kernel/bpf/cpumap.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* bpf/cpumap.c
   3  *
   4  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   5  */
   6
   7 /**
   8  * DOC: cpu map
   9  * The 'cpumap' is primarily used as a backend map for XDP BPF helper
  10  * call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'.
  11  *
  12  * Unlike devmap which redirects XDP frames out to another NIC device,
  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.
  15  */
  16 /*
  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  */
  22 #include <linux/bitops.h>
  23 #include <linux/bpf.h>
  24 #include <linux/filter.h>
  25 #include <linux/ptr_ring.h>
  26 #include <net/xdp.h>
  27 #include <net/hotdata.h>
  28
  29 #include <linux/sched.h>
  30 #include <linux/workqueue.h>
  31 #include <linux/kthread.h>
  32 #include <linux/completion.h>
  33 #include <trace/events/xdp.h>
  34 #include <linux/btf_ids.h>
  35
  36 #include <linux/netdevice.h>   /* netif_receive_skb_list */
  37 #include <linux/etherdevice.h> /* eth_type_trans */
  38
  39 /* General idea: XDP packets getting XDP redirected to another CPU,
  40  * will maximum be stored/queued for one driver ->poll() call.  It is
  41  * guaranteed that queueing the frame and the flush operation happen on
  42  * same CPU.  Thus, cpu_map_flush operation can deduct via this_cpu_ptr()
  43  * which queue in bpf_cpu_map_entry contains packets.
  44  */
  45
  46 #define CPU_MAP_BULK_SIZE 8  /* 8 == one cacheline on 64-bit archs */
  47 struct bpf_cpu_map_entry;
  48 struct bpf_cpu_map;
  49
  50 struct xdp_bulk_queue {
  51         void *q[CPU_MAP_BULK_SIZE];
  52         struct list_head flush_node;
  53         struct bpf_cpu_map_entry *obj;
  54         unsigned int count;
  55 };
  56
  57 /* Struct for every remote "destination" CPU in map */
  58 struct bpf_cpu_map_entry {
  59         u32 cpu;    /* kthread CPU and map index */
  60         int map_id; /* Back reference to map */
  61
  62         /* XDP can run multiple RX-ring queues, need __percpu enqueue store */
  63         struct xdp_bulk_queue __percpu *bulkq;
  64
  65         /* Queue with potential multi-producers, and single-consumer kthread */
  66         struct ptr_ring *queue;
  67         struct task_struct *kthread;
  68
  69         struct bpf_cpumap_val value;
  70         struct bpf_prog *prog;
  71
  72         struct completion kthread_running;
  73         struct rcu_work free_work;
  74 };
  75
  76 struct bpf_cpu_map {
  77         struct bpf_map map;
  78         /* Below members specific for map type */
  79         struct bpf_cpu_map_entry __rcu **cpu_map;
  80 };
  81
  82 static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list);
  83
  84 static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
  85 {
  86         u32 value_size = attr->value_size;
  87         struct bpf_cpu_map *cmap;
  88
  89         /* check sanity of attributes */
  90         if (attr->max_entries == 0 || attr->key_size != 4 ||
  91             (value_size != offsetofend(struct bpf_cpumap_val, qsize) &&
  92              value_size != offsetofend(struct bpf_cpumap_val, bpf_prog.fd)) ||
  93             attr->map_flags & ~BPF_F_NUMA_NODE)
  94                 return ERR_PTR(-EINVAL);
  95
  96         /* Pre-limit array size based on NR_CPUS, not final CPU check */
  97         if (attr->max_entries > NR_CPUS)
  98                 return ERR_PTR(-E2BIG);
  99
 100         cmap = bpf_map_area_alloc(sizeof(*cmap), NUMA_NO_NODE);
 101         if (!cmap)
 102                 return ERR_PTR(-ENOMEM);
 103
 104         bpf_map_init_from_attr(&cmap->map, attr);
 105
 106         /* Alloc array for possible remote "destination" CPUs */
 107         cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries *
 108                                            sizeof(struct bpf_cpu_map_entry *),
 109                                            cmap->map.numa_node);
 110         if (!cmap->cpu_map) {
 111                 bpf_map_area_free(cmap);
 112                 return ERR_PTR(-ENOMEM);
 113         }
 114
 115         return &cmap->map;
 116 }
 117
 118 static void __cpu_map_ring_cleanup(struct ptr_ring *ring)
 119 {
 120         /* The tear-down procedure should have made sure that queue is
 121          * empty.  See __cpu_map_entry_replace() and work-queue
 122          * invoked cpu_map_kthread_stop(). Catch any broken behaviour
 123          * gracefully and warn once.
 124          */
 125         void *ptr;
 126
 127         while ((ptr = ptr_ring_consume(ring))) {
 128                 WARN_ON_ONCE(1);
 129                 if (unlikely(__ptr_test_bit(0, &ptr))) {
 130                         __ptr_clear_bit(0, &ptr);
 131                         kfree_skb(ptr);
 132                         continue;
 133                 }
 134                 xdp_return_frame(ptr);
 135         }
 136 }
 137
 138 static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu,
 139                                      struct list_head *listp,
 140                                      struct xdp_cpumap_stats *stats)
 141 {
 142         struct sk_buff *skb, *tmp;
 143         struct xdp_buff xdp;
 144         u32 act;
 145         int err;
 146
 147         list_for_each_entry_safe(skb, tmp, listp, list) {
 148                 act = bpf_prog_run_generic_xdp(skb, &xdp, rcpu->prog);
 149                 switch (act) {
 150                 case XDP_PASS:
 151                         break;
 152                 case XDP_REDIRECT:
 153                         skb_list_del_init(skb);
 154                         err = xdp_do_generic_redirect(skb->dev, skb, &xdp,
 155                                                       rcpu->prog);
 156                         if (unlikely(err)) {
 157                                 kfree_skb(skb);
 158                                 stats->drop++;
 159                         } else {
 160                                 stats->redirect++;
 161                         }
 162                         return;
 163                 default:
 164                         bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act);
 165                         fallthrough;
 166                 case XDP_ABORTED:
 167                         trace_xdp_exception(skb->dev, rcpu->prog, act);
 168                         fallthrough;
 169                 case XDP_DROP:
 170                         skb_list_del_init(skb);
 171                         kfree_skb(skb);
 172                         stats->drop++;
 173                         return;
 174                 }
 175         }
 176 }
 177
 178 static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
 179                                     void **frames, int n,
 180                                     struct xdp_cpumap_stats *stats)
 181 {
 182         struct xdp_rxq_info rxq = {};
 183         struct xdp_buff xdp;
 184         int i, nframes = 0;
 185
 186         xdp_set_return_frame_no_direct();
 187         xdp.rxq = &rxq;
 188
 189         for (i = 0; i < n; i++) {
 190                 struct xdp_frame *xdpf = frames[i];
 191                 u32 act;
 192                 int err;
 193
 194                 rxq.dev = xdpf->dev_rx;
 195                 rxq.mem = xdpf->mem;
 196                 /* TODO: report queue_index to xdp_rxq_info */
 197
 198                 xdp_convert_frame_to_buff(xdpf, &xdp);
 199
 200                 act = bpf_prog_run_xdp(rcpu->prog, &xdp);
 201                 switch (act) {
 202                 case XDP_PASS:
 203                         err = xdp_update_frame_from_buff(&xdp, xdpf);
 204                         if (err < 0) {
 205                                 xdp_return_frame(xdpf);
 206                                 stats->drop++;
 207                         } else {
 208                                 frames[nframes++] = xdpf;
 209                                 stats->pass++;
 210                         }
 211                         break;
 212                 case XDP_REDIRECT:
 213                         err = xdp_do_redirect(xdpf->dev_rx, &xdp,
 214                                               rcpu->prog);
 215                         if (unlikely(err)) {
 216                                 xdp_return_frame(xdpf);
 217                                 stats->drop++;
 218                         } else {
 219                                 stats->redirect++;
 220                         }
 221                         break;
 222                 default:
 223                         bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act);
 224                         fallthrough;
 225                 case XDP_DROP:
 226                         xdp_return_frame(xdpf);
 227                         stats->drop++;
 228                         break;
 229                 }
 230         }
 231
 232         xdp_clear_return_frame_no_direct();
 233
 234         return nframes;
 235 }
 236
 237 #define CPUMAP_BATCH 8
 238
 239 static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
 240                                 int xdp_n, struct xdp_cpumap_stats *stats,
 241                                 struct list_head *list)
 242 {
 243         int nframes;
 244
 245         if (!rcpu->prog)
 246                 return xdp_n;
 247
 248         rcu_read_lock_bh();
 249
 250         nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats);
 251
 252         if (stats->redirect)
 253                 xdp_do_flush();
 254
 255         if (unlikely(!list_empty(list)))
 256                 cpu_map_bpf_prog_run_skb(rcpu, list, stats);
 257
 258         rcu_read_unlock_bh(); /* resched point, may call do_softirq() */
 259
 260         return nframes;
 261 }
 262
 263 static int cpu_map_kthread_run(void *data)
 264 {
 265         struct bpf_cpu_map_entry *rcpu = data;
 266         unsigned long last_qs = jiffies;
 267
 268         complete(&rcpu->kthread_running);
 269         set_current_state(TASK_INTERRUPTIBLE);
 270
 271         /* When kthread gives stop order, then rcpu have been disconnected
 272          * from map, thus no new packets can enter. Remaining in-flight
 273          * per CPU stored packets are flushed to this queue.  Wait honoring
 274          * kthread_stop signal until queue is empty.
 275          */
 276         while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) {
 277                 struct xdp_cpumap_stats stats = {}; /* zero stats */
 278                 unsigned int kmem_alloc_drops = 0, sched = 0;
 279                 gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
 280                 int i, n, m, nframes, xdp_n;
 281                 void *frames[CPUMAP_BATCH];
 282                 void *skbs[CPUMAP_BATCH];
 283                 LIST_HEAD(list);
 284
 285                 /* Release CPU reschedule checks */
 286                 if (__ptr_ring_empty(rcpu->queue)) {
 287                         set_current_state(TASK_INTERRUPTIBLE);
 288                         /* Recheck to avoid lost wake-up */
 289                         if (__ptr_ring_empty(rcpu->queue)) {
 290                                 schedule();
 291                                 sched = 1;
 292                                 last_qs = jiffies;
 293                         } else {
 294                                 __set_current_state(TASK_RUNNING);
 295                         }
 296                 } else {
 297                         rcu_softirq_qs_periodic(last_qs);
 298                         sched = cond_resched();
 299                 }
 300
 301                 /*
 302                  * The bpf_cpu_map_entry is single consumer, with this
 303                  * kthread CPU pinned. Lockless access to ptr_ring
 304                  * consume side valid as no-resize allowed of queue.
 305                  */
 306                 n = __ptr_ring_consume_batched(rcpu->queue, frames,
 307                                                CPUMAP_BATCH);
 308                 for (i = 0, xdp_n = 0; i < n; i++) {
 309                         void *f = frames[i];
 310                         struct page *page;
 311
 312                         if (unlikely(__ptr_test_bit(0, &f))) {
 313                                 struct sk_buff *skb = f;
 314
 315                                 __ptr_clear_bit(0, &skb);
 316                                 list_add_tail(&skb->list, &list);
 317                                 continue;
 318                         }
 319
 320                         frames[xdp_n++] = f;
 321                         page = virt_to_page(f);
 322
 323                         /* Bring struct page memory area to curr CPU. Read by
 324                          * build_skb_around via page_is_pfmemalloc(), and when
 325                          * freed written by page_frag_free call.
 326                          */
 327                         prefetchw(page);
 328                 }
 329
 330                 /* Support running another XDP prog on this CPU */
 331                 nframes = cpu_map_bpf_prog_run(rcpu, frames, xdp_n, &stats, &list);
 332                 if (nframes) {
 333                         m = kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
 334                                                   gfp, nframes, skbs);
 335                         if (unlikely(m == 0)) {
 336                                 for (i = 0; i < nframes; i++)
 337                                         skbs[i] = NULL; /* effect: xdp_return_frame */
 338                                 kmem_alloc_drops += nframes;
 339                         }
 340                 }
 341
 342                 local_bh_disable();
 343                 for (i = 0; i < nframes; i++) {
 344                         struct xdp_frame *xdpf = frames[i];
 345                         struct sk_buff *skb = skbs[i];
 346
 347                         skb = __xdp_build_skb_from_frame(xdpf, skb,
 348                                                          xdpf->dev_rx);
 349                         if (!skb) {
 350                                 xdp_return_frame(xdpf);
 351                                 continue;
 352                         }
 353
 354                         list_add_tail(&skb->list, &list);
 355                 }
 356                 netif_receive_skb_list(&list);
 357
 358                 /* Feedback loop via tracepoint */
 359                 trace_xdp_cpumap_kthread(rcpu->map_id, n, kmem_alloc_drops,
 360                                          sched, &stats);
 361
 362                 local_bh_enable(); /* resched point, may call do_softirq() */
 363         }
 364         __set_current_state(TASK_RUNNING);
 365
 366         return 0;
 367 }
 368
 369 static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu,
 370                                       struct bpf_map *map, int fd)
 371 {
 372         struct bpf_prog *prog;
 373
 374         prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
 375         if (IS_ERR(prog))
 376                 return PTR_ERR(prog);
 377
 378         if (prog->expected_attach_type != BPF_XDP_CPUMAP ||
 379             !bpf_prog_map_compatible(map, prog)) {
 380                 bpf_prog_put(prog);
 381                 return -EINVAL;
 382         }
 383
 384         rcpu->value.bpf_prog.id = prog->aux->id;
 385         rcpu->prog = prog;
 386
 387         return 0;
 388 }
 389
 390 static struct bpf_cpu_map_entry *
 391 __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
 392                       u32 cpu)
 393 {
 394         int numa, err, i, fd = value->bpf_prog.fd;
 395         gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
 396         struct bpf_cpu_map_entry *rcpu;
 397         struct xdp_bulk_queue *bq;
 398
 399         /* Have map->numa_node, but choose node of redirect target CPU */
 400         numa = cpu_to_node(cpu);
 401
 402         rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa);
 403         if (!rcpu)
 404                 return NULL;
 405
 406         /* Alloc percpu bulkq */
 407         rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq),
 408                                            sizeof(void *), gfp);
 409         if (!rcpu->bulkq)
 410                 goto free_rcu;
 411
 412         for_each_possible_cpu(i) {
 413                 bq = per_cpu_ptr(rcpu->bulkq, i);
 414                 bq->obj = rcpu;
 415         }
 416
 417         /* Alloc queue */
 418         rcpu->queue = bpf_map_kmalloc_node(map, sizeof(*rcpu->queue), gfp,
 419                                            numa);
 420         if (!rcpu->queue)
 421                 goto free_bulkq;
 422
 423         err = ptr_ring_init(rcpu->queue, value->qsize, gfp);
 424         if (err)
 425                 goto free_queue;
 426
 427         rcpu->cpu    = cpu;
 428         rcpu->map_id = map->id;
 429         rcpu->value.qsize  = value->qsize;
 430
 431         if (fd > 0 && __cpu_map_load_bpf_program(rcpu, map, fd))
 432                 goto free_ptr_ring;
 433
 434         /* Setup kthread */
 435         init_completion(&rcpu->kthread_running);
 436         rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
 437                                                "cpumap/%d/map:%d", cpu,
 438                                                map->id);
 439         if (IS_ERR(rcpu->kthread))
 440                 goto free_prog;
 441
 442         /* Make sure kthread runs on a single CPU */
 443         kthread_bind(rcpu->kthread, cpu);
 444         wake_up_process(rcpu->kthread);
 445
 446         /* Make sure kthread has been running, so kthread_stop() will not
 447          * stop the kthread prematurely and all pending frames or skbs
 448          * will be handled by the kthread before kthread_stop() returns.
 449          */
 450         wait_for_completion(&rcpu->kthread_running);
 451
 452         return rcpu;
 453
 454 free_prog:
 455         if (rcpu->prog)
 456                 bpf_prog_put(rcpu->prog);
 457 free_ptr_ring:
 458         ptr_ring_cleanup(rcpu->queue, NULL);
 459 free_queue:
 460         kfree(rcpu->queue);
 461 free_bulkq:
 462         free_percpu(rcpu->bulkq);
 463 free_rcu:
 464         kfree(rcpu);
 465         return NULL;
 466 }
 467
 468 static void __cpu_map_entry_free(struct work_struct *work)
 469 {
 470         struct bpf_cpu_map_entry *rcpu;
 471
 472         /* This cpu_map_entry have been disconnected from map and one
 473          * RCU grace-period have elapsed. Thus, XDP cannot queue any
 474          * new packets and cannot change/set flush_needed that can
 475          * find this entry.
 476          */
 477         rcpu = container_of(to_rcu_work(work), struct bpf_cpu_map_entry, free_work);
 478
 479         /* kthread_stop will wake_up_process and wait for it to complete.
 480          * cpu_map_kthread_run() makes sure the pointer ring is empty
 481          * before exiting.
 482          */
 483         kthread_stop(rcpu->kthread);
 484
 485         if (rcpu->prog)
 486                 bpf_prog_put(rcpu->prog);
 487         /* The queue should be empty at this point */
 488         __cpu_map_ring_cleanup(rcpu->queue);
 489         ptr_ring_cleanup(rcpu->queue, NULL);
 490         kfree(rcpu->queue);
 491         free_percpu(rcpu->bulkq);
 492         kfree(rcpu);
 493 }
 494
 495 /* After the xchg of the bpf_cpu_map_entry pointer, we need to make sure the old
 496  * entry is no longer in use before freeing. We use queue_rcu_work() to call
 497  * __cpu_map_entry_free() in a separate workqueue after waiting for an RCU grace
 498  * period. This means that (a) all pending enqueue and flush operations have
 499  * completed (because of the RCU callback), and (b) we are in a workqueue
 500  * context where we can stop the kthread and wait for it to exit before freeing
 501  * everything.
 502  */
 503 static void __cpu_map_entry_replace(struct bpf_cpu_map *cmap,
 504                                     u32 key_cpu, struct bpf_cpu_map_entry *rcpu)
 505 {
 506         struct bpf_cpu_map_entry *old_rcpu;
 507
 508         old_rcpu = unrcu_pointer(xchg(&cmap->cpu_map[key_cpu], RCU_INITIALIZER(rcpu)));
 509         if (old_rcpu) {
 510                 INIT_RCU_WORK(&old_rcpu->free_work, __cpu_map_entry_free);
 511                 queue_rcu_work(system_wq, &old_rcpu->free_work);
 512         }
 513 }
 514
 515 static long cpu_map_delete_elem(struct bpf_map *map, void *key)
 516 {
 517         struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
 518         u32 key_cpu = *(u32 *)key;
 519
 520         if (key_cpu >= map->max_entries)
 521                 return -EINVAL;
 522
 523         /* notice caller map_delete_elem() uses rcu_read_lock() */
 524         __cpu_map_entry_replace(cmap, key_cpu, NULL);
 525         return 0;
 526 }
 527
 528 static long cpu_map_update_elem(struct bpf_map *map, void *key, void *value,
 529                                 u64 map_flags)
 530 {
 531         struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
 532         struct bpf_cpumap_val cpumap_value = {};
 533         struct bpf_cpu_map_entry *rcpu;
 534         /* Array index key correspond to CPU number */
 535         u32 key_cpu = *(u32 *)key;
 536
 537         memcpy(&cpumap_value, value, map->value_size);
 538
 539         if (unlikely(map_flags > BPF_EXIST))
 540                 return -EINVAL;
 541         if (unlikely(key_cpu >= cmap->map.max_entries))
 542                 return -E2BIG;
 543         if (unlikely(map_flags == BPF_NOEXIST))
 544                 return -EEXIST;
 545         if (unlikely(cpumap_value.qsize > 16384)) /* sanity limit on qsize */
 546                 return -EOVERFLOW;
 547
 548         /* Make sure CPU is a valid possible cpu */
 549         if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu))
 550                 return -ENODEV;
 551
 552         if (cpumap_value.qsize == 0) {
 553                 rcpu = NULL; /* Same as deleting */
 554         } else {
 555                 /* Updating qsize cause re-allocation of bpf_cpu_map_entry */
 556                 rcpu = __cpu_map_entry_alloc(map, &cpumap_value, key_cpu);
 557                 if (!rcpu)
 558                         return -ENOMEM;
 559         }
 560         rcu_read_lock();
 561         __cpu_map_entry_replace(cmap, key_cpu, rcpu);
 562         rcu_read_unlock();
 563         return 0;
 564 }
 565
 566 static void cpu_map_free(struct bpf_map *map)
 567 {
 568         struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
 569         u32 i;
 570
 571         /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 572          * so the bpf programs (can be more than one that used this map) were
 573          * disconnected from events. Wait for outstanding critical sections in
 574          * these programs to complete. synchronize_rcu() below not only
 575          * guarantees no further "XDP/bpf-side" reads against
 576          * bpf_cpu_map->cpu_map, but also ensure pending flush operations
 577          * (if any) are completed.
 578          */
 579         synchronize_rcu();
 580
 581         /* The only possible user of bpf_cpu_map_entry is
 582          * cpu_map_kthread_run().
 583          */
 584         for (i = 0; i < cmap->map.max_entries; i++) {
 585                 struct bpf_cpu_map_entry *rcpu;
 586
 587                 rcpu = rcu_dereference_raw(cmap->cpu_map[i]);
 588                 if (!rcpu)
 589                         continue;
 590
 591                 /* Stop kthread and cleanup entry directly */
 592                 __cpu_map_entry_free(&rcpu->free_work.work);
 593         }
 594         bpf_map_area_free(cmap->cpu_map);
 595         bpf_map_area_free(cmap);
 596 }
 597
 598 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
 599  * by local_bh_disable() (from XDP calls inside NAPI). The
 600  * rcu_read_lock_bh_held() below makes lockdep accept both.
 601  */
 602 static void *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
 603 {
 604         struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
 605         struct bpf_cpu_map_entry *rcpu;
 606
 607         if (key >= map->max_entries)
 608                 return NULL;
 609
 610         rcpu = rcu_dereference_check(cmap->cpu_map[key],
 611                                      rcu_read_lock_bh_held());
 612         return rcpu;
 613 }
 614
 615 static void *cpu_map_lookup_elem(struct bpf_map *map, void *key)
 616 {
 617         struct bpf_cpu_map_entry *rcpu =
 618                 __cpu_map_lookup_elem(map, *(u32 *)key);
 619
 620         return rcpu ? &rcpu->value : NULL;
 621 }
 622
 623 static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 624 {
 625         struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
 626         u32 index = key ? *(u32 *)key : U32_MAX;
 627         u32 *next = next_key;
 628
 629         if (index >= cmap->map.max_entries) {
 630                 *next = 0;
 631                 return 0;
 632         }
 633
 634         if (index == cmap->map.max_entries - 1)
 635                 return -ENOENT;
 636         *next = index + 1;
 637         return 0;
 638 }
 639
 640 static long cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags)
 641 {
 642         return __bpf_xdp_redirect_map(map, index, flags, 0,
 643                                       __cpu_map_lookup_elem);
 644 }
 645
 646 static u64 cpu_map_mem_usage(const struct bpf_map *map)
 647 {
 648         u64 usage = sizeof(struct bpf_cpu_map);
 649
 650         /* Currently the dynamically allocated elements are not counted */
 651         usage += (u64)map->max_entries * sizeof(struct bpf_cpu_map_entry *);
 652         return usage;
 653 }
 654
 655 BTF_ID_LIST_SINGLE(cpu_map_btf_ids, struct, bpf_cpu_map)
 656 const struct bpf_map_ops cpu_map_ops = {
 657         .map_meta_equal         = bpf_map_meta_equal,
 658         .map_alloc              = cpu_map_alloc,
 659         .map_free               = cpu_map_free,
 660         .map_delete_elem        = cpu_map_delete_elem,
 661         .map_update_elem        = cpu_map_update_elem,
 662         .map_lookup_elem        = cpu_map_lookup_elem,
 663         .map_get_next_key       = cpu_map_get_next_key,
 664         .map_check_btf          = map_check_no_btf,
 665         .map_mem_usage          = cpu_map_mem_usage,
 666         .map_btf_id             = &cpu_map_btf_ids[0],
 667         .map_redirect           = cpu_map_redirect,
 668 };
 669
 670 static void bq_flush_to_queue(struct xdp_bulk_queue *bq)
 671 {
 672         struct bpf_cpu_map_entry *rcpu = bq->obj;
 673         unsigned int processed = 0, drops = 0;
 674         const int to_cpu = rcpu->cpu;
 675         struct ptr_ring *q;
 676         int i;
 677
 678         if (unlikely(!bq->count))
 679                 return;
 680
 681         q = rcpu->queue;
 682         spin_lock(&q->producer_lock);
 683
 684         for (i = 0; i < bq->count; i++) {
 685                 struct xdp_frame *xdpf = bq->q[i];
 686                 int err;
 687
 688                 err = __ptr_ring_produce(q, xdpf);
 689                 if (err) {
 690                         drops++;
 691                         xdp_return_frame_rx_napi(xdpf);
 692                 }
 693                 processed++;
 694         }
 695         bq->count = 0;
 696         spin_unlock(&q->producer_lock);
 697
 698         __list_del_clearprev(&bq->flush_node);
 699
 700         /* Feedback loop via tracepoints */
 701         trace_xdp_cpumap_enqueue(rcpu->map_id, processed, drops, to_cpu);
 702 }
 703
 704 /* Runs under RCU-read-side, plus in softirq under NAPI protection.
 705  * Thus, safe percpu variable access.
 706  */
 707 static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
 708 {
 709         struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
 710         struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);
 711
 712         if (unlikely(bq->count == CPU_MAP_BULK_SIZE))
 713                 bq_flush_to_queue(bq);
 714
 715         /* Notice, xdp_buff/page MUST be queued here, long enough for
 716          * driver to code invoking us to finished, due to driver
 717          * (e.g. ixgbe) recycle tricks based on page-refcnt.
 718          *
 719          * Thus, incoming xdp_frame is always queued here (else we race
 720          * with another CPU on page-refcnt and remaining driver code).
 721          * Queue time is very short, as driver will invoke flush
 722          * operation, when completing napi->poll call.
 723          */
 724         bq->q[bq->count++] = xdpf;
 725
 726         if (!bq->flush_node.prev)
 727                 list_add(&bq->flush_node, flush_list);
 728 }
 729
 730 int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf,
 731                     struct net_device *dev_rx)
 732 {
 733         /* Info needed when constructing SKB on remote CPU */
 734         xdpf->dev_rx = dev_rx;
 735
 736         bq_enqueue(rcpu, xdpf);
 737         return 0;
 738 }
 739
 740 int cpu_map_generic_redirect(struct bpf_cpu_map_entry *rcpu,
 741                              struct sk_buff *skb)
 742 {
 743         int ret;
 744
 745         __skb_pull(skb, skb->mac_len);
 746         skb_set_redirected(skb, false);
 747         __ptr_set_bit(0, &skb);
 748
 749         ret = ptr_ring_produce(rcpu->queue, skb);
 750         if (ret < 0)
 751                 goto trace;
 752
 753         wake_up_process(rcpu->kthread);
 754 trace:
 755         trace_xdp_cpumap_enqueue(rcpu->map_id, !ret, !!ret, rcpu->cpu);
 756         return ret;
 757 }
 758
 759 void __cpu_map_flush(void)
 760 {
 761         struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
 762         struct xdp_bulk_queue *bq, *tmp;
 763
 764         list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
 765                 bq_flush_to_queue(bq);
 766
 767                 /* If already running, costs spin_lock_irqsave + smb_mb */
 768                 wake_up_process(bq->obj->kthread);
 769         }
 770 }
 771
 772 #ifdef CONFIG_DEBUG_NET
 773 bool cpu_map_check_flush(void)
 774 {
 775         if (list_empty(this_cpu_ptr(&cpu_map_flush_list)))
 776                 return false;
 777         __cpu_map_flush();
 778         return true;
 779 }
 780 #endif
 781
 782 static int __init cpu_map_init(void)
 783 {
 784         int cpu;
 785
 786         for_each_possible_cpu(cpu)
 787                 INIT_LIST_HEAD(&per_cpu(cpu_map_flush_list, cpu));
 788         return 0;
 789 }
 790
 791 subsys_initcall(cpu_map_init);