| // SPDX-License-Identifier: GPL-2.0-only |
| /* bpf/cpumap.c |
| * |
| * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. |
| */ |
| |
| /* 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/bitops.h> |
| #include <linux/bpf.h> |
| #include <linux/filter.h> |
| #include <linux/ptr_ring.h> |
| #include <net/xdp.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_list */ |
| #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 queueing the frame and the 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 bpf_cpu_map_entry; |
| struct bpf_cpu_map; |
| |
| struct xdp_bulk_queue { |
| void *q[CPU_MAP_BULK_SIZE]; |
| struct list_head flush_node; |
| struct bpf_cpu_map_entry *obj; |
| 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 */ |
| |
| /* XDP can run multiple RX-ring queues, need __percpu enqueue store */ |
| struct xdp_bulk_queue __percpu *bulkq; |
| |
| struct bpf_cpu_map *cmap; |
| |
| /* Queue with potential multi-producers, and single-consumer kthread */ |
| struct ptr_ring *queue; |
| struct task_struct *kthread; |
| |
| struct bpf_cpumap_val value; |
| struct bpf_prog *prog; |
| |
| atomic_t refcnt; /* Control when this struct can be free'ed */ |
| struct rcu_head rcu; |
| |
| struct work_struct kthread_stop_wq; |
| }; |
| |
| struct bpf_cpu_map { |
| struct bpf_map map; |
| /* Below members specific for map type */ |
| struct bpf_cpu_map_entry __rcu **cpu_map; |
| }; |
| |
| static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list); |
| |
| static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) |
| { |
| u32 value_size = attr->value_size; |
| struct bpf_cpu_map *cmap; |
| int err = -ENOMEM; |
| |
| if (!bpf_capable()) |
| return ERR_PTR(-EPERM); |
| |
| /* check sanity of attributes */ |
| if (attr->max_entries == 0 || attr->key_size != 4 || |
| (value_size != offsetofend(struct bpf_cpumap_val, qsize) && |
| value_size != offsetofend(struct bpf_cpumap_val, bpf_prog.fd)) || |
| attr->map_flags & ~BPF_F_NUMA_NODE) |
| return ERR_PTR(-EINVAL); |
| |
| cmap = kzalloc(sizeof(*cmap), GFP_USER | __GFP_ACCOUNT); |
| if (!cmap) |
| return ERR_PTR(-ENOMEM); |
| |
| bpf_map_init_from_attr(&cmap->map, 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; |
| } |
| |
| /* 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_cmap; |
| |
| return &cmap->map; |
| free_cmap: |
| kfree(cmap); |
| return ERR_PTR(err); |
| } |
| |
| 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); |
| } |
| |
| static void __cpu_map_ring_cleanup(struct ptr_ring *ring) |
| { |
| /* 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. |
| */ |
| struct xdp_frame *xdpf; |
| |
| while ((xdpf = ptr_ring_consume(ring))) |
| if (WARN_ON_ONCE(xdpf)) |
| xdp_return_frame(xdpf); |
| } |
| |
| static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) |
| { |
| if (atomic_dec_and_test(&rcpu->refcnt)) { |
| if (rcpu->prog) |
| bpf_prog_put(rcpu->prog); |
| /* The queue should be empty at this point */ |
| __cpu_map_ring_cleanup(rcpu->queue); |
| ptr_ring_cleanup(rcpu->queue, NULL); |
| kfree(rcpu->queue); |
| kfree(rcpu); |
| } |
| } |
| |
| static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu, |
| struct list_head *listp, |
| struct xdp_cpumap_stats *stats) |
| { |
| struct sk_buff *skb, *tmp; |
| struct xdp_buff xdp; |
| u32 act; |
| int err; |
| |
| list_for_each_entry_safe(skb, tmp, listp, list) { |
| act = bpf_prog_run_generic_xdp(skb, &xdp, rcpu->prog); |
| switch (act) { |
| case XDP_PASS: |
| break; |
| case XDP_REDIRECT: |
| skb_list_del_init(skb); |
| err = xdp_do_generic_redirect(skb->dev, skb, &xdp, |
| rcpu->prog); |
| if (unlikely(err)) { |
| kfree_skb(skb); |
| stats->drop++; |
| } else { |
| stats->redirect++; |
| } |
| return; |
| default: |
| bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act); |
| fallthrough; |
| case XDP_ABORTED: |
| trace_xdp_exception(skb->dev, rcpu->prog, act); |
| fallthrough; |
| case XDP_DROP: |
| skb_list_del_init(skb); |
| kfree_skb(skb); |
| stats->drop++; |
| return; |
| } |
| } |
| } |
| |
| static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu, |
| void **frames, int n, |
| struct xdp_cpumap_stats *stats) |
| { |
| struct xdp_rxq_info rxq; |
| struct xdp_buff xdp; |
| int i, nframes = 0; |
| |
| xdp_set_return_frame_no_direct(); |
| xdp.rxq = &rxq; |
| |
| for (i = 0; i < n; i++) { |
| struct xdp_frame *xdpf = frames[i]; |
| u32 act; |
| int err; |
| |
| rxq.dev = xdpf->dev_rx; |
| rxq.mem = xdpf->mem; |
| /* TODO: report queue_index to xdp_rxq_info */ |
| |
| xdp_convert_frame_to_buff(xdpf, &xdp); |
| |
| act = bpf_prog_run_xdp(rcpu->prog, &xdp); |
| switch (act) { |
| case XDP_PASS: |
| err = xdp_update_frame_from_buff(&xdp, xdpf); |
| if (err < 0) { |
| xdp_return_frame(xdpf); |
| stats->drop++; |
| } else { |
| frames[nframes++] = xdpf; |
| stats->pass++; |
| } |
| break; |
| case XDP_REDIRECT: |
| err = xdp_do_redirect(xdpf->dev_rx, &xdp, |
| rcpu->prog); |
| if (unlikely(err)) { |
| xdp_return_frame(xdpf); |
| stats->drop++; |
| } else { |
| stats->redirect++; |
| } |
| break; |
| default: |
| bpf_warn_invalid_xdp_action(NULL, rcpu->prog, act); |
| fallthrough; |
| case XDP_DROP: |
| xdp_return_frame(xdpf); |
| stats->drop++; |
| break; |
| } |
| } |
| |
| xdp_clear_return_frame_no_direct(); |
| |
| return nframes; |
| } |
| |
| #define CPUMAP_BATCH 8 |
| |
| static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames, |
| int xdp_n, struct xdp_cpumap_stats *stats, |
| struct list_head *list) |
| { |
| int nframes; |
| |
| if (!rcpu->prog) |
| return xdp_n; |
| |
| rcu_read_lock_bh(); |
| |
| nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats); |
| |
| if (stats->redirect) |
| xdp_do_flush(); |
| |
| if (unlikely(!list_empty(list))) |
| cpu_map_bpf_prog_run_skb(rcpu, list, stats); |
| |
| rcu_read_unlock_bh(); /* resched point, may call do_softirq() */ |
| |
| return nframes; |
| } |
| |
| |
| 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)) { |
| struct xdp_cpumap_stats stats = {}; /* zero stats */ |
| unsigned int kmem_alloc_drops = 0, sched = 0; |
| gfp_t gfp = __GFP_ZERO | GFP_ATOMIC; |
| int i, n, m, nframes, xdp_n; |
| void *frames[CPUMAP_BATCH]; |
| void *skbs[CPUMAP_BATCH]; |
| LIST_HEAD(list); |
| |
| /* 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(); |
| } |
| |
| /* |
| * 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. |
| */ |
| n = __ptr_ring_consume_batched(rcpu->queue, frames, |
| CPUMAP_BATCH); |
| for (i = 0, xdp_n = 0; i < n; i++) { |
| void *f = frames[i]; |
| struct page *page; |
| |
| if (unlikely(__ptr_test_bit(0, &f))) { |
| struct sk_buff *skb = f; |
| |
| __ptr_clear_bit(0, &skb); |
| list_add_tail(&skb->list, &list); |
| continue; |
| } |
| |
| frames[xdp_n++] = f; |
| page = virt_to_page(f); |
| |
| /* Bring struct page memory area to curr CPU. Read by |
| * build_skb_around via page_is_pfmemalloc(), and when |
| * freed written by page_frag_free call. |
| */ |
| prefetchw(page); |
| } |
| |
| /* Support running another XDP prog on this CPU */ |
| nframes = cpu_map_bpf_prog_run(rcpu, frames, xdp_n, &stats, &list); |
| if (nframes) { |
| m = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, skbs); |
| if (unlikely(m == 0)) { |
| for (i = 0; i < nframes; i++) |
| skbs[i] = NULL; /* effect: xdp_return_frame */ |
| kmem_alloc_drops += nframes; |
| } |
| } |
| |
| local_bh_disable(); |
| for (i = 0; i < nframes; i++) { |
| struct xdp_frame *xdpf = frames[i]; |
| struct sk_buff *skb = skbs[i]; |
| |
| skb = __xdp_build_skb_from_frame(xdpf, skb, |
| xdpf->dev_rx); |
| if (!skb) { |
| xdp_return_frame(xdpf); |
| continue; |
| } |
| |
| list_add_tail(&skb->list, &list); |
| } |
| netif_receive_skb_list(&list); |
| |
| /* Feedback loop via tracepoint */ |
| trace_xdp_cpumap_kthread(rcpu->map_id, n, kmem_alloc_drops, |
| sched, &stats); |
| |
| local_bh_enable(); /* resched point, may call do_softirq() */ |
| } |
| __set_current_state(TASK_RUNNING); |
| |
| put_cpu_map_entry(rcpu); |
| return 0; |
| } |
| |
| static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu, int fd) |
| { |
| struct bpf_prog *prog; |
| |
| prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP); |
| if (IS_ERR(prog)) |
| return PTR_ERR(prog); |
| |
| if (prog->expected_attach_type != BPF_XDP_CPUMAP) { |
| bpf_prog_put(prog); |
| return -EINVAL; |
| } |
| |
| rcpu->value.bpf_prog.id = prog->aux->id; |
| rcpu->prog = prog; |
| |
| return 0; |
| } |
| |
| static struct bpf_cpu_map_entry * |
| __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value, |
| u32 cpu) |
| { |
| int numa, err, i, fd = value->bpf_prog.fd; |
| gfp_t gfp = GFP_KERNEL | __GFP_NOWARN; |
| struct bpf_cpu_map_entry *rcpu; |
| struct xdp_bulk_queue *bq; |
| |
| /* Have map->numa_node, but choose node of redirect target CPU */ |
| numa = cpu_to_node(cpu); |
| |
| rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa); |
| if (!rcpu) |
| return NULL; |
| |
| /* Alloc percpu bulkq */ |
| rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq), |
| sizeof(void *), gfp); |
| if (!rcpu->bulkq) |
| goto free_rcu; |
| |
| for_each_possible_cpu(i) { |
| bq = per_cpu_ptr(rcpu->bulkq, i); |
| bq->obj = rcpu; |
| } |
| |
| /* Alloc queue */ |
| rcpu->queue = bpf_map_kmalloc_node(map, sizeof(*rcpu->queue), gfp, |
| numa); |
| if (!rcpu->queue) |
| goto free_bulkq; |
| |
| err = ptr_ring_init(rcpu->queue, value->qsize, gfp); |
| if (err) |
| goto free_queue; |
| |
| rcpu->cpu = cpu; |
| rcpu->map_id = map->id; |
| rcpu->value.qsize = value->qsize; |
| |
| if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd)) |
| goto free_ptr_ring; |
| |
| /* 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_prog; |
| |
| 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_prog: |
| if (rcpu->prog) |
| bpf_prog_put(rcpu->prog); |
| 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; |
| } |
| |
| static void __cpu_map_entry_free(struct rcu_head *rcu) |
| { |
| struct bpf_cpu_map_entry *rcpu; |
| |
| /* This cpu_map_entry have been disconnected from map and one |
| * RCU grace-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); |
| |
| 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 grace period before |
| * stopping kthread, emptying the queue. |
| */ |
| static 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 = unrcu_pointer(xchg(&cmap->cpu_map[key_cpu], RCU_INITIALIZER(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); |
| } |
| } |
| |
| static 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; |
| } |
| |
| static 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_cpumap_val cpumap_value = {}; |
| struct bpf_cpu_map_entry *rcpu; |
| /* Array index key correspond to CPU number */ |
| u32 key_cpu = *(u32 *)key; |
| |
| memcpy(&cpumap_value, value, map->value_size); |
| |
| 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(cpumap_value.qsize > 16384)) /* sanity limit on qsize */ |
| return -EOVERFLOW; |
| |
| /* Make sure CPU is a valid possible cpu */ |
| if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu)) |
| return -ENODEV; |
| |
| if (cpumap_value.qsize == 0) { |
| rcpu = NULL; /* Same as deleting */ |
| } else { |
| /* Updating qsize cause re-allocation of bpf_cpu_map_entry */ |
| rcpu = __cpu_map_entry_alloc(map, &cpumap_value, key_cpu); |
| if (!rcpu) |
| return -ENOMEM; |
| rcpu->cmap = cmap; |
| } |
| rcu_read_lock(); |
| __cpu_map_entry_replace(cmap, key_cpu, rcpu); |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| static void cpu_map_free(struct bpf_map *map) |
| { |
| struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
| 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(); |
| |
| /* 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 = rcu_dereference_raw(cmap->cpu_map[i]); |
| if (!rcpu) |
| continue; |
| |
| /* bq flush and cleanup happens after RCU grace-period */ |
| __cpu_map_entry_replace(cmap, i, NULL); /* call_rcu */ |
| } |
| bpf_map_area_free(cmap->cpu_map); |
| kfree(cmap); |
| } |
| |
| /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or |
| * by local_bh_disable() (from XDP calls inside NAPI). The |
| * rcu_read_lock_bh_held() below makes lockdep accept both. |
| */ |
| static void *__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 = rcu_dereference_check(cmap->cpu_map[key], |
| rcu_read_lock_bh_held()); |
| 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->value : 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; |
| } |
| |
| static int cpu_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags) |
| { |
| return __bpf_xdp_redirect_map(map, ifindex, flags, 0, |
| __cpu_map_lookup_elem); |
| } |
| |
| static int cpu_map_btf_id; |
| const struct bpf_map_ops cpu_map_ops = { |
| .map_meta_equal = bpf_map_meta_equal, |
| .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, |
| .map_check_btf = map_check_no_btf, |
| .map_btf_name = "bpf_cpu_map", |
| .map_btf_id = &cpu_map_btf_id, |
| .map_redirect = cpu_map_redirect, |
| }; |
| |
| static void bq_flush_to_queue(struct xdp_bulk_queue *bq) |
| { |
| struct bpf_cpu_map_entry *rcpu = bq->obj; |
| unsigned int processed = 0, drops = 0; |
| const int to_cpu = rcpu->cpu; |
| struct ptr_ring *q; |
| int i; |
| |
| if (unlikely(!bq->count)) |
| return; |
| |
| q = rcpu->queue; |
| spin_lock(&q->producer_lock); |
| |
| for (i = 0; i < bq->count; i++) { |
| struct xdp_frame *xdpf = bq->q[i]; |
| int err; |
| |
| err = __ptr_ring_produce(q, xdpf); |
| if (err) { |
| drops++; |
| xdp_return_frame_rx_napi(xdpf); |
| } |
| processed++; |
| } |
| bq->count = 0; |
| spin_unlock(&q->producer_lock); |
| |
| __list_del_clearprev(&bq->flush_node); |
| |
| /* Feedback loop via tracepoints */ |
| trace_xdp_cpumap_enqueue(rcpu->map_id, processed, drops, to_cpu); |
| } |
| |
| /* Runs under RCU-read-side, plus in softirq under NAPI protection. |
| * Thus, safe percpu variable access. |
| */ |
| static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf) |
| { |
| struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list); |
| struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq); |
| |
| if (unlikely(bq->count == CPU_MAP_BULK_SIZE)) |
| bq_flush_to_queue(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_frame 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++] = xdpf; |
| |
| if (!bq->flush_node.prev) |
| list_add(&bq->flush_node, flush_list); |
| } |
| |
| int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp, |
| struct net_device *dev_rx) |
| { |
| struct xdp_frame *xdpf; |
| |
| xdpf = xdp_convert_buff_to_frame(xdp); |
| if (unlikely(!xdpf)) |
| return -EOVERFLOW; |
| |
| /* Info needed when constructing SKB on remote CPU */ |
| xdpf->dev_rx = dev_rx; |
| |
| bq_enqueue(rcpu, xdpf); |
| return 0; |
| } |
| |
| int cpu_map_generic_redirect(struct bpf_cpu_map_entry *rcpu, |
| struct sk_buff *skb) |
| { |
| int ret; |
| |
| __skb_pull(skb, skb->mac_len); |
| skb_set_redirected(skb, false); |
| __ptr_set_bit(0, &skb); |
| |
| ret = ptr_ring_produce(rcpu->queue, skb); |
| if (ret < 0) |
| goto trace; |
| |
| wake_up_process(rcpu->kthread); |
| trace: |
| trace_xdp_cpumap_enqueue(rcpu->map_id, !ret, !!ret, rcpu->cpu); |
| return ret; |
| } |
| |
| void __cpu_map_flush(void) |
| { |
| struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list); |
| struct xdp_bulk_queue *bq, *tmp; |
| |
| list_for_each_entry_safe(bq, tmp, flush_list, flush_node) { |
| bq_flush_to_queue(bq); |
| |
| /* If already running, costs spin_lock_irqsave + smb_mb */ |
| wake_up_process(bq->obj->kthread); |
| } |
| } |
| |
| static int __init cpu_map_init(void) |
| { |
| int cpu; |
| |
| for_each_possible_cpu(cpu) |
| INIT_LIST_HEAD(&per_cpu(cpu_map_flush_list, cpu)); |
| return 0; |
| } |
| |
| subsys_initcall(cpu_map_init); |