xref: /freebsd/sys/compat/linuxkpi/common/src/linux_skbuff.c (revision 685dc743dc3b5645e34836464128e1c0558b404b)
1 /*-
2  * Copyright (c) 2020-2022 The FreeBSD Foundation
3  * Copyright (c) 2021-2022 Bjoern A. Zeeb
4  *
5  * This software was developed by Björn Zeeb under sponsorship from
6  * the FreeBSD Foundation.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 /*
31  * NOTE: this socket buffer compatibility code is highly EXPERIMENTAL.
32  *       Do not rely on the internals of this implementation.  They are highly
33  *       likely to change as we will improve the integration to FreeBSD mbufs.
34  */
35 
36 #include <sys/cdefs.h>
37 #include "opt_ddb.h"
38 
39 #include <sys/param.h>
40 #include <sys/types.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/sysctl.h>
44 
45 #ifdef DDB
46 #include <ddb/ddb.h>
47 #endif
48 
49 #include <linux/skbuff.h>
50 #include <linux/slab.h>
51 #include <linux/gfp.h>
52 #ifdef __LP64__
53 #include <linux/log2.h>
54 #endif
55 
56 SYSCTL_DECL(_compat_linuxkpi);
57 SYSCTL_NODE(_compat_linuxkpi, OID_AUTO, skb, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
58     "LinuxKPI skbuff");
59 
60 #ifdef SKB_DEBUG
61 int linuxkpi_debug_skb;
62 SYSCTL_INT(_compat_linuxkpi_skb, OID_AUTO, debug, CTLFLAG_RWTUN,
63     &linuxkpi_debug_skb, 0, "SKB debug level");
64 #endif
65 
66 #ifdef __LP64__
67 /*
68  * Realtek wireless drivers (e.g., rtw88) require 32bit DMA in a single segment.
69  * busdma(9) has a hard time providing this currently for 3-ish pages at large
70  * quantities (see lkpi_pci_nseg1_fail in linux_pci.c).
71  * Work around this for now by allowing a tunable to enforce physical addresses
72  * allocation limits on 64bit platforms using "old-school" contigmalloc(9) to
73  * avoid bouncing.
74  */
75 static int linuxkpi_skb_memlimit;
76 SYSCTL_INT(_compat_linuxkpi_skb, OID_AUTO, mem_limit, CTLFLAG_RDTUN,
77     &linuxkpi_skb_memlimit, 0, "SKB memory limit: 0=no limit, "
78     "1=32bit, 2=36bit, other=undef (currently 32bit)");
79 #endif
80 
81 static MALLOC_DEFINE(M_LKPISKB, "lkpiskb", "Linux KPI skbuff compat");
82 
83 struct sk_buff *
linuxkpi_alloc_skb(size_t size,gfp_t gfp)84 linuxkpi_alloc_skb(size_t size, gfp_t gfp)
85 {
86 	struct sk_buff *skb;
87 	size_t len;
88 
89 	len = sizeof(*skb) + size + sizeof(struct skb_shared_info);
90 	/*
91 	 * Using our own type here not backing my kmalloc.
92 	 * We assume no one calls kfree directly on the skb.
93 	 */
94 #ifdef __LP64__
95 	if (__predict_true(linuxkpi_skb_memlimit == 0)) {
96 		skb = malloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO);
97 	} else {
98 		vm_paddr_t high;
99 
100 		switch (linuxkpi_skb_memlimit) {
101 		case 2:
102 			high = (0xfffffffff);	/* 1<<36 really. */
103 			break;
104 		case 1:
105 		default:
106 			high = (0xffffffff);	/* 1<<32 really. */
107 			break;
108 		}
109 		len = roundup_pow_of_two(len);
110 		skb = contigmalloc(len, M_LKPISKB,
111 		    linux_check_m_flags(gfp) | M_ZERO, 0, high, PAGE_SIZE, 0);
112 	}
113 #else
114 	skb = malloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO);
115 #endif
116 	if (skb == NULL)
117 		return (skb);
118 	skb->_alloc_len = len;
119 	skb->truesize = size;
120 
121 	skb->head = skb->data = skb->tail = (uint8_t *)(skb+1);
122 	skb->end = skb->head + size;
123 
124 	skb->prev = skb->next = skb;
125 
126 	skb->shinfo = (struct skb_shared_info *)(skb->end);
127 
128 	SKB_TRACE_FMT(skb, "data %p size %zu", (skb) ? skb->data : NULL, size);
129 	return (skb);
130 }
131 
132 struct sk_buff *
linuxkpi_dev_alloc_skb(size_t size,gfp_t gfp)133 linuxkpi_dev_alloc_skb(size_t size, gfp_t gfp)
134 {
135 	struct sk_buff *skb;
136 	size_t len;
137 
138 	len = size + NET_SKB_PAD;
139 	skb = linuxkpi_alloc_skb(len, gfp);
140 
141 	if (skb != NULL)
142 		skb_reserve(skb, NET_SKB_PAD);
143 
144 	SKB_TRACE_FMT(skb, "data %p size %zu len %zu",
145 	    (skb) ? skb->data : NULL, size, len);
146 	return (skb);
147 }
148 
149 struct sk_buff *
linuxkpi_build_skb(void * data,size_t fragsz)150 linuxkpi_build_skb(void *data, size_t fragsz)
151 {
152 	struct sk_buff *skb;
153 
154 	if (data == NULL || fragsz == 0)
155 		return (NULL);
156 
157 	/* Just allocate a skb without data area. */
158 	skb = linuxkpi_alloc_skb(0, GFP_KERNEL);
159 	if (skb == NULL)
160 		return (NULL);
161 
162 	skb->_flags |= _SKB_FLAGS_SKBEXTFRAG;
163 	skb->truesize = fragsz;
164 	skb->head = skb->data = data;
165 	skb_reset_tail_pointer(skb);	/* XXX is that correct? */
166 	skb->end = (void *)((uintptr_t)skb->head + fragsz);
167 
168 	return (skb);
169 }
170 
171 struct sk_buff *
linuxkpi_skb_copy(struct sk_buff * skb,gfp_t gfp)172 linuxkpi_skb_copy(struct sk_buff *skb, gfp_t gfp)
173 {
174 	struct sk_buff *new;
175 	struct skb_shared_info *shinfo;
176 	size_t len;
177 	unsigned int headroom;
178 
179 	/* Full buffer size + any fragments. */
180 	len = skb->end - skb->head + skb->data_len;
181 
182 	new = linuxkpi_alloc_skb(len, gfp);
183 	if (new == NULL)
184 		return (NULL);
185 
186 	headroom = skb_headroom(skb);
187 	/* Fixup head and end. */
188 	skb_reserve(new, headroom);	/* data and tail move headroom forward. */
189 	skb_put(new, skb->len);		/* tail and len get adjusted */
190 
191 	/* Copy data. */
192 	memcpy(new->head, skb->data - headroom, headroom + skb->len);
193 
194 	/* Deal with fragments. */
195 	shinfo = skb->shinfo;
196 	if (shinfo->nr_frags > 0) {
197 		printf("%s:%d: NOT YET SUPPORTED; missing %d frags\n",
198 		    __func__, __LINE__, shinfo->nr_frags);
199 		SKB_TODO();
200 	}
201 
202 	/* Deal with header fields. */
203 	memcpy(new->cb, skb->cb, sizeof(skb->cb));
204 	SKB_IMPROVE("more header fields to copy?");
205 
206 	return (new);
207 }
208 
209 void
linuxkpi_kfree_skb(struct sk_buff * skb)210 linuxkpi_kfree_skb(struct sk_buff *skb)
211 {
212 	struct skb_shared_info *shinfo;
213 	uint16_t fragno, count;
214 
215 	SKB_TRACE(skb);
216 	if (skb == NULL)
217 		return;
218 
219 	/*
220 	 * XXX TODO this will go away once we have skb backed by mbuf.
221 	 * currently we allow the mbuf to stay around and use a private
222 	 * free function to allow secondary resources to be freed along.
223 	 */
224 	if (skb->m != NULL) {
225 		void *m;
226 
227 		m = skb->m;
228 		skb->m = NULL;
229 
230 		KASSERT(skb->m_free_func != NULL, ("%s: skb %p has m %p but no "
231 		    "m_free_func %p\n", __func__, skb, m, skb->m_free_func));
232 		skb->m_free_func(m);
233 	}
234 	KASSERT(skb->m == NULL,
235 	    ("%s: skb %p m %p != NULL\n", __func__, skb, skb->m));
236 
237 	shinfo = skb->shinfo;
238 	for (count = fragno = 0;
239 	    count < shinfo->nr_frags && fragno < nitems(shinfo->frags);
240 	    fragno++) {
241 
242 		if (shinfo->frags[fragno].page != NULL) {
243 			struct page *p;
244 
245 			p = shinfo->frags[fragno].page;
246 			shinfo->frags[fragno].size = 0;
247 			shinfo->frags[fragno].offset = 0;
248 			shinfo->frags[fragno].page = NULL;
249 			__free_page(p);
250 			count++;
251 		}
252 	}
253 
254 	if ((skb->_flags & _SKB_FLAGS_SKBEXTFRAG) != 0) {
255 		void *p;
256 
257 		p = skb->head;
258 		skb_free_frag(p);
259 	}
260 
261 #ifdef __LP64__
262 	if (__predict_true(linuxkpi_skb_memlimit == 0))
263 		free(skb, M_LKPISKB);
264 	else
265 		contigfree(skb, skb->_alloc_len, M_LKPISKB);
266 #else
267 	free(skb, M_LKPISKB);
268 #endif
269 }
270 
271 #ifdef DDB
DB_SHOW_COMMAND(skb,db_show_skb)272 DB_SHOW_COMMAND(skb, db_show_skb)
273 {
274 	struct sk_buff *skb;
275 	int i;
276 
277 	if (!have_addr) {
278 		db_printf("usage: show skb <addr>\n");
279 			return;
280 	}
281 
282 	skb = (struct sk_buff *)addr;
283 
284 	db_printf("skb %p\n", skb);
285 	db_printf("\tnext %p prev %p\n", skb->next, skb->prev);
286 	db_printf("\tlist %p\n", &skb->list);
287 	db_printf("\t_alloc_len %u len %u data_len %u truesize %u mac_len %u\n",
288 	    skb->_alloc_len, skb->len, skb->data_len, skb->truesize,
289 	    skb->mac_len);
290 	db_printf("\tcsum %#06x l3hdroff %u l4hdroff %u priority %u qmap %u\n",
291 	    skb->csum, skb->l3hdroff, skb->l4hdroff, skb->priority, skb->qmap);
292 	db_printf("\tpkt_type %d dev %p sk %p\n",
293 	    skb->pkt_type, skb->dev, skb->sk);
294 	db_printf("\tcsum_offset %d csum_start %d ip_summed %d protocol %d\n",
295 	    skb->csum_offset, skb->csum_start, skb->ip_summed, skb->protocol);
296 	db_printf("\t_flags %#06x\n", skb->_flags);		/* XXX-BZ print names? */
297 	db_printf("\thead %p data %p tail %p end %p\n",
298 	    skb->head, skb->data, skb->tail, skb->end);
299 	db_printf("\tshinfo %p m %p m_free_func %p\n",
300 	    skb->shinfo, skb->m, skb->m_free_func);
301 
302 	if (skb->shinfo != NULL) {
303 		struct skb_shared_info *shinfo;
304 
305 		shinfo = skb->shinfo;
306 		db_printf("\t\tgso_type %d gso_size %u nr_frags %u\n",
307 		    shinfo->gso_type, shinfo->gso_size, shinfo->nr_frags);
308 		for (i = 0; i < nitems(shinfo->frags); i++) {
309 			struct skb_frag *frag;
310 
311 			frag = &shinfo->frags[i];
312 			if (frag == NULL || frag->page == NULL)
313 				continue;
314 			db_printf("\t\t\tfrag %p fragno %d page %p %p "
315 			    "offset %ju size %zu\n",
316 			    frag, i, frag->page, linux_page_address(frag->page),
317 			    (uintmax_t)frag->offset, frag->size);
318 		}
319 	}
320 	db_printf("\tcb[] %p {", skb->cb);
321 	for (i = 0; i < nitems(skb->cb); i++) {
322 		db_printf("%#04x%s",
323 		    skb->cb[i], (i < (nitems(skb->cb)-1)) ? ", " : "");
324 	}
325 	db_printf("}\n");
326 
327 	db_printf("\t__scratch[0] %p\n", skb->__scratch);
328 };
329 #endif
330