227 	dp->f = choose_lookup_fn(da);
1228 	dp->arg = dxr;
1229 
1230 	return (FLM_SUCCESS);
1231 }
1232 
1233 static enum flm_op_result
1234 dxr_dump_rib_item(struct rtentry *rt, void *data)
1235 {
1236 
1237 	return (FLM_SUCCESS);
1238 }
1239 
1240 static enum flm_op_result
1241 dxr_change_rib_item(struct rib_head *rnh, struct rib_cmd_info *rc,
1242     void *data)
1243 {
1244 
1245 	return (FLM_BATCH);
1246 }
1247 
1248 static enum flm_op_result
1249 dxr_change_rib_batch(struct rib_head *rnh, struct fib_change_queue *q,
1250     void *data)
1251 {
1252 	struct dxr *dxr = data;
1253 	struct dxr *new_dxr;
1254 	struct dxr_aux *da;
1255 	struct fib_dp new_dp;
1256 	enum flm_op_result res;
1257 	uint32_t ip, plen, hmask, start, end, i, ui;
1258 #ifdef INVARIANTS
1259 	struct rib_rtable_info rinfo;
1260 	int update_delta = 0;
1261 #endif
1262 
1263 	KASSERT(data != NULL, ("%s: NULL data", __FUNCTION__));
1264 	KASSERT(q != NULL, ("%s: NULL q", __FUNCTION__));
1265 	KASSERT(q->count < q->size, ("%s: q->count %d q->size %d",
1266 	    __FUNCTION__, q->count, q->size));
1267 
1268 	da = dxr->aux;
1269 	KASSERT(da != NULL, ("%s: NULL dxr->aux", __FUNCTION__));
1270 
1271 	FIB_PRINTF(LOG_INFO, da->fd, "processing %d update(s)", q->count);
1272 	for (ui = 0; ui < q->count; ui++) {
1273 #ifdef INVARIANTS
1274 		if (q->entries[ui].nh_new != NULL)
1275 			update_delta++;
1276 		if (q->entries[ui].nh_old != NULL)
1277 			update_delta--;
1278 #endif
1279 		plen = q->entries[ui].plen;
1280 		ip = ntohl(q->entries[ui].addr4.s_addr);
1281 		if (plen < 32)
1282 			hmask = 0xffffffffU >> plen;
1283 		else
1284 			hmask = 0;
1285 		start = (ip & ~hmask) >> DXR_RANGE_SHIFT;
1286 		end = (ip | hmask) >> DXR_RANGE_SHIFT;
1287 
1288 		if ((start & 0x1f) == 0 && (end & 0x1f) == 0x1f)
1289 			for (i = start >> 5; i <= end >> 5; i++)
1290 				da->updates_mask[i] = 0xffffffffU;
1291 		else
1292 			for (i = start; i <= end; i++)
1293 				da->updates_mask[i >> 5] |= (1 << (i & 0x1f));
1294 		if (start < da->updates_low)
1295 			da->updates_low = start;
1296 		if (end > da->updates_high)
1297 			da->updates_high = end;
1298 	}
1299 
1300 #ifdef INVARIANTS
1301 	fib_get_rtable_info(fib_get_rh(da->fd), &rinfo);
1302 	KASSERT(da->prefixes + update_delta == rinfo.num_prefixes,
1303 	    ("%s: update count mismatch", __FUNCTION__));
1304 #endif
1305 
1306 	res = dxr_init(0, dxr->fd, data, (void **) &new_dxr);
1307 	if (res != FLM_SUCCESS)
1308 		return (res);
1309 
1310 	dxr_build(new_dxr);
1311 
1312 	/* Structural limit exceeded, hard error */
1313 	if (da->rtbl_top >= BASE_MAX) {
1314 		dxr_destroy(new_dxr);
1315 		return (FLM_ERROR);
1316 	}
1317 
1318 	/* A malloc(,, M_NOWAIT) failed somewhere, retry later */
1319 	if (new_dxr->d == NULL) {
1320 		dxr_destroy(new_dxr);
1321 		return (FLM_REBUILD);
1322 	}
1323 
1324 	new_dp.f = choose_lookup_fn(da);
1325 	new_dp.arg = new_dxr;
1326 	if (fib_set_datapath_ptr(dxr->fd, &new_dp)) {
1327 		fib_set_algo_ptr(dxr->fd, new_dxr);
1328 		fib_epoch_call(epoch_dxr_destroy, &dxr->epoch_ctx);
1329 		return (FLM_SUCCESS);
1330 	}
1331 
1332 	dxr_destroy(new_dxr);
1333 	return (FLM_REBUILD);
1334 }
1335 
1336 static uint8_t
1337 dxr_get_pref(const struct rib_rtable_info *rinfo)
1338 {
1339 
1340 	/* Below bsearch4 up to 10 prefixes. Always supersedes dpdk_lpm4. */
1341 	return (251);
1342 }
1343 
1344 SYSCTL_DECL(_net_route_algo);
1345 SYSCTL_NODE(_net_route_algo, OID_AUTO, dxr, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
1346     "DXR tunables");
1347 
1348 static int
1349 sysctl_dxr_frag_limit(SYSCTL_HANDLER_ARGS)
1350 {
1351 	char buf[8];
1352 	int error, new, i;
1353 
1354 	snprintf(buf, sizeof(buf), "%d.%02d%%", V_frag_limit / 100,
1355 	    V_frag_limit % 100);
1356 	error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
1357 	if (error != 0 || req->newptr == NULL)
1358 		return (error);
1359 	if (!isdigit(*buf) && *buf != '.')
1360 		return (EINVAL);
1361 	for (i = 0, new = 0; isdigit(buf[i]) && i < sizeof(buf); i++)
1362 		new = new * 10 + buf[i] - '0';
1363 	new *= 100;
1364 	if (buf[i++] == '.') {
1365 		if (!isdigit(buf[i]))
1366 			return (EINVAL);
1367 		new += (buf[i++] - '0') * 10;
1368 		if (isdigit(buf[i]))
1369 			new += buf[i++] - '0';
1370 	}
1371 	if (new > 1000)
1372 		return (EINVAL);
1373 	V_frag_limit = new;
1374 	snprintf(buf, sizeof(buf), "%d.%02d%%", V_frag_limit / 100,
1375 	    V_frag_limit % 100);
1376 	return (0);
1377 }
1378 
1379 SYSCTL_PROC(_net_route_algo_dxr, OID_AUTO, frag_limit,
1380     CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_VNET,
1381     0, 0, sysctl_dxr_frag_limit, "A",
1382     "Fragmentation threshold to full rebuild");
1383 
1384 static struct fib_lookup_module fib_dxr_mod = {
1385 	.flm_name = "dxr",
1386 	.flm_family = AF_INET,
1387 	.flm_init_cb = dxr_init,
1388 	.flm_destroy_cb = dxr_destroy,
1389 	.flm_dump_rib_item_cb = dxr_dump_rib_item,
1390 	.flm_dump_end_cb = dxr_dump_end,
1391 	.flm_change_rib_item_cb = dxr_change_rib_item,
1392 	.flm_change_rib_items_cb = dxr_change_rib_batch,
1393 	.flm_get_pref = dxr_get_pref,
1394 };
1395 
1396 static int
1397 dxr_modevent(module_t mod, int type, void *unused)
1398 {
1399 	int error;
1400 
1401 	switch (type) {
1402 	case MOD_LOAD:
1403 		chunk_zone = uma_zcreate("dxr chunk", sizeof(struct chunk_desc),
1404 		    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
1405 		trie_zone = uma_zcreate("dxr trie", sizeof(struct trie_desc),
1406 		    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
1407 		fib_module_register(&fib_dxr_mod);
1408 		return(0);
1409 	case MOD_UNLOAD:
1410 		error = fib_module_unregister(&fib_dxr_mod);
1411 		if (error)
1412 			return (error);
1413 		uma_zdestroy(chunk_zone);
1414 		uma_zdestroy(trie_zone);
1415 		return(0);
1416 	default:
1417 		return(EOPNOTSUPP);
1418 	}
1419 }
1420 
1421 static moduledata_t dxr_mod = {"fib_dxr", dxr_modevent, 0};
1422 
1423 DECLARE_MODULE(fib_dxr, dxr_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
1424 MODULE_VERSION(fib_dxr, 1);
1425