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-rw-r--r--kernel/bpf/cpumap.c776
1 files changed, 776 insertions, 0 deletions
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
new file mode 100644
index 0000000000..e42a1bdb7f
--- /dev/null
+++ b/kernel/bpf/cpumap.c
@@ -0,0 +1,776 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* bpf/cpumap.c
+ *
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ */
+
+/**
+ * DOC: cpu map
+ * 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 to 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/completion.h>
+#include <trace/events/xdp.h>
+#include <linux/btf_ids.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;
+
+ /* 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;
+
+ struct completion kthread_running;
+ struct rcu_work free_work;
+};
+
+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;
+
+ /* 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);
+
+ /* Pre-limit array size based on NR_CPUS, not final CPU check */
+ if (attr->max_entries > NR_CPUS)
+ return ERR_PTR(-E2BIG);
+
+ cmap = bpf_map_area_alloc(sizeof(*cmap), NUMA_NO_NODE);
+ if (!cmap)
+ return ERR_PTR(-ENOMEM);
+
+ bpf_map_init_from_attr(&cmap->map, attr);
+
+ /* 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) {
+ bpf_map_area_free(cmap);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ return &cmap->map;
+}
+
+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.
+ */
+ void *ptr;
+
+ while ((ptr = ptr_ring_consume(ring))) {
+ WARN_ON_ONCE(1);
+ if (unlikely(__ptr_test_bit(0, &ptr))) {
+ __ptr_clear_bit(0, &ptr);
+ kfree_skb(ptr);
+ continue;
+ }
+ xdp_return_frame(ptr);
+ }
+}
+
+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;
+
+ complete(&rcpu->kthread_running);
+ 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_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);
+
+ return 0;
+}
+
+static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu,
+ struct bpf_map *map, 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_map_compatible(map, prog)) {
+ 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, map, fd))
+ goto free_ptr_ring;
+
+ /* Setup kthread */
+ init_completion(&rcpu->kthread_running);
+ 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;
+
+ /* Make sure kthread runs on a single CPU */
+ kthread_bind(rcpu->kthread, cpu);
+ wake_up_process(rcpu->kthread);
+
+ /* Make sure kthread has been running, so kthread_stop() will not
+ * stop the kthread prematurely and all pending frames or skbs
+ * will be handled by the kthread before kthread_stop() returns.
+ */
+ wait_for_completion(&rcpu->kthread_running);
+
+ 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 work_struct *work)
+{
+ 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(to_rcu_work(work), struct bpf_cpu_map_entry, free_work);
+
+ /* kthread_stop will wake_up_process and wait for it to complete.
+ * cpu_map_kthread_run() makes sure the pointer ring is empty
+ * before exiting.
+ */
+ kthread_stop(rcpu->kthread);
+
+ 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);
+ free_percpu(rcpu->bulkq);
+ kfree(rcpu);
+}
+
+/* After the xchg of the bpf_cpu_map_entry pointer, we need to make sure the old
+ * entry is no longer in use before freeing. We use queue_rcu_work() to call
+ * __cpu_map_entry_free() in a separate workqueue after waiting for an RCU grace
+ * period. This means that (a) all pending enqueue and flush operations have
+ * completed (because of the RCU callback), and (b) we are in a workqueue
+ * context where we can stop the kthread and wait for it to exit before freeing
+ * everything.
+ */
+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) {
+ INIT_RCU_WORK(&old_rcpu->free_work, __cpu_map_entry_free);
+ queue_rcu_work(system_wq, &old_rcpu->free_work);
+ }
+}
+
+static long 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() uses rcu_read_lock() */
+ __cpu_map_entry_replace(cmap, key_cpu, NULL);
+ return 0;
+}
+
+static long 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;
+ }
+ 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. synchronize_rcu() below not only
+ * guarantees no further "XDP/bpf-side" reads against
+ * bpf_cpu_map->cpu_map, but also ensure pending flush operations
+ * (if any) are completed.
+ */
+ synchronize_rcu();
+
+ /* The only possible user of bpf_cpu_map_entry is
+ * cpu_map_kthread_run().
+ */
+ 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;
+
+ /* Stop kthread and cleanup entry directly */
+ __cpu_map_entry_free(&rcpu->free_work.work);
+ }
+ bpf_map_area_free(cmap->cpu_map);
+ bpf_map_area_free(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 long cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags)
+{
+ return __bpf_xdp_redirect_map(map, index, flags, 0,
+ __cpu_map_lookup_elem);
+}
+
+static u64 cpu_map_mem_usage(const struct bpf_map *map)
+{
+ u64 usage = sizeof(struct bpf_cpu_map);
+
+ /* Currently the dynamically allocated elements are not counted */
+ usage += (u64)map->max_entries * sizeof(struct bpf_cpu_map_entry *);
+ return usage;
+}
+
+BTF_ID_LIST_SINGLE(cpu_map_btf_ids, struct, bpf_cpu_map)
+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_mem_usage = cpu_map_mem_usage,
+ .map_btf_id = &cpu_map_btf_ids[0],
+ .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_frame *xdpf,
+ struct net_device *dev_rx)
+{
+ /* 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 22:08:55 +0000