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ddc64d0a | 1 | // SPDX-License-Identifier: GPL-2.0-only |
6710e112 JDB |
2 | /* bpf/cpumap.c |
3 | * | |
4 | * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. | |
6710e112 JDB |
5 | */ |
6 | ||
161939ab MT |
7 | /** |
8 | * DOC: cpu map | |
9 | * The 'cpumap' is primarily used as a backend map for XDP BPF helper | |
6710e112 JDB |
10 | * call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'. |
11 | * | |
161939ab | 12 | * Unlike devmap which redirects XDP frames out to another NIC device, |
6710e112 JDB |
13 | * this map type redirects raw XDP frames to another CPU. The remote |
14 | * CPU will do SKB-allocation and call the normal network stack. | |
161939ab MT |
15 | */ |
16 | /* | |
6710e112 JDB |
17 | * This is a scalability and isolation mechanism, that allow |
18 | * separating the early driver network XDP layer, from the rest of the | |
19 | * netstack, and assigning dedicated CPUs for this stage. This | |
20 | * basically allows for 10G wirespeed pre-filtering via bpf. | |
21 | */ | |
11941f8a | 22 | #include <linux/bitops.h> |
6710e112 JDB |
23 | #include <linux/bpf.h> |
24 | #include <linux/filter.h> | |
25 | #include <linux/ptr_ring.h> | |
5ab073ff | 26 | #include <net/xdp.h> |
6710e112 JDB |
27 | |
28 | #include <linux/sched.h> | |
29 | #include <linux/workqueue.h> | |
30 | #include <linux/kthread.h> | |
640a6045 | 31 | #include <linux/completion.h> |
f9419f7b | 32 | #include <trace/events/xdp.h> |
c317ab71 | 33 | #include <linux/btf_ids.h> |
6710e112 | 34 | |
bb024780 | 35 | #include <linux/netdevice.h> /* netif_receive_skb_list */ |
1c601d82 JDB |
36 | #include <linux/etherdevice.h> /* eth_type_trans */ |
37 | ||
6710e112 JDB |
38 | /* General idea: XDP packets getting XDP redirected to another CPU, |
39 | * will maximum be stored/queued for one driver ->poll() call. It is | |
d5df2830 | 40 | * guaranteed that queueing the frame and the flush operation happen on |
6710e112 JDB |
41 | * same CPU. Thus, cpu_map_flush operation can deduct via this_cpu_ptr() |
42 | * which queue in bpf_cpu_map_entry contains packets. | |
43 | */ | |
44 | ||
45 | #define CPU_MAP_BULK_SIZE 8 /* 8 == one cacheline on 64-bit archs */ | |
d5df2830 THJ |
46 | struct bpf_cpu_map_entry; |
47 | struct bpf_cpu_map; | |
48 | ||
6710e112 JDB |
49 | struct xdp_bulk_queue { |
50 | void *q[CPU_MAP_BULK_SIZE]; | |
d5df2830 THJ |
51 | struct list_head flush_node; |
52 | struct bpf_cpu_map_entry *obj; | |
6710e112 JDB |
53 | unsigned int count; |
54 | }; | |
55 | ||
56 | /* Struct for every remote "destination" CPU in map */ | |
57 | struct bpf_cpu_map_entry { | |
f9419f7b JDB |
58 | u32 cpu; /* kthread CPU and map index */ |
59 | int map_id; /* Back reference to map */ | |
6710e112 JDB |
60 | |
61 | /* XDP can run multiple RX-ring queues, need __percpu enqueue store */ | |
62 | struct xdp_bulk_queue __percpu *bulkq; | |
63 | ||
64 | /* Queue with potential multi-producers, and single-consumer kthread */ | |
65 | struct ptr_ring *queue; | |
66 | struct task_struct *kthread; | |
644bfe51 LB |
67 | |
68 | struct bpf_cpumap_val value; | |
92164774 | 69 | struct bpf_prog *prog; |
6710e112 | 70 | |
640a6045 | 71 | struct completion kthread_running; |
8f8500a2 | 72 | struct rcu_work free_work; |
6710e112 JDB |
73 | }; |
74 | ||
75 | struct bpf_cpu_map { | |
76 | struct bpf_map map; | |
77 | /* Below members specific for map type */ | |
782347b6 | 78 | struct bpf_cpu_map_entry __rcu **cpu_map; |
6710e112 JDB |
79 | }; |
80 | ||
cdfafe98 BT |
81 | static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list); |
82 | ||
6710e112 JDB |
83 | static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) |
84 | { | |
92164774 | 85 | u32 value_size = attr->value_size; |
6710e112 | 86 | struct bpf_cpu_map *cmap; |
6710e112 | 87 | |
6710e112 JDB |
88 | /* check sanity of attributes */ |
89 | if (attr->max_entries == 0 || attr->key_size != 4 || | |
92164774 LB |
90 | (value_size != offsetofend(struct bpf_cpumap_val, qsize) && |
91 | value_size != offsetofend(struct bpf_cpumap_val, bpf_prog.fd)) || | |
92 | attr->map_flags & ~BPF_F_NUMA_NODE) | |
6710e112 JDB |
93 | return ERR_PTR(-EINVAL); |
94 | ||
e39e739a FL |
95 | /* Pre-limit array size based on NR_CPUS, not final CPU check */ |
96 | if (attr->max_entries > NR_CPUS) | |
97 | return ERR_PTR(-E2BIG); | |
98 | ||
73cf09a3 | 99 | cmap = bpf_map_area_alloc(sizeof(*cmap), NUMA_NO_NODE); |
6710e112 JDB |
100 | if (!cmap) |
101 | return ERR_PTR(-ENOMEM); | |
102 | ||
bd475643 | 103 | bpf_map_init_from_attr(&cmap->map, attr); |
6710e112 | 104 | |
6710e112 JDB |
105 | /* Alloc array for possible remote "destination" CPUs */ |
106 | cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries * | |
107 | sizeof(struct bpf_cpu_map_entry *), | |
108 | cmap->map.numa_node); | |
e39e739a FL |
109 | if (!cmap->cpu_map) { |
110 | bpf_map_area_free(cmap); | |
111 | return ERR_PTR(-ENOMEM); | |
112 | } | |
6710e112 JDB |
113 | |
114 | return &cmap->map; | |
6710e112 JDB |
115 | } |
116 | ||
5ab073ff JDB |
117 | static void __cpu_map_ring_cleanup(struct ptr_ring *ring) |
118 | { | |
119 | /* The tear-down procedure should have made sure that queue is | |
120 | * empty. See __cpu_map_entry_replace() and work-queue | |
121 | * invoked cpu_map_kthread_stop(). Catch any broken behaviour | |
122 | * gracefully and warn once. | |
123 | */ | |
7c62b75c HT |
124 | void *ptr; |
125 | ||
126 | while ((ptr = ptr_ring_consume(ring))) { | |
127 | WARN_ON_ONCE(1); | |
128 | if (unlikely(__ptr_test_bit(0, &ptr))) { | |
129 | __ptr_clear_bit(0, &ptr); | |
130 | kfree_skb(ptr); | |
131 | continue; | |
132 | } | |
133 | xdp_return_frame(ptr); | |
134 | } | |
5ab073ff JDB |
135 | } |
136 | ||
11941f8a KKD |
137 | static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu, |
138 | struct list_head *listp, | |
139 | struct xdp_cpumap_stats *stats) | |
140 | { | |
141 | struct sk_buff *skb, *tmp; | |
142 | struct xdp_buff xdp; | |
143 | u32 act; | |
144 | int err; | |
145 | ||
146 | list_for_each_entry_safe(skb, tmp, listp, list) { | |
147 | act = bpf_prog_run_generic_xdp(skb, &xdp, rcpu->prog); | |
148 | switch (act) { | |
149 | case XDP_PASS: | |
150 | break; | |
151 | case XDP_REDIRECT: | |
152 | skb_list_del_init(skb); | |
153 | err = xdp_do_generic_redirect(skb->dev, skb, &xdp, | |
154 | rcpu->prog); | |
155 | if (unlikely(err)) { | |
156 | kfree_skb(skb); | |
157 | stats->drop++; | |
158 | } else { | |
159 | stats->redirect++; | |
160 | } | |
161 | return; | |
162 | default: | |
c8064e5b | 163 | bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act); |
11941f8a KKD |
164 | fallthrough; |
165 | case XDP_ABORTED: | |
166 | trace_xdp_exception(skb->dev, rcpu->prog, act); | |
167 | fallthrough; | |
168 | case XDP_DROP: | |
169 | skb_list_del_init(skb); | |
170 | kfree_skb(skb); | |
171 | stats->drop++; | |
172 | return; | |
173 | } | |
174 | } | |
175 | } | |
176 | ||
92164774 LB |
177 | static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu, |
178 | void **frames, int n, | |
179 | struct xdp_cpumap_stats *stats) | |
180 | { | |
181 | struct xdp_rxq_info rxq; | |
182 | struct xdp_buff xdp; | |
183 | int i, nframes = 0; | |
184 | ||
92164774 LB |
185 | xdp_set_return_frame_no_direct(); |
186 | xdp.rxq = &rxq; | |
187 | ||
188 | for (i = 0; i < n; i++) { | |
189 | struct xdp_frame *xdpf = frames[i]; | |
190 | u32 act; | |
191 | int err; | |
192 | ||
193 | rxq.dev = xdpf->dev_rx; | |
194 | rxq.mem = xdpf->mem; | |
195 | /* TODO: report queue_index to xdp_rxq_info */ | |
196 | ||
197 | xdp_convert_frame_to_buff(xdpf, &xdp); | |
198 | ||
199 | act = bpf_prog_run_xdp(rcpu->prog, &xdp); | |
200 | switch (act) { | |
201 | case XDP_PASS: | |
202 | err = xdp_update_frame_from_buff(&xdp, xdpf); | |
203 | if (err < 0) { | |
204 | xdp_return_frame(xdpf); | |
205 | stats->drop++; | |
206 | } else { | |
207 | frames[nframes++] = xdpf; | |
208 | stats->pass++; | |
209 | } | |
210 | break; | |
28b1520e LB |
211 | case XDP_REDIRECT: |
212 | err = xdp_do_redirect(xdpf->dev_rx, &xdp, | |
213 | rcpu->prog); | |
214 | if (unlikely(err)) { | |
215 | xdp_return_frame(xdpf); | |
216 | stats->drop++; | |
217 | } else { | |
218 | stats->redirect++; | |
219 | } | |
220 | break; | |
92164774 | 221 | default: |
c8064e5b | 222 | bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act); |
df561f66 | 223 | fallthrough; |
92164774 LB |
224 | case XDP_DROP: |
225 | xdp_return_frame(xdpf); | |
226 | stats->drop++; | |
227 | break; | |
228 | } | |
229 | } | |
230 | ||
11941f8a KKD |
231 | xdp_clear_return_frame_no_direct(); |
232 | ||
233 | return nframes; | |
234 | } | |
235 | ||
236 | #define CPUMAP_BATCH 8 | |
237 | ||
238 | static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames, | |
239 | int xdp_n, struct xdp_cpumap_stats *stats, | |
240 | struct list_head *list) | |
241 | { | |
242 | int nframes; | |
243 | ||
244 | if (!rcpu->prog) | |
245 | return xdp_n; | |
246 | ||
247 | rcu_read_lock_bh(); | |
248 | ||
249 | nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats); | |
250 | ||
28b1520e | 251 | if (stats->redirect) |
11941f8a | 252 | xdp_do_flush(); |
28b1520e | 253 | |
11941f8a KKD |
254 | if (unlikely(!list_empty(list))) |
255 | cpu_map_bpf_prog_run_skb(rcpu, list, stats); | |
92164774 | 256 | |
28b1520e | 257 | rcu_read_unlock_bh(); /* resched point, may call do_softirq() */ |
92164774 LB |
258 | |
259 | return nframes; | |
260 | } | |
261 | ||
6710e112 JDB |
262 | static int cpu_map_kthread_run(void *data) |
263 | { | |
264 | struct bpf_cpu_map_entry *rcpu = data; | |
265 | ||
640a6045 | 266 | complete(&rcpu->kthread_running); |
6710e112 JDB |
267 | set_current_state(TASK_INTERRUPTIBLE); |
268 | ||
269 | /* When kthread gives stop order, then rcpu have been disconnected | |
270 | * from map, thus no new packets can enter. Remaining in-flight | |
271 | * per CPU stored packets are flushed to this queue. Wait honoring | |
272 | * kthread_stop signal until queue is empty. | |
273 | */ | |
274 | while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) { | |
92164774 | 275 | struct xdp_cpumap_stats stats = {}; /* zero stats */ |
bb024780 | 276 | unsigned int kmem_alloc_drops = 0, sched = 0; |
92164774 | 277 | gfp_t gfp = __GFP_ZERO | GFP_ATOMIC; |
11941f8a | 278 | int i, n, m, nframes, xdp_n; |
77361825 | 279 | void *frames[CPUMAP_BATCH]; |
8f0504a9 | 280 | void *skbs[CPUMAP_BATCH]; |
bb024780 | 281 | LIST_HEAD(list); |
6710e112 | 282 | |
1c601d82 JDB |
283 | /* Release CPU reschedule checks */ |
284 | if (__ptr_ring_empty(rcpu->queue)) { | |
31749468 JDB |
285 | set_current_state(TASK_INTERRUPTIBLE); |
286 | /* Recheck to avoid lost wake-up */ | |
287 | if (__ptr_ring_empty(rcpu->queue)) { | |
288 | schedule(); | |
289 | sched = 1; | |
290 | } else { | |
291 | __set_current_state(TASK_RUNNING); | |
292 | } | |
1c601d82 | 293 | } else { |
f9419f7b | 294 | sched = cond_resched(); |
6710e112 | 295 | } |
1c601d82 | 296 | |
1c601d82 JDB |
297 | /* |
298 | * The bpf_cpu_map_entry is single consumer, with this | |
299 | * kthread CPU pinned. Lockless access to ptr_ring | |
300 | * consume side valid as no-resize allowed of queue. | |
301 | */ | |
92164774 LB |
302 | n = __ptr_ring_consume_batched(rcpu->queue, frames, |
303 | CPUMAP_BATCH); | |
11941f8a | 304 | for (i = 0, xdp_n = 0; i < n; i++) { |
86d23145 | 305 | void *f = frames[i]; |
11941f8a KKD |
306 | struct page *page; |
307 | ||
308 | if (unlikely(__ptr_test_bit(0, &f))) { | |
309 | struct sk_buff *skb = f; | |
310 | ||
311 | __ptr_clear_bit(0, &skb); | |
312 | list_add_tail(&skb->list, &list); | |
313 | continue; | |
314 | } | |
315 | ||
316 | frames[xdp_n++] = f; | |
317 | page = virt_to_page(f); | |
86d23145 JDB |
318 | |
319 | /* Bring struct page memory area to curr CPU. Read by | |
320 | * build_skb_around via page_is_pfmemalloc(), and when | |
321 | * freed written by page_frag_free call. | |
322 | */ | |
323 | prefetchw(page); | |
324 | } | |
325 | ||
92164774 | 326 | /* Support running another XDP prog on this CPU */ |
11941f8a | 327 | nframes = cpu_map_bpf_prog_run(rcpu, frames, xdp_n, &stats, &list); |
92164774 | 328 | if (nframes) { |
025a785f | 329 | m = kmem_cache_alloc_bulk(skbuff_cache, gfp, nframes, skbs); |
92164774 LB |
330 | if (unlikely(m == 0)) { |
331 | for (i = 0; i < nframes; i++) | |
332 | skbs[i] = NULL; /* effect: xdp_return_frame */ | |
bb024780 | 333 | kmem_alloc_drops += nframes; |
92164774 | 334 | } |
8f0504a9 | 335 | } |
77361825 JDB |
336 | |
337 | local_bh_disable(); | |
92164774 | 338 | for (i = 0; i < nframes; i++) { |
77361825 | 339 | struct xdp_frame *xdpf = frames[i]; |
8f0504a9 | 340 | struct sk_buff *skb = skbs[i]; |
1c601d82 | 341 | |
97a0e1ea LB |
342 | skb = __xdp_build_skb_from_frame(xdpf, skb, |
343 | xdpf->dev_rx); | |
1c601d82 | 344 | if (!skb) { |
03993094 | 345 | xdp_return_frame(xdpf); |
1c601d82 JDB |
346 | continue; |
347 | } | |
348 | ||
bb024780 | 349 | list_add_tail(&skb->list, &list); |
1c601d82 | 350 | } |
bb024780 LB |
351 | netif_receive_skb_list(&list); |
352 | ||
f9419f7b | 353 | /* Feedback loop via tracepoint */ |
bb024780 LB |
354 | trace_xdp_cpumap_kthread(rcpu->map_id, n, kmem_alloc_drops, |
355 | sched, &stats); | |
f9419f7b | 356 | |
1c601d82 | 357 | local_bh_enable(); /* resched point, may call do_softirq() */ |
6710e112 JDB |
358 | } |
359 | __set_current_state(TASK_RUNNING); | |
360 | ||
6710e112 JDB |
361 | return 0; |
362 | } | |
363 | ||
f45d5b6c THJ |
364 | static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu, |
365 | struct bpf_map *map, int fd) | |
92164774 LB |
366 | { |
367 | struct bpf_prog *prog; | |
368 | ||
369 | prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP); | |
370 | if (IS_ERR(prog)) | |
371 | return PTR_ERR(prog); | |
372 | ||
f45d5b6c THJ |
373 | if (prog->expected_attach_type != BPF_XDP_CPUMAP || |
374 | !bpf_prog_map_compatible(map, prog)) { | |
92164774 LB |
375 | bpf_prog_put(prog); |
376 | return -EINVAL; | |
377 | } | |
378 | ||
379 | rcpu->value.bpf_prog.id = prog->aux->id; | |
380 | rcpu->prog = prog; | |
381 | ||
382 | return 0; | |
383 | } | |
384 | ||
644bfe51 | 385 | static struct bpf_cpu_map_entry * |
e88cc05b RG |
386 | __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value, |
387 | u32 cpu) | |
6710e112 | 388 | { |
92164774 | 389 | int numa, err, i, fd = value->bpf_prog.fd; |
7fc17e90 | 390 | gfp_t gfp = GFP_KERNEL | __GFP_NOWARN; |
6710e112 | 391 | struct bpf_cpu_map_entry *rcpu; |
d5df2830 | 392 | struct xdp_bulk_queue *bq; |
6710e112 JDB |
393 | |
394 | /* Have map->numa_node, but choose node of redirect target CPU */ | |
395 | numa = cpu_to_node(cpu); | |
396 | ||
e88cc05b | 397 | rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa); |
6710e112 JDB |
398 | if (!rcpu) |
399 | return NULL; | |
400 | ||
401 | /* Alloc percpu bulkq */ | |
e88cc05b RG |
402 | rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq), |
403 | sizeof(void *), gfp); | |
6710e112 JDB |
404 | if (!rcpu->bulkq) |
405 | goto free_rcu; | |
406 | ||
d5df2830 THJ |
407 | for_each_possible_cpu(i) { |
408 | bq = per_cpu_ptr(rcpu->bulkq, i); | |
409 | bq->obj = rcpu; | |
410 | } | |
411 | ||
6710e112 | 412 | /* Alloc queue */ |
e88cc05b RG |
413 | rcpu->queue = bpf_map_kmalloc_node(map, sizeof(*rcpu->queue), gfp, |
414 | numa); | |
6710e112 JDB |
415 | if (!rcpu->queue) |
416 | goto free_bulkq; | |
417 | ||
644bfe51 | 418 | err = ptr_ring_init(rcpu->queue, value->qsize, gfp); |
6710e112 JDB |
419 | if (err) |
420 | goto free_queue; | |
421 | ||
f9419f7b | 422 | rcpu->cpu = cpu; |
e88cc05b | 423 | rcpu->map_id = map->id; |
644bfe51 | 424 | rcpu->value.qsize = value->qsize; |
6710e112 | 425 | |
f45d5b6c | 426 | if (fd > 0 && __cpu_map_load_bpf_program(rcpu, map, fd)) |
c576b9c7 LB |
427 | goto free_ptr_ring; |
428 | ||
6710e112 | 429 | /* Setup kthread */ |
640a6045 | 430 | init_completion(&rcpu->kthread_running); |
6710e112 | 431 | rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa, |
e88cc05b RG |
432 | "cpumap/%d/map:%d", cpu, |
433 | map->id); | |
6710e112 | 434 | if (IS_ERR(rcpu->kthread)) |
c576b9c7 | 435 | goto free_prog; |
6710e112 | 436 | |
6710e112 JDB |
437 | /* Make sure kthread runs on a single CPU */ |
438 | kthread_bind(rcpu->kthread, cpu); | |
439 | wake_up_process(rcpu->kthread); | |
440 | ||
640a6045 HT |
441 | /* Make sure kthread has been running, so kthread_stop() will not |
442 | * stop the kthread prematurely and all pending frames or skbs | |
443 | * will be handled by the kthread before kthread_stop() returns. | |
444 | */ | |
445 | wait_for_completion(&rcpu->kthread_running); | |
446 | ||
6710e112 JDB |
447 | return rcpu; |
448 | ||
c576b9c7 LB |
449 | free_prog: |
450 | if (rcpu->prog) | |
451 | bpf_prog_put(rcpu->prog); | |
6710e112 JDB |
452 | free_ptr_ring: |
453 | ptr_ring_cleanup(rcpu->queue, NULL); | |
454 | free_queue: | |
455 | kfree(rcpu->queue); | |
456 | free_bulkq: | |
457 | free_percpu(rcpu->bulkq); | |
458 | free_rcu: | |
459 | kfree(rcpu); | |
460 | return NULL; | |
461 | } | |
462 | ||
8f8500a2 | 463 | static void __cpu_map_entry_free(struct work_struct *work) |
6710e112 JDB |
464 | { |
465 | struct bpf_cpu_map_entry *rcpu; | |
6710e112 JDB |
466 | |
467 | /* This cpu_map_entry have been disconnected from map and one | |
8f8500a2 | 468 | * RCU grace-period have elapsed. Thus, XDP cannot queue any |
6710e112 JDB |
469 | * new packets and cannot change/set flush_needed that can |
470 | * find this entry. | |
471 | */ | |
8f8500a2 HT |
472 | rcpu = container_of(to_rcu_work(work), struct bpf_cpu_map_entry, free_work); |
473 | ||
474 | /* kthread_stop will wake_up_process and wait for it to complete. | |
475 | * cpu_map_kthread_run() makes sure the pointer ring is empty | |
476 | * before exiting. | |
477 | */ | |
478 | kthread_stop(rcpu->kthread); | |
6710e112 | 479 | |
8f8500a2 HT |
480 | if (rcpu->prog) |
481 | bpf_prog_put(rcpu->prog); | |
482 | /* The queue should be empty at this point */ | |
483 | __cpu_map_ring_cleanup(rcpu->queue); | |
484 | ptr_ring_cleanup(rcpu->queue, NULL); | |
485 | kfree(rcpu->queue); | |
6710e112 | 486 | free_percpu(rcpu->bulkq); |
8f8500a2 | 487 | kfree(rcpu); |
6710e112 JDB |
488 | } |
489 | ||
8f8500a2 HT |
490 | /* After the xchg of the bpf_cpu_map_entry pointer, we need to make sure the old |
491 | * entry is no longer in use before freeing. We use queue_rcu_work() to call | |
492 | * __cpu_map_entry_free() in a separate workqueue after waiting for an RCU grace | |
493 | * period. This means that (a) all pending enqueue and flush operations have | |
494 | * completed (because of the RCU callback), and (b) we are in a workqueue | |
495 | * context where we can stop the kthread and wait for it to exit before freeing | |
496 | * everything. | |
6710e112 | 497 | */ |
0fe875c5 WY |
498 | static void __cpu_map_entry_replace(struct bpf_cpu_map *cmap, |
499 | u32 key_cpu, struct bpf_cpu_map_entry *rcpu) | |
6710e112 JDB |
500 | { |
501 | struct bpf_cpu_map_entry *old_rcpu; | |
502 | ||
782347b6 | 503 | old_rcpu = unrcu_pointer(xchg(&cmap->cpu_map[key_cpu], RCU_INITIALIZER(rcpu))); |
6710e112 | 504 | if (old_rcpu) { |
8f8500a2 HT |
505 | INIT_RCU_WORK(&old_rcpu->free_work, __cpu_map_entry_free); |
506 | queue_rcu_work(system_wq, &old_rcpu->free_work); | |
6710e112 JDB |
507 | } |
508 | } | |
509 | ||
d7ba4cc9 | 510 | static long cpu_map_delete_elem(struct bpf_map *map, void *key) |
6710e112 JDB |
511 | { |
512 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
513 | u32 key_cpu = *(u32 *)key; | |
514 | ||
515 | if (key_cpu >= map->max_entries) | |
516 | return -EINVAL; | |
517 | ||
8f8500a2 | 518 | /* notice caller map_delete_elem() uses rcu_read_lock() */ |
6710e112 JDB |
519 | __cpu_map_entry_replace(cmap, key_cpu, NULL); |
520 | return 0; | |
521 | } | |
522 | ||
d7ba4cc9 JK |
523 | static long cpu_map_update_elem(struct bpf_map *map, void *key, void *value, |
524 | u64 map_flags) | |
6710e112 JDB |
525 | { |
526 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
644bfe51 | 527 | struct bpf_cpumap_val cpumap_value = {}; |
6710e112 | 528 | struct bpf_cpu_map_entry *rcpu; |
6710e112 JDB |
529 | /* Array index key correspond to CPU number */ |
530 | u32 key_cpu = *(u32 *)key; | |
644bfe51 LB |
531 | |
532 | memcpy(&cpumap_value, value, map->value_size); | |
6710e112 JDB |
533 | |
534 | if (unlikely(map_flags > BPF_EXIST)) | |
535 | return -EINVAL; | |
536 | if (unlikely(key_cpu >= cmap->map.max_entries)) | |
537 | return -E2BIG; | |
538 | if (unlikely(map_flags == BPF_NOEXIST)) | |
539 | return -EEXIST; | |
644bfe51 | 540 | if (unlikely(cpumap_value.qsize > 16384)) /* sanity limit on qsize */ |
6710e112 JDB |
541 | return -EOVERFLOW; |
542 | ||
543 | /* Make sure CPU is a valid possible cpu */ | |
bc23d0e3 | 544 | if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu)) |
6710e112 JDB |
545 | return -ENODEV; |
546 | ||
644bfe51 | 547 | if (cpumap_value.qsize == 0) { |
6710e112 JDB |
548 | rcpu = NULL; /* Same as deleting */ |
549 | } else { | |
550 | /* Updating qsize cause re-allocation of bpf_cpu_map_entry */ | |
e88cc05b | 551 | rcpu = __cpu_map_entry_alloc(map, &cpumap_value, key_cpu); |
6710e112 JDB |
552 | if (!rcpu) |
553 | return -ENOMEM; | |
554 | } | |
555 | rcu_read_lock(); | |
556 | __cpu_map_entry_replace(cmap, key_cpu, rcpu); | |
557 | rcu_read_unlock(); | |
558 | return 0; | |
559 | } | |
560 | ||
0fe875c5 | 561 | static void cpu_map_free(struct bpf_map *map) |
6710e112 JDB |
562 | { |
563 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
6710e112 JDB |
564 | u32 i; |
565 | ||
566 | /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, | |
567 | * so the bpf programs (can be more than one that used this map) were | |
568 | * disconnected from events. Wait for outstanding critical sections in | |
c2e42ddf HT |
569 | * these programs to complete. synchronize_rcu() below not only |
570 | * guarantees no further "XDP/bpf-side" reads against | |
571 | * bpf_cpu_map->cpu_map, but also ensure pending flush operations | |
572 | * (if any) are completed. | |
6710e112 JDB |
573 | */ |
574 | synchronize_rcu(); | |
575 | ||
c2e42ddf HT |
576 | /* The only possible user of bpf_cpu_map_entry is |
577 | * cpu_map_kthread_run(). | |
6710e112 JDB |
578 | */ |
579 | for (i = 0; i < cmap->map.max_entries; i++) { | |
580 | struct bpf_cpu_map_entry *rcpu; | |
581 | ||
782347b6 | 582 | rcpu = rcu_dereference_raw(cmap->cpu_map[i]); |
6710e112 JDB |
583 | if (!rcpu) |
584 | continue; | |
585 | ||
c2e42ddf HT |
586 | /* Stop kthread and cleanup entry directly */ |
587 | __cpu_map_entry_free(&rcpu->free_work.work); | |
6710e112 | 588 | } |
6710e112 | 589 | bpf_map_area_free(cmap->cpu_map); |
73cf09a3 | 590 | bpf_map_area_free(cmap); |
6710e112 JDB |
591 | } |
592 | ||
782347b6 THJ |
593 | /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or |
594 | * by local_bh_disable() (from XDP calls inside NAPI). The | |
595 | * rcu_read_lock_bh_held() below makes lockdep accept both. | |
596 | */ | |
e6a4750f | 597 | static void *__cpu_map_lookup_elem(struct bpf_map *map, u32 key) |
6710e112 JDB |
598 | { |
599 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
600 | struct bpf_cpu_map_entry *rcpu; | |
601 | ||
602 | if (key >= map->max_entries) | |
603 | return NULL; | |
604 | ||
782347b6 THJ |
605 | rcpu = rcu_dereference_check(cmap->cpu_map[key], |
606 | rcu_read_lock_bh_held()); | |
6710e112 JDB |
607 | return rcpu; |
608 | } | |
609 | ||
610 | static void *cpu_map_lookup_elem(struct bpf_map *map, void *key) | |
611 | { | |
612 | struct bpf_cpu_map_entry *rcpu = | |
613 | __cpu_map_lookup_elem(map, *(u32 *)key); | |
614 | ||
644bfe51 | 615 | return rcpu ? &rcpu->value : NULL; |
6710e112 JDB |
616 | } |
617 | ||
618 | static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key) | |
619 | { | |
620 | struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); | |
621 | u32 index = key ? *(u32 *)key : U32_MAX; | |
622 | u32 *next = next_key; | |
623 | ||
624 | if (index >= cmap->map.max_entries) { | |
625 | *next = 0; | |
626 | return 0; | |
627 | } | |
628 | ||
629 | if (index == cmap->map.max_entries - 1) | |
630 | return -ENOENT; | |
631 | *next = index + 1; | |
632 | return 0; | |
633 | } | |
634 | ||
d7ba4cc9 | 635 | static long cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags) |
e6a4750f | 636 | { |
32637e33 | 637 | return __bpf_xdp_redirect_map(map, index, flags, 0, |
e624d4ed | 638 | __cpu_map_lookup_elem); |
e6a4750f BT |
639 | } |
640 | ||
835f1fca YS |
641 | static u64 cpu_map_mem_usage(const struct bpf_map *map) |
642 | { | |
643 | u64 usage = sizeof(struct bpf_cpu_map); | |
644 | ||
645 | /* Currently the dynamically allocated elements are not counted */ | |
646 | usage += (u64)map->max_entries * sizeof(struct bpf_cpu_map_entry *); | |
647 | return usage; | |
648 | } | |
649 | ||
c317ab71 | 650 | BTF_ID_LIST_SINGLE(cpu_map_btf_ids, struct, bpf_cpu_map) |
6710e112 | 651 | const struct bpf_map_ops cpu_map_ops = { |
f4d05259 | 652 | .map_meta_equal = bpf_map_meta_equal, |
6710e112 JDB |
653 | .map_alloc = cpu_map_alloc, |
654 | .map_free = cpu_map_free, | |
655 | .map_delete_elem = cpu_map_delete_elem, | |
656 | .map_update_elem = cpu_map_update_elem, | |
657 | .map_lookup_elem = cpu_map_lookup_elem, | |
658 | .map_get_next_key = cpu_map_get_next_key, | |
e8d2bec0 | 659 | .map_check_btf = map_check_no_btf, |
835f1fca | 660 | .map_mem_usage = cpu_map_mem_usage, |
c317ab71 | 661 | .map_btf_id = &cpu_map_btf_ids[0], |
e6a4750f | 662 | .map_redirect = cpu_map_redirect, |
6710e112 JDB |
663 | }; |
664 | ||
ebc4ecd4 | 665 | static void bq_flush_to_queue(struct xdp_bulk_queue *bq) |
6710e112 | 666 | { |
d5df2830 | 667 | struct bpf_cpu_map_entry *rcpu = bq->obj; |
f9419f7b JDB |
668 | unsigned int processed = 0, drops = 0; |
669 | const int to_cpu = rcpu->cpu; | |
6710e112 JDB |
670 | struct ptr_ring *q; |
671 | int i; | |
672 | ||
673 | if (unlikely(!bq->count)) | |
ebc4ecd4 | 674 | return; |
6710e112 JDB |
675 | |
676 | q = rcpu->queue; | |
677 | spin_lock(&q->producer_lock); | |
678 | ||
679 | for (i = 0; i < bq->count; i++) { | |
70280ed9 | 680 | struct xdp_frame *xdpf = bq->q[i]; |
6710e112 JDB |
681 | int err; |
682 | ||
70280ed9 | 683 | err = __ptr_ring_produce(q, xdpf); |
6710e112 | 684 | if (err) { |
f9419f7b | 685 | drops++; |
4bc188c7 | 686 | xdp_return_frame_rx_napi(xdpf); |
6710e112 | 687 | } |
f9419f7b | 688 | processed++; |
6710e112 JDB |
689 | } |
690 | bq->count = 0; | |
691 | spin_unlock(&q->producer_lock); | |
692 | ||
d5df2830 THJ |
693 | __list_del_clearprev(&bq->flush_node); |
694 | ||
f9419f7b JDB |
695 | /* Feedback loop via tracepoints */ |
696 | trace_xdp_cpumap_enqueue(rcpu->map_id, processed, drops, to_cpu); | |
6710e112 JDB |
697 | } |
698 | ||
6710e112 JDB |
699 | /* Runs under RCU-read-side, plus in softirq under NAPI protection. |
700 | * Thus, safe percpu variable access. | |
701 | */ | |
ebc4ecd4 | 702 | static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf) |
6710e112 | 703 | { |
cdfafe98 | 704 | struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list); |
6710e112 JDB |
705 | struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq); |
706 | ||
707 | if (unlikely(bq->count == CPU_MAP_BULK_SIZE)) | |
4bc188c7 | 708 | bq_flush_to_queue(bq); |
6710e112 JDB |
709 | |
710 | /* Notice, xdp_buff/page MUST be queued here, long enough for | |
711 | * driver to code invoking us to finished, due to driver | |
712 | * (e.g. ixgbe) recycle tricks based on page-refcnt. | |
713 | * | |
70280ed9 | 714 | * Thus, incoming xdp_frame is always queued here (else we race |
6710e112 JDB |
715 | * with another CPU on page-refcnt and remaining driver code). |
716 | * Queue time is very short, as driver will invoke flush | |
717 | * operation, when completing napi->poll call. | |
718 | */ | |
70280ed9 | 719 | bq->q[bq->count++] = xdpf; |
d5df2830 THJ |
720 | |
721 | if (!bq->flush_node.prev) | |
722 | list_add(&bq->flush_node, flush_list); | |
6710e112 JDB |
723 | } |
724 | ||
d53ad5d8 | 725 | int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf, |
9c270af3 JDB |
726 | struct net_device *dev_rx) |
727 | { | |
1c601d82 | 728 | /* Info needed when constructing SKB on remote CPU */ |
70280ed9 | 729 | xdpf->dev_rx = dev_rx; |
9c270af3 | 730 | |
70280ed9 | 731 | bq_enqueue(rcpu, xdpf); |
9c270af3 JDB |
732 | return 0; |
733 | } | |
734 | ||
11941f8a KKD |
735 | int cpu_map_generic_redirect(struct bpf_cpu_map_entry *rcpu, |
736 | struct sk_buff *skb) | |
737 | { | |
738 | int ret; | |
739 | ||
740 | __skb_pull(skb, skb->mac_len); | |
741 | skb_set_redirected(skb, false); | |
742 | __ptr_set_bit(0, &skb); | |
743 | ||
744 | ret = ptr_ring_produce(rcpu->queue, skb); | |
745 | if (ret < 0) | |
746 | goto trace; | |
747 | ||
748 | wake_up_process(rcpu->kthread); | |
749 | trace: | |
750 | trace_xdp_cpumap_enqueue(rcpu->map_id, !ret, !!ret, rcpu->cpu); | |
751 | return ret; | |
752 | } | |
753 | ||
cdfafe98 | 754 | void __cpu_map_flush(void) |
6710e112 | 755 | { |
cdfafe98 | 756 | struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list); |
d5df2830 | 757 | struct xdp_bulk_queue *bq, *tmp; |
6710e112 | 758 | |
d5df2830 | 759 | list_for_each_entry_safe(bq, tmp, flush_list, flush_node) { |
4bc188c7 | 760 | bq_flush_to_queue(bq); |
6710e112 JDB |
761 | |
762 | /* If already running, costs spin_lock_irqsave + smb_mb */ | |
d5df2830 | 763 | wake_up_process(bq->obj->kthread); |
6710e112 JDB |
764 | } |
765 | } | |
cdfafe98 BT |
766 | |
767 | static int __init cpu_map_init(void) | |
768 | { | |
769 | int cpu; | |
770 | ||
771 | for_each_possible_cpu(cpu) | |
772 | INIT_LIST_HEAD(&per_cpu(cpu_map_flush_list, cpu)); | |
773 | return 0; | |
774 | } | |
775 | ||
776 | subsys_initcall(cpu_map_init); |