git: 49ed6e979c3b - main - LinuxKPI: add a work-in-progress skbuff implementation
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Date: Mon, 27 Dec 2021 19:11:43 UTC
The branch main has been updated by bz:
URL: https://cgit.FreeBSD.org/src/commit/?id=49ed6e979c3b327ae466a559884802d901aa5792
commit 49ed6e979c3b327ae466a559884802d901aa5792
Author: Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2021-12-26 18:26:26 +0000
Commit: Bjoern A. Zeeb <bz@FreeBSD.org>
CommitDate: 2021-12-27 18:47:25 +0000
LinuxKPI: add a work-in-progress skbuff implementation
This is a work-in-progress implementation of sk_buff compat code
used for wireless drivers only currently.
Bring in this version of the code as it has proven to be good enough
to have packets going for a few months.
The current implementation has several drawbacks including the need
for us to copy data between sk_buffs and mbufs.
Do not rely on the internals of this implementation. They are highly
likely to change as we will improve the integration to FreeBSD mbufs.
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
---
sys/compat/linuxkpi/common/include/linux/skbuff.h | 826 ++++++++++++++++++++++
sys/compat/linuxkpi/common/src/linux_skbuff.c | 113 +++
sys/conf/files | 2 +
sys/modules/linuxkpi/Makefile | 1 +
4 files changed, 942 insertions(+)
diff --git a/sys/compat/linuxkpi/common/include/linux/skbuff.h b/sys/compat/linuxkpi/common/include/linux/skbuff.h
new file mode 100644
index 000000000000..37fb6109c784
--- /dev/null
+++ b/sys/compat/linuxkpi/common/include/linux/skbuff.h
@@ -0,0 +1,826 @@
+/*-
+ * Copyright (c) 2020-2021 The FreeBSD Foundation
+ * Copyright (c) 2021 Bjoern A. Zeeb
+ *
+ * This software was developed by Björn Zeeb under sponsorship from
+ * the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * NOTE: this socket buffer compatibility code is highly EXPERIMENTAL.
+ * Do not rely on the internals of this implementation. They are highly
+ * likely to change as we will improve the integration to FreeBSD mbufs.
+ */
+
+#ifndef _LINUXKPI_LINUX_SKBUFF_H
+#define _LINUXKPI_LINUX_SKBUFF_H
+
+#include <linux/page.h>
+#include <linux/dma-mapping.h>
+#include <linux/netdev_features.h>
+#include <linux/list.h>
+#include <linux/gfp.h>
+
+/* #define SKB_DEBUG */
+#ifdef SKB_DEBUG
+
+#define DSKB_TODO 0x01
+#define DSKB_TRACE 0x02
+#define DSKB_TRACEX 0x04
+extern int debug_skb;
+
+#define SKB_TRACE(_s) if (debug_skb & DSKB_TRACE) \
+ printf("SKB_TRACE %s:%d %p\n", __func__, __LINE__, _s)
+#define SKB_TRACE2(_s, _p) if (debug_skb & DSKB_TRACE) \
+ printf("SKB_TRACE %s:%d %p, %p\n", __func__, __LINE__, _s, _p)
+#define SKB_TRACE_FMT(_s, _fmt, ...) if (debug_skb & DSKB_TRACE) \
+ printf("SKB_TRACE %s:%d %p" _fmt "\n", __func__, __LINE__, _s, __VA_ARGS__)
+#define SKB_TODO() if (debug_skb & DSKB_TODO) \
+ printf("SKB_TODO %s:%d\n", __func__, __LINE__)
+#else
+#define SKB_TRACE(_s) do { } while(0)
+#define SKB_TRACE2(_s, _p) do { } while(0)
+#define SKB_TRACE_FMT(_s, ...) do { } while(0)
+#define SKB_TODO() do { } while(0)
+#endif
+
+enum sk_buff_pkt_type {
+ PACKET_BROADCAST,
+ PACKET_MULTICAST,
+ PACKET_OTHERHOST,
+};
+
+#define NET_SKB_PAD CACHE_LINE_SIZE /* ? */
+
+struct sk_buff_head {
+ /* XXX TODO */
+ struct sk_buff *next;
+ struct sk_buff *prev;
+ size_t qlen;
+ int lock; /* XXX TYPE */
+};
+
+enum sk_checksum_flags {
+ CHECKSUM_NONE = 0x00,
+ CHECKSUM_UNNECESSARY = 0x01,
+ CHECKSUM_PARTIAL = 0x02,
+ CHECKSUM_COMPLETE = 0x04,
+};
+
+struct skb_frag {
+ /* XXX TODO */
+ struct page *page; /* XXX-BZ These three are a wild guess so far! */
+ off_t offset;
+ size_t size;
+};
+typedef struct skb_frag skb_frag_t;
+
+enum skb_shared_info_gso_type {
+ SKB_GSO_TCPV4,
+ SKB_GSO_TCPV6,
+};
+
+struct skb_shared_info {
+ enum skb_shared_info_gso_type gso_type;
+ uint16_t gso_size;
+ uint16_t nr_frags;
+ skb_frag_t frags[64]; /* XXX TODO, 16xpage? */
+};
+
+struct sk_buff {
+ /* XXX TODO */
+ /* struct sk_buff_head */
+ struct sk_buff *next;
+ struct sk_buff *prev;
+ int list; /* XXX TYPE */
+ uint32_t _alloc_len; /* Length of alloc data-buf. XXX-BZ give up for truesize? */
+ uint32_t len; /* ? */
+ uint32_t data_len; /* ? If we have frags? */
+ uint32_t truesize; /* The total size of all buffers, incl. frags. */
+ uint16_t mac_len; /* Link-layer header length. */
+ __sum16 csum;
+ uint16_t l3hdroff; /* network header offset from *head */
+ uint16_t l4hdroff; /* transport header offset from *head */
+ uint32_t priority;
+ uint16_t qmap; /* queue mapping */
+ uint16_t _spareu16_0;
+ enum sk_buff_pkt_type pkt_type;
+
+ /* "Scratch" area for layers to store metadata. */
+ /* ??? I see sizeof() operations so probably an array. */
+ uint8_t cb[64] __aligned(CACHE_LINE_SIZE);
+
+ struct net_device *dev;
+ void *sk; /* XXX net/sock.h? */
+
+ int csum_offset, csum_start, ip_summed, protocol;
+
+ uint8_t *head; /* Head of buffer. */
+ uint8_t *data; /* Head of data. */
+ uint8_t *tail; /* End of data. */
+ uint8_t *end; /* End of buffer. */
+
+ struct skb_shared_info *shinfo;
+
+ /* FreeBSD specific bandaid (see linuxkpi_kfree_skb). */
+ void *m;
+ void(*m_free_func)(void *);
+
+ /* Force padding to CACHE_LINE_SIZE. */
+ uint8_t __scratch[0] __aligned(CACHE_LINE_SIZE);
+};
+
+/* -------------------------------------------------------------------------- */
+
+struct sk_buff *linuxkpi_alloc_skb(size_t, gfp_t);
+void linuxkpi_kfree_skb(struct sk_buff *);
+
+/* -------------------------------------------------------------------------- */
+
+static inline struct sk_buff *
+alloc_skb(size_t size, gfp_t gfp)
+{
+ struct sk_buff *skb;
+
+ skb = linuxkpi_alloc_skb(size, gfp);
+ SKB_TRACE(skb);
+ return (skb);
+}
+
+static inline struct sk_buff *
+dev_alloc_skb(size_t len)
+{
+ struct sk_buff *skb;
+
+ skb = alloc_skb(len, GFP_KERNEL);
+ /* XXX TODO */
+ SKB_TRACE(skb);
+ return (skb);
+}
+
+static inline void
+kfree_skb(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ linuxkpi_kfree_skb(skb);
+}
+
+static inline void
+dev_kfree_skb(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ kfree_skb(skb);
+}
+
+static inline void
+dev_kfree_skb_any(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ dev_kfree_skb(skb);
+}
+
+static inline void
+dev_kfree_skb_irq(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+/* -------------------------------------------------------------------------- */
+
+/* XXX BZ review this one for terminal condition as Linux "queues" are special. */
+#define skb_list_walk_safe(_q, skb, tmp) \
+ for ((skb) = (_q)->next; (skb) != NULL && ((tmp) = (skb)->next); (skb) = (tmp))
+
+/* Add headroom; cannot do once there is data in there. */
+static inline void
+skb_reserve(struct sk_buff *skb, size_t len)
+{
+ SKB_TRACE(skb);
+ KASSERT(skb->data == skb->head, ("%s: skb %p not empty head %p data %p "
+ "tail %p\n", __func__, skb, skb->head, skb->data, skb->tail));
+ skb->data += len;
+ skb->tail += len;
+}
+
+/*
+ * Remove headroom; return new data pointer; basically make space at the
+ * front to copy data in (manually).
+ */
+static inline void *
+skb_push(struct sk_buff *skb, size_t len)
+{
+ SKB_TRACE(skb);
+ KASSERT(((skb->data - len) >= skb->head), ("%s: skb %p (data %p - "
+ "len %zu) < head %p\n", __func__, skb, skb->data, len, skb->data));
+ skb->len += len;
+ skb->data -= len;
+ return (skb->data);
+}
+
+/*
+ * Length of the data on the skb (without any frags)???
+ */
+static inline size_t
+skb_headlen(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ return (skb->len - skb->data_len);
+}
+
+
+/* Return the end of data (tail pointer). */
+static inline uint8_t *
+skb_tail_pointer(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ return (skb->tail);
+}
+
+/* Return number of bytes available at end of buffer. */
+static inline unsigned int
+skb_tailroom(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ KASSERT((skb->end - skb->tail) >= 0, ("%s: skb %p tailroom < 0, "
+ "end %p tail %p\n", __func__, skb, skb->end, skb->tail));
+ return (skb->end - skb->tail);
+}
+
+/* Return numer of bytes available at the beginning of buffer. */
+static inline unsigned int
+skb_headroom(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ KASSERT((skb->data - skb->head) >= 0, ("%s: skb %p headroom < 0, "
+ "data %p head %p\n", __func__, skb, skb->data, skb->head));
+ return (skb->data - skb->head);
+}
+
+
+/*
+ * Remove tailroom; return the old tail pointer; basically make space at
+ * the end to copy data in (manually). See also skb_put_data() below.
+ */
+static inline void *
+skb_put(struct sk_buff *skb, size_t len)
+{
+ void *s;
+
+ SKB_TRACE(skb);
+ KASSERT(((skb->tail + len) <= skb->end), ("%s: skb %p (tail %p + "
+ "len %zu) > end %p, head %p data %p len %u\n", __func__,
+ skb, skb->tail, len, skb->end, skb->head, skb->data, skb->len));
+
+ s = skb_tail_pointer(skb);
+ skb->tail += len;
+ skb->len += len;
+#ifdef SKB_DEBUG
+ if (debug_skb & DSKB_TRACEX)
+ printf("%s: skb %p (%u) head %p data %p tail %p end %p, s %p len %zu\n",
+ __func__, skb,skb->len, skb->head, skb->data, skb->tail, skb->end,
+ s, len);
+#endif
+ return (s);
+}
+
+/* skb_put() + copying data in. */
+static inline void *
+skb_put_data(struct sk_buff *skb, const void *buf, size_t len)
+{
+ void *s;
+
+ SKB_TRACE2(skb, buf);
+ s = skb_put(skb, len);
+ memcpy(s, buf, len);
+ return (s);
+}
+
+/* skb_put() + filling with zeros. */
+static inline void *
+skb_put_zero(struct sk_buff *skb, size_t len)
+{
+ void *s;
+
+ SKB_TRACE(skb);
+ s = skb_put(skb, len);
+ memset(s, '\0', len);
+ return (s);
+}
+
+/*
+ * Remove len bytes from beginning of data.
+ *
+ * XXX-BZ ath10k checks for !NULL conditions so I assume this doesn't panic;
+ * we return the advanced data pointer so we don't have to keep a temp, correct?
+ */
+static inline void *
+skb_pull(struct sk_buff *skb, size_t len)
+{
+
+ SKB_TRACE(skb);
+#if 0 /* Apparently this doesn't barf... */
+ KASSERT(skb->len >= len, ("%s: skb %p skb->len %u < len %u, data %p\n",
+ __func__, skb, skb->len, len, skb->data));
+#endif
+ if (skb->len < len)
+ return (NULL);
+ skb->len -= len;
+ skb->data += len;
+ return (skb->data);
+}
+
+/* Reduce skb data to given length or do nothing if smaller already. */
+static inline void
+__skb_trim(struct sk_buff *skb, unsigned int len)
+{
+
+ SKB_TRACE(skb);
+ if (skb->len < len)
+ return;
+
+ skb->len = len;
+ skb->tail = skb->data + skb->len;
+}
+
+static inline void
+skb_trim(struct sk_buff *skb, unsigned int len)
+{
+
+ return (__skb_trim(skb, len));
+}
+
+static inline struct skb_shared_info *
+skb_shinfo(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ return (skb->shinfo);
+}
+
+static inline void
+skb_add_rx_frag(struct sk_buff *skb, int fragno, struct page *page,
+ off_t offset, size_t size, unsigned int truesize)
+{
+ struct skb_shared_info *shinfo;
+
+ SKB_TRACE(skb);
+#ifdef SKB_DEBUG
+ if (debug_skb & DSKB_TRACEX)
+ printf("%s: skb %p head %p data %p tail %p end %p len %u fragno %d "
+ "page %#jx offset %ju size %zu truesize %u\n", __func__,
+ skb, skb->head, skb->data, skb->tail, skb->end, skb->len, fragno,
+ (uintmax_t)(uintptr_t)linux_page_address(page), (uintmax_t)offset,
+ size, truesize);
+#endif
+
+ shinfo = skb_shinfo(skb);
+ KASSERT(fragno >= 0 && fragno < nitems(shinfo->frags), ("%s: skb %p "
+ "fragno %d too big\n", __func__, skb, fragno));
+ shinfo->frags[fragno].page = page;
+ shinfo->frags[fragno].offset = offset;
+ shinfo->frags[fragno].size = size;
+ shinfo->nr_frags = fragno + 1;
+ skb->len += size;
+ skb->truesize += truesize;
+
+ /* XXX TODO EXTEND truesize? */
+}
+
+/* -------------------------------------------------------------------------- */
+
+/* XXX BZ review this one for terminal condition as Linux "queues" are special. */
+#define skb_queue_walk(_q, skb) \
+ for ((skb) = (_q)->next; (skb) != (struct sk_buff *)(_q); \
+ (skb) = (skb)->next)
+
+#define skb_queue_walk_safe(_q, skb, tmp) \
+ for ((skb) = (_q)->next, (tmp) = (skb)->next; \
+ (skb) != (struct sk_buff *)(_q); (skb) = (tmp), (tmp) = (skb)->next)
+
+static inline bool
+skb_queue_empty(struct sk_buff_head *q)
+{
+
+ SKB_TRACE(q);
+ return (q->qlen == 0);
+}
+
+static inline void
+__skb_queue_head_init(struct sk_buff_head *q)
+{
+ SKB_TRACE(q);
+ q->prev = q->next = (struct sk_buff *)q;
+ q->qlen = 0;
+}
+
+static inline void
+skb_queue_head_init(struct sk_buff_head *q)
+{
+ SKB_TRACE(q);
+ return (__skb_queue_head_init(q));
+}
+
+static inline void
+__skb_insert(struct sk_buff *new, struct sk_buff *prev, struct sk_buff *next,
+ struct sk_buff_head *q)
+{
+
+ SKB_TRACE_FMT(new, "prev %p next %p q %p", prev, next, q);
+ new->prev = prev;
+ new->next = next;
+ next->prev = new;
+ prev->next = new;
+ q->qlen++;
+}
+
+static inline void
+__skb_queue_after(struct sk_buff_head *q, struct sk_buff *skb,
+ struct sk_buff *new)
+{
+
+ SKB_TRACE_FMT(q, "skb %p new %p", skb, new);
+ __skb_insert(new, skb, skb->next, q);
+}
+
+static inline void
+__skb_queue_before(struct sk_buff_head *q, struct sk_buff *skb,
+ struct sk_buff *new)
+{
+
+ SKB_TRACE_FMT(q, "skb %p new %p", skb, new);
+ __skb_insert(new, skb->prev, skb, q);
+}
+
+static inline void
+__skb_queue_tail(struct sk_buff_head *q, struct sk_buff *skb)
+{
+ struct sk_buff *s;
+
+ SKB_TRACE2(q, skb);
+ q->qlen++;
+ s = (struct sk_buff *)q;
+ s->prev->next = skb;
+ skb->prev = s->prev;
+ skb->next = s;
+ s->prev = skb;
+}
+
+static inline void
+skb_queue_tail(struct sk_buff_head *q, struct sk_buff *skb)
+{
+ SKB_TRACE2(q, skb);
+ return (__skb_queue_tail(q, skb));
+}
+
+static inline struct sk_buff *
+skb_peek_tail(struct sk_buff_head *q)
+{
+ struct sk_buff *skb;
+
+ skb = q->prev;
+ SKB_TRACE2(q, skb);
+ if (skb == (struct sk_buff *)q)
+ return (NULL);
+ return (skb);
+}
+
+static inline void
+__skb_unlink(struct sk_buff *skb, struct sk_buff_head *head)
+{
+ SKB_TRACE2(skb, head);
+ struct sk_buff *p, *n;;
+
+ head->qlen--;
+ p = skb->prev;
+ n = skb->next;
+ p->next = n;
+ n->prev = p;
+ skb->prev = skb->next = NULL;
+}
+
+static inline void
+skb_unlink(struct sk_buff *skb, struct sk_buff_head *head)
+{
+ SKB_TRACE2(skb, head);
+ return (__skb_unlink(skb, head));
+}
+
+static inline struct sk_buff *
+__skb_dequeue(struct sk_buff_head *q)
+{
+ struct sk_buff *skb;
+
+ SKB_TRACE(q);
+ skb = q->next;
+ if (skb == (struct sk_buff *)q)
+ return (NULL);
+ if (skb != NULL)
+ __skb_unlink(skb, q);
+ SKB_TRACE(skb);
+ return (skb);
+}
+
+static inline struct sk_buff *
+skb_dequeue(struct sk_buff_head *q)
+{
+ SKB_TRACE(q);
+ return (__skb_dequeue(q));
+}
+
+static inline struct sk_buff *
+skb_dequeue_tail(struct sk_buff_head *q)
+{
+ struct sk_buff *skb;
+
+ skb = skb_peek_tail(q);
+ if (skb != NULL)
+ __skb_unlink(skb, q);
+
+ SKB_TRACE2(q, skb);
+ return (skb);
+}
+
+static inline void
+skb_queue_head(struct sk_buff_head *q, struct sk_buff *skb)
+{
+
+ SKB_TRACE2(q, skb);
+ __skb_queue_after(q, (struct sk_buff *)q, skb);
+}
+
+static inline uint32_t
+skb_queue_len(struct sk_buff_head *head)
+{
+ SKB_TRACE(head);
+ return (head->qlen);
+}
+
+static inline void
+__skb_queue_purge(struct sk_buff_head *q)
+{
+ struct sk_buff *skb;
+
+ SKB_TRACE(q);
+ while ((skb = __skb_dequeue(q)) != NULL)
+ kfree_skb(skb);
+}
+
+static inline void
+skb_queue_purge(struct sk_buff_head *q)
+{
+ SKB_TRACE(q);
+ return (__skb_queue_purge(q));
+}
+
+static inline struct sk_buff *
+skb_queue_prev(struct sk_buff_head *q, struct sk_buff *skb)
+{
+
+ SKB_TRACE2(q, skb);
+ /* XXX what is the q argument good for? */
+ return (skb->prev);
+}
+
+/* -------------------------------------------------------------------------- */
+
+static inline struct sk_buff *
+skb_copy(struct sk_buff *skb, gfp_t gfp)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (NULL);
+}
+
+static inline void
+consume_skb(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+static inline uint16_t
+skb_checksum(struct sk_buff *skb, int offs, size_t len, int x)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (0xffff);
+}
+
+static inline int
+skb_checksum_start_offset(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (-1);
+}
+
+static inline dma_addr_t
+skb_frag_dma_map(struct device *dev, const skb_frag_t *frag, int x,
+ size_t fragsz, enum dma_data_direction dir)
+{
+ SKB_TRACE2(frag, dev);
+ SKB_TODO();
+ return (-1);
+}
+
+static inline size_t
+skb_frag_size(const skb_frag_t *frag)
+{
+ SKB_TRACE(frag);
+ SKB_TODO();
+ return (-1);
+}
+
+static inline bool
+skb_is_nonlinear(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ return ((skb->data_len > 0) ? true : false);
+}
+
+#define skb_walk_frags(_skb, _frag) \
+ for ((_frag) = (_skb); false; (_frag)++)
+
+static inline void
+skb_checksum_help(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+static inline bool
+skb_ensure_writable(struct sk_buff *skb, size_t off)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (false);
+}
+
+static inline void *
+skb_frag_address(const skb_frag_t *frag)
+{
+ SKB_TRACE(frag);
+ SKB_TODO();
+ return (NULL);
+}
+
+static inline struct sk_buff *
+skb_gso_segment(struct sk_buff *skb, netdev_features_t netdev_flags)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (NULL);
+}
+
+static inline bool
+skb_is_gso(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (false);
+}
+
+static inline void
+skb_mark_not_on_list(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+static inline void
+skb_queue_splice_init(struct sk_buff_head *qa, struct sk_buff_head *qb)
+{
+ SKB_TRACE2(qa, qb);
+ SKB_TODO();
+}
+
+static inline void
+skb_reset_transport_header(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ skb->l4hdroff = skb->data - skb->head;
+}
+
+static inline uint8_t *
+skb_transport_header(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ return (skb->head + skb->l4hdroff);
+}
+
+static inline uint8_t *
+skb_network_header(struct sk_buff *skb)
+{
+
+ SKB_TRACE(skb);
+ return (skb->head + skb->l3hdroff);
+}
+
+static inline int
+__skb_linearize(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (ENXIO);
+}
+
+static inline bool
+pskb_expand_head(struct sk_buff *skb, int x, int len, gfp_t gfp)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (false);
+}
+
+/* Not really seen this one but need it as symmetric accessor function. */
+static inline void
+skb_set_queue_mapping(struct sk_buff *skb, uint16_t qmap)
+{
+
+ SKB_TRACE_FMT(skb, "qmap %u", qmap);
+ skb->qmap = qmap;
+}
+
+static inline uint16_t
+skb_get_queue_mapping(struct sk_buff *skb)
+{
+
+ SKB_TRACE_FMT(skb, "qmap %u", skb->qmap);
+ return (skb->qmap);
+}
+
+static inline bool
+skb_header_cloned(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (false);
+}
+
+static inline uint8_t *
+skb_mac_header(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+ return (NULL);
+}
+
+static inline void
+skb_orphan(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+static inline void
+skb_reset_mac_header(struct sk_buff *skb)
+{
+ SKB_TRACE(skb);
+ SKB_TODO();
+}
+
+static inline struct sk_buff *
+skb_peek(struct sk_buff_head *q)
+{
+ SKB_TRACE(q);
+ SKB_TODO();
+ return (NULL);
+}
+
+static inline __sum16
+csum_unfold(__sum16 sum)
+{
+ SKB_TODO();
+ return (sum);
+}
+
+#endif /* _LINUXKPI_LINUX_SKBUFF_H */
diff --git a/sys/compat/linuxkpi/common/src/linux_skbuff.c b/sys/compat/linuxkpi/common/src/linux_skbuff.c
new file mode 100644
index 000000000000..e9935e65b466
--- /dev/null
+++ b/sys/compat/linuxkpi/common/src/linux_skbuff.c
@@ -0,0 +1,113 @@
+/*-
+ * Copyright (c) 2020-2021 The FreeBSD Foundation
+ * Copyright (c) 2021 Bjoern A. Zeeb
+ *
+ * This software was developed by Björn Zeeb under sponsorship from
+ * the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * NOTE: this socket buffer compatibility code is highly EXPERIMENTAL.
+ * Do not rely on the internals of this implementation. They are highly
+ * likely to change as we will improve the integration to FreeBSD mbufs.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+
+static MALLOC_DEFINE(M_LKPISKB, "lkpiskb", "Linux KPI skbuff compat");
+
+struct sk_buff *
+linuxkpi_alloc_skb(size_t size, gfp_t gfp)
+{
+ struct sk_buff *skb;
+ size_t len;
+
+ len = sizeof(*skb) + size + sizeof(struct skb_shared_info);
+ /*
+ * Using or own type here not backing my kmalloc.
+ * We assume no one calls kfree directly on the skb.
+ */
+ skb = malloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO);
+ if (skb == NULL)
+ return (skb);
+ skb->_alloc_len = size;
+ skb->truesize = size;
+
+ skb->head = skb->data = skb->tail = (uint8_t *)(skb+1);
+ skb->end = skb->head + size;
+
+ skb->shinfo = (struct skb_shared_info *)(skb->end);
+
+ SKB_TRACE_FMT(skb, "data %p size %zu", skb->data, size);
+ return (skb);
+}
+
+void
+linuxkpi_kfree_skb(struct sk_buff *skb)
+{
+ struct skb_shared_info *shinfo;
+ uint16_t fragno;
+
+ SKB_TRACE(skb);
+ if (skb == NULL)
+ return;
+
+ /*
+ * XXX TODO this will go away once we have skb backed by mbuf.
+ * currently we allow the mbuf to stay around and use a private
+ * free function to allow secondary resources to be freed along.
+ */
+ if (skb->m != NULL) {
+ void *m;
+
+ m = skb->m;
+ skb->m = NULL;
+
+ KASSERT(skb->m_free_func != NULL, ("%s: skb %p has m %p but no "
+ "m_free_func %p\n", __func__, skb, m, skb->m_free_func));
+ skb->m_free_func(m);
+ }
+ KASSERT(skb->m == NULL,
+ ("%s: skb %p m %p != NULL\n", __func__, skb, skb->m));
+
+ shinfo = skb->shinfo;
+ for (fragno = 0; fragno < nitems(shinfo->frags); fragno++) {
+
+ if (shinfo->frags[fragno].page != NULL)
+ __free_page(shinfo->frags[fragno].page);
+ }
+
+ free(skb, M_LKPISKB);
+}
diff --git a/sys/conf/files b/sys/conf/files
index 517168b5a5d5..6a809efe75d1 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -4570,6 +4570,8 @@ compat/linuxkpi/common/src/linux_shmemfs.c optional compat_linuxkpi \
*** 20 LINES SKIPPED ***