// 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_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)

  {
  	struct xdp_mem_allocator *xa;
  	int id = xdp_rxq->mem.id;

  	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
  		WARN(1, "Missing register, driver bug");
  		return;
  	}

  	if (id == 0)
  		return;

  	if (xdp_rxq->mem.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_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;
  
  	WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");

  	xdp_rxq_info_unreg_mem_model(xdp_rxq);

  	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
  	xdp_rxq->dev = NULL;

  
  	/* Reset mem info to defaults */
  	xdp_rxq->mem.id = 0;
  	xdp_rxq->mem.type = 0;

  }
  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)

  {
  	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);
  	}
  
  	if (!dev) {
  		WARN(1, "Missing net_device from driver");
  		return -ENODEV;
  	}
  
  	/* 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->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;
  }

  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;
  	gfp_t gfp = GFP_KERNEL;
  	int id, errno, ret;
  	void *ptr;
  
  	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
  		WARN(1, "Missing register, driver bug");
  		return -EFAULT;
  	}

  	if (!__is_supported_mem_type(type))
  		return -EOPNOTSUPP;

  
  	xdp_rxq->mem.type = type;

  	if (!allocator) {

  		if (type == MEM_TYPE_PAGE_POOL)

  			return -EINVAL; /* Setup time check page_pool req */

  		return 0;

  	}

  
  	/* 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 ret;
  		}
  	}
  
  	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
  	if (!xdp_alloc)
  		return -ENOMEM;
  
  	mutex_lock(&mem_id_lock);
  	id = __mem_id_cyclic_get(gfp);
  	if (id < 0) {
  		errno = id;
  		goto err;
  	}
  	xdp_rxq->mem.id = id;
  	xdp_alloc->mem  = xdp_rxq->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, xdp_rxq->mem.id);
  		xdp_rxq->mem.id = 0;

  		errno = PTR_ERR(ptr);
  		goto err;
  	}

  	if (type == MEM_TYPE_PAGE_POOL)

  		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect);

  	mutex_unlock(&mem_id_lock);

  	trace_mem_connect(xdp_alloc, xdp_rxq);

  	return 0;

  err:
  	mutex_unlock(&mem_id_lock);
  	kfree(xdp_alloc);
  	return errno;

  }
  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.

   */

  static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
  			 struct xdp_buff *xdp)

  {

  	struct xdp_mem_allocator *xa;
  	struct page *page;
  
  	switch (mem->type) {
  	case MEM_TYPE_PAGE_POOL:
  		rcu_read_lock();
  		/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
  		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
  		page = virt_to_head_page(data);

  		napi_direct &= !xdp_return_frame_no_direct();

  		page_pool_put_full_page(xa->page_pool, page, napi_direct);

  		rcu_read_unlock();
  		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)
  {

  	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);

  }

  EXPORT_SYMBOL_GPL(xdp_return_frame);

  void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
  {

  	__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(xdpf->data, &xdpf->mem, false, NULL);

  		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);
  	}
  
  	bq->q[bq->count++] = xdpf->data;
  }
  EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);

  void xdp_return_buff(struct xdp_buff *xdp)
  {

  	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);

  }

  /* 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
  ", func, line, msg);
  };
  EXPORT_SYMBOL_GPL(xdp_warn);