linuxdebug/net/core/xdp.c

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2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: GPL-2.0-only
/* net/core/xdp.c
*
* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
*/
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/rhashtable.h>
#include <linux/bug.h>
#include <net/page_pool.h>
#include <net/xdp.h>
#include <net/xdp_priv.h> /* struct xdp_mem_allocator */
#include <trace/events/xdp.h>
#include <net/xdp_sock_drv.h>
#define REG_STATE_NEW 0x0
#define REG_STATE_REGISTERED 0x1
#define REG_STATE_UNREGISTERED 0x2
#define REG_STATE_UNUSED 0x3
static DEFINE_IDA(mem_id_pool);
static DEFINE_MUTEX(mem_id_lock);
#define MEM_ID_MAX 0xFFFE
#define MEM_ID_MIN 1
static int mem_id_next = MEM_ID_MIN;
static bool mem_id_init; /* false */
static struct rhashtable *mem_id_ht;
static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
{
const u32 *k = data;
const u32 key = *k;
BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
!= sizeof(u32));
/* Use cyclic increasing ID as direct hash key */
return key;
}
static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
const struct xdp_mem_allocator *xa = ptr;
u32 mem_id = *(u32 *)arg->key;
return xa->mem.id != mem_id;
}
static const struct rhashtable_params mem_id_rht_params = {
.nelem_hint = 64,
.head_offset = offsetof(struct xdp_mem_allocator, node),
.key_offset = offsetof(struct xdp_mem_allocator, mem.id),
.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
.max_size = MEM_ID_MAX,
.min_size = 8,
.automatic_shrinking = true,
.hashfn = xdp_mem_id_hashfn,
.obj_cmpfn = xdp_mem_id_cmp,
};
static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
{
struct xdp_mem_allocator *xa;
xa = container_of(rcu, struct xdp_mem_allocator, rcu);
/* Allow this ID to be reused */
ida_simple_remove(&mem_id_pool, xa->mem.id);
kfree(xa);
}
static void mem_xa_remove(struct xdp_mem_allocator *xa)
{
trace_mem_disconnect(xa);
if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
}
static void mem_allocator_disconnect(void *allocator)
{
struct xdp_mem_allocator *xa;
struct rhashtable_iter iter;
mutex_lock(&mem_id_lock);
rhashtable_walk_enter(mem_id_ht, &iter);
do {
rhashtable_walk_start(&iter);
while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
if (xa->allocator == allocator)
mem_xa_remove(xa);
}
rhashtable_walk_stop(&iter);
} while (xa == ERR_PTR(-EAGAIN));
rhashtable_walk_exit(&iter);
mutex_unlock(&mem_id_lock);
}
void xdp_unreg_mem_model(struct xdp_mem_info *mem)
{
struct xdp_mem_allocator *xa;
int type = mem->type;
int id = mem->id;
/* Reset mem info to defaults */
mem->id = 0;
mem->type = 0;
if (id == 0)
return;
if (type == MEM_TYPE_PAGE_POOL) {
rcu_read_lock();
xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
page_pool_destroy(xa->page_pool);
rcu_read_unlock();
}
}
EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);
void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
{
if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
WARN(1, "Missing register, driver bug");
return;
}
xdp_unreg_mem_model(&xdp_rxq->mem);
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
{
/* Simplify driver cleanup code paths, allow unreg "unused" */
if (xdp_rxq->reg_state == REG_STATE_UNUSED)
return;
xdp_rxq_info_unreg_mem_model(xdp_rxq);
xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
xdp_rxq->dev = NULL;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
{
memset(xdp_rxq, 0, sizeof(*xdp_rxq));
}
/* Returns 0 on success, negative on failure */
int __xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
struct net_device *dev, u32 queue_index,
unsigned int napi_id, u32 frag_size)
{
if (!dev) {
WARN(1, "Missing net_device from driver");
return -ENODEV;
}
if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
WARN(1, "Driver promised not to register this");
return -EINVAL;
}
if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
WARN(1, "Missing unregister, handled but fix driver");
xdp_rxq_info_unreg(xdp_rxq);
}
/* State either UNREGISTERED or NEW */
xdp_rxq_info_init(xdp_rxq);
xdp_rxq->dev = dev;
xdp_rxq->queue_index = queue_index;
xdp_rxq->napi_id = napi_id;
xdp_rxq->frag_size = frag_size;
xdp_rxq->reg_state = REG_STATE_REGISTERED;
return 0;
}
EXPORT_SYMBOL_GPL(__xdp_rxq_info_reg);
void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
{
xdp_rxq->reg_state = REG_STATE_UNUSED;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
{
return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
static int __mem_id_init_hash_table(void)
{
struct rhashtable *rht;
int ret;
if (unlikely(mem_id_init))
return 0;
rht = kzalloc(sizeof(*rht), GFP_KERNEL);
if (!rht)
return -ENOMEM;
ret = rhashtable_init(rht, &mem_id_rht_params);
if (ret < 0) {
kfree(rht);
return ret;
}
mem_id_ht = rht;
smp_mb(); /* mutex lock should provide enough pairing */
mem_id_init = true;
return 0;
}
/* Allocate a cyclic ID that maps to allocator pointer.
* See: https://www.kernel.org/doc/html/latest/core-api/idr.html
*
* Caller must lock mem_id_lock.
*/
static int __mem_id_cyclic_get(gfp_t gfp)
{
int retries = 1;
int id;
again:
id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
if (id < 0) {
if (id == -ENOSPC) {
/* Cyclic allocator, reset next id */
if (retries--) {
mem_id_next = MEM_ID_MIN;
goto again;
}
}
return id; /* errno */
}
mem_id_next = id + 1;
return id;
}
static bool __is_supported_mem_type(enum xdp_mem_type type)
{
if (type == MEM_TYPE_PAGE_POOL)
return is_page_pool_compiled_in();
if (type >= MEM_TYPE_MAX)
return false;
return true;
}
static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
enum xdp_mem_type type,
void *allocator)
{
struct xdp_mem_allocator *xdp_alloc;
gfp_t gfp = GFP_KERNEL;
int id, errno, ret;
void *ptr;
if (!__is_supported_mem_type(type))
return ERR_PTR(-EOPNOTSUPP);
mem->type = type;
if (!allocator) {
if (type == MEM_TYPE_PAGE_POOL)
return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
return NULL;
}
/* Delay init of rhashtable to save memory if feature isn't used */
if (!mem_id_init) {
mutex_lock(&mem_id_lock);
ret = __mem_id_init_hash_table();
mutex_unlock(&mem_id_lock);
if (ret < 0) {
WARN_ON(1);
return ERR_PTR(ret);
}
}
xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
if (!xdp_alloc)
return ERR_PTR(-ENOMEM);
mutex_lock(&mem_id_lock);
id = __mem_id_cyclic_get(gfp);
if (id < 0) {
errno = id;
goto err;
}
mem->id = id;
xdp_alloc->mem = *mem;
xdp_alloc->allocator = allocator;
/* Insert allocator into ID lookup table */
ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
if (IS_ERR(ptr)) {
ida_simple_remove(&mem_id_pool, mem->id);
mem->id = 0;
errno = PTR_ERR(ptr);
goto err;
}
if (type == MEM_TYPE_PAGE_POOL)
page_pool_use_xdp_mem(allocator, mem_allocator_disconnect, mem);
mutex_unlock(&mem_id_lock);
return xdp_alloc;
err:
mutex_unlock(&mem_id_lock);
kfree(xdp_alloc);
return ERR_PTR(errno);
}
int xdp_reg_mem_model(struct xdp_mem_info *mem,
enum xdp_mem_type type, void *allocator)
{
struct xdp_mem_allocator *xdp_alloc;
xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
if (IS_ERR(xdp_alloc))
return PTR_ERR(xdp_alloc);
return 0;
}
EXPORT_SYMBOL_GPL(xdp_reg_mem_model);
int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
enum xdp_mem_type type, void *allocator)
{
struct xdp_mem_allocator *xdp_alloc;
if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
WARN(1, "Missing register, driver bug");
return -EFAULT;
}
xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
if (IS_ERR(xdp_alloc))
return PTR_ERR(xdp_alloc);
if (trace_mem_connect_enabled() && xdp_alloc)
trace_mem_connect(xdp_alloc, xdp_rxq);
return 0;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
/* XDP RX runs under NAPI protection, and in different delivery error
* scenarios (e.g. queue full), it is possible to return the xdp_frame
* while still leveraging this protection. The @napi_direct boolean
* is used for those calls sites. Thus, allowing for faster recycling
* of xdp_frames/pages in those cases.
*/
void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
struct xdp_buff *xdp)
{
struct page *page;
switch (mem->type) {
case MEM_TYPE_PAGE_POOL:
page = virt_to_head_page(data);
if (napi_direct && xdp_return_frame_no_direct())
napi_direct = false;
/* No need to check ((page->pp_magic & ~0x3UL) == PP_SIGNATURE)
* as mem->type knows this a page_pool page
*/
page_pool_put_full_page(page->pp, page, napi_direct);
break;
case MEM_TYPE_PAGE_SHARED:
page_frag_free(data);
break;
case MEM_TYPE_PAGE_ORDER0:
page = virt_to_page(data); /* Assumes order0 page*/
put_page(page);
break;
case MEM_TYPE_XSK_BUFF_POOL:
/* NB! Only valid from an xdp_buff! */
xsk_buff_free(xdp);
break;
default:
/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
break;
}
}
void xdp_return_frame(struct xdp_frame *xdpf)
{
struct skb_shared_info *sinfo;
int i;
if (likely(!xdp_frame_has_frags(xdpf)))
goto out;
sinfo = xdp_get_shared_info_from_frame(xdpf);
for (i = 0; i < sinfo->nr_frags; i++) {
struct page *page = skb_frag_page(&sinfo->frags[i]);
__xdp_return(page_address(page), &xdpf->mem, false, NULL);
}
out:
__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
}
EXPORT_SYMBOL_GPL(xdp_return_frame);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
{
struct skb_shared_info *sinfo;
int i;
if (likely(!xdp_frame_has_frags(xdpf)))
goto out;
sinfo = xdp_get_shared_info_from_frame(xdpf);
for (i = 0; i < sinfo->nr_frags; i++) {
struct page *page = skb_frag_page(&sinfo->frags[i]);
__xdp_return(page_address(page), &xdpf->mem, true, NULL);
}
out:
__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
}
EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
/* XDP bulk APIs introduce a defer/flush mechanism to return
* pages belonging to the same xdp_mem_allocator object
* (identified via the mem.id field) in bulk to optimize
* I-cache and D-cache.
* The bulk queue size is set to 16 to be aligned to how
* XDP_REDIRECT bulking works. The bulk is flushed when
* it is full or when mem.id changes.
* xdp_frame_bulk is usually stored/allocated on the function
* call-stack to avoid locking penalties.
*/
void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
{
struct xdp_mem_allocator *xa = bq->xa;
if (unlikely(!xa || !bq->count))
return;
page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
bq->count = 0;
}
EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
/* Must be called with rcu_read_lock held */
void xdp_return_frame_bulk(struct xdp_frame *xdpf,
struct xdp_frame_bulk *bq)
{
struct xdp_mem_info *mem = &xdpf->mem;
struct xdp_mem_allocator *xa;
if (mem->type != MEM_TYPE_PAGE_POOL) {
xdp_return_frame(xdpf);
return;
}
xa = bq->xa;
if (unlikely(!xa)) {
xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
bq->count = 0;
bq->xa = xa;
}
if (bq->count == XDP_BULK_QUEUE_SIZE)
xdp_flush_frame_bulk(bq);
if (unlikely(mem->id != xa->mem.id)) {
xdp_flush_frame_bulk(bq);
bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
}
if (unlikely(xdp_frame_has_frags(xdpf))) {
struct skb_shared_info *sinfo;
int i;
sinfo = xdp_get_shared_info_from_frame(xdpf);
for (i = 0; i < sinfo->nr_frags; i++) {
skb_frag_t *frag = &sinfo->frags[i];
bq->q[bq->count++] = skb_frag_address(frag);
if (bq->count == XDP_BULK_QUEUE_SIZE)
xdp_flush_frame_bulk(bq);
}
}
bq->q[bq->count++] = xdpf->data;
}
EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
void xdp_return_buff(struct xdp_buff *xdp)
{
struct skb_shared_info *sinfo;
int i;
if (likely(!xdp_buff_has_frags(xdp)))
goto out;
sinfo = xdp_get_shared_info_from_buff(xdp);
for (i = 0; i < sinfo->nr_frags; i++) {
struct page *page = skb_frag_page(&sinfo->frags[i]);
__xdp_return(page_address(page), &xdp->rxq->mem, true, xdp);
}
out:
__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
}
EXPORT_SYMBOL_GPL(xdp_return_buff);
/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
{
struct xdp_mem_allocator *xa;
struct page *page;
rcu_read_lock();
xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
page = virt_to_head_page(data);
if (xa)
page_pool_release_page(xa->page_pool, page);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(__xdp_release_frame);
void xdp_attachment_setup(struct xdp_attachment_info *info,
struct netdev_bpf *bpf)
{
if (info->prog)
bpf_prog_put(info->prog);
info->prog = bpf->prog;
info->flags = bpf->flags;
}
EXPORT_SYMBOL_GPL(xdp_attachment_setup);
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
{
unsigned int metasize, totsize;
void *addr, *data_to_copy;
struct xdp_frame *xdpf;
struct page *page;
/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
metasize = xdp_data_meta_unsupported(xdp) ? 0 :
xdp->data - xdp->data_meta;
totsize = xdp->data_end - xdp->data + metasize;
if (sizeof(*xdpf) + totsize > PAGE_SIZE)
return NULL;
page = dev_alloc_page();
if (!page)
return NULL;
addr = page_to_virt(page);
xdpf = addr;
memset(xdpf, 0, sizeof(*xdpf));
addr += sizeof(*xdpf);
data_to_copy = metasize ? xdp->data_meta : xdp->data;
memcpy(addr, data_to_copy, totsize);
xdpf->data = addr + metasize;
xdpf->len = totsize - metasize;
xdpf->headroom = 0;
xdpf->metasize = metasize;
xdpf->frame_sz = PAGE_SIZE;
xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
xsk_buff_free(xdp);
return xdpf;
}
EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);
/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
void xdp_warn(const char *msg, const char *func, const int line)
{
WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
};
EXPORT_SYMBOL_GPL(xdp_warn);
int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
{
n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
n_skb, skbs);
if (unlikely(!n_skb))
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);
struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
struct sk_buff *skb,
struct net_device *dev)
{
struct skb_shared_info *sinfo = xdp_get_shared_info_from_frame(xdpf);
unsigned int headroom, frame_size;
void *hard_start;
u8 nr_frags;
/* xdp frags frame */
if (unlikely(xdp_frame_has_frags(xdpf)))
nr_frags = sinfo->nr_frags;
/* Part of headroom was reserved to xdpf */
headroom = sizeof(*xdpf) + 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;
hard_start = xdpf->data - headroom;
skb = build_skb_around(skb, hard_start, frame_size);
if (unlikely(!skb))
return NULL;
skb_reserve(skb, headroom);
__skb_put(skb, xdpf->len);
if (xdpf->metasize)
skb_metadata_set(skb, xdpf->metasize);
if (unlikely(xdp_frame_has_frags(xdpf)))
xdp_update_skb_shared_info(skb, nr_frags,
sinfo->xdp_frags_size,
nr_frags * xdpf->frame_sz,
xdp_frame_is_frag_pfmemalloc(xdpf));
/* Essential SKB info: protocol and skb->dev */
skb->protocol = eth_type_trans(skb, dev);
/* 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;
}
EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
struct net_device *dev)
{
struct sk_buff *skb;
skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
if (unlikely(!skb))
return NULL;
memset(skb, 0, offsetof(struct sk_buff, tail));
return __xdp_build_skb_from_frame(xdpf, skb, dev);
}
EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf)
{
unsigned int headroom, totalsize;
struct xdp_frame *nxdpf;
struct page *page;
void *addr;
headroom = xdpf->headroom + sizeof(*xdpf);
totalsize = headroom + xdpf->len;
if (unlikely(totalsize > PAGE_SIZE))
return NULL;
page = dev_alloc_page();
if (!page)
return NULL;
addr = page_to_virt(page);
memcpy(addr, xdpf, totalsize);
nxdpf = addr;
nxdpf->data = addr + headroom;
nxdpf->frame_sz = PAGE_SIZE;
nxdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
nxdpf->mem.id = 0;
return nxdpf;
}