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6710e112 JDB |
1 | /* bpf/cpumap.c |
2 | * | |
3 | * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. | |
4 | * Released under terms in GPL version 2. See COPYING. | |
5 | */ | |
6 | ||
7 | /* The 'cpumap' is primarily used as a backend map for XDP BPF helper | |
8 | * call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'. | |
9 | * | |
10 | * Unlike devmap which redirects XDP frames out another NIC device, | |
11 | * this map type redirects raw XDP frames to another CPU. The remote | |
12 | * CPU will do SKB-allocation and call the normal network stack. | |
13 | * | |
14 | * This is a scalability and isolation mechanism, that allow | |
15 | * separating the early driver network XDP layer, from the rest of the | |
16 | * netstack, and assigning dedicated CPUs for this stage. This | |
17 | * basically allows for 10G wirespeed pre-filtering via bpf. | |
18 | */ | |
19 | #include <linux/bpf.h> | |
20 | #include <linux/filter.h> | |
21 | #include <linux/ptr_ring.h> | |
22 | ||
23 | #include <linux/sched.h> | |
24 | #include <linux/workqueue.h> | |
25 | #include <linux/kthread.h> | |
26 | #include <linux/capability.h> | |
27 | ||
28 | /* General idea: XDP packets getting XDP redirected to another CPU, | |
29 | * will maximum be stored/queued for one driver ->poll() call. It is | |
30 | * guaranteed that setting flush bit and flush operation happen on | |
31 | * same CPU. Thus, cpu_map_flush operation can deduct via this_cpu_ptr() | |
32 | * which queue in bpf_cpu_map_entry contains packets. | |
33 | */ | |
34 | ||
35 | #define CPU_MAP_BULK_SIZE 8 /* 8 == one cacheline on 64-bit archs */ | |
36 | struct xdp_bulk_queue { | |
37 | void *q[CPU_MAP_BULK_SIZE]; | |
38 | unsigned int count; | |
39 | }; | |
40 | ||
41 | /* Struct for every remote "destination" CPU in map */ | |
42 | struct bpf_cpu_map_entry { | |
43 | u32 qsize; /* Queue size placeholder for map lookup */ | |
44 | ||
45 | /* XDP can run multiple RX-ring queues, need __percpu enqueue store */ | |
46 | struct xdp_bulk_queue __percpu *bulkq; | |
47 | ||
48 | /* Queue with potential multi-producers, and single-consumer kthread */ | |
49 | struct ptr_ring *queue; | |
50 | struct task_struct *kthread; | |
51 | struct work_struct kthread_stop_wq; | |
52 | ||
53 | atomic_t refcnt; /* Control when this struct can be free'ed */ | |
54 | struct rcu_head rcu; | |
55 | }; | |
56 | ||
57 | struct bpf_cpu_map { | |
58 | struct bpf_map map; | |
59 | /* Below members specific for map type */ | |
60 | struct bpf_cpu_map_entry **cpu_map; | |
61 | unsigned long __percpu *flush_needed; | |
62 | }; | |
63 | ||
64 | static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu, | |
65 | struct xdp_bulk_queue *bq); | |
66 | ||
67 | static u64 cpu_map_bitmap_size(const union bpf_attr *attr) | |
68 | { | |
69 | return BITS_TO_LONGS(attr->max_entries) * sizeof(unsigned long); | |
70 | } | |
71 | ||
72 | static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) | |
73 | { | |
74 | struct bpf_cpu_map *cmap; | |
75 | int err = -ENOMEM; | |
76 | u64 cost; | |
77 | int ret; | |
78 | ||
79 | if (!capable(CAP_SYS_ADMIN)) | |
80 | return ERR_PTR(-EPERM); | |
81 | ||
82 | /* check sanity of attributes */ | |
83 | if (attr->max_entries == 0 || attr->key_size != 4 || | |
84 | attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE) | |
85 | return ERR_PTR(-EINVAL); | |
86 | ||
87 | cmap = kzalloc(sizeof(*cmap), GFP_USER); | |
88 | if (!cmap) | |
89 | return ERR_PTR(-ENOMEM); | |
90 | ||
91 | /* mandatory map attributes */ | |
92 | cmap->map.map_type = attr->map_type; | |
93 | cmap->map.key_size = attr->key_size; | |
94 | cmap->map.value_size = attr->value_size; | |
95 | cmap->map.max_entries = attr->max_entries; | |
96 | cmap->map.map_flags = attr->map_flags; | |
97 | cmap->map.numa_node = bpf_map_attr_numa_node(attr); | |
98 | ||
99 | /* Pre-limit array size based on NR_CPUS, not final CPU check */ | |
100 | if (cmap->map.max_entries > NR_CPUS) { | |
101 | err = -E2BIG; | |
102 | goto free_cmap; | |
103 | } | |
104 | ||
105 | /* make sure page count doesn't overflow */ | |
106 | cost = (u64) cmap->map.max_entries * sizeof(struct bpf_cpu_map_entry *); | |
107 | cost += cpu_map_bitmap_size(attr) * num_possible_cpus(); | |
108 | if (cost >= U32_MAX - PAGE_SIZE) | |
109 | goto free_cmap; | |
110 | cmap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; | |
111 | ||
112 | /* Notice returns -EPERM on if map size is larger than memlock limit */ | |
113 | ret = bpf_map_precharge_memlock(cmap->map.pages); | |
114 | if (ret) { | |
115 | err = ret; | |
116 | goto free_cmap; | |
117 | } | |
118 | ||
119 | /* A per cpu bitfield with a bit per possible CPU in map */ | |
120 | cmap->flush_needed = __alloc_percpu(cpu_map_bitmap_size(attr), | |
121 | __alignof__(unsigned long)); | |
122 | if (!cmap->flush_needed) | |
123 | goto free_cmap; | |
124 | ||
125 | /* Alloc array for possible remote "destination" CPUs */ | |
126 | cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries * | |
127 | sizeof(struct bpf_cpu_map_entry *), | |
128 | cmap->map.numa_node); | |
129 | if (!cmap->cpu_map) | |
130 | goto free_percpu; | |
131 | ||
132 | return &cmap->map; | |
133 | free_percpu: | |
134 | free_percpu(cmap->flush_needed); | |
135 | free_cmap: | |
136 | kfree(cmap); | |
137 | return ERR_PTR(err); | |
138 | } | |
139 | ||
140 | void __cpu_map_queue_destructor(void *ptr) | |
141 | { | |
142 | /* The tear-down procedure should have made sure that queue is | |
143 | * empty. See __cpu_map_entry_replace() and work-queue | |
144 | * invoked cpu_map_kthread_stop(). Catch any broken behaviour | |
145 | * gracefully and warn once. | |
146 | */ | |
147 | if (WARN_ON_ONCE(ptr)) | |
148 | page_frag_free(ptr); | |
149 | } | |
150 | ||
151 | static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) | |
152 | { | |
153 | if (atomic_dec_and_test(&rcpu->refcnt)) { | |
154 | /* The queue should be empty at this point */ | |
155 | ptr_ring_cleanup(rcpu->queue, __cpu_map_queue_destructor); | |
156 | kfree(rcpu->queue); | |
157 | kfree(rcpu); | |
158 | } | |
159 | } | |
160 | ||
161 | static void get_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) | |
162 | { | |
163 | atomic_inc(&rcpu->refcnt); | |
164 | } | |
165 | ||
166 | /* called from workqueue, to workaround syscall using preempt_disable */ | |
167 | static void cpu_map_kthread_stop(struct work_struct *work) | |
168 | { | |
169 | struct bpf_cpu_map_entry *rcpu; | |
170 | ||
171 | rcpu = container_of(work, struct bpf_cpu_map_entry, kthread_stop_wq); | |
172 | ||
173 | /* Wait for flush in __cpu_map_entry_free(), via full RCU barrier, | |
174 | * as it waits until all in-flight call_rcu() callbacks complete. | |
175 | */ | |
176 | rcu_barrier(); | |
177 | ||
178 | /* kthread_stop will wake_up_process and wait for it to complete */ | |
179 | kthread_stop(rcpu->kthread); | |
180 | } | |
181 | ||
182 | static int cpu_map_kthread_run(void *data) | |
183 | { | |
184 | struct bpf_cpu_map_entry *rcpu = data; | |
185 | ||
186 | set_current_state(TASK_INTERRUPTIBLE); | |
187 | ||
188 | /* When kthread gives stop order, then rcpu have been disconnected | |
189 | * from map, thus no new packets can enter. Remaining in-flight | |
190 | * per CPU stored packets are flushed to this queue. Wait honoring | |
191 | * kthread_stop signal until queue is empty. | |
192 | */ | |
193 | while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) { | |
194 | struct xdp_pkt *xdp_pkt; | |
195 | ||
196 | schedule(); | |
197 | /* Do work */ | |
198 | while ((xdp_pkt = ptr_ring_consume(rcpu->queue))) { | |
199 | /* For now just "refcnt-free" */ | |
200 | page_frag_free(xdp_pkt); | |
201 | } | |
202 | __set_current_state(TASK_INTERRUPTIBLE); | |
203 | } | |
204 | __set_current_state(TASK_RUNNING); | |
205 | ||
206 | put_cpu_map_entry(rcpu); | |
207 | return 0; | |
208 | } | |
209 | ||
210 | struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu, int map_id) | |
211 | { | |
212 | gfp_t gfp = GFP_ATOMIC|__GFP_NOWARN; | |
213 | struct bpf_cpu_map_entry *rcpu; | |
214 | int numa, err; | |
215 | ||
216 | /* Have map->numa_node, but choose node of redirect target CPU */ | |
217 | numa = cpu_to_node(cpu); | |
218 | ||
219 | rcpu = kzalloc_node(sizeof(*rcpu), gfp, numa); | |
220 | if (!rcpu) | |
221 | return NULL; | |
222 | ||
223 | /* Alloc percpu bulkq */ | |
224 | rcpu->bulkq = __alloc_percpu_gfp(sizeof(*rcpu->bulkq), | |
225 | sizeof(void *), gfp); | |
226 | if (!rcpu->bulkq) | |
227 | goto free_rcu; | |
228 | ||
229 | /* Alloc queue */ | |
230 | rcpu->queue = kzalloc_node(sizeof(*rcpu->queue), gfp, numa); | |
231 | if (!rcpu->queue) | |
232 | goto free_bulkq; | |
233 | ||
234 | err = ptr_ring_init(rcpu->queue, qsize, gfp); | |
235 | if (err) | |
236 | goto free_queue; | |
237 | ||
238 | rcpu->qsize = qsize; | |
239 | ||
240 | /* Setup kthread */ | |
241 | rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa, | |
242 | "cpumap/%d/map:%d", cpu, map_id); | |
243 | if (IS_ERR(rcpu->kthread)) | |
244 | goto free_ptr_ring; | |
245 | ||
246 | get_cpu_map_entry(rcpu); /* 1-refcnt for being in cmap->cpu_map[] */ | |
247 | get_cpu_map_entry(rcpu); /* 1-refcnt for kthread */ | |
248 | ||
249 | /* Make sure kthread runs on a single CPU */ | |
250 | kthread_bind(rcpu->kthread, cpu); | |
251 | wake_up_process(rcpu->kthread); | |
252 | ||
253 | return rcpu; | |
254 | ||
255 | free_ptr_ring: | |
256 | ptr_ring_cleanup(rcpu->queue, NULL); | |
257 | free_queue: | |
258 | kfree(rcpu->queue); | |
259 | free_bulkq: | |
260 | free_percpu(rcpu->bulkq); | |
261 | free_rcu: | |
262 | kfree(rcpu); | |
263 | return NULL; | |
264 | } | |
265 | ||
266 | void __cpu_map_entry_free(struct rcu_head *rcu) | |
267 | { | |
268 | struct bpf_cpu_map_entry *rcpu; | |
269 | int cpu; | |
270 | ||
271 | /* This cpu_map_entry have been disconnected from map and one | |
272 | * RCU graze-period have elapsed. Thus, XDP cannot queue any | |
273 | * new packets and cannot change/set flush_needed that can | |
274 | * find this entry. | |
275 | */ | |
276 | rcpu = container_of(rcu, struct bpf_cpu_map_entry, rcu); | |
277 | ||
278 | /* Flush remaining packets in percpu bulkq */ | |
279 | for_each_online_cpu(cpu) { | |
280 | struct xdp_bulk_queue *bq = per_cpu_ptr(rcpu->bulkq, cpu); | |
281 | ||
282 | /* No concurrent bq_enqueue can run at this point */ | |
283 | bq_flush_to_queue(rcpu, bq); | |
284 | } | |
285 | free_percpu(rcpu->bulkq); | |
286 | /* Cannot kthread_stop() here, last put free rcpu resources */ | |
287 | put_cpu_map_entry(rcpu); | |
288 | } | |
289 | ||
290 | /* After xchg pointer to bpf_cpu_map_entry, use the call_rcu() to | |
291 | * ensure any driver rcu critical sections have completed, but this | |
292 | * does not guarantee a flush has happened yet. Because driver side | |
293 | * rcu_read_lock/unlock only protects the running XDP program. The | |
294 | * atomic xchg and NULL-ptr check in __cpu_map_flush() makes sure a | |
295 | * pending flush op doesn't fail. | |
296 | * | |
297 | * The bpf_cpu_map_entry is still used by the kthread, and there can | |
298 | * still be pending packets (in queue and percpu bulkq). A refcnt | |
299 | * makes sure to last user (kthread_stop vs. call_rcu) free memory | |
300 | * resources. | |
301 | * | |
302 | * The rcu callback __cpu_map_entry_free flush remaining packets in | |
303 | * percpu bulkq to queue. Due to caller map_delete_elem() disable | |
304 | * preemption, cannot call kthread_stop() to make sure queue is empty. | |
305 | * Instead a work_queue is started for stopping kthread, | |
306 | * cpu_map_kthread_stop, which waits for an RCU graze period before | |
307 | * stopping kthread, emptying the queue. | |
308 | */ | |
309 | void __cpu_map_entry_replace(struct bpf_cpu_map *cmap, | |
310 | u32 key_cpu, struct bpf_cpu_map_entry *rcpu) | |
311 | { | |
312 | struct bpf_cpu_map_entry *old_rcpu; | |
313 | ||
314 | old_rcpu = xchg(&cmap->cpu_map[key_cpu], rcpu); | |
315 | if (old_rcpu) { | |
316 | call_rcu(&old_rcpu->rcu, __cpu_map_entry_free); | |
317 | INIT_WORK(&old_rcpu->kthread_stop_wq, cpu_map_kthread_stop); | |
318 | schedule_work(&old_rcpu->kthread_stop_wq); | |
319 | } | |
320 | } | |
321 | ||
322 | int cpu_map_delete_elem(struct bpf_map *map, void *key) | |
323 | { | |
324 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
325 | u32 key_cpu = *(u32 *)key; | |
326 | ||
327 | if (key_cpu >= map->max_entries) | |
328 | return -EINVAL; | |
329 | ||
330 | /* notice caller map_delete_elem() use preempt_disable() */ | |
331 | __cpu_map_entry_replace(cmap, key_cpu, NULL); | |
332 | return 0; | |
333 | } | |
334 | ||
335 | int cpu_map_update_elem(struct bpf_map *map, void *key, void *value, | |
336 | u64 map_flags) | |
337 | { | |
338 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
339 | struct bpf_cpu_map_entry *rcpu; | |
340 | ||
341 | /* Array index key correspond to CPU number */ | |
342 | u32 key_cpu = *(u32 *)key; | |
343 | /* Value is the queue size */ | |
344 | u32 qsize = *(u32 *)value; | |
345 | ||
346 | if (unlikely(map_flags > BPF_EXIST)) | |
347 | return -EINVAL; | |
348 | if (unlikely(key_cpu >= cmap->map.max_entries)) | |
349 | return -E2BIG; | |
350 | if (unlikely(map_flags == BPF_NOEXIST)) | |
351 | return -EEXIST; | |
352 | if (unlikely(qsize > 16384)) /* sanity limit on qsize */ | |
353 | return -EOVERFLOW; | |
354 | ||
355 | /* Make sure CPU is a valid possible cpu */ | |
356 | if (!cpu_possible(key_cpu)) | |
357 | return -ENODEV; | |
358 | ||
359 | if (qsize == 0) { | |
360 | rcpu = NULL; /* Same as deleting */ | |
361 | } else { | |
362 | /* Updating qsize cause re-allocation of bpf_cpu_map_entry */ | |
363 | rcpu = __cpu_map_entry_alloc(qsize, key_cpu, map->id); | |
364 | if (!rcpu) | |
365 | return -ENOMEM; | |
366 | } | |
367 | rcu_read_lock(); | |
368 | __cpu_map_entry_replace(cmap, key_cpu, rcpu); | |
369 | rcu_read_unlock(); | |
370 | return 0; | |
371 | } | |
372 | ||
373 | void cpu_map_free(struct bpf_map *map) | |
374 | { | |
375 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
376 | int cpu; | |
377 | u32 i; | |
378 | ||
379 | /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, | |
380 | * so the bpf programs (can be more than one that used this map) were | |
381 | * disconnected from events. Wait for outstanding critical sections in | |
382 | * these programs to complete. The rcu critical section only guarantees | |
383 | * no further "XDP/bpf-side" reads against bpf_cpu_map->cpu_map. | |
384 | * It does __not__ ensure pending flush operations (if any) are | |
385 | * complete. | |
386 | */ | |
387 | synchronize_rcu(); | |
388 | ||
389 | /* To ensure all pending flush operations have completed wait for flush | |
390 | * bitmap to indicate all flush_needed bits to be zero on _all_ cpus. | |
391 | * Because the above synchronize_rcu() ensures the map is disconnected | |
392 | * from the program we can assume no new bits will be set. | |
393 | */ | |
394 | for_each_online_cpu(cpu) { | |
395 | unsigned long *bitmap = per_cpu_ptr(cmap->flush_needed, cpu); | |
396 | ||
397 | while (!bitmap_empty(bitmap, cmap->map.max_entries)) | |
398 | cond_resched(); | |
399 | } | |
400 | ||
401 | /* For cpu_map the remote CPUs can still be using the entries | |
402 | * (struct bpf_cpu_map_entry). | |
403 | */ | |
404 | for (i = 0; i < cmap->map.max_entries; i++) { | |
405 | struct bpf_cpu_map_entry *rcpu; | |
406 | ||
407 | rcpu = READ_ONCE(cmap->cpu_map[i]); | |
408 | if (!rcpu) | |
409 | continue; | |
410 | ||
411 | /* bq flush and cleanup happens after RCU graze-period */ | |
412 | __cpu_map_entry_replace(cmap, i, NULL); /* call_rcu */ | |
413 | } | |
414 | free_percpu(cmap->flush_needed); | |
415 | bpf_map_area_free(cmap->cpu_map); | |
416 | kfree(cmap); | |
417 | } | |
418 | ||
419 | struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key) | |
420 | { | |
421 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
422 | struct bpf_cpu_map_entry *rcpu; | |
423 | ||
424 | if (key >= map->max_entries) | |
425 | return NULL; | |
426 | ||
427 | rcpu = READ_ONCE(cmap->cpu_map[key]); | |
428 | return rcpu; | |
429 | } | |
430 | ||
431 | static void *cpu_map_lookup_elem(struct bpf_map *map, void *key) | |
432 | { | |
433 | struct bpf_cpu_map_entry *rcpu = | |
434 | __cpu_map_lookup_elem(map, *(u32 *)key); | |
435 | ||
436 | return rcpu ? &rcpu->qsize : NULL; | |
437 | } | |
438 | ||
439 | static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key) | |
440 | { | |
441 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
442 | u32 index = key ? *(u32 *)key : U32_MAX; | |
443 | u32 *next = next_key; | |
444 | ||
445 | if (index >= cmap->map.max_entries) { | |
446 | *next = 0; | |
447 | return 0; | |
448 | } | |
449 | ||
450 | if (index == cmap->map.max_entries - 1) | |
451 | return -ENOENT; | |
452 | *next = index + 1; | |
453 | return 0; | |
454 | } | |
455 | ||
456 | const struct bpf_map_ops cpu_map_ops = { | |
457 | .map_alloc = cpu_map_alloc, | |
458 | .map_free = cpu_map_free, | |
459 | .map_delete_elem = cpu_map_delete_elem, | |
460 | .map_update_elem = cpu_map_update_elem, | |
461 | .map_lookup_elem = cpu_map_lookup_elem, | |
462 | .map_get_next_key = cpu_map_get_next_key, | |
463 | }; | |
464 | ||
465 | static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu, | |
466 | struct xdp_bulk_queue *bq) | |
467 | { | |
468 | struct ptr_ring *q; | |
469 | int i; | |
470 | ||
471 | if (unlikely(!bq->count)) | |
472 | return 0; | |
473 | ||
474 | q = rcpu->queue; | |
475 | spin_lock(&q->producer_lock); | |
476 | ||
477 | for (i = 0; i < bq->count; i++) { | |
478 | void *xdp_pkt = bq->q[i]; | |
479 | int err; | |
480 | ||
481 | err = __ptr_ring_produce(q, xdp_pkt); | |
482 | if (err) { | |
483 | /* Free xdp_pkt */ | |
484 | page_frag_free(xdp_pkt); | |
485 | } | |
486 | } | |
487 | bq->count = 0; | |
488 | spin_unlock(&q->producer_lock); | |
489 | ||
490 | return 0; | |
491 | } | |
492 | ||
493 | /* Notice: Will change in later patch */ | |
494 | struct xdp_pkt { | |
495 | void *data; | |
496 | u16 len; | |
497 | u16 headroom; | |
498 | }; | |
499 | ||
500 | /* Runs under RCU-read-side, plus in softirq under NAPI protection. | |
501 | * Thus, safe percpu variable access. | |
502 | */ | |
9c270af3 | 503 | static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_pkt *xdp_pkt) |
6710e112 JDB |
504 | { |
505 | struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq); | |
506 | ||
507 | if (unlikely(bq->count == CPU_MAP_BULK_SIZE)) | |
508 | bq_flush_to_queue(rcpu, bq); | |
509 | ||
510 | /* Notice, xdp_buff/page MUST be queued here, long enough for | |
511 | * driver to code invoking us to finished, due to driver | |
512 | * (e.g. ixgbe) recycle tricks based on page-refcnt. | |
513 | * | |
514 | * Thus, incoming xdp_pkt is always queued here (else we race | |
515 | * with another CPU on page-refcnt and remaining driver code). | |
516 | * Queue time is very short, as driver will invoke flush | |
517 | * operation, when completing napi->poll call. | |
518 | */ | |
519 | bq->q[bq->count++] = xdp_pkt; | |
520 | return 0; | |
521 | } | |
522 | ||
9c270af3 JDB |
523 | int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp, |
524 | struct net_device *dev_rx) | |
525 | { | |
526 | struct xdp_pkt *xdp_pkt; | |
527 | int headroom; | |
528 | ||
529 | /* For now this is just used as a void pointer to data_hard_start. | |
530 | * Followup patch will generalize this. | |
531 | */ | |
532 | xdp_pkt = xdp->data_hard_start; | |
533 | ||
534 | /* Fake writing into xdp_pkt->data to measure overhead */ | |
535 | headroom = xdp->data - xdp->data_hard_start; | |
536 | if (headroom < sizeof(*xdp_pkt)) | |
537 | xdp_pkt->data = xdp->data; | |
538 | ||
539 | bq_enqueue(rcpu, xdp_pkt); | |
540 | return 0; | |
541 | } | |
542 | ||
6710e112 JDB |
543 | void __cpu_map_insert_ctx(struct bpf_map *map, u32 bit) |
544 | { | |
545 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
546 | unsigned long *bitmap = this_cpu_ptr(cmap->flush_needed); | |
547 | ||
548 | __set_bit(bit, bitmap); | |
549 | } | |
550 | ||
551 | void __cpu_map_flush(struct bpf_map *map) | |
552 | { | |
553 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
554 | unsigned long *bitmap = this_cpu_ptr(cmap->flush_needed); | |
555 | u32 bit; | |
556 | ||
557 | /* The napi->poll softirq makes sure __cpu_map_insert_ctx() | |
558 | * and __cpu_map_flush() happen on same CPU. Thus, the percpu | |
559 | * bitmap indicate which percpu bulkq have packets. | |
560 | */ | |
561 | for_each_set_bit(bit, bitmap, map->max_entries) { | |
562 | struct bpf_cpu_map_entry *rcpu = READ_ONCE(cmap->cpu_map[bit]); | |
563 | struct xdp_bulk_queue *bq; | |
564 | ||
565 | /* This is possible if entry is removed by user space | |
566 | * between xdp redirect and flush op. | |
567 | */ | |
568 | if (unlikely(!rcpu)) | |
569 | continue; | |
570 | ||
571 | __clear_bit(bit, bitmap); | |
572 | ||
573 | /* Flush all frames in bulkq to real queue */ | |
574 | bq = this_cpu_ptr(rcpu->bulkq); | |
575 | bq_flush_to_queue(rcpu, bq); | |
576 | ||
577 | /* If already running, costs spin_lock_irqsave + smb_mb */ | |
578 | wake_up_process(rcpu->kthread); | |
579 | } | |
580 | } |