| /* bpf/cpumap.c |
| * |
| * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. |
| * Released under terms in GPL version 2. See COPYING. |
| */ |
| |
| /* The 'cpumap' is primarily used as a backend map for XDP BPF helper |
| * call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'. |
| * |
| * Unlike devmap which redirects XDP frames out another NIC device, |
| * this map type redirects raw XDP frames to another CPU. The remote |
| * CPU will do SKB-allocation and call the normal network stack. |
| * |
| * This is a scalability and isolation mechanism, that allow |
| * separating the early driver network XDP layer, from the rest of the |
| * netstack, and assigning dedicated CPUs for this stage. This |
| * basically allows for 10G wirespeed pre-filtering via bpf. |
| */ |
| #include <linux/bpf.h> |
| #include <linux/filter.h> |
| #include <linux/ptr_ring.h> |
| |
| #include <linux/sched.h> |
| #include <linux/workqueue.h> |
| #include <linux/kthread.h> |
| #include <linux/capability.h> |
| #include <trace/events/xdp.h> |
| |
| #include <linux/netdevice.h> /* netif_receive_skb_core */ |
| #include <linux/etherdevice.h> /* eth_type_trans */ |
| |
| /* General idea: XDP packets getting XDP redirected to another CPU, |
| * will maximum be stored/queued for one driver ->poll() call. It is |
| * guaranteed that setting flush bit and flush operation happen on |
| * same CPU. Thus, cpu_map_flush operation can deduct via this_cpu_ptr() |
| * which queue in bpf_cpu_map_entry contains packets. |
| */ |
| |
| #define CPU_MAP_BULK_SIZE 8 /* 8 == one cacheline on 64-bit archs */ |
| struct xdp_bulk_queue { |
| void *q[CPU_MAP_BULK_SIZE]; |
| unsigned int count; |
| }; |
| |
| /* Struct for every remote "destination" CPU in map */ |
| struct bpf_cpu_map_entry { |
| u32 cpu; /* kthread CPU and map index */ |
| int map_id; /* Back reference to map */ |
| u32 qsize; /* Queue size placeholder for map lookup */ |
| |
| /* XDP can run multiple RX-ring queues, need __percpu enqueue store */ |
| struct xdp_bulk_queue __percpu *bulkq; |
| |
| /* Queue with potential multi-producers, and single-consumer kthread */ |
| struct ptr_ring *queue; |
| struct task_struct *kthread; |
| struct work_struct kthread_stop_wq; |
| |
| atomic_t refcnt; /* Control when this struct can be free'ed */ |
| struct rcu_head rcu; |
| }; |
| |
| struct bpf_cpu_map { |
| struct bpf_map map; |
| /* Below members specific for map type */ |
| struct bpf_cpu_map_entry **cpu_map; |
| unsigned long __percpu *flush_needed; |
| }; |
| |
| static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu, |
| struct xdp_bulk_queue *bq); |
| |
| static u64 cpu_map_bitmap_size(const union bpf_attr *attr) |
| { |
| return BITS_TO_LONGS(attr->max_entries) * sizeof(unsigned long); |
| } |
| |
| static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) |
| { |
| struct bpf_cpu_map *cmap; |
| int err = -ENOMEM; |
| u64 cost; |
| int ret; |
| |
| if (!capable(CAP_SYS_ADMIN)) |
| return ERR_PTR(-EPERM); |
| |
| /* check sanity of attributes */ |
| if (attr->max_entries == 0 || attr->key_size != 4 || |
| attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE) |
| return ERR_PTR(-EINVAL); |
| |
| cmap = kzalloc(sizeof(*cmap), GFP_USER); |
| if (!cmap) |
| return ERR_PTR(-ENOMEM); |
| |
| /* mandatory map attributes */ |
| cmap->map.map_type = attr->map_type; |
| cmap->map.key_size = attr->key_size; |
| cmap->map.value_size = attr->value_size; |
| cmap->map.max_entries = attr->max_entries; |
| cmap->map.map_flags = attr->map_flags; |
| cmap->map.numa_node = bpf_map_attr_numa_node(attr); |
| |
| /* Pre-limit array size based on NR_CPUS, not final CPU check */ |
| if (cmap->map.max_entries > NR_CPUS) { |
| err = -E2BIG; |
| goto free_cmap; |
| } |
| |
| /* make sure page count doesn't overflow */ |
| cost = (u64) cmap->map.max_entries * sizeof(struct bpf_cpu_map_entry *); |
| cost += cpu_map_bitmap_size(attr) * num_possible_cpus(); |
| if (cost >= U32_MAX - PAGE_SIZE) |
| goto free_cmap; |
| cmap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; |
| |
| /* Notice returns -EPERM on if map size is larger than memlock limit */ |
| ret = bpf_map_precharge_memlock(cmap->map.pages); |
| if (ret) { |
| err = ret; |
| goto free_cmap; |
| } |
| |
| /* A per cpu bitfield with a bit per possible CPU in map */ |
| cmap->flush_needed = __alloc_percpu(cpu_map_bitmap_size(attr), |
| __alignof__(unsigned long)); |
| if (!cmap->flush_needed) |
| goto free_cmap; |
| |
| /* Alloc array for possible remote "destination" CPUs */ |
| cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries * |
| sizeof(struct bpf_cpu_map_entry *), |
| cmap->map.numa_node); |
| if (!cmap->cpu_map) |
| goto free_percpu; |
| |
| return &cmap->map; |
| free_percpu: |
| free_percpu(cmap->flush_needed); |
| free_cmap: |
| kfree(cmap); |
| return ERR_PTR(err); |
| } |
| |
| void __cpu_map_queue_destructor(void *ptr) |
| { |
| /* The tear-down procedure should have made sure that queue is |
| * empty. See __cpu_map_entry_replace() and work-queue |
| * invoked cpu_map_kthread_stop(). Catch any broken behaviour |
| * gracefully and warn once. |
| */ |
| if (WARN_ON_ONCE(ptr)) |
| page_frag_free(ptr); |
| } |
| |
| static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) |
| { |
| if (atomic_dec_and_test(&rcpu->refcnt)) { |
| /* The queue should be empty at this point */ |
| ptr_ring_cleanup(rcpu->queue, __cpu_map_queue_destructor); |
| kfree(rcpu->queue); |
| kfree(rcpu); |
| } |
| } |
| |
| static void get_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) |
| { |
| atomic_inc(&rcpu->refcnt); |
| } |
| |
| /* called from workqueue, to workaround syscall using preempt_disable */ |
| static void cpu_map_kthread_stop(struct work_struct *work) |
| { |
| struct bpf_cpu_map_entry *rcpu; |
| |
| rcpu = container_of(work, struct bpf_cpu_map_entry, kthread_stop_wq); |
| |
| /* Wait for flush in __cpu_map_entry_free(), via full RCU barrier, |
| * as it waits until all in-flight call_rcu() callbacks complete. |
| */ |
| rcu_barrier(); |
| |
| /* kthread_stop will wake_up_process and wait for it to complete */ |
| kthread_stop(rcpu->kthread); |
| } |
| |
| /* For now, xdp_pkt is a cpumap internal data structure, with info |
| * carried between enqueue to dequeue. It is mapped into the top |
| * headroom of the packet, to avoid allocating separate mem. |
| */ |
| struct xdp_pkt { |
| void *data; |
| u16 len; |
| u16 headroom; |
| u16 metasize; |
| struct net_device *dev_rx; |
| }; |
| |
| /* Convert xdp_buff to xdp_pkt */ |
| static struct xdp_pkt *convert_to_xdp_pkt(struct xdp_buff *xdp) |
| { |
| struct xdp_pkt *xdp_pkt; |
| int metasize; |
| int headroom; |
| |
| /* Assure headroom is available for storing info */ |
| headroom = xdp->data - xdp->data_hard_start; |
| metasize = xdp->data - xdp->data_meta; |
| metasize = metasize > 0 ? metasize : 0; |
| if (unlikely((headroom - metasize) < sizeof(*xdp_pkt))) |
| return NULL; |
| |
| /* Store info in top of packet */ |
| xdp_pkt = xdp->data_hard_start; |
| |
| xdp_pkt->data = xdp->data; |
| xdp_pkt->len = xdp->data_end - xdp->data; |
| xdp_pkt->headroom = headroom - sizeof(*xdp_pkt); |
| xdp_pkt->metasize = metasize; |
| |
| return xdp_pkt; |
| } |
| |
| struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu, |
| struct xdp_pkt *xdp_pkt) |
| { |
| unsigned int frame_size; |
| void *pkt_data_start; |
| struct sk_buff *skb; |
| |
| /* build_skb need to place skb_shared_info after SKB end, and |
| * also want to know the memory "truesize". Thus, need to |
| * know the memory frame size backing xdp_buff. |
| * |
| * XDP was designed to have PAGE_SIZE frames, but this |
| * assumption is not longer true with ixgbe and i40e. It |
| * would be preferred to set frame_size to 2048 or 4096 |
| * depending on the driver. |
| * frame_size = 2048; |
| * frame_len = frame_size - sizeof(*xdp_pkt); |
| * |
| * Instead, with info avail, skb_shared_info in placed after |
| * packet len. This, unfortunately fakes the truesize. |
| * Another disadvantage of this approach, the skb_shared_info |
| * is not at a fixed memory location, with mixed length |
| * packets, which is bad for cache-line hotness. |
| */ |
| frame_size = SKB_DATA_ALIGN(xdp_pkt->len) + xdp_pkt->headroom + |
| SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); |
| |
| pkt_data_start = xdp_pkt->data - xdp_pkt->headroom; |
| skb = build_skb(pkt_data_start, frame_size); |
| if (!skb) |
| return NULL; |
| |
| skb_reserve(skb, xdp_pkt->headroom); |
| __skb_put(skb, xdp_pkt->len); |
| if (xdp_pkt->metasize) |
| skb_metadata_set(skb, xdp_pkt->metasize); |
| |
| /* Essential SKB info: protocol and skb->dev */ |
| skb->protocol = eth_type_trans(skb, xdp_pkt->dev_rx); |
| |
| /* Optional SKB info, currently missing: |
| * - HW checksum info (skb->ip_summed) |
| * - HW RX hash (skb_set_hash) |
| * - RX ring dev queue index (skb_record_rx_queue) |
| */ |
| |
| return skb; |
| } |
| |
| static int cpu_map_kthread_run(void *data) |
| { |
| struct bpf_cpu_map_entry *rcpu = data; |
| |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| /* When kthread gives stop order, then rcpu have been disconnected |
| * from map, thus no new packets can enter. Remaining in-flight |
| * per CPU stored packets are flushed to this queue. Wait honoring |
| * kthread_stop signal until queue is empty. |
| */ |
| while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) { |
| unsigned int processed = 0, drops = 0, sched = 0; |
| struct xdp_pkt *xdp_pkt; |
| |
| /* Release CPU reschedule checks */ |
| if (__ptr_ring_empty(rcpu->queue)) { |
| set_current_state(TASK_INTERRUPTIBLE); |
| /* Recheck to avoid lost wake-up */ |
| if (__ptr_ring_empty(rcpu->queue)) { |
| schedule(); |
| sched = 1; |
| } else { |
| __set_current_state(TASK_RUNNING); |
| } |
| } else { |
| sched = cond_resched(); |
| } |
| |
| /* Process packets in rcpu->queue */ |
| local_bh_disable(); |
| /* |
| * The bpf_cpu_map_entry is single consumer, with this |
| * kthread CPU pinned. Lockless access to ptr_ring |
| * consume side valid as no-resize allowed of queue. |
| */ |
| while ((xdp_pkt = __ptr_ring_consume(rcpu->queue))) { |
| struct sk_buff *skb; |
| int ret; |
| |
| skb = cpu_map_build_skb(rcpu, xdp_pkt); |
| if (!skb) { |
| page_frag_free(xdp_pkt); |
| continue; |
| } |
| |
| /* Inject into network stack */ |
| ret = netif_receive_skb_core(skb); |
| if (ret == NET_RX_DROP) |
| drops++; |
| |
| /* Limit BH-disable period */ |
| if (++processed == 8) |
| break; |
| } |
| /* Feedback loop via tracepoint */ |
| trace_xdp_cpumap_kthread(rcpu->map_id, processed, drops, sched); |
| |
| local_bh_enable(); /* resched point, may call do_softirq() */ |
| } |
| __set_current_state(TASK_RUNNING); |
| |
| put_cpu_map_entry(rcpu); |
| return 0; |
| } |
| |
| struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu, int map_id) |
| { |
| gfp_t gfp = GFP_ATOMIC|__GFP_NOWARN; |
| struct bpf_cpu_map_entry *rcpu; |
| int numa, err; |
| |
| /* Have map->numa_node, but choose node of redirect target CPU */ |
| numa = cpu_to_node(cpu); |
| |
| rcpu = kzalloc_node(sizeof(*rcpu), gfp, numa); |
| if (!rcpu) |
| return NULL; |
| |
| /* Alloc percpu bulkq */ |
| rcpu->bulkq = __alloc_percpu_gfp(sizeof(*rcpu->bulkq), |
| sizeof(void *), gfp); |
| if (!rcpu->bulkq) |
| goto free_rcu; |
| |
| /* Alloc queue */ |
| rcpu->queue = kzalloc_node(sizeof(*rcpu->queue), gfp, numa); |
| if (!rcpu->queue) |
| goto free_bulkq; |
| |
| err = ptr_ring_init(rcpu->queue, qsize, gfp); |
| if (err) |
| goto free_queue; |
| |
| rcpu->cpu = cpu; |
| rcpu->map_id = map_id; |
| rcpu->qsize = qsize; |
| |
| /* Setup kthread */ |
| rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa, |
| "cpumap/%d/map:%d", cpu, map_id); |
| if (IS_ERR(rcpu->kthread)) |
| goto free_ptr_ring; |
| |
| get_cpu_map_entry(rcpu); /* 1-refcnt for being in cmap->cpu_map[] */ |
| get_cpu_map_entry(rcpu); /* 1-refcnt for kthread */ |
| |
| /* Make sure kthread runs on a single CPU */ |
| kthread_bind(rcpu->kthread, cpu); |
| wake_up_process(rcpu->kthread); |
| |
| return rcpu; |
| |
| free_ptr_ring: |
| ptr_ring_cleanup(rcpu->queue, NULL); |
| free_queue: |
| kfree(rcpu->queue); |
| free_bulkq: |
| free_percpu(rcpu->bulkq); |
| free_rcu: |
| kfree(rcpu); |
| return NULL; |
| } |
| |
| void __cpu_map_entry_free(struct rcu_head *rcu) |
| { |
| struct bpf_cpu_map_entry *rcpu; |
| int cpu; |
| |
| /* This cpu_map_entry have been disconnected from map and one |
| * RCU graze-period have elapsed. Thus, XDP cannot queue any |
| * new packets and cannot change/set flush_needed that can |
| * find this entry. |
| */ |
| rcpu = container_of(rcu, struct bpf_cpu_map_entry, rcu); |
| |
| /* Flush remaining packets in percpu bulkq */ |
| for_each_online_cpu(cpu) { |
| struct xdp_bulk_queue *bq = per_cpu_ptr(rcpu->bulkq, cpu); |
| |
| /* No concurrent bq_enqueue can run at this point */ |
| bq_flush_to_queue(rcpu, bq); |
| } |
| free_percpu(rcpu->bulkq); |
| /* Cannot kthread_stop() here, last put free rcpu resources */ |
| put_cpu_map_entry(rcpu); |
| } |
| |
| /* After xchg pointer to bpf_cpu_map_entry, use the call_rcu() to |
| * ensure any driver rcu critical sections have completed, but this |
| * does not guarantee a flush has happened yet. Because driver side |
| * rcu_read_lock/unlock only protects the running XDP program. The |
| * atomic xchg and NULL-ptr check in __cpu_map_flush() makes sure a |
| * pending flush op doesn't fail. |
| * |
| * The bpf_cpu_map_entry is still used by the kthread, and there can |
| * still be pending packets (in queue and percpu bulkq). A refcnt |
| * makes sure to last user (kthread_stop vs. call_rcu) free memory |
| * resources. |
| * |
| * The rcu callback __cpu_map_entry_free flush remaining packets in |
| * percpu bulkq to queue. Due to caller map_delete_elem() disable |
| * preemption, cannot call kthread_stop() to make sure queue is empty. |
| * Instead a work_queue is started for stopping kthread, |
| * cpu_map_kthread_stop, which waits for an RCU graze period before |
| * stopping kthread, emptying the queue. |
| */ |
| void __cpu_map_entry_replace(struct bpf_cpu_map *cmap, |
| u32 key_cpu, struct bpf_cpu_map_entry *rcpu) |
| { |
| struct bpf_cpu_map_entry *old_rcpu; |
| |
| old_rcpu = xchg(&cmap->cpu_map[key_cpu], rcpu); |
| if (old_rcpu) { |
| call_rcu(&old_rcpu->rcu, __cpu_map_entry_free); |
| INIT_WORK(&old_rcpu->kthread_stop_wq, cpu_map_kthread_stop); |
| schedule_work(&old_rcpu->kthread_stop_wq); |
| } |
| } |
| |
| int cpu_map_delete_elem(struct bpf_map *map, void *key) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| u32 key_cpu = *(u32 *)key; |
| |
| if (key_cpu >= map->max_entries) |
| return -EINVAL; |
| |
| /* notice caller map_delete_elem() use preempt_disable() */ |
| __cpu_map_entry_replace(cmap, key_cpu, NULL); |
| return 0; |
| } |
| |
| int cpu_map_update_elem(struct bpf_map *map, void *key, void *value, |
| u64 map_flags) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| struct bpf_cpu_map_entry *rcpu; |
| |
| /* Array index key correspond to CPU number */ |
| u32 key_cpu = *(u32 *)key; |
| /* Value is the queue size */ |
| u32 qsize = *(u32 *)value; |
| |
| if (unlikely(map_flags > BPF_EXIST)) |
| return -EINVAL; |
| if (unlikely(key_cpu >= cmap->map.max_entries)) |
| return -E2BIG; |
| if (unlikely(map_flags == BPF_NOEXIST)) |
| return -EEXIST; |
| if (unlikely(qsize > 16384)) /* sanity limit on qsize */ |
| return -EOVERFLOW; |
| |
| /* Make sure CPU is a valid possible cpu */ |
| if (!cpu_possible(key_cpu)) |
| return -ENODEV; |
| |
| if (qsize == 0) { |
| rcpu = NULL; /* Same as deleting */ |
| } else { |
| /* Updating qsize cause re-allocation of bpf_cpu_map_entry */ |
| rcpu = __cpu_map_entry_alloc(qsize, key_cpu, map->id); |
| if (!rcpu) |
| return -ENOMEM; |
| } |
| rcu_read_lock(); |
| __cpu_map_entry_replace(cmap, key_cpu, rcpu); |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| void cpu_map_free(struct bpf_map *map) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| int cpu; |
| u32 i; |
| |
| /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, |
| * so the bpf programs (can be more than one that used this map) were |
| * disconnected from events. Wait for outstanding critical sections in |
| * these programs to complete. The rcu critical section only guarantees |
| * no further "XDP/bpf-side" reads against bpf_cpu_map->cpu_map. |
| * It does __not__ ensure pending flush operations (if any) are |
| * complete. |
| */ |
| synchronize_rcu(); |
| |
| /* To ensure all pending flush operations have completed wait for flush |
| * bitmap to indicate all flush_needed bits to be zero on _all_ cpus. |
| * Because the above synchronize_rcu() ensures the map is disconnected |
| * from the program we can assume no new bits will be set. |
| */ |
| for_each_online_cpu(cpu) { |
| unsigned long *bitmap = per_cpu_ptr(cmap->flush_needed, cpu); |
| |
| while (!bitmap_empty(bitmap, cmap->map.max_entries)) |
| cond_resched(); |
| } |
| |
| /* For cpu_map the remote CPUs can still be using the entries |
| * (struct bpf_cpu_map_entry). |
| */ |
| for (i = 0; i < cmap->map.max_entries; i++) { |
| struct bpf_cpu_map_entry *rcpu; |
| |
| rcpu = READ_ONCE(cmap->cpu_map[i]); |
| if (!rcpu) |
| continue; |
| |
| /* bq flush and cleanup happens after RCU graze-period */ |
| __cpu_map_entry_replace(cmap, i, NULL); /* call_rcu */ |
| } |
| free_percpu(cmap->flush_needed); |
| bpf_map_area_free(cmap->cpu_map); |
| kfree(cmap); |
| } |
| |
| struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| struct bpf_cpu_map_entry *rcpu; |
| |
| if (key >= map->max_entries) |
| return NULL; |
| |
| rcpu = READ_ONCE(cmap->cpu_map[key]); |
| return rcpu; |
| } |
| |
| static void *cpu_map_lookup_elem(struct bpf_map *map, void *key) |
| { |
| struct bpf_cpu_map_entry *rcpu = |
| __cpu_map_lookup_elem(map, *(u32 *)key); |
| |
| return rcpu ? &rcpu->qsize : NULL; |
| } |
| |
| static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| u32 index = key ? *(u32 *)key : U32_MAX; |
| u32 *next = next_key; |
| |
| if (index >= cmap->map.max_entries) { |
| *next = 0; |
| return 0; |
| } |
| |
| if (index == cmap->map.max_entries - 1) |
| return -ENOENT; |
| *next = index + 1; |
| return 0; |
| } |
| |
| const struct bpf_map_ops cpu_map_ops = { |
| .map_alloc = cpu_map_alloc, |
| .map_free = cpu_map_free, |
| .map_delete_elem = cpu_map_delete_elem, |
| .map_update_elem = cpu_map_update_elem, |
| .map_lookup_elem = cpu_map_lookup_elem, |
| .map_get_next_key = cpu_map_get_next_key, |
| }; |
| |
| static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu, |
| struct xdp_bulk_queue *bq) |
| { |
| unsigned int processed = 0, drops = 0; |
| const int to_cpu = rcpu->cpu; |
| struct ptr_ring *q; |
| int i; |
| |
| if (unlikely(!bq->count)) |
| return 0; |
| |
| q = rcpu->queue; |
| spin_lock(&q->producer_lock); |
| |
| for (i = 0; i < bq->count; i++) { |
| void *xdp_pkt = bq->q[i]; |
| int err; |
| |
| err = __ptr_ring_produce(q, xdp_pkt); |
| if (err) { |
| drops++; |
| page_frag_free(xdp_pkt); /* Free xdp_pkt */ |
| } |
| processed++; |
| } |
| bq->count = 0; |
| spin_unlock(&q->producer_lock); |
| |
| /* Feedback loop via tracepoints */ |
| trace_xdp_cpumap_enqueue(rcpu->map_id, processed, drops, to_cpu); |
| return 0; |
| } |
| |
| /* Runs under RCU-read-side, plus in softirq under NAPI protection. |
| * Thus, safe percpu variable access. |
| */ |
| static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_pkt *xdp_pkt) |
| { |
| struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq); |
| |
| if (unlikely(bq->count == CPU_MAP_BULK_SIZE)) |
| bq_flush_to_queue(rcpu, bq); |
| |
| /* Notice, xdp_buff/page MUST be queued here, long enough for |
| * driver to code invoking us to finished, due to driver |
| * (e.g. ixgbe) recycle tricks based on page-refcnt. |
| * |
| * Thus, incoming xdp_pkt is always queued here (else we race |
| * with another CPU on page-refcnt and remaining driver code). |
| * Queue time is very short, as driver will invoke flush |
| * operation, when completing napi->poll call. |
| */ |
| bq->q[bq->count++] = xdp_pkt; |
| return 0; |
| } |
| |
| int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp, |
| struct net_device *dev_rx) |
| { |
| struct xdp_pkt *xdp_pkt; |
| |
| xdp_pkt = convert_to_xdp_pkt(xdp); |
| if (unlikely(!xdp_pkt)) |
| return -EOVERFLOW; |
| |
| /* Info needed when constructing SKB on remote CPU */ |
| xdp_pkt->dev_rx = dev_rx; |
| |
| bq_enqueue(rcpu, xdp_pkt); |
| return 0; |
| } |
| |
| void __cpu_map_insert_ctx(struct bpf_map *map, u32 bit) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| unsigned long *bitmap = this_cpu_ptr(cmap->flush_needed); |
| |
| __set_bit(bit, bitmap); |
| } |
| |
| void __cpu_map_flush(struct bpf_map *map) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| unsigned long *bitmap = this_cpu_ptr(cmap->flush_needed); |
| u32 bit; |
| |
| /* The napi->poll softirq makes sure __cpu_map_insert_ctx() |
| * and __cpu_map_flush() happen on same CPU. Thus, the percpu |
| * bitmap indicate which percpu bulkq have packets. |
| */ |
| for_each_set_bit(bit, bitmap, map->max_entries) { |
| struct bpf_cpu_map_entry *rcpu = READ_ONCE(cmap->cpu_map[bit]); |
| struct xdp_bulk_queue *bq; |
| |
| /* This is possible if entry is removed by user space |
| * between xdp redirect and flush op. |
| */ |
| if (unlikely(!rcpu)) |
| continue; |
| |
| __clear_bit(bit, bitmap); |
| |
| /* Flush all frames in bulkq to real queue */ |
| bq = this_cpu_ptr(rcpu->bulkq); |
| bq_flush_to_queue(rcpu, bq); |
| |
| /* If already running, costs spin_lock_irqsave + smb_mb */ |
| wake_up_process(rcpu->kthread); |
| } |
| } |