// SPDX-License-Identifier: GPL-2.0-only
|
/* bpf/cpumap.c
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*
|
* 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/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>
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#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 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 **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;
|
u64 cost;
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int ret;
|
|
if (!bpf_capable())
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return ERR_PTR(-EPERM);
|
|
/* check sanity of attributes */
|
if (attr->max_entries == 0 || attr->key_size != 4 ||
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(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);
|
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;
|
}
|
|
/* make sure page count doesn't overflow */
|
cost = (u64) cmap->map.max_entries * sizeof(struct bpf_cpu_map_entry *);
|
|
/* Notice returns -EPERM on if map size is larger than memlock limit */
|
ret = bpf_map_charge_init(&cmap->map.memory, cost);
|
if (ret) {
|
err = ret;
|
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_charge;
|
|
return &cmap->map;
|
free_charge:
|
bpf_map_charge_finish(&cmap->map.memory);
|
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 struct sk_buff *cpu_map_build_skb(struct xdp_frame *xdpf,
|
struct sk_buff *skb)
|
{
|
unsigned int hard_start_headroom;
|
unsigned int frame_size;
|
void *pkt_data_start;
|
|
/* Part of headroom was reserved to xdpf */
|
hard_start_headroom = sizeof(struct xdp_frame) + xdpf->headroom;
|
|
/* Memory size backing xdp_frame data already have reserved
|
* room for build_skb to place skb_shared_info in tailroom.
|
*/
|
frame_size = xdpf->frame_sz;
|
|
pkt_data_start = xdpf->data - hard_start_headroom;
|
skb = build_skb_around(skb, pkt_data_start, frame_size);
|
if (unlikely(!skb))
|
return NULL;
|
|
skb_reserve(skb, hard_start_headroom);
|
__skb_put(skb, xdpf->len);
|
if (xdpf->metasize)
|
skb_metadata_set(skb, xdpf->metasize);
|
|
/* Essential SKB info: protocol and skb->dev */
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skb->protocol = eth_type_trans(skb, xdpf->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)
|
*/
|
|
/* Until page_pool get SKB return path, release DMA here */
|
xdp_release_frame(xdpf);
|
|
/* Allow SKB to reuse area used by xdp_frame */
|
xdp_scrub_frame(xdpf);
|
|
return skb;
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}
|
|
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 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;
|
|
if (!rcpu->prog)
|
return n;
|
|
rcu_read_lock_bh();
|
|
xdp_set_return_frame_no_direct();
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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++;
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} else {
|
frames[nframes++] = xdpf;
|
stats->pass++;
|
}
|
break;
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case XDP_REDIRECT:
|
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:
|
bpf_warn_invalid_xdp_action(act);
|
fallthrough;
|
case XDP_DROP:
|
xdp_return_frame(xdpf);
|
stats->drop++;
|
break;
|
}
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}
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|
if (stats->redirect)
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xdp_do_flush_map();
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|
xdp_clear_return_frame_no_direct();
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|
rcu_read_unlock_bh(); /* resched point, may call do_softirq() */
|
|
return nframes;
|
}
|
|
#define CPUMAP_BATCH 8
|
|
static int cpu_map_kthread_run(void *data)
|
{
|
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
|
* 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 */
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gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
|
unsigned int drops = 0, sched = 0;
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void *frames[CPUMAP_BATCH];
|
void *skbs[CPUMAP_BATCH];
|
int i, n, m, nframes;
|
|
/* 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; i < n; i++) {
|
void *f = frames[i];
|
struct page *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_xdp(rcpu, frames, n, &stats);
|
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 */
|
drops += nframes;
|
}
|
}
|
|
local_bh_disable();
|
for (i = 0; i < nframes; i++) {
|
struct xdp_frame *xdpf = frames[i];
|
struct sk_buff *skb = skbs[i];
|
int ret;
|
|
skb = cpu_map_build_skb(xdpf, skb);
|
if (!skb) {
|
xdp_return_frame(xdpf);
|
continue;
|
}
|
|
/* Inject into network stack */
|
ret = netif_receive_skb_core(skb);
|
if (ret == NET_RX_DROP)
|
drops++;
|
}
|
/* Feedback loop via tracepoint */
|
trace_xdp_cpumap_kthread(rcpu->map_id, n, drops, sched, &stats);
|
|
local_bh_enable(); /* resched point, may call do_softirq() */
|
}
|
__set_current_state(TASK_RUNNING);
|
|
put_cpu_map_entry(rcpu);
|
return 0;
|
}
|
|
bool cpu_map_prog_allowed(struct bpf_map *map)
|
{
|
return map->map_type == BPF_MAP_TYPE_CPUMAP &&
|
map->value_size != offsetofend(struct bpf_cpumap_val, qsize);
|
}
|
|
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_cpumap_val *value, u32 cpu, int map_id)
|
{
|
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 = 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;
|
|
for_each_possible_cpu(i) {
|
bq = per_cpu_ptr(rcpu->bulkq, i);
|
bq->obj = rcpu;
|
}
|
|
/* Alloc queue */
|
rcpu->queue = kzalloc_node(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 = 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);
|
}
|
}
|
|
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(&cpumap_value, key_cpu, map->id);
|
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.
|
*/
|
|
bpf_clear_redirect_map(map);
|
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 = READ_ONCE(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);
|
}
|
|
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->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_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,
|
};
|
|
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;
|
}
|
|
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);
|
