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806 lines
21 KiB
806 lines
21 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* bpf/cpumap.c |
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* |
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* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. |
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*/ |
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|
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/* The 'cpumap' is primarily used as a backend map for XDP BPF helper |
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* call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'. |
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* |
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* Unlike devmap which redirects XDP frames out another NIC device, |
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* this map type redirects raw XDP frames to another CPU. The remote |
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* CPU will do SKB-allocation and call the normal network stack. |
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* |
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* This is a scalability and isolation mechanism, that allow |
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* separating the early driver network XDP layer, from the rest of the |
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* netstack, and assigning dedicated CPUs for this stage. This |
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* basically allows for 10G wirespeed pre-filtering via bpf. |
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*/ |
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#include <linux/bitops.h> |
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#include <linux/bpf.h> |
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#include <linux/filter.h> |
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#include <linux/ptr_ring.h> |
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#include <net/xdp.h> |
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#include <linux/sched.h> |
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#include <linux/workqueue.h> |
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#include <linux/kthread.h> |
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#include <linux/capability.h> |
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#include <trace/events/xdp.h> |
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#include <linux/netdevice.h> /* netif_receive_skb_list */ |
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#include <linux/etherdevice.h> /* eth_type_trans */ |
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/* General idea: XDP packets getting XDP redirected to another CPU, |
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* will maximum be stored/queued for one driver ->poll() call. It is |
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* guaranteed that queueing the frame and the flush operation happen on |
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* same CPU. Thus, cpu_map_flush operation can deduct via this_cpu_ptr() |
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* which queue in bpf_cpu_map_entry contains packets. |
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*/ |
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#define CPU_MAP_BULK_SIZE 8 /* 8 == one cacheline on 64-bit archs */ |
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struct bpf_cpu_map_entry; |
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struct bpf_cpu_map; |
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struct xdp_bulk_queue { |
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void *q[CPU_MAP_BULK_SIZE]; |
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struct list_head flush_node; |
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struct bpf_cpu_map_entry *obj; |
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unsigned int count; |
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}; |
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/* Struct for every remote "destination" CPU in map */ |
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struct bpf_cpu_map_entry { |
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u32 cpu; /* kthread CPU and map index */ |
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int map_id; /* Back reference to map */ |
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/* XDP can run multiple RX-ring queues, need __percpu enqueue store */ |
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struct xdp_bulk_queue __percpu *bulkq; |
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struct bpf_cpu_map *cmap; |
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/* Queue with potential multi-producers, and single-consumer kthread */ |
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struct ptr_ring *queue; |
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struct task_struct *kthread; |
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struct bpf_cpumap_val value; |
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struct bpf_prog *prog; |
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atomic_t refcnt; /* Control when this struct can be free'ed */ |
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struct rcu_head rcu; |
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struct work_struct kthread_stop_wq; |
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}; |
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struct bpf_cpu_map { |
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struct bpf_map map; |
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/* Below members specific for map type */ |
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struct bpf_cpu_map_entry __rcu **cpu_map; |
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}; |
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static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list); |
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static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) |
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{ |
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u32 value_size = attr->value_size; |
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struct bpf_cpu_map *cmap; |
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int err = -ENOMEM; |
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if (!bpf_capable()) |
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return ERR_PTR(-EPERM); |
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/* check sanity of attributes */ |
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if (attr->max_entries == 0 || attr->key_size != 4 || |
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(value_size != offsetofend(struct bpf_cpumap_val, qsize) && |
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value_size != offsetofend(struct bpf_cpumap_val, bpf_prog.fd)) || |
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attr->map_flags & ~BPF_F_NUMA_NODE) |
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return ERR_PTR(-EINVAL); |
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cmap = kzalloc(sizeof(*cmap), GFP_USER | __GFP_ACCOUNT); |
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if (!cmap) |
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return ERR_PTR(-ENOMEM); |
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bpf_map_init_from_attr(&cmap->map, attr); |
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/* Pre-limit array size based on NR_CPUS, not final CPU check */ |
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if (cmap->map.max_entries > NR_CPUS) { |
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err = -E2BIG; |
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goto free_cmap; |
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} |
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/* Alloc array for possible remote "destination" CPUs */ |
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cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries * |
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sizeof(struct bpf_cpu_map_entry *), |
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cmap->map.numa_node); |
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if (!cmap->cpu_map) |
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goto free_cmap; |
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return &cmap->map; |
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free_cmap: |
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kfree(cmap); |
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return ERR_PTR(err); |
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} |
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static void get_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) |
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{ |
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atomic_inc(&rcpu->refcnt); |
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} |
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/* called from workqueue, to workaround syscall using preempt_disable */ |
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static void cpu_map_kthread_stop(struct work_struct *work) |
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{ |
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struct bpf_cpu_map_entry *rcpu; |
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rcpu = container_of(work, struct bpf_cpu_map_entry, kthread_stop_wq); |
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/* Wait for flush in __cpu_map_entry_free(), via full RCU barrier, |
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* as it waits until all in-flight call_rcu() callbacks complete. |
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*/ |
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rcu_barrier(); |
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/* kthread_stop will wake_up_process and wait for it to complete */ |
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kthread_stop(rcpu->kthread); |
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} |
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static void __cpu_map_ring_cleanup(struct ptr_ring *ring) |
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{ |
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/* The tear-down procedure should have made sure that queue is |
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* empty. See __cpu_map_entry_replace() and work-queue |
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* invoked cpu_map_kthread_stop(). Catch any broken behaviour |
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* gracefully and warn once. |
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*/ |
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struct xdp_frame *xdpf; |
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while ((xdpf = ptr_ring_consume(ring))) |
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if (WARN_ON_ONCE(xdpf)) |
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xdp_return_frame(xdpf); |
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} |
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static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu) |
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{ |
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if (atomic_dec_and_test(&rcpu->refcnt)) { |
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if (rcpu->prog) |
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bpf_prog_put(rcpu->prog); |
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/* The queue should be empty at this point */ |
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__cpu_map_ring_cleanup(rcpu->queue); |
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ptr_ring_cleanup(rcpu->queue, NULL); |
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kfree(rcpu->queue); |
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kfree(rcpu); |
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} |
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} |
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static void cpu_map_bpf_prog_run_skb(struct bpf_cpu_map_entry *rcpu, |
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struct list_head *listp, |
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struct xdp_cpumap_stats *stats) |
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{ |
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struct sk_buff *skb, *tmp; |
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struct xdp_buff xdp; |
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u32 act; |
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int err; |
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list_for_each_entry_safe(skb, tmp, listp, list) { |
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act = bpf_prog_run_generic_xdp(skb, &xdp, rcpu->prog); |
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switch (act) { |
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case XDP_PASS: |
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break; |
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case XDP_REDIRECT: |
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skb_list_del_init(skb); |
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err = xdp_do_generic_redirect(skb->dev, skb, &xdp, |
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rcpu->prog); |
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if (unlikely(err)) { |
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kfree_skb(skb); |
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stats->drop++; |
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} else { |
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stats->redirect++; |
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} |
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return; |
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default: |
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bpf_warn_invalid_xdp_action(act); |
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fallthrough; |
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case XDP_ABORTED: |
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trace_xdp_exception(skb->dev, rcpu->prog, act); |
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fallthrough; |
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case XDP_DROP: |
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skb_list_del_init(skb); |
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kfree_skb(skb); |
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stats->drop++; |
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return; |
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} |
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} |
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} |
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static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu, |
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void **frames, int n, |
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struct xdp_cpumap_stats *stats) |
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{ |
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struct xdp_rxq_info rxq; |
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struct xdp_buff xdp; |
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int i, nframes = 0; |
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xdp_set_return_frame_no_direct(); |
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xdp.rxq = &rxq; |
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for (i = 0; i < n; i++) { |
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struct xdp_frame *xdpf = frames[i]; |
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u32 act; |
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int err; |
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rxq.dev = xdpf->dev_rx; |
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rxq.mem = xdpf->mem; |
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/* TODO: report queue_index to xdp_rxq_info */ |
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xdp_convert_frame_to_buff(xdpf, &xdp); |
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act = bpf_prog_run_xdp(rcpu->prog, &xdp); |
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switch (act) { |
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case XDP_PASS: |
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err = xdp_update_frame_from_buff(&xdp, xdpf); |
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if (err < 0) { |
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xdp_return_frame(xdpf); |
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stats->drop++; |
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} else { |
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frames[nframes++] = xdpf; |
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stats->pass++; |
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} |
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break; |
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case XDP_REDIRECT: |
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err = xdp_do_redirect(xdpf->dev_rx, &xdp, |
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rcpu->prog); |
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if (unlikely(err)) { |
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xdp_return_frame(xdpf); |
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stats->drop++; |
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} else { |
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stats->redirect++; |
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} |
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break; |
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default: |
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bpf_warn_invalid_xdp_action(act); |
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fallthrough; |
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case XDP_DROP: |
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xdp_return_frame(xdpf); |
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stats->drop++; |
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break; |
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} |
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} |
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xdp_clear_return_frame_no_direct(); |
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return nframes; |
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} |
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#define CPUMAP_BATCH 8 |
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static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames, |
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int xdp_n, struct xdp_cpumap_stats *stats, |
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struct list_head *list) |
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{ |
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int nframes; |
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if (!rcpu->prog) |
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return xdp_n; |
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rcu_read_lock_bh(); |
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nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats); |
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if (stats->redirect) |
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xdp_do_flush(); |
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if (unlikely(!list_empty(list))) |
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cpu_map_bpf_prog_run_skb(rcpu, list, stats); |
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rcu_read_unlock_bh(); /* resched point, may call do_softirq() */ |
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return nframes; |
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} |
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static int cpu_map_kthread_run(void *data) |
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{ |
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struct bpf_cpu_map_entry *rcpu = data; |
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set_current_state(TASK_INTERRUPTIBLE); |
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/* When kthread gives stop order, then rcpu have been disconnected |
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* from map, thus no new packets can enter. Remaining in-flight |
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* per CPU stored packets are flushed to this queue. Wait honoring |
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* kthread_stop signal until queue is empty. |
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*/ |
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while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) { |
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struct xdp_cpumap_stats stats = {}; /* zero stats */ |
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unsigned int kmem_alloc_drops = 0, sched = 0; |
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gfp_t gfp = __GFP_ZERO | GFP_ATOMIC; |
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int i, n, m, nframes, xdp_n; |
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void *frames[CPUMAP_BATCH]; |
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void *skbs[CPUMAP_BATCH]; |
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LIST_HEAD(list); |
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/* Release CPU reschedule checks */ |
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if (__ptr_ring_empty(rcpu->queue)) { |
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set_current_state(TASK_INTERRUPTIBLE); |
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/* Recheck to avoid lost wake-up */ |
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if (__ptr_ring_empty(rcpu->queue)) { |
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schedule(); |
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sched = 1; |
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} else { |
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__set_current_state(TASK_RUNNING); |
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} |
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} else { |
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sched = cond_resched(); |
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} |
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/* |
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* The bpf_cpu_map_entry is single consumer, with this |
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* kthread CPU pinned. Lockless access to ptr_ring |
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* consume side valid as no-resize allowed of queue. |
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*/ |
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n = __ptr_ring_consume_batched(rcpu->queue, frames, |
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CPUMAP_BATCH); |
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for (i = 0, xdp_n = 0; i < n; i++) { |
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void *f = frames[i]; |
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struct page *page; |
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if (unlikely(__ptr_test_bit(0, &f))) { |
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struct sk_buff *skb = f; |
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__ptr_clear_bit(0, &skb); |
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list_add_tail(&skb->list, &list); |
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continue; |
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} |
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frames[xdp_n++] = f; |
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page = virt_to_page(f); |
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/* Bring struct page memory area to curr CPU. Read by |
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* build_skb_around via page_is_pfmemalloc(), and when |
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* freed written by page_frag_free call. |
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*/ |
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prefetchw(page); |
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} |
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/* Support running another XDP prog on this CPU */ |
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nframes = cpu_map_bpf_prog_run(rcpu, frames, xdp_n, &stats, &list); |
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if (nframes) { |
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m = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, skbs); |
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if (unlikely(m == 0)) { |
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for (i = 0; i < nframes; i++) |
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skbs[i] = NULL; /* effect: xdp_return_frame */ |
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kmem_alloc_drops += nframes; |
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} |
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} |
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local_bh_disable(); |
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for (i = 0; i < nframes; i++) { |
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struct xdp_frame *xdpf = frames[i]; |
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struct sk_buff *skb = skbs[i]; |
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skb = __xdp_build_skb_from_frame(xdpf, skb, |
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xdpf->dev_rx); |
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if (!skb) { |
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xdp_return_frame(xdpf); |
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continue; |
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} |
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list_add_tail(&skb->list, &list); |
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} |
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netif_receive_skb_list(&list); |
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/* Feedback loop via tracepoint */ |
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trace_xdp_cpumap_kthread(rcpu->map_id, n, kmem_alloc_drops, |
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sched, &stats); |
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local_bh_enable(); /* resched point, may call do_softirq() */ |
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} |
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__set_current_state(TASK_RUNNING); |
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put_cpu_map_entry(rcpu); |
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return 0; |
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} |
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static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu, int fd) |
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{ |
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struct bpf_prog *prog; |
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prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP); |
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if (IS_ERR(prog)) |
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return PTR_ERR(prog); |
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if (prog->expected_attach_type != BPF_XDP_CPUMAP) { |
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bpf_prog_put(prog); |
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return -EINVAL; |
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} |
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rcpu->value.bpf_prog.id = prog->aux->id; |
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rcpu->prog = prog; |
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return 0; |
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} |
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static struct bpf_cpu_map_entry * |
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__cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value, |
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u32 cpu) |
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{ |
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int numa, err, i, fd = value->bpf_prog.fd; |
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gfp_t gfp = GFP_KERNEL | __GFP_NOWARN; |
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struct bpf_cpu_map_entry *rcpu; |
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struct xdp_bulk_queue *bq; |
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/* Have map->numa_node, but choose node of redirect target CPU */ |
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numa = cpu_to_node(cpu); |
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rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa); |
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if (!rcpu) |
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return NULL; |
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/* Alloc percpu bulkq */ |
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rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq), |
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sizeof(void *), gfp); |
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if (!rcpu->bulkq) |
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goto free_rcu; |
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for_each_possible_cpu(i) { |
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bq = per_cpu_ptr(rcpu->bulkq, i); |
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bq->obj = rcpu; |
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} |
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/* Alloc queue */ |
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rcpu->queue = bpf_map_kmalloc_node(map, sizeof(*rcpu->queue), gfp, |
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numa); |
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if (!rcpu->queue) |
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goto free_bulkq; |
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err = ptr_ring_init(rcpu->queue, value->qsize, gfp); |
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if (err) |
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goto free_queue; |
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rcpu->cpu = cpu; |
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rcpu->map_id = map->id; |
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rcpu->value.qsize = value->qsize; |
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if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd)) |
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goto free_ptr_ring; |
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/* Setup kthread */ |
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rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa, |
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"cpumap/%d/map:%d", cpu, |
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map->id); |
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if (IS_ERR(rcpu->kthread)) |
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goto free_prog; |
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get_cpu_map_entry(rcpu); /* 1-refcnt for being in cmap->cpu_map[] */ |
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get_cpu_map_entry(rcpu); /* 1-refcnt for kthread */ |
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/* Make sure kthread runs on a single CPU */ |
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kthread_bind(rcpu->kthread, cpu); |
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wake_up_process(rcpu->kthread); |
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return rcpu; |
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free_prog: |
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if (rcpu->prog) |
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bpf_prog_put(rcpu->prog); |
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free_ptr_ring: |
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ptr_ring_cleanup(rcpu->queue, NULL); |
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free_queue: |
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kfree(rcpu->queue); |
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free_bulkq: |
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free_percpu(rcpu->bulkq); |
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free_rcu: |
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kfree(rcpu); |
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return NULL; |
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} |
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static void __cpu_map_entry_free(struct rcu_head *rcu) |
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{ |
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struct bpf_cpu_map_entry *rcpu; |
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|
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/* This cpu_map_entry have been disconnected from map and one |
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* RCU grace-period have elapsed. Thus, XDP cannot queue any |
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* new packets and cannot change/set flush_needed that can |
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* find this entry. |
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*/ |
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rcpu = container_of(rcu, struct bpf_cpu_map_entry, rcu); |
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free_percpu(rcpu->bulkq); |
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/* Cannot kthread_stop() here, last put free rcpu resources */ |
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put_cpu_map_entry(rcpu); |
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} |
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|
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/* After xchg pointer to bpf_cpu_map_entry, use the call_rcu() to |
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* ensure any driver rcu critical sections have completed, but this |
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* does not guarantee a flush has happened yet. Because driver side |
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* rcu_read_lock/unlock only protects the running XDP program. The |
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* atomic xchg and NULL-ptr check in __cpu_map_flush() makes sure a |
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* pending flush op doesn't fail. |
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* |
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* The bpf_cpu_map_entry is still used by the kthread, and there can |
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* still be pending packets (in queue and percpu bulkq). A refcnt |
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* makes sure to last user (kthread_stop vs. call_rcu) free memory |
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* resources. |
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* |
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* The rcu callback __cpu_map_entry_free flush remaining packets in |
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* percpu bulkq to queue. Due to caller map_delete_elem() disable |
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* preemption, cannot call kthread_stop() to make sure queue is empty. |
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* Instead a work_queue is started for stopping kthread, |
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* cpu_map_kthread_stop, which waits for an RCU grace period before |
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* stopping kthread, emptying the queue. |
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*/ |
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static void __cpu_map_entry_replace(struct bpf_cpu_map *cmap, |
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u32 key_cpu, struct bpf_cpu_map_entry *rcpu) |
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{ |
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struct bpf_cpu_map_entry *old_rcpu; |
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old_rcpu = unrcu_pointer(xchg(&cmap->cpu_map[key_cpu], RCU_INITIALIZER(rcpu))); |
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if (old_rcpu) { |
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call_rcu(&old_rcpu->rcu, __cpu_map_entry_free); |
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INIT_WORK(&old_rcpu->kthread_stop_wq, cpu_map_kthread_stop); |
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schedule_work(&old_rcpu->kthread_stop_wq); |
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} |
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} |
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|
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static int cpu_map_delete_elem(struct bpf_map *map, void *key) |
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{ |
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struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map); |
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u32 key_cpu = *(u32 *)key; |
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|
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if (key_cpu >= map->max_entries) |
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return -EINVAL; |
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|
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/* notice caller map_delete_elem() use preempt_disable() */ |
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__cpu_map_entry_replace(cmap, key_cpu, NULL); |
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return 0; |
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} |
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|
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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);
|
|
|