1 /* $NetBSD: if_shmem.c,v 1.7 2009/05/26 19:03:05 pooka 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 1.7 2009/05/26 19:03:05 pooka 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 #if 0 52 #define DPRINTF(x) printf x 53 #else 54 #define DPRINTF(x) 55 #endif 56 57 /* 58 * A virtual ethernet interface which uses shared memory from a 59 * memory mapped file as the bus. 60 */ 61 62 static int shmif_init(struct ifnet *); 63 static int shmif_ioctl(struct ifnet *, u_long, void *); 64 static void shmif_start(struct ifnet *); 65 static void shmif_stop(struct ifnet *, int); 66 67 struct shmif_sc { 68 struct ethercom sc_ec; 69 uint8_t sc_myaddr[6]; 70 uint8_t *sc_busmem; 71 int sc_memfd; 72 int sc_kq; 73 74 uint32_t sc_nextpacket; 75 uint32_t sc_prevgen; 76 }; 77 #define IFMEM_LOCK (0) 78 #define IFMEM_GENERATION (8) 79 #define IFMEM_LASTPACKET (12) 80 #define IFMEM_WAKEUP (16) 81 #define IFMEM_DATA (20) 82 83 #define BUSCTRL_ATOFF(sc, off) ((uint32_t *)(sc->sc_busmem+(off))) 84 85 #define BUSMEM_SIZE 65536 /* enough? */ 86 87 static void shmif_rcv(void *); 88 89 static uint32_t numif; 90 91 /* 92 * This locking needs work and will misbehave severely if: 93 * 1) the backing memory has to be paged in 94 * 2) some lockholder exits while holding the lock 95 */ 96 static void 97 lockbus(struct shmif_sc *sc) 98 { 99 100 __cpu_simple_lock((__cpu_simple_lock_t *)sc->sc_busmem); 101 } 102 103 static void 104 unlockbus(struct shmif_sc *sc) 105 { 106 107 __cpu_simple_unlock((__cpu_simple_lock_t *)sc->sc_busmem); 108 } 109 110 static uint32_t 111 busread(struct shmif_sc *sc, void *dest, uint32_t off, size_t len) 112 { 113 size_t chunk; 114 115 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE); 116 chunk = MIN(len, BUSMEM_SIZE - off); 117 memcpy(dest, sc->sc_busmem + off, chunk); 118 len -= chunk; 119 120 if (len == 0) 121 return off + chunk; 122 123 /* else, wraps around */ 124 off = IFMEM_DATA; 125 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 126 127 /* finish reading */ 128 memcpy((uint8_t *)dest + chunk, sc->sc_busmem + off, len); 129 return off + len; 130 } 131 132 static uint32_t 133 buswrite(struct shmif_sc *sc, uint32_t off, void *data, size_t len) 134 { 135 size_t chunk; 136 137 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE); 138 139 chunk = MIN(len, BUSMEM_SIZE - off); 140 memcpy(sc->sc_busmem + off, data, chunk); 141 len -= chunk; 142 143 if (len == 0) 144 return off + chunk; 145 146 DPRINTF(("buswrite wrap: wrote %d bytes to %d, left %d to %d", 147 chunk, off, len, IFMEM_DATA)); 148 149 /* else, wraps around */ 150 off = IFMEM_DATA; 151 (*BUSCTRL_ATOFF(sc, IFMEM_GENERATION))++; 152 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 153 154 /* finish writing */ 155 memcpy(sc->sc_busmem + off, (uint8_t *)data + chunk, len); 156 return off + len; 157 } 158 159 static inline uint32_t 160 advance(uint32_t oldoff, uint32_t delta) 161 { 162 uint32_t newoff; 163 164 newoff = oldoff + delta; 165 if (newoff >= BUSMEM_SIZE) 166 newoff -= (BUSMEM_SIZE - IFMEM_DATA); 167 return newoff; 168 169 } 170 171 static uint32_t 172 nextpktoff(struct shmif_sc *sc, uint32_t oldoff) 173 { 174 uint32_t oldlen; 175 176 busread(sc, &oldlen, oldoff, 4); 177 KASSERT(oldlen < BUSMEM_SIZE - IFMEM_DATA); 178 179 return advance(oldoff, 4 + oldlen); 180 } 181 182 int rump_shmif_create(const char *, int *); /* XXX */ 183 184 int 185 rump_shmif_create(const char *path, int *ifnum) 186 { 187 struct shmif_sc *sc; 188 struct ifnet *ifp; 189 uint8_t enaddr[ETHER_ADDR_LEN] = { 0xb2, 0xa0, 0x00, 0x00, 0x00, 0x00 }; 190 uint32_t randnum; 191 unsigned mynum; 192 int error; 193 194 randnum = arc4random(); 195 memcpy(&enaddr[2], &randnum, 4); 196 mynum = atomic_inc_uint_nv(&numif)-1; 197 198 sc = kmem_zalloc(sizeof(*sc), KM_SLEEP); 199 ifp = &sc->sc_ec.ec_if; 200 memcpy(sc->sc_myaddr, enaddr, sizeof(enaddr)); 201 202 sc->sc_memfd = rumpuser_open(path, O_RDWR | O_CREAT, &error); 203 if (sc->sc_memfd == -1) 204 goto fail; 205 sc->sc_busmem = rumpuser_filemmap(sc->sc_memfd, 0, BUSMEM_SIZE, 206 RUMPUSER_FILEMMAP_TRUNCATE | RUMPUSER_FILEMMAP_SHARED 207 | RUMPUSER_FILEMMAP_READ | RUMPUSER_FILEMMAP_WRITE, &error); 208 if (error) 209 goto fail; 210 211 lockbus(sc); 212 if (*BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) == 0) 213 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = IFMEM_DATA; 214 sc->sc_nextpacket = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 215 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 216 unlockbus(sc); 217 218 sc->sc_kq = rumpuser_writewatchfile_setup(-1, sc->sc_memfd, 0, &error); 219 if (sc->sc_kq == -1) 220 goto fail; 221 222 sprintf(ifp->if_xname, "shmif%d", mynum); 223 ifp->if_softc = sc; 224 ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST; 225 ifp->if_init = shmif_init; 226 ifp->if_ioctl = shmif_ioctl; 227 ifp->if_start = shmif_start; 228 ifp->if_stop = shmif_stop; 229 ifp->if_mtu = 1518; 230 231 if_attach(ifp); 232 ether_ifattach(ifp, enaddr); 233 234 if (ifnum) 235 *ifnum = mynum; 236 return 0; 237 238 fail: 239 panic("rump_shmemif_create: fixme"); 240 } 241 242 static int 243 shmif_init(struct ifnet *ifp) 244 { 245 int error = 0; 246 247 if (rump_threads) { 248 error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL, 249 shmif_rcv, ifp, NULL, "shmif"); 250 } else { 251 printf("WARNING: threads not enabled, shmif NOT working\n"); 252 } 253 254 ifp->if_flags |= IFF_RUNNING; 255 return error; 256 } 257 258 static int 259 shmif_ioctl(struct ifnet *ifp, u_long cmd, void *data) 260 { 261 int s, rv; 262 263 s = splnet(); 264 rv = ether_ioctl(ifp, cmd, data); 265 if (rv == ENETRESET) 266 rv = 0; 267 splx(s); 268 269 return rv; 270 } 271 272 /* send everything in-context */ 273 static void 274 shmif_start(struct ifnet *ifp) 275 { 276 struct shmif_sc *sc = ifp->if_softc; 277 struct mbuf *m, *m0; 278 uint32_t lastoff, dataoff, npktlenoff; 279 uint32_t pktsize = 0; 280 bool wrote = false; 281 int error; 282 283 for (;;) { 284 IF_DEQUEUE(&ifp->if_snd, m0); 285 if (m0 == NULL) { 286 break; 287 } 288 289 lockbus(sc); 290 lastoff = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 291 292 npktlenoff = nextpktoff(sc, lastoff); 293 dataoff = advance(npktlenoff, 4); 294 295 for (m = m0; m != NULL; m = m->m_next) { 296 pktsize += m->m_len; 297 dataoff = buswrite(sc, dataoff, mtod(m, void *), 298 m->m_len); 299 } 300 buswrite(sc, npktlenoff, &pktsize, 4); 301 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = npktlenoff; 302 unlockbus(sc); 303 304 m_freem(m0); 305 wrote = true; 306 307 DPRINTF(("shmif_start: send %d bytes at off %d\n", 308 pktsize, npktlenoff)); 309 } 310 /* wakeup */ 311 if (wrote) 312 rumpuser_pwrite(sc->sc_memfd, &error, 4, IFMEM_WAKEUP, &error); 313 } 314 315 static void 316 shmif_stop(struct ifnet *ifp, int disable) 317 { 318 319 panic("%s: unimpl", __func__); 320 } 321 322 static void 323 shmif_rcv(void *arg) 324 { 325 struct ifnet *ifp = arg; 326 struct shmif_sc *sc = ifp->if_softc; 327 struct mbuf *m = NULL; 328 struct ether_header *eth; 329 uint32_t nextpkt, pktlen, lastpkt, busgen, lastnext; 330 int error; 331 332 for (;;) { 333 if (m == NULL) { 334 m = m_gethdr(M_WAIT, MT_DATA); 335 MCLGET(m, M_WAIT); 336 } 337 338 DPRINTF(("waiting %d/%d\n", sc->sc_nextpacket, sc->sc_prevgen)); 339 340 KASSERT(m->m_flags & M_EXT); 341 lockbus(sc); 342 lastpkt = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 343 busgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 344 lastnext = nextpktoff(sc, lastpkt); 345 if ((lastnext > sc->sc_nextpacket && busgen > sc->sc_prevgen) 346 || (busgen > sc->sc_prevgen+1)) { 347 nextpkt = lastpkt; 348 sc->sc_prevgen = busgen; 349 printf("DROPPING\n"); 350 } else { 351 nextpkt = sc->sc_nextpacket; 352 } 353 354 /* need more data? */ 355 if (lastnext == nextpkt && sc->sc_prevgen == busgen){ 356 unlockbus(sc); 357 error = 0; 358 rumpuser_writewatchfile_wait(sc->sc_kq, NULL, &error); 359 if (__predict_false(error)) 360 printf("shmif_rcv: wait failed %d\n", error); 361 continue; 362 } 363 364 busread(sc, &pktlen, nextpkt, 4); 365 busread(sc, mtod(m, void *), advance(nextpkt, 4), pktlen); 366 367 DPRINTF(("shmif_rcv: read packet of length %d at %d\n", 368 pktlen, nextpkt)); 369 370 sc->sc_nextpacket = nextpktoff(sc, nextpkt); 371 sc->sc_prevgen = busgen; 372 unlockbus(sc); 373 374 m->m_len = m->m_pkthdr.len = pktlen; 375 m->m_pkthdr.rcvif = ifp; 376 377 /* if it's to us, don't pass up and reuse storage space */ 378 eth = mtod(m, struct ether_header *); 379 if (memcmp(eth->ether_shost, sc->sc_myaddr, 6) != 0) { 380 ifp->if_input(ifp, m); 381 m = NULL; 382 } 383 } 384 385 panic("shmif_worker is a lazy boy %d\n", error); 386 } 387