if_shmem.c revision 1.13
1 /* $NetBSD: if_shmem.c,v 1.13 2010/08/10 18:17:12 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 1.13 2010/08/10 18:17:12 pooka Exp $"); 32 33 #include <sys/param.h> 34 #include <sys/atomic.h> 35 #include <sys/fcntl.h> 36 #include <sys/kmem.h> 37 #include <sys/kthread.h> 38 #include <sys/lock.h> 39 #include <sys/atomic.h> 40 41 #include <net/if.h> 42 #include <net/if_ether.h> 43 44 #include <netinet/in.h> 45 #include <netinet/in_var.h> 46 47 #include <rump/rump.h> 48 #include <rump/rumpuser.h> 49 50 #include "rump_private.h" 51 #include "rump_net_private.h" 52 53 #if 0 54 #define DPRINTF(x) rumpuser_dprintf x 55 #else 56 #define DPRINTF(x) 57 #endif 58 59 /* 60 * A virtual ethernet interface which uses shared memory from a 61 * memory mapped file as the bus. 62 */ 63 64 static int shmif_init(struct ifnet *); 65 static int shmif_ioctl(struct ifnet *, u_long, void *); 66 static void shmif_start(struct ifnet *); 67 static void shmif_stop(struct ifnet *, int); 68 69 struct shmif_sc { 70 struct ethercom sc_ec; 71 uint8_t sc_myaddr[6]; 72 uint8_t *sc_busmem; 73 int sc_memfd; 74 int sc_kq; 75 76 uint32_t sc_nextpacket; 77 uint32_t sc_prevgen; 78 }; 79 #define IFMEM_LOCK (0) 80 #define IFMEM_GENERATION (8) 81 #define IFMEM_LASTPACKET (12) 82 #define IFMEM_WAKEUP (16) 83 #define IFMEM_DATA (20) 84 85 #define BUSCTRL_ATOFF(sc, off) ((uint32_t *)(sc->sc_busmem+(off))) 86 87 #define BUSMEM_SIZE (1024*1024) /* need write throttling? */ 88 89 static void shmif_rcv(void *); 90 91 static uint32_t numif; 92 93 #define LOCK_UNLOCKED 0 94 #define LOCK_LOCKED 1 95 96 /* 97 * This locking needs work and will misbehave severely if: 98 * 1) the backing memory has to be paged in 99 * 2) some lockholder exits while holding the lock 100 */ 101 static void 102 lockbus(struct shmif_sc *sc) 103 { 104 105 while (atomic_cas_uint((void *)sc->sc_busmem, 106 LOCK_UNLOCKED, LOCK_LOCKED) == LOCK_LOCKED) 107 continue; 108 membar_enter(); 109 } 110 111 static void 112 unlockbus(struct shmif_sc *sc) 113 { 114 unsigned int old; 115 116 membar_exit(); 117 old = atomic_swap_uint((void *)sc->sc_busmem, LOCK_UNLOCKED); 118 KASSERT(old == LOCK_LOCKED); 119 } 120 121 static uint32_t 122 busread(struct shmif_sc *sc, void *dest, uint32_t off, size_t len) 123 { 124 size_t chunk; 125 126 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE); 127 chunk = MIN(len, BUSMEM_SIZE - off); 128 memcpy(dest, sc->sc_busmem + off, chunk); 129 len -= chunk; 130 131 if (len == 0) 132 return off + chunk; 133 134 /* else, wraps around */ 135 off = IFMEM_DATA; 136 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 137 138 /* finish reading */ 139 memcpy((uint8_t *)dest + chunk, sc->sc_busmem + off, len); 140 return off + len; 141 } 142 143 static uint32_t 144 buswrite(struct shmif_sc *sc, uint32_t off, void *data, size_t len) 145 { 146 size_t chunk; 147 148 KASSERT(len < (BUSMEM_SIZE - IFMEM_DATA) && off <= BUSMEM_SIZE 149 && off >= IFMEM_DATA); 150 151 chunk = MIN(len, BUSMEM_SIZE - off); 152 memcpy(sc->sc_busmem + off, data, chunk); 153 len -= chunk; 154 155 if (len == 0) 156 return off + chunk; 157 158 DPRINTF(("buswrite wrap: wrote %d bytes to %d, left %d to %d", 159 chunk, off, len, IFMEM_DATA)); 160 161 /* else, wraps around */ 162 off = IFMEM_DATA; 163 (*BUSCTRL_ATOFF(sc, IFMEM_GENERATION))++; 164 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 165 166 /* finish writing */ 167 memcpy(sc->sc_busmem + off, (uint8_t *)data + chunk, len); 168 return off + len; 169 } 170 171 static inline uint32_t 172 advance(uint32_t oldoff, uint32_t delta) 173 { 174 uint32_t newoff; 175 176 newoff = oldoff + delta; 177 if (newoff >= BUSMEM_SIZE) 178 newoff -= (BUSMEM_SIZE - IFMEM_DATA); 179 return newoff; 180 181 } 182 183 static uint32_t 184 nextpktoff(struct shmif_sc *sc, uint32_t oldoff) 185 { 186 uint32_t oldlen; 187 188 busread(sc, &oldlen, oldoff, 4); 189 KASSERT(oldlen < BUSMEM_SIZE - IFMEM_DATA); 190 191 return advance(oldoff, 4 + oldlen); 192 } 193 194 int 195 rump_shmif_create(const char *path, int *ifnum) 196 { 197 struct shmif_sc *sc; 198 struct ifnet *ifp; 199 uint8_t enaddr[ETHER_ADDR_LEN] = { 0xb2, 0xa0, 0x00, 0x00, 0x00, 0x00 }; 200 uint32_t randnum; 201 unsigned mynum; 202 int error; 203 204 randnum = arc4random(); 205 memcpy(&enaddr[2], &randnum, 4); 206 mynum = atomic_inc_uint_nv(&numif)-1; 207 208 sc = kmem_zalloc(sizeof(*sc), KM_SLEEP); 209 ifp = &sc->sc_ec.ec_if; 210 memcpy(sc->sc_myaddr, enaddr, sizeof(enaddr)); 211 212 sc->sc_memfd = rumpuser_open(path, O_RDWR | O_CREAT, &error); 213 if (sc->sc_memfd == -1) 214 goto fail; 215 sc->sc_busmem = rumpuser_filemmap(sc->sc_memfd, 0, BUSMEM_SIZE, 216 RUMPUSER_FILEMMAP_TRUNCATE | RUMPUSER_FILEMMAP_SHARED 217 | RUMPUSER_FILEMMAP_READ | RUMPUSER_FILEMMAP_WRITE, &error); 218 if (error) 219 goto fail; 220 221 lockbus(sc); 222 if (*BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) == 0) 223 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = IFMEM_DATA; 224 sc->sc_nextpacket = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 225 sc->sc_prevgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 226 unlockbus(sc); 227 228 sc->sc_kq = rumpuser_writewatchfile_setup(-1, sc->sc_memfd, 0, &error); 229 if (sc->sc_kq == -1) 230 goto fail; 231 232 sprintf(ifp->if_xname, "shmif%d", mynum); 233 ifp->if_softc = sc; 234 ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST; 235 ifp->if_init = shmif_init; 236 ifp->if_ioctl = shmif_ioctl; 237 ifp->if_start = shmif_start; 238 ifp->if_stop = shmif_stop; 239 ifp->if_mtu = 1518; 240 241 if_attach(ifp); 242 ether_ifattach(ifp, enaddr); 243 244 aprint_verbose("shmif%d: bus %s\n", mynum, path); 245 aprint_verbose("shmif%d: Ethernet address %s\n", 246 mynum, ether_sprintf(enaddr)); 247 248 if (ifnum) 249 *ifnum = mynum; 250 return 0; 251 252 fail: 253 panic("rump_shmemif_create: fixme"); 254 } 255 256 static int 257 shmif_init(struct ifnet *ifp) 258 { 259 int error = 0; 260 261 if (rump_threads) { 262 error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL, 263 shmif_rcv, ifp, NULL, "shmif"); 264 } else { 265 printf("WARNING: threads not enabled, shmif NOT working\n"); 266 } 267 268 ifp->if_flags |= IFF_RUNNING; 269 return error; 270 } 271 272 static int 273 shmif_ioctl(struct ifnet *ifp, u_long cmd, void *data) 274 { 275 int s, rv; 276 277 s = splnet(); 278 rv = ether_ioctl(ifp, cmd, data); 279 if (rv == ENETRESET) 280 rv = 0; 281 splx(s); 282 283 return rv; 284 } 285 286 /* send everything in-context */ 287 static void 288 shmif_start(struct ifnet *ifp) 289 { 290 struct shmif_sc *sc = ifp->if_softc; 291 struct mbuf *m, *m0; 292 uint32_t lastoff, dataoff, npktlenoff; 293 uint32_t pktsize = 0; 294 bool wrote = false; 295 int error; 296 297 for (;;) { 298 IF_DEQUEUE(&ifp->if_snd, m0); 299 if (m0 == NULL) { 300 break; 301 } 302 303 lockbus(sc); 304 lastoff = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 305 306 npktlenoff = nextpktoff(sc, lastoff); 307 dataoff = advance(npktlenoff, 4); 308 309 for (m = m0; m != NULL; m = m->m_next) { 310 pktsize += m->m_len; 311 dataoff = buswrite(sc, dataoff, mtod(m, void *), 312 m->m_len); 313 } 314 buswrite(sc, npktlenoff, &pktsize, 4); 315 *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET) = npktlenoff; 316 unlockbus(sc); 317 318 m_freem(m0); 319 wrote = true; 320 321 DPRINTF(("shmif_start: send %d bytes at off %d\n", 322 pktsize, npktlenoff)); 323 } 324 /* wakeup */ 325 if (wrote) 326 rumpuser_pwrite(sc->sc_memfd, &error, 4, IFMEM_WAKEUP, &error); 327 } 328 329 static void 330 shmif_stop(struct ifnet *ifp, int disable) 331 { 332 333 panic("%s: unimpl", __func__); 334 } 335 336 static void 337 shmif_rcv(void *arg) 338 { 339 struct ifnet *ifp = arg; 340 struct shmif_sc *sc = ifp->if_softc; 341 struct mbuf *m = NULL; 342 struct ether_header *eth; 343 uint32_t nextpkt, pktlen, lastpkt, busgen, lastnext; 344 int error; 345 346 for (;;) { 347 if (m == NULL) { 348 m = m_gethdr(M_WAIT, MT_DATA); 349 MCLGET(m, M_WAIT); 350 } 351 352 DPRINTF(("waiting %d/%d\n", sc->sc_nextpacket, sc->sc_prevgen)); 353 354 KASSERT(m->m_flags & M_EXT); 355 lockbus(sc); 356 lastpkt = *BUSCTRL_ATOFF(sc, IFMEM_LASTPACKET); 357 busgen = *BUSCTRL_ATOFF(sc, IFMEM_GENERATION); 358 lastnext = nextpktoff(sc, lastpkt); 359 if ((lastnext > sc->sc_nextpacket && busgen > sc->sc_prevgen) 360 || (busgen > sc->sc_prevgen+1)) { 361 nextpkt = lastpkt; 362 sc->sc_prevgen = busgen; 363 rumpuser_dprintf("shmif_rcv: generation overrun, " 364 "skipping invalid packets\n"); 365 } else { 366 nextpkt = sc->sc_nextpacket; 367 } 368 369 /* need more data? */ 370 if (lastnext == nextpkt && sc->sc_prevgen == busgen){ 371 unlockbus(sc); 372 error = 0; 373 rumpuser_writewatchfile_wait(sc->sc_kq, NULL, &error); 374 if (__predict_false(error)) 375 printf("shmif_rcv: wait failed %d\n", error); 376 continue; 377 } 378 379 busread(sc, &pktlen, nextpkt, 4); 380 busread(sc, mtod(m, void *), advance(nextpkt, 4), pktlen); 381 382 DPRINTF(("shmif_rcv: read packet of length %d at %d\n", 383 pktlen, nextpkt)); 384 385 sc->sc_nextpacket = nextpktoff(sc, nextpkt); 386 sc->sc_prevgen = busgen; 387 unlockbus(sc); 388 389 m->m_len = m->m_pkthdr.len = pktlen; 390 m->m_pkthdr.rcvif = ifp; 391 392 /* if it's from us, don't pass up and reuse storage space */ 393 eth = mtod(m, struct ether_header *); 394 if (memcmp(eth->ether_shost, sc->sc_myaddr, 6) != 0) { 395 ifp->if_input(ifp, m); 396 m = NULL; 397 } 398 } 399 400 panic("shmif_worker is a lazy boy %d\n", error); 401 } 402
Indexes created Tue Sep 23 02:09:52 GMT 2025