net/xdp/xsk_queue.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /* XDP user-space ring structure
  * Copyright(c) 2018 Intel Corporation.
  */

 #ifndef _LINUX_XSK_QUEUE_H
 #define _LINUX_XSK_QUEUE_H

 #include <linux/types.h>
 #include <linux/if_xdp.h>
 #include <net/xdp_sock.h>

 struct xdp_ring {
 	u32 producer ____cacheline_aligned_in_smp;
 	u32 consumer ____cacheline_aligned_in_smp;
 	u32 flags;
 };

 /* Used for the RX and TX queues for packets */
 struct xdp_rxtx_ring {
 	struct xdp_ring ptrs;
 	struct xdp_desc desc[0] ____cacheline_aligned_in_smp;
 };

 /* Used for the fill and completion queues for buffers */
 struct xdp_umem_ring {
 	struct xdp_ring ptrs;
 	u64 desc[0] ____cacheline_aligned_in_smp;
 };

 struct xsk_queue {
 	u64 chunk_mask;
 	u64 size;
 	u32 ring_mask;
 	u32 nentries;
 	u32 cached_prod;
 	u32 cached_cons;
 	struct xdp_ring *ring;
 	u64 invalid_descs;
 };

 /* The structure of the shared state of the rings are the same as the
  * ring buffer in kernel/events/ring_buffer.c. For the Rx and completion
  * ring, the kernel is the producer and user space is the consumer. For
  * the Tx and fill rings, the kernel is the consumer and user space is
  * the producer.
  *
  * producer                         consumer
  *
  * if (LOAD ->consumer) {           LOAD ->producer
  *                    (A)           smp_rmb()       (C)
  *    STORE $data                   LOAD $data
  *    smp_wmb()       (B)           smp_mb()        (D)
  *    STORE ->producer              STORE ->consumer
  * }
  *
  * (A) pairs with (D), and (B) pairs with (C).
  *
  * Starting with (B), it protects the data from being written after
  * the producer pointer. If this barrier was missing, the consumer
  * could observe the producer pointer being set and thus load the data
  * before the producer has written the new data. The consumer would in
  * this case load the old data.
  *
  * (C) protects the consumer from speculatively loading the data before
  * the producer pointer actually has been read. If we do not have this
  * barrier, some architectures could load old data as speculative loads
  * are not discarded as the CPU does not know there is a dependency
  * between ->producer and data.
  *
  * (A) is a control dependency that separates the load of ->consumer
  * from the stores of $data. In case ->consumer indicates there is no
  * room in the buffer to store $data we do not. So no barrier is needed.
  *
  * (D) protects the load of the data to be observed to happen after the
  * store of the consumer pointer. If we did not have this memory
  * barrier, the producer could observe the consumer pointer being set
  * and overwrite the data with a new value before the consumer got the
  * chance to read the old value. The consumer would thus miss reading
  * the old entry and very likely read the new entry twice, once right
  * now and again after circling through the ring.
  */

 /* The operations on the rings are the following:
  *
  * producer                           consumer
  *
  * RESERVE entries                    PEEK in the ring for entries
  * WRITE data into the ring           READ data from the ring
  * SUBMIT entries                     RELEASE entries
  *
  * The producer reserves one or more entries in the ring. It can then
  * fill in these entries and finally submit them so that they can be
  * seen and read by the consumer.
  *
  * The consumer peeks into the ring to see if the producer has written
  * any new entries. If so, the producer can then read these entries
  * and when it is done reading them release them back to the producer
  * so that the producer can use these slots to fill in new entries.
  *
  * The function names below reflect these operations.
  */

 /* Functions that read and validate content from consumer rings. */

 static inline bool xskq_cons_crosses_non_contig_pg(struct xdp_umem *umem,
 						   u64 addr,
 						   u64 length)
 {
 	bool cross_pg = (addr & (PAGE_SIZE - 1)) + length > PAGE_SIZE;
 	bool next_pg_contig =
 		(unsigned long)umem->pages[(addr >> PAGE_SHIFT)].addr &
 			XSK_NEXT_PG_CONTIG_MASK;

 	return cross_pg && !next_pg_contig;
 }

 static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
 						u64 addr,
 						u64 length,
 						struct xdp_umem *umem)
 {
 	u64 base_addr = xsk_umem_extract_addr(addr);

 	addr = xsk_umem_add_offset_to_addr(addr);
 	if (base_addr >= q->size || addr >= q->size ||
 	    xskq_cons_crosses_non_contig_pg(umem, addr, length)) {
 		q->invalid_descs++;
 		return false;
 	}

 	return true;
 }

 static inline bool xskq_cons_is_valid_addr(struct xsk_queue *q, u64 addr)
 {
 	if (addr >= q->size) {
 		q->invalid_descs++;
 		return false;
 	}

 	return true;
 }

 static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
 				       struct xdp_umem *umem)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

 	while (q->cached_cons != q->cached_prod) {
 		u32 idx = q->cached_cons & q->ring_mask;

 		*addr = ring->desc[idx] & q->chunk_mask;

 		if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
 			if (xskq_cons_is_valid_unaligned(q, *addr,
 							 umem->chunk_size_nohr,
 							 umem))
 				return true;
 			goto out;
 		}

 		if (xskq_cons_is_valid_addr(q, *addr))
 			return true;

 out:
 		q->cached_cons++;
 	}

 	return false;
 }

 static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
 					   struct xdp_desc *d,
 					   struct xdp_umem *umem)
 {
 	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
 		if (!xskq_cons_is_valid_unaligned(q, d->addr, d->len, umem))
 			return false;

 		if (d->len > umem->chunk_size_nohr || d->options) {
 			q->invalid_descs++;
 			return false;
 		}

 		return true;
 	}

 	if (!xskq_cons_is_valid_addr(q, d->addr))
 		return false;

 	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
 	    d->options) {
 		q->invalid_descs++;
 		return false;
 	}

 	return true;
 }

 static inline bool xskq_cons_read_desc(struct xsk_queue *q,
 				       struct xdp_desc *desc,
 				       struct xdp_umem *umem)
 {
 	while (q->cached_cons != q->cached_prod) {
 		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
 		u32 idx = q->cached_cons & q->ring_mask;

 		*desc = ring->desc[idx];
 		if (xskq_cons_is_valid_desc(q, desc, umem))
 			return true;

 		q->cached_cons++;
 	}

 	return false;
 }

 /* Functions for consumers */

 static inline void __xskq_cons_release(struct xsk_queue *q)
 {
 	smp_mb(); /* D, matches A */
 	WRITE_ONCE(q->ring->consumer, q->cached_cons);
 }

 static inline void __xskq_cons_peek(struct xsk_queue *q)
 {
 	/* Refresh the local pointer */
 	q->cached_prod = READ_ONCE(q->ring->producer);
 	smp_rmb(); /* C, matches B */
 }

 static inline void xskq_cons_get_entries(struct xsk_queue *q)
 {
 	__xskq_cons_release(q);
 	__xskq_cons_peek(q);
 }

 static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
 {
 	u32 entries = q->cached_prod - q->cached_cons;

 	if (entries >= cnt)
 		return true;

 	__xskq_cons_peek(q);
 	entries = q->cached_prod - q->cached_cons;

 	return entries >= cnt;
 }

 static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
 				       struct xdp_umem *umem)
 {
 	if (q->cached_prod == q->cached_cons)
 		xskq_cons_get_entries(q);
 	return xskq_cons_read_addr(q, addr, umem);
 }

 static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
 				       struct xdp_desc *desc,
 				       struct xdp_umem *umem)
 {
 	if (q->cached_prod == q->cached_cons)
 		xskq_cons_get_entries(q);
 	return xskq_cons_read_desc(q, desc, umem);
 }

 static inline void xskq_cons_release(struct xsk_queue *q)
 {
 	/* To improve performance, only update local state here.
 	 * Reflect this to global state when we get new entries
 	 * from the ring in xskq_cons_get_entries().
 	 */
 	q->cached_cons++;
 }

 static inline bool xskq_cons_is_full(struct xsk_queue *q)
 {
 	/* No barriers needed since data is not accessed */
 	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
 		q->nentries;
 }

 /* Functions for producers */

 static inline bool xskq_prod_is_full(struct xsk_queue *q)
 {
 	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);

 	if (free_entries)
 		return false;

 	/* Refresh the local tail pointer */
 	q->cached_cons = READ_ONCE(q->ring->consumer);
 	free_entries = q->nentries - (q->cached_prod - q->cached_cons);

 	return !free_entries;
 }

 static inline int xskq_prod_reserve(struct xsk_queue *q)
 {
 	if (xskq_prod_is_full(q))
 		return -ENOSPC;

 	/* A, matches D */
 	q->cached_prod++;
 	return 0;
 }

 static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

 	if (xskq_prod_is_full(q))
 		return -ENOSPC;

 	/* A, matches D */
 	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
 	return 0;
 }

 static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 					 u64 addr, u32 len)
 {
 	struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
 	u32 idx;

 	if (xskq_prod_is_full(q))
 		return -ENOSPC;

 	/* A, matches D */
 	idx = q->cached_prod++ & q->ring_mask;
 	ring->desc[idx].addr = addr;
 	ring->desc[idx].len = len;

 	return 0;
 }

 static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
 {
 	smp_wmb(); /* B, matches C */

 	WRITE_ONCE(q->ring->producer, idx);
 }

 static inline void xskq_prod_submit(struct xsk_queue *q)
 {
 	__xskq_prod_submit(q, q->cached_prod);
 }

 static inline void xskq_prod_submit_addr(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 	u32 idx = q->ring->producer;

 	ring->desc[idx++ & q->ring_mask] = addr;

 	__xskq_prod_submit(q, idx);
 }

 static inline void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
 {
 	__xskq_prod_submit(q, q->ring->producer + nb_entries);
 }

 static inline bool xskq_prod_is_empty(struct xsk_queue *q)
 {
 	/* No barriers needed since data is not accessed */
 	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);
 }

 /* For both producers and consumers */

 static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
 {
 	return q ? q->invalid_descs : 0;
 }

 void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);
 struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
 void xskq_destroy(struct xsk_queue *q_ops);

 /* Executed by the core when the entire UMEM gets freed */
 void xsk_reuseq_destroy(struct xdp_umem *umem);

 #endif /* _LINUX_XSK_QUEUE_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/* XDP user-space ring structure
	* Copyright(c) 2018 Intel Corporation.
	*/

	#ifndef _LINUX_XSK_QUEUE_H
	#define _LINUX_XSK_QUEUE_H

	#include <linux/types.h>
	#include <linux/if_xdp.h>
	#include <net/xdp_sock.h>

	struct xdp_ring {
	u32 producer ____cacheline_aligned_in_smp;
	u32 consumer ____cacheline_aligned_in_smp;
	u32 flags;
	};

	/* Used for the RX and TX queues for packets */
	struct xdp_rxtx_ring {
	struct xdp_ring ptrs;
	struct xdp_desc desc[0] ____cacheline_aligned_in_smp;
	};

	/* Used for the fill and completion queues for buffers */
	struct xdp_umem_ring {
	struct xdp_ring ptrs;
	u64 desc[0] ____cacheline_aligned_in_smp;
	};

	struct xsk_queue {
	u64 chunk_mask;
	u64 size;
	u32 ring_mask;
	u32 nentries;
	u32 cached_prod;
	u32 cached_cons;
	struct xdp_ring *ring;
	u64 invalid_descs;
	};

	/* The structure of the shared state of the rings are the same as the
	* ring buffer in kernel/events/ring_buffer.c. For the Rx and completion
	* ring, the kernel is the producer and user space is the consumer. For
	* the Tx and fill rings, the kernel is the consumer and user space is
	* the producer.
	*
	* producer consumer
	*
	* if (LOAD ->consumer) { LOAD ->producer
	* (A) smp_rmb() (C)
	* STORE $data LOAD $data
	* smp_wmb() (B) smp_mb() (D)
	* STORE ->producer STORE ->consumer
	* }
	*
	* (A) pairs with (D), and (B) pairs with (C).
	*
	* Starting with (B), it protects the data from being written after
	* the producer pointer. If this barrier was missing, the consumer
	* could observe the producer pointer being set and thus load the data
	* before the producer has written the new data. The consumer would in
	* this case load the old data.
	*
	* (C) protects the consumer from speculatively loading the data before
	* the producer pointer actually has been read. If we do not have this
	* barrier, some architectures could load old data as speculative loads
	* are not discarded as the CPU does not know there is a dependency
	* between ->producer and data.
	*
	* (A) is a control dependency that separates the load of ->consumer
	* from the stores of $data. In case ->consumer indicates there is no
	* room in the buffer to store $data we do not. So no barrier is needed.
	*
	* (D) protects the load of the data to be observed to happen after the
	* store of the consumer pointer. If we did not have this memory
	* barrier, the producer could observe the consumer pointer being set
	* and overwrite the data with a new value before the consumer got the
	* chance to read the old value. The consumer would thus miss reading
	* the old entry and very likely read the new entry twice, once right
	* now and again after circling through the ring.
	*/

	/* The operations on the rings are the following:
	*
	* producer consumer
	*
	* RESERVE entries PEEK in the ring for entries
	* WRITE data into the ring READ data from the ring
	* SUBMIT entries RELEASE entries
	*
	* The producer reserves one or more entries in the ring. It can then
	* fill in these entries and finally submit them so that they can be
	* seen and read by the consumer.
	*
	* The consumer peeks into the ring to see if the producer has written
	* any new entries. If so, the producer can then read these entries
	* and when it is done reading them release them back to the producer
	* so that the producer can use these slots to fill in new entries.
	*
	* The function names below reflect these operations.
	*/

	/* Functions that read and validate content from consumer rings. */

	static inline bool xskq_cons_crosses_non_contig_pg(struct xdp_umem *umem,
	u64 addr,
	u64 length)
	{
	bool cross_pg = (addr & (PAGE_SIZE - 1)) + length > PAGE_SIZE;
	bool next_pg_contig =
	(unsigned long)umem->pages[(addr >> PAGE_SHIFT)].addr &
	XSK_NEXT_PG_CONTIG_MASK;

	return cross_pg && !next_pg_contig;
	}

	static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
	u64 addr,
	u64 length,
	struct xdp_umem *umem)
	{
	u64 base_addr = xsk_umem_extract_addr(addr);

	addr = xsk_umem_add_offset_to_addr(addr);
	if (base_addr >= q->size \|\| addr >= q->size \|\|
	xskq_cons_crosses_non_contig_pg(umem, addr, length)) {
	q->invalid_descs++;
	return false;
	}

	return true;
	}

	static inline bool xskq_cons_is_valid_addr(struct xsk_queue *q, u64 addr)
	{
	if (addr >= q->size) {
	q->invalid_descs++;
	return false;
	}

	return true;
	}

	static inline bool xskq_cons_read_addr(struct xsk_queue q, u64 addr,
	struct xdp_umem *umem)
	{
	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;

	while (q->cached_cons != q->cached_prod) {
	u32 idx = q->cached_cons & q->ring_mask;

	*addr = ring->desc[idx] & q->chunk_mask;

	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
	if (xskq_cons_is_valid_unaligned(q, *addr,
	umem->chunk_size_nohr,
	umem))
	return true;
	goto out;
	}

	if (xskq_cons_is_valid_addr(q, *addr))
	return true;

	out:
	q->cached_cons++;
	}

	return false;
	}

	static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
	struct xdp_desc *d,
	struct xdp_umem *umem)
	{
	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
	if (!xskq_cons_is_valid_unaligned(q, d->addr, d->len, umem))
	return false;

	if (d->len > umem->chunk_size_nohr \|\| d->options) {
	q->invalid_descs++;
	return false;
	}

	return true;
	}

	if (!xskq_cons_is_valid_addr(q, d->addr))
	return false;

	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) \|\|
	d->options) {
	q->invalid_descs++;
	return false;
	}

	return true;
	}

	static inline bool xskq_cons_read_desc(struct xsk_queue *q,
	struct xdp_desc *desc,
	struct xdp_umem *umem)
	{
	while (q->cached_cons != q->cached_prod) {
	struct xdp_rxtx_ring ring = (struct xdp_rxtx_ring )q->ring;
	u32 idx = q->cached_cons & q->ring_mask;

	*desc = ring->desc[idx];
	if (xskq_cons_is_valid_desc(q, desc, umem))
	return true;

	q->cached_cons++;
	}

	return false;
	}

	/* Functions for consumers */

	static inline void __xskq_cons_release(struct xsk_queue *q)
	{
	smp_mb(); /* D, matches A */
	WRITE_ONCE(q->ring->consumer, q->cached_cons);
	}

	static inline void __xskq_cons_peek(struct xsk_queue *q)
	{
	/* Refresh the local pointer */
	q->cached_prod = READ_ONCE(q->ring->producer);
	smp_rmb(); /* C, matches B */
	}

	static inline void xskq_cons_get_entries(struct xsk_queue *q)
	{
	__xskq_cons_release(q);
	__xskq_cons_peek(q);
	}

	static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
	{
	u32 entries = q->cached_prod - q->cached_cons;

	if (entries >= cnt)
	return true;

	__xskq_cons_peek(q);
	entries = q->cached_prod - q->cached_cons;

	return entries >= cnt;
	}

	static inline bool xskq_cons_peek_addr(struct xsk_queue q, u64 addr,
	struct xdp_umem *umem)
	{
	if (q->cached_prod == q->cached_cons)
	xskq_cons_get_entries(q);
	return xskq_cons_read_addr(q, addr, umem);
	}

	static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
	struct xdp_desc *desc,
	struct xdp_umem *umem)
	{
	if (q->cached_prod == q->cached_cons)
	xskq_cons_get_entries(q);
	return xskq_cons_read_desc(q, desc, umem);
	}

	static inline void xskq_cons_release(struct xsk_queue *q)
	{
	/* To improve performance, only update local state here.
	* Reflect this to global state when we get new entries
	* from the ring in xskq_cons_get_entries().
	*/
	q->cached_cons++;
	}

	static inline bool xskq_cons_is_full(struct xsk_queue *q)
	{
	/* No barriers needed since data is not accessed */
	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
	q->nentries;
	}

	/* Functions for producers */

	static inline bool xskq_prod_is_full(struct xsk_queue *q)
	{
	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);

	if (free_entries)
	return false;

	/* Refresh the local tail pointer */
	q->cached_cons = READ_ONCE(q->ring->consumer);
	free_entries = q->nentries - (q->cached_prod - q->cached_cons);

	return !free_entries;
	}

	static inline int xskq_prod_reserve(struct xsk_queue *q)
	{
	if (xskq_prod_is_full(q))
	return -ENOSPC;

	/* A, matches D */
	q->cached_prod++;
	return 0;
	}

	static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
	{
	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;

	if (xskq_prod_is_full(q))
	return -ENOSPC;

	/* A, matches D */
	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
	return 0;
	}

	static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
	u64 addr, u32 len)
	{
	struct xdp_rxtx_ring ring = (struct xdp_rxtx_ring )q->ring;
	u32 idx;

	if (xskq_prod_is_full(q))
	return -ENOSPC;

	/* A, matches D */
	idx = q->cached_prod++ & q->ring_mask;
	ring->desc[idx].addr = addr;
	ring->desc[idx].len = len;

	return 0;
	}

	static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
	{
	smp_wmb(); /* B, matches C */

	WRITE_ONCE(q->ring->producer, idx);
	}

	static inline void xskq_prod_submit(struct xsk_queue *q)
	{
	__xskq_prod_submit(q, q->cached_prod);
	}

	static inline void xskq_prod_submit_addr(struct xsk_queue *q, u64 addr)
	{
	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;
	u32 idx = q->ring->producer;

	ring->desc[idx++ & q->ring_mask] = addr;

	__xskq_prod_submit(q, idx);
	}

	static inline void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
	{
	__xskq_prod_submit(q, q->ring->producer + nb_entries);
	}

	static inline bool xskq_prod_is_empty(struct xsk_queue *q)
	{
	/* No barriers needed since data is not accessed */
	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);
	}

	/* For both producers and consumers */

	static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
	{
	return q ? q->invalid_descs : 0;
	}

	void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);
	struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
	void xskq_destroy(struct xsk_queue *q_ops);

	/* Executed by the core when the entire UMEM gets freed */
	void xsk_reuseq_destroy(struct xdp_umem *umem);

	#endif /* _LINUX_XSK_QUEUE_H */