if_shmem.c revision 1.6.4.3
1 /* $NetBSD: if_shmem.c,v 1.6.4.3 2009/07/23 23:32:56 jym Exp $ */ 2 3 /* 4 * Copyright (c) 2009 Antti Kantee. All Rights Reserved. 5 * 6 * Development of this software was supported by The Nokia 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 ``AS IS'' AND ANY EXPRESS 18 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * 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 OR 23 * 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 #include <sys/cdefs.h> 31 __KERNEL_RCSID(0, "$NetBSD: if_shmem.c,v 1.6.4.3 2009/07/23 23:32:56 jym Exp $"); 32 33 #include <sys/param.h> 34 #include <sys/fcntl.h> 35 #include <sys/kmem.h> 36 #include <sys/kthread.h> 37 #include <sys/lock.h> 38 #include <sys/atomic.h> 39 40 #include <net/if.h> 41 #include <net/if_ether.h> 42 43 #include <netinet/in.h> 44 #include <netinet/in_var.h> 45 46 #include <rump/rump.h> 47 #include <rump/rumpuser.h> 48 49 #include "rump_private.h" 50 51 /* 52 * A virtual ethernet interface which uses shared memory from a 53 * memory mapped file as the bus. 54 */ 55 56 static int shmif_init(struct ifnet *); 57 static int shmif_ioctl(struct ifnet *, u_long, void *); 58 static void shmif_start(struct ifnet *); 59 static void shmif_stop(struct ifnet *, int); 60 61 struct shmif_sc { 62 struct ethercom sc_ec; 63 uint8_t sc_myaddr[6]; 64 uint8_t *sc_busmem; 65 int sc_memfd; 66 int sc_kq; 67 68 uint32_t sc_nextpacket; 69 uint32_t sc_prevgen; 70 }; 71 #define IFMEM_LOCK (0) 72 #define IFMEM_GENERATION (8) 73 #define IFMEM_LASTPACKET (12) 74 #define IFMEM_WAKEUP (16) 75 #define IFMEM_DATA (20) 76 77 #define BUSCTRL_ATOFF(sc, off) ((uint32_t *)(sc->sc_busmem+(off))) 78 79 #define BUSMEM_SIZE 65536 /* enough? */ 80 81 static void shmif_rcv(void *); 82 83 static uint32_t numif; 84 85 /* 86 * This locking needs work and will misbehave severely if: 87 * 1) the backing memory has to be paged in 88 * 2) some lockholder exits while holding the lock 89 */ 90 static void 91 lockbus(struct shmif_sc *sc) 92 { 93 94 __cpu_simple_lock((__cpu_simple_lock_t *)sc->sc_busmem); 95 } 96 97 static void 98 unlockbus(struct shmif_sc *sc) 99 { 100 101 __cpu_simple_unlock((__cpu_simple_lock_t *)sc->sc_busmem); 102 } 103 104 static uint32_t 105 busread(struct shmif_sc *sc, void *dest, uint32_t off, size_t len) 106 { 107 size_t chunk; 108 109 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE); 110 chunk = MIN(len, BUSMEM_SIZE - off); 111 memcpy(dest, sc->sc_busmem + off, chunk); 112 len -= chunk; 113 114 if (len == 0) 115 return off + chunk; 116 117 /* else, wraps around */ 118 off = IFMEM_DATA; 119 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 120 121 /* finish reading */ 122 memcpy((uint8_t *)dest + chunk, sc->sc_busmem + off, len); 123 return off + len; 124 } 125 126 static uint32_t 127 buswrite(struct shmif_sc *sc, uint32_t off, void *data, size_t len) 128 { 129 size_t chunk; 130 131 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE); 132 133 chunk = MIN(len, BUSMEM_SIZE - off); 134 memcpy(sc->sc_busmem + off, data, chunk); 135 len -= chunk; 136 137 if (len == 0) 138 return off + chunk; 139 140 DPRINTF(("buswrite wrap: wrote %d bytes to %d, left %d to %d", 141 chunk, off, len, IFMEM_DATA)); 142 143 /* else, wraps around */ 144 off = IFMEM_DATA; 145 (*BUSCTRL_ATOFF(sc, IFMEM_GENERATION))++; 146 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 147 148 /* finish writing */ 149 memcpy(sc->sc_busmem + off, (uint8_t *)data + chunk, len); 150 return off + len; 151 } 152 153 static inline uint32_t 154 advance(uint32_t oldoff, uint32_t delta) 155 { 156 uint32_t newoff; 157 158 newoff = oldoff + delta; 159 if (newoff >= BUSMEM_SIZE) 160 newoff -= (BUSMEM_SIZE - IFMEM_DATA); 161 return newoff; 162 163 } 164 165 static uint32_t 166 nextpktoff(struct shmif_sc *sc, uint32_t oldoff) 167 { 168 uint32_t oldlen; 169 170 busread(sc, &oldlen, oldoff, 4); 171 KASSERT(oldlen < BUSMEM_SIZE - IFMEM_DATA); 172 173 return advance(oldoff, 4 + oldlen); 174 } 175 176 int rump_shmif_create(const char *, int *); /* XXX */ 177 178 int 179 rump_shmif_create(const char *path, int *ifnum) 180 { 181 struct shmif_sc *sc; 182 struct ifnet *ifp; 183 uint8_t enaddr[ETHER_ADDR_LEN] = { 0xb2, 0xa0, 0x00, 0x00, 0x00, 0x00 }; 184 uint32_t randnum; 185 unsigned mynum; 186 int error; 187 188 randnum = arc4random(); 189 memcpy(&enaddr[2], &randnum, 4); 190 mynum = atomic_inc_uint_nv(&numif)-1; 191 192 sc = kmem_zalloc(sizeof(*sc), KM_SLEEP); 193 ifp = &sc->sc_ec.ec_if; 194 memcpy(sc->sc_myaddr, enaddr, sizeof(enaddr)); 195 196 sc->sc_memfd = rumpuser_open(path, O_RDWR | O_CREAT, &error); 197 if (sc->sc_memfd == -1) 198 goto fail; 199 sc->sc_busmem = rumpuser_filemmap(sc->sc_memfd, 0, BUSMEM_SIZE, 200 1, 1, &error); 201 if (error) 202 goto fail; 203 204 lockbus(sc); 205 if (*BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) == 0) 206 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = IFMEM_DATA; 207 sc->sc_nextpacket = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 208 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 209 unlockbus(sc); 210 211 sc->sc_kq = rumpuser_writewatchfile_setup(-1, sc->sc_memfd, 0, &error); 212 if (sc->sc_kq == -1) 213 goto fail; 214 215 sprintf(ifp->if_xname, "shmif%d", mynum); 216 ifp->if_softc = sc; 217 ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST; 218 ifp->if_init = shmif_init; 219 ifp->if_ioctl = shmif_ioctl; 220 ifp->if_start = shmif_start; 221 ifp->if_stop = shmif_stop; 222 ifp->if_mtu = 1518; 223 224 if_attach(ifp); 225 ether_ifattach(ifp, enaddr); 226 227 if (ifnum) 228 *ifnum = mynum; 229 return 0; 230 231 fail: 232 panic("rump_shmemif_create: fixme"); 233 } 234 235 static int 236 shmif_init(struct ifnet *ifp) 237 { 238 int error = 0; 239 240 if (rump_threads) { 241 error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL, 242 shmif_rcv, ifp, NULL, "shmif"); 243 } else { 244 printf("WARNING: threads not enabled, shmif NOT working\n"); 245 } 246 247 ifp->if_flags |= IFF_RUNNING; 248 return error; 249 } 250 251 static int 252 shmif_ioctl(struct ifnet *ifp, u_long cmd, void *data) 253 { 254 int s, rv; 255 256 s = splnet(); 257 rv = ether_ioctl(ifp, cmd, data); 258 if (rv == ENETRESET) 259 rv = 0; 260 splx(s); 261 262 return rv; 263 } 264 265 /* send everything in-context */ 266 static void 267 shmif_start(struct ifnet *ifp) 268 { 269 struct shmif_sc *sc = ifp->if_softc; 270 struct mbuf *m, *m0; 271 uint32_t lastoff, dataoff, npktlenoff; 272 uint32_t pktsize = 0; 273 bool wrote = false; 274 int error; 275 276 for (;;) { 277 IF_DEQUEUE(&ifp->if_snd, m0); 278 if (m0 == NULL) { 279 break; 280 } 281 282 lockbus(sc); 283 lastoff = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 284 285 npktlenoff = nextpktoff(sc, lastoff); 286 dataoff = advance(npktlenoff, 4); 287 288 for (m = m0; m != NULL; m = m->m_next) { 289 pktsize += m->m_len; 290 dataoff = buswrite(sc, dataoff, mtod(m, void *), 291 m->m_len); 292 } 293 buswrite(sc, npktlenoff, &pktsize, 4); 294 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = npktlenoff; 295 unlockbus(sc); 296 297 m_freem(m0); 298 wrote = true; 299 300 DPRINTF(("shmif_start: send %d bytes at off %d\n", 301 pktsize, npktlenoff)); 302 } 303 /* wakeup */ 304 if (wrote) 305 rumpuser_pwrite(sc->sc_memfd, &error, 4, IFMEM_WAKEUP, &error); 306 } 307 308 static void 309 shmif_stop(struct ifnet *ifp, int disable) 310 { 311 312 panic("%s: unimpl", __func__); 313 } 314 315 static void 316 shmif_rcv(void *arg) 317 { 318 struct ifnet *ifp = arg; 319 struct shmif_sc *sc = ifp->if_softc; 320 struct mbuf *m = NULL; 321 struct ether_header *eth; 322 uint32_t nextpkt, pktlen, lastpkt, busgen, lastnext; 323 int error; 324 325 for (;;) { 326 if (m == NULL) { 327 m = m_gethdr(M_WAIT, MT_DATA); 328 MCLGET(m, M_WAIT); 329 } 330 331 DPRINTF(("waiting %d/%d\n", sc->sc_nextpacket, sc->sc_prevgen)); 332 333 KASSERT(m->m_flags & M_EXT); 334 lockbus(sc); 335 lastpkt = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 336 busgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 337 lastnext = nextpktoff(sc, lastpkt); 338 if ((lastnext > sc->sc_nextpacket && busgen > sc->sc_prevgen) 339 || (busgen > sc->sc_prevgen+1)) { 340 nextpkt = lastpkt; 341 sc->sc_prevgen = busgen; 342 printf("DROPPING\n"); 343 } else { 344 nextpkt = sc->sc_nextpacket; 345 } 346 347 /* need more data? */ 348 if (lastnext == nextpkt && sc->sc_prevgen == busgen){ 349 unlockbus(sc); 350 error = 0; 351 rumpuser_writewatchfile_wait(sc->sc_kq, NULL, &error); 352 if (__predict_false(error)) 353 printf("shmif_rcv: wait failed %d\n", error); 354 continue; 355 } 356 357 busread(sc, &pktlen, nextpkt, 4); 358 busread(sc, mtod(m, void *), advance(nextpkt, 4), pktlen); 359 360 DPRINTF(("shmif_rcv: read packet of length %d at %d\n", 361 pktlen, nextpkt)); 362 363 sc->sc_nextpacket = nextpktoff(sc, nextpkt); 364 sc->sc_prevgen = busgen; 365 unlockbus(sc); 366 367 m->m_len = m->m_pkthdr.len = pktlen; 368 m->m_pkthdr.rcvif = ifp; 369 370 /* if it's to us, don't pass up and reuse storage space */ 371 eth = mtod(m, struct ether_header *); 372 if (memcmp(eth->ether_shost, sc->sc_myaddr, 6) != 0) { 373 ifp->if_input(ifp, m); 374 m = NULL; 375 } 376 } 377 378 panic("shmif_worker is a lazy boy %d\n", error); 379 } 380
Indexes created Thu Sep 25 16:09:42 GMT 2025