| 1 | /* $NetBSD: linux_futex.c,v 1.35 2016/08/15 09:20:11 maxv Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * 3. All advertising materials mentioning features or use of this software |
| 15 | * must display the following acknowledgement: |
| 16 | * This product includes software developed by Emmanuel Dreyfus |
| 17 | * 4. The name of the author may not be used to endorse or promote |
| 18 | * products derived from this software without specific prior written |
| 19 | * permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS'' |
| 22 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| 23 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 24 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS |
| 25 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 31 | * POSSIBILITY OF SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | #include <sys/cdefs.h> |
| 35 | __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.35 2016/08/15 09:20:11 maxv Exp $" ); |
| 36 | |
| 37 | #include <sys/param.h> |
| 38 | #include <sys/time.h> |
| 39 | #include <sys/systm.h> |
| 40 | #include <sys/proc.h> |
| 41 | #include <sys/lwp.h> |
| 42 | #include <sys/queue.h> |
| 43 | #include <sys/condvar.h> |
| 44 | #include <sys/mutex.h> |
| 45 | #include <sys/kmem.h> |
| 46 | #include <sys/kernel.h> |
| 47 | #include <sys/atomic.h> |
| 48 | |
| 49 | #include <compat/linux/common/linux_types.h> |
| 50 | #include <compat/linux/common/linux_emuldata.h> |
| 51 | #include <compat/linux/common/linux_exec.h> |
| 52 | #include <compat/linux/common/linux_signal.h> |
| 53 | #include <compat/linux/common/linux_futex.h> |
| 54 | #include <compat/linux/common/linux_sched.h> |
| 55 | #include <compat/linux/common/linux_machdep.h> |
| 56 | #include <compat/linux/linux_syscallargs.h> |
| 57 | |
| 58 | struct futex; |
| 59 | |
| 60 | struct waiting_proc { |
| 61 | struct futex *wp_futex; |
| 62 | kcondvar_t wp_futex_cv; |
| 63 | TAILQ_ENTRY(waiting_proc) wp_list; |
| 64 | bool wp_onlist; |
| 65 | }; |
| 66 | struct futex { |
| 67 | void *f_uaddr; |
| 68 | int f_refcount; |
| 69 | uint32_t f_bitset; |
| 70 | LIST_ENTRY(futex) f_list; |
| 71 | TAILQ_HEAD(, waiting_proc) f_waiting_proc; |
| 72 | }; |
| 73 | |
| 74 | static LIST_HEAD(futex_list, futex) futex_list; |
| 75 | static kmutex_t futex_lock; |
| 76 | |
| 77 | #define FUTEX_LOCK mutex_enter(&futex_lock) |
| 78 | #define FUTEX_UNLOCK mutex_exit(&futex_lock) |
| 79 | #define FUTEX_LOCKASSERT KASSERT(mutex_owned(&futex_lock)) |
| 80 | |
| 81 | #define FUTEX_SYSTEM_LOCK KERNEL_LOCK(1, NULL) |
| 82 | #define FUTEX_SYSTEM_UNLOCK KERNEL_UNLOCK_ONE(0) |
| 83 | |
| 84 | #ifdef DEBUG_LINUX_FUTEX |
| 85 | int debug_futex = 1; |
| 86 | #define FUTEXPRINTF(a) do { if (debug_futex) printf a; } while (0) |
| 87 | #else |
| 88 | #define FUTEXPRINTF(a) |
| 89 | #endif |
| 90 | |
| 91 | void |
| 92 | linux_futex_init(void) |
| 93 | { |
| 94 | FUTEXPRINTF(("%s: initializing futex\n" , __func__)); |
| 95 | mutex_init(&futex_lock, MUTEX_DEFAULT, IPL_NONE); |
| 96 | } |
| 97 | |
| 98 | void |
| 99 | linux_futex_fini(void) |
| 100 | { |
| 101 | FUTEXPRINTF(("%s: destroying futex\n" , __func__)); |
| 102 | mutex_destroy(&futex_lock); |
| 103 | } |
| 104 | |
| 105 | static struct waiting_proc *futex_wp_alloc(void); |
| 106 | static void futex_wp_free(struct waiting_proc *); |
| 107 | static struct futex *futex_get(void *, uint32_t); |
| 108 | static void futex_ref(struct futex *); |
| 109 | static void futex_put(struct futex *); |
| 110 | static int futex_sleep(struct futex **, lwp_t *, int, struct waiting_proc *); |
| 111 | static int futex_wake(struct futex *, int, struct futex *, int); |
| 112 | static int futex_atomic_op(lwp_t *, int, void *); |
| 113 | |
| 114 | int |
| 115 | linux_sys_futex(struct lwp *l, const struct linux_sys_futex_args *uap, register_t *retval) |
| 116 | { |
| 117 | /* { |
| 118 | syscallarg(int *) uaddr; |
| 119 | syscallarg(int) op; |
| 120 | syscallarg(int) val; |
| 121 | syscallarg(const struct linux_timespec *) timeout; |
| 122 | syscallarg(int *) uaddr2; |
| 123 | syscallarg(int) val3; |
| 124 | } */ |
| 125 | struct linux_timespec lts; |
| 126 | struct timespec ts = { 0, 0 }; |
| 127 | int error; |
| 128 | |
| 129 | if ((SCARG(uap, op) & LINUX_FUTEX_CMD_MASK) == LINUX_FUTEX_WAIT && |
| 130 | SCARG(uap, timeout) != NULL) { |
| 131 | if ((error = copyin(SCARG(uap, timeout), |
| 132 | <s, sizeof(lts))) != 0) { |
| 133 | return error; |
| 134 | } |
| 135 | linux_to_native_timespec(&ts, <s); |
| 136 | } |
| 137 | return linux_do_futex(l, uap, retval, &ts); |
| 138 | } |
| 139 | |
| 140 | int |
| 141 | linux_do_futex(struct lwp *l, const struct linux_sys_futex_args *uap, register_t *retval, struct timespec *ts) |
| 142 | { |
| 143 | /* { |
| 144 | syscallarg(int *) uaddr; |
| 145 | syscallarg(int) op; |
| 146 | syscallarg(int) val; |
| 147 | syscallarg(const struct linux_timespec *) timeout; |
| 148 | syscallarg(int *) uaddr2; |
| 149 | syscallarg(int) val3; |
| 150 | } */ |
| 151 | int val, val3; |
| 152 | int ret; |
| 153 | int error = 0; |
| 154 | struct futex *f; |
| 155 | struct futex *newf; |
| 156 | int tout; |
| 157 | struct futex *f2; |
| 158 | struct waiting_proc *wp; |
| 159 | int op_ret, cmd; |
| 160 | clockid_t clk; |
| 161 | |
| 162 | cmd = SCARG(uap, op) & LINUX_FUTEX_CMD_MASK; |
| 163 | val3 = SCARG(uap, val3); |
| 164 | |
| 165 | if (SCARG(uap, op) & LINUX_FUTEX_CLOCK_REALTIME) { |
| 166 | switch (cmd) { |
| 167 | case LINUX_FUTEX_WAIT_BITSET: |
| 168 | case LINUX_FUTEX_WAIT: |
| 169 | clk = CLOCK_REALTIME; |
| 170 | break; |
| 171 | default: |
| 172 | return ENOSYS; |
| 173 | } |
| 174 | } else |
| 175 | clk = CLOCK_MONOTONIC; |
| 176 | |
| 177 | /* |
| 178 | * Our implementation provides only private futexes. Most of the apps |
| 179 | * should use private futexes but don't claim so. Therefore we treat |
| 180 | * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works |
| 181 | * in most cases (ie. when futexes are not shared on file descriptor |
| 182 | * or between different processes). |
| 183 | * |
| 184 | * Note that we don't handle bitsets at all at the moment. We need |
| 185 | * to move from refcounting uaddr's to handling multiple futex entries |
| 186 | * pointing to the same uaddr, but having possibly different bitmask. |
| 187 | * Perhaps move to an implementation where each uaddr has a list of |
| 188 | * futexes. |
| 189 | */ |
| 190 | switch (cmd) { |
| 191 | case LINUX_FUTEX_WAIT: |
| 192 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 193 | /*FALLTHROUGH*/ |
| 194 | case LINUX_FUTEX_WAIT_BITSET: |
| 195 | if ((error = ts2timo(clk, 0, ts, &tout, NULL)) != 0) { |
| 196 | if (error != ETIMEDOUT) |
| 197 | return error; |
| 198 | /* |
| 199 | * If the user process requests a non null timeout, |
| 200 | * make sure we do not turn it into an infinite |
| 201 | * timeout because tout is 0. |
| 202 | * |
| 203 | * We use a minimal timeout of 1/hz. Maybe it would make |
| 204 | * sense to just return ETIMEDOUT without sleeping. |
| 205 | */ |
| 206 | if (SCARG(uap, timeout) != NULL) |
| 207 | tout = 1; |
| 208 | else |
| 209 | tout = 0; |
| 210 | } |
| 211 | FUTEX_SYSTEM_LOCK; |
| 212 | if ((error = copyin(SCARG(uap, uaddr), |
| 213 | &val, sizeof(val))) != 0) { |
| 214 | FUTEX_SYSTEM_UNLOCK; |
| 215 | return error; |
| 216 | } |
| 217 | |
| 218 | if (val != SCARG(uap, val)) { |
| 219 | FUTEX_SYSTEM_UNLOCK; |
| 220 | return EWOULDBLOCK; |
| 221 | } |
| 222 | |
| 223 | FUTEXPRINTF(("FUTEX_WAIT %d.%d: val = %d, uaddr = %p, " |
| 224 | "*uaddr = %d, timeout = %lld.%09ld\n" , |
| 225 | l->l_proc->p_pid, l->l_lid, SCARG(uap, val), |
| 226 | SCARG(uap, uaddr), val, (long long)ts->tv_sec, |
| 227 | ts->tv_nsec)); |
| 228 | |
| 229 | |
| 230 | wp = futex_wp_alloc(); |
| 231 | FUTEX_LOCK; |
| 232 | f = futex_get(SCARG(uap, uaddr), val3); |
| 233 | ret = futex_sleep(&f, l, tout, wp); |
| 234 | futex_put(f); |
| 235 | FUTEX_UNLOCK; |
| 236 | futex_wp_free(wp); |
| 237 | |
| 238 | FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, " |
| 239 | "ret = %d\n" , l->l_proc->p_pid, l->l_lid, |
| 240 | SCARG(uap, uaddr), ret)); |
| 241 | |
| 242 | FUTEX_SYSTEM_UNLOCK; |
| 243 | switch (ret) { |
| 244 | case EWOULDBLOCK: /* timeout */ |
| 245 | return ETIMEDOUT; |
| 246 | break; |
| 247 | case EINTR: /* signal */ |
| 248 | return EINTR; |
| 249 | break; |
| 250 | case 0: /* FUTEX_WAKE received */ |
| 251 | FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, got it\n" , |
| 252 | l->l_proc->p_pid, l->l_lid, SCARG(uap, uaddr))); |
| 253 | return 0; |
| 254 | break; |
| 255 | default: |
| 256 | FUTEXPRINTF(("FUTEX_WAIT: unexpected ret = %d\n" , ret)); |
| 257 | break; |
| 258 | } |
| 259 | |
| 260 | /* NOTREACHED */ |
| 261 | break; |
| 262 | |
| 263 | case LINUX_FUTEX_WAKE: |
| 264 | val = FUTEX_BITSET_MATCH_ANY; |
| 265 | /*FALLTHROUGH*/ |
| 266 | case LINUX_FUTEX_WAKE_BITSET: |
| 267 | /* |
| 268 | * XXX: Linux is able cope with different addresses |
| 269 | * corresponding to the same mapped memory in the sleeping |
| 270 | * and the waker process(es). |
| 271 | */ |
| 272 | FUTEXPRINTF(("FUTEX_WAKE %d.%d: uaddr = %p, val = %d\n" , |
| 273 | l->l_proc->p_pid, l->l_lid, |
| 274 | SCARG(uap, uaddr), SCARG(uap, val))); |
| 275 | |
| 276 | FUTEX_SYSTEM_LOCK; |
| 277 | FUTEX_LOCK; |
| 278 | f = futex_get(SCARG(uap, uaddr), val3); |
| 279 | *retval = futex_wake(f, SCARG(uap, val), NULL, 0); |
| 280 | futex_put(f); |
| 281 | FUTEX_UNLOCK; |
| 282 | FUTEX_SYSTEM_UNLOCK; |
| 283 | |
| 284 | break; |
| 285 | |
| 286 | case LINUX_FUTEX_CMP_REQUEUE: |
| 287 | FUTEX_SYSTEM_LOCK; |
| 288 | |
| 289 | if ((error = copyin(SCARG(uap, uaddr), |
| 290 | &val, sizeof(val))) != 0) { |
| 291 | FUTEX_SYSTEM_UNLOCK; |
| 292 | return error; |
| 293 | } |
| 294 | |
| 295 | if (val != val3) { |
| 296 | FUTEX_SYSTEM_UNLOCK; |
| 297 | return EAGAIN; |
| 298 | } |
| 299 | |
| 300 | FUTEXPRINTF(("FUTEX_CMP_REQUEUE %d.%d: uaddr = %p, val = %d, " |
| 301 | "uaddr2 = %p, val2 = %d\n" , |
| 302 | l->l_proc->p_pid, l->l_lid, |
| 303 | SCARG(uap, uaddr), SCARG(uap, val), SCARG(uap, uaddr2), |
| 304 | (int)(unsigned long)SCARG(uap, timeout))); |
| 305 | |
| 306 | FUTEX_LOCK; |
| 307 | f = futex_get(SCARG(uap, uaddr), val3); |
| 308 | newf = futex_get(SCARG(uap, uaddr2), val3); |
| 309 | *retval = futex_wake(f, SCARG(uap, val), newf, |
| 310 | (int)(unsigned long)SCARG(uap, timeout)); |
| 311 | futex_put(f); |
| 312 | futex_put(newf); |
| 313 | FUTEX_UNLOCK; |
| 314 | |
| 315 | FUTEX_SYSTEM_UNLOCK; |
| 316 | break; |
| 317 | |
| 318 | case LINUX_FUTEX_REQUEUE: |
| 319 | FUTEX_SYSTEM_LOCK; |
| 320 | |
| 321 | FUTEXPRINTF(("FUTEX_REQUEUE %d.%d: uaddr = %p, val = %d, " |
| 322 | "uaddr2 = %p, val2 = %d\n" , |
| 323 | l->l_proc->p_pid, l->l_lid, |
| 324 | SCARG(uap, uaddr), SCARG(uap, val), SCARG(uap, uaddr2), |
| 325 | (int)(unsigned long)SCARG(uap, timeout))); |
| 326 | |
| 327 | FUTEX_LOCK; |
| 328 | f = futex_get(SCARG(uap, uaddr), val3); |
| 329 | newf = futex_get(SCARG(uap, uaddr2), val3); |
| 330 | *retval = futex_wake(f, SCARG(uap, val), newf, |
| 331 | (int)(unsigned long)SCARG(uap, timeout)); |
| 332 | futex_put(f); |
| 333 | futex_put(newf); |
| 334 | FUTEX_UNLOCK; |
| 335 | |
| 336 | FUTEX_SYSTEM_UNLOCK; |
| 337 | break; |
| 338 | |
| 339 | case LINUX_FUTEX_FD: |
| 340 | FUTEXPRINTF(("%s: unimplemented op %d\n" , __func__, cmd)); |
| 341 | return ENOSYS; |
| 342 | case LINUX_FUTEX_WAKE_OP: |
| 343 | FUTEX_SYSTEM_LOCK; |
| 344 | |
| 345 | FUTEXPRINTF(("FUTEX_WAKE_OP %d.%d: uaddr = %p, op = %d, " |
| 346 | "val = %d, uaddr2 = %p, val2 = %d\n" , |
| 347 | l->l_proc->p_pid, l->l_lid, |
| 348 | SCARG(uap, uaddr), cmd, SCARG(uap, val), |
| 349 | SCARG(uap, uaddr2), |
| 350 | (int)(unsigned long)SCARG(uap, timeout))); |
| 351 | |
| 352 | FUTEX_LOCK; |
| 353 | f = futex_get(SCARG(uap, uaddr), val3); |
| 354 | f2 = futex_get(SCARG(uap, uaddr2), val3); |
| 355 | FUTEX_UNLOCK; |
| 356 | |
| 357 | /* |
| 358 | * This function returns positive number as results and |
| 359 | * negative as errors |
| 360 | */ |
| 361 | op_ret = futex_atomic_op(l, val3, SCARG(uap, uaddr2)); |
| 362 | FUTEX_LOCK; |
| 363 | if (op_ret < 0) { |
| 364 | futex_put(f); |
| 365 | futex_put(f2); |
| 366 | FUTEX_UNLOCK; |
| 367 | FUTEX_SYSTEM_UNLOCK; |
| 368 | return -op_ret; |
| 369 | } |
| 370 | |
| 371 | ret = futex_wake(f, SCARG(uap, val), NULL, 0); |
| 372 | futex_put(f); |
| 373 | if (op_ret > 0) { |
| 374 | op_ret = 0; |
| 375 | /* |
| 376 | * Linux abuses the address of the timespec parameter |
| 377 | * as the number of retries |
| 378 | */ |
| 379 | op_ret += futex_wake(f2, |
| 380 | (int)(unsigned long)SCARG(uap, timeout), NULL, 0); |
| 381 | ret += op_ret; |
| 382 | } |
| 383 | futex_put(f2); |
| 384 | FUTEX_UNLOCK; |
| 385 | FUTEX_SYSTEM_UNLOCK; |
| 386 | *retval = ret; |
| 387 | break; |
| 388 | default: |
| 389 | FUTEXPRINTF(("%s: unknown op %d\n" , __func__, cmd)); |
| 390 | return ENOSYS; |
| 391 | } |
| 392 | return 0; |
| 393 | } |
| 394 | |
| 395 | static struct waiting_proc * |
| 396 | futex_wp_alloc(void) |
| 397 | { |
| 398 | struct waiting_proc *wp; |
| 399 | |
| 400 | wp = kmem_zalloc(sizeof(*wp), KM_SLEEP); |
| 401 | cv_init(&wp->wp_futex_cv, "futex" ); |
| 402 | return wp; |
| 403 | } |
| 404 | |
| 405 | static void |
| 406 | futex_wp_free(struct waiting_proc *wp) |
| 407 | { |
| 408 | |
| 409 | cv_destroy(&wp->wp_futex_cv); |
| 410 | kmem_free(wp, sizeof(*wp)); |
| 411 | } |
| 412 | |
| 413 | static struct futex * |
| 414 | futex_get(void *uaddr, uint32_t bitset) |
| 415 | { |
| 416 | struct futex *f; |
| 417 | |
| 418 | FUTEX_LOCKASSERT; |
| 419 | |
| 420 | LIST_FOREACH(f, &futex_list, f_list) { |
| 421 | if (f->f_uaddr == uaddr) { |
| 422 | f->f_refcount++; |
| 423 | return f; |
| 424 | } |
| 425 | } |
| 426 | |
| 427 | /* Not found, create it */ |
| 428 | f = kmem_zalloc(sizeof(*f), KM_SLEEP); |
| 429 | f->f_uaddr = uaddr; |
| 430 | f->f_bitset = bitset; |
| 431 | f->f_refcount = 1; |
| 432 | TAILQ_INIT(&f->f_waiting_proc); |
| 433 | LIST_INSERT_HEAD(&futex_list, f, f_list); |
| 434 | |
| 435 | return f; |
| 436 | } |
| 437 | |
| 438 | static void |
| 439 | futex_ref(struct futex *f) |
| 440 | { |
| 441 | |
| 442 | FUTEX_LOCKASSERT; |
| 443 | |
| 444 | f->f_refcount++; |
| 445 | } |
| 446 | |
| 447 | static void |
| 448 | futex_put(struct futex *f) |
| 449 | { |
| 450 | |
| 451 | FUTEX_LOCKASSERT; |
| 452 | |
| 453 | f->f_refcount--; |
| 454 | if (f->f_refcount == 0) { |
| 455 | KASSERT(TAILQ_EMPTY(&f->f_waiting_proc)); |
| 456 | LIST_REMOVE(f, f_list); |
| 457 | kmem_free(f, sizeof(*f)); |
| 458 | } |
| 459 | } |
| 460 | |
| 461 | static int |
| 462 | futex_sleep(struct futex **fp, lwp_t *l, int timeout, struct waiting_proc *wp) |
| 463 | { |
| 464 | struct futex *f; |
| 465 | int ret; |
| 466 | |
| 467 | FUTEX_LOCKASSERT; |
| 468 | |
| 469 | f = *fp; |
| 470 | wp->wp_futex = f; |
| 471 | TAILQ_INSERT_TAIL(&f->f_waiting_proc, wp, wp_list); |
| 472 | wp->wp_onlist = true; |
| 473 | ret = cv_timedwait_sig(&wp->wp_futex_cv, &futex_lock, timeout); |
| 474 | |
| 475 | /* |
| 476 | * we may have been requeued to a different futex before we were |
| 477 | * woken up, so let the caller know which futex to put. if we were |
| 478 | * woken by futex_wake() then it took us off the waiting list, |
| 479 | * but if our sleep was interrupted or timed out then we might |
| 480 | * need to take ourselves off the waiting list. |
| 481 | */ |
| 482 | |
| 483 | f = wp->wp_futex; |
| 484 | if (wp->wp_onlist) { |
| 485 | TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); |
| 486 | } |
| 487 | *fp = f; |
| 488 | return ret; |
| 489 | } |
| 490 | |
| 491 | static int |
| 492 | futex_wake(struct futex *f, int n, struct futex *newf, int n2) |
| 493 | { |
| 494 | struct waiting_proc *wp; |
| 495 | int count = 0; |
| 496 | |
| 497 | FUTEX_LOCKASSERT; |
| 498 | |
| 499 | /* |
| 500 | * wake up up to n threads waiting on this futex. |
| 501 | */ |
| 502 | |
| 503 | while (n--) { |
| 504 | wp = TAILQ_FIRST(&f->f_waiting_proc); |
| 505 | if (wp == NULL) |
| 506 | return count; |
| 507 | |
| 508 | KASSERT(f == wp->wp_futex); |
| 509 | TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); |
| 510 | wp->wp_onlist = false; |
| 511 | cv_signal(&wp->wp_futex_cv); |
| 512 | count++; |
| 513 | } |
| 514 | if (newf == NULL) |
| 515 | return count; |
| 516 | |
| 517 | /* |
| 518 | * then requeue up to n2 additional threads to newf |
| 519 | * (without waking them up). |
| 520 | */ |
| 521 | |
| 522 | while (n2--) { |
| 523 | wp = TAILQ_FIRST(&f->f_waiting_proc); |
| 524 | if (wp == NULL) |
| 525 | return count; |
| 526 | |
| 527 | KASSERT(f == wp->wp_futex); |
| 528 | TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); |
| 529 | futex_put(f); |
| 530 | |
| 531 | wp->wp_futex = newf; |
| 532 | futex_ref(newf); |
| 533 | TAILQ_INSERT_TAIL(&newf->f_waiting_proc, wp, wp_list); |
| 534 | count++; |
| 535 | } |
| 536 | return count; |
| 537 | } |
| 538 | |
| 539 | static int |
| 540 | futex_atomic_op(lwp_t *l, int encoded_op, void *uaddr) |
| 541 | { |
| 542 | const int op = (encoded_op >> 28) & 7; |
| 543 | const int cmp = (encoded_op >> 24) & 15; |
| 544 | const int cmparg = (encoded_op << 20) >> 20; |
| 545 | int oparg = (encoded_op << 8) >> 20; |
| 546 | int error, oldval, cval; |
| 547 | |
| 548 | if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) |
| 549 | oparg = 1 << oparg; |
| 550 | |
| 551 | /* XXX: linux verifies access here and returns EFAULT */ |
| 552 | |
| 553 | if (copyin(uaddr, &cval, sizeof(int)) != 0) |
| 554 | return -EFAULT; |
| 555 | |
| 556 | for (;;) { |
| 557 | int nval; |
| 558 | |
| 559 | switch (op) { |
| 560 | case FUTEX_OP_SET: |
| 561 | nval = oparg; |
| 562 | break; |
| 563 | case FUTEX_OP_ADD: |
| 564 | nval = cval + oparg; |
| 565 | break; |
| 566 | case FUTEX_OP_OR: |
| 567 | nval = cval | oparg; |
| 568 | break; |
| 569 | case FUTEX_OP_ANDN: |
| 570 | nval = cval & ~oparg; |
| 571 | break; |
| 572 | case FUTEX_OP_XOR: |
| 573 | nval = cval ^ oparg; |
| 574 | break; |
| 575 | default: |
| 576 | return -ENOSYS; |
| 577 | } |
| 578 | |
| 579 | error = ucas_int(uaddr, cval, nval, &oldval); |
| 580 | if (error || oldval == cval) { |
| 581 | break; |
| 582 | } |
| 583 | cval = oldval; |
| 584 | } |
| 585 | |
| 586 | if (error) |
| 587 | return -EFAULT; |
| 588 | |
| 589 | switch (cmp) { |
| 590 | case FUTEX_OP_CMP_EQ: |
| 591 | return (oldval == cmparg); |
| 592 | case FUTEX_OP_CMP_NE: |
| 593 | return (oldval != cmparg); |
| 594 | case FUTEX_OP_CMP_LT: |
| 595 | return (oldval < cmparg); |
| 596 | case FUTEX_OP_CMP_GE: |
| 597 | return (oldval >= cmparg); |
| 598 | case FUTEX_OP_CMP_LE: |
| 599 | return (oldval <= cmparg); |
| 600 | case FUTEX_OP_CMP_GT: |
| 601 | return (oldval > cmparg); |
| 602 | default: |
| 603 | return -ENOSYS; |
| 604 | } |
| 605 | } |
| 606 | |
| 607 | int |
| 608 | linux_sys_set_robust_list(struct lwp *l, |
| 609 | const struct linux_sys_set_robust_list_args *uap, register_t *retval) |
| 610 | { |
| 611 | /* { |
| 612 | syscallarg(struct linux_robust_list_head *) head; |
| 613 | syscallarg(size_t) len; |
| 614 | } */ |
| 615 | struct linux_emuldata *led; |
| 616 | |
| 617 | if (SCARG(uap, len) != sizeof(struct linux_robust_list_head)) |
| 618 | return EINVAL; |
| 619 | led = l->l_emuldata; |
| 620 | led->led_robust_head = SCARG(uap, head); |
| 621 | *retval = 0; |
| 622 | return 0; |
| 623 | } |
| 624 | |
| 625 | int |
| 626 | linux_sys_get_robust_list(struct lwp *l, |
| 627 | const struct linux_sys_get_robust_list_args *uap, register_t *retval) |
| 628 | { |
| 629 | /* { |
| 630 | syscallarg(int) pid; |
| 631 | syscallarg(struct linux_robust_list_head **) head; |
| 632 | syscallarg(size_t *) len; |
| 633 | } */ |
| 634 | struct proc *p; |
| 635 | struct linux_emuldata *led; |
| 636 | struct linux_robust_list_head *head; |
| 637 | size_t len; |
| 638 | int error = 0; |
| 639 | |
| 640 | p = l->l_proc; |
| 641 | if (!SCARG(uap, pid)) { |
| 642 | led = l->l_emuldata; |
| 643 | head = led->led_robust_head; |
| 644 | } else { |
| 645 | mutex_enter(p->p_lock); |
| 646 | l = lwp_find(p, SCARG(uap, pid)); |
| 647 | if (l != NULL) { |
| 648 | led = l->l_emuldata; |
| 649 | head = led->led_robust_head; |
| 650 | } |
| 651 | mutex_exit(p->p_lock); |
| 652 | if (l == NULL) { |
| 653 | return ESRCH; |
| 654 | } |
| 655 | } |
| 656 | #ifdef __arch64__ |
| 657 | if (p->p_flag & PK_32) { |
| 658 | uint32_t u32; |
| 659 | |
| 660 | u32 = 12; |
| 661 | error = copyout(&u32, SCARG(uap, len), sizeof(u32)); |
| 662 | if (error) |
| 663 | return error; |
| 664 | u32 = (uint32_t)(uintptr_t)head; |
| 665 | return copyout(&u32, SCARG(uap, head), sizeof(u32)); |
| 666 | } |
| 667 | #endif |
| 668 | |
| 669 | len = sizeof(*head); |
| 670 | error = copyout(&len, SCARG(uap, len), sizeof(len)); |
| 671 | if (error) |
| 672 | return error; |
| 673 | return copyout(&head, SCARG(uap, head), sizeof(head)); |
| 674 | } |
| 675 | |
| 676 | static int |
| 677 | handle_futex_death(void *uaddr, pid_t pid, int pi) |
| 678 | { |
| 679 | int uval, nval, mval; |
| 680 | struct futex *f; |
| 681 | |
| 682 | retry: |
| 683 | if (copyin(uaddr, &uval, sizeof(uval))) |
| 684 | return EFAULT; |
| 685 | |
| 686 | if ((uval & FUTEX_TID_MASK) == pid) { |
| 687 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
| 688 | nval = atomic_cas_32(uaddr, uval, mval); |
| 689 | |
| 690 | if (nval == -1) |
| 691 | return EFAULT; |
| 692 | |
| 693 | if (nval != uval) |
| 694 | goto retry; |
| 695 | |
| 696 | if (!pi && (uval & FUTEX_WAITERS)) { |
| 697 | FUTEX_LOCK; |
| 698 | f = futex_get(uaddr, FUTEX_BITSET_MATCH_ANY); |
| 699 | futex_wake(f, 1, NULL, 0); |
| 700 | FUTEX_UNLOCK; |
| 701 | } |
| 702 | } |
| 703 | |
| 704 | return 0; |
| 705 | } |
| 706 | |
| 707 | static int |
| 708 | fetch_robust_entry(struct lwp *l, struct linux_robust_list **entry, |
| 709 | struct linux_robust_list **head, int *pi) |
| 710 | { |
| 711 | unsigned long uentry; |
| 712 | |
| 713 | #ifdef __arch64__ |
| 714 | if (l->l_proc->p_flag & PK_32) { |
| 715 | uint32_t u32; |
| 716 | |
| 717 | if (copyin(head, &u32, sizeof(u32))) |
| 718 | return EFAULT; |
| 719 | uentry = (unsigned long)u32; |
| 720 | } else |
| 721 | #endif |
| 722 | if (copyin(head, &uentry, sizeof(uentry))) |
| 723 | return EFAULT; |
| 724 | |
| 725 | *entry = (void *)(uentry & ~1UL); |
| 726 | *pi = uentry & 1; |
| 727 | |
| 728 | return 0; |
| 729 | } |
| 730 | |
| 731 | /* This walks the list of robust futexes, releasing them. */ |
| 732 | void |
| 733 | release_futexes(struct lwp *l) |
| 734 | { |
| 735 | struct linux_robust_list_head head; |
| 736 | struct linux_robust_list *entry, *next_entry = NULL, *pending; |
| 737 | unsigned int limit = 2048, pi, next_pi, pip; |
| 738 | struct linux_emuldata *led; |
| 739 | unsigned long futex_offset; |
| 740 | int rc; |
| 741 | |
| 742 | led = l->l_emuldata; |
| 743 | if (led->led_robust_head == NULL) |
| 744 | return; |
| 745 | |
| 746 | #ifdef __arch64__ |
| 747 | if (l->l_proc->p_flag & PK_32) { |
| 748 | uint32_t u32s[3]; |
| 749 | |
| 750 | if (copyin(led->led_robust_head, u32s, sizeof(u32s))) |
| 751 | return; |
| 752 | |
| 753 | head.list.next = (void *)(uintptr_t)u32s[0]; |
| 754 | head.futex_offset = (unsigned long)u32s[1]; |
| 755 | head.pending_list = (void *)(uintptr_t)u32s[2]; |
| 756 | } else |
| 757 | #endif |
| 758 | if (copyin(led->led_robust_head, &head, sizeof(head))) |
| 759 | return; |
| 760 | |
| 761 | if (fetch_robust_entry(l, &entry, &head.list.next, &pi)) |
| 762 | return; |
| 763 | |
| 764 | #ifdef __arch64__ |
| 765 | if (l->l_proc->p_flag & PK_32) { |
| 766 | uint32_t u32; |
| 767 | |
| 768 | if (copyin(led->led_robust_head, &u32, sizeof(u32))) |
| 769 | return; |
| 770 | |
| 771 | head.futex_offset = (unsigned long)u32; |
| 772 | futex_offset = head.futex_offset; |
| 773 | } else |
| 774 | #endif |
| 775 | if (copyin(&head.futex_offset, &futex_offset, sizeof(unsigned long))) |
| 776 | return; |
| 777 | |
| 778 | if (fetch_robust_entry(l, &pending, &head.pending_list, &pip)) |
| 779 | return; |
| 780 | |
| 781 | while (entry != &head.list) { |
| 782 | rc = fetch_robust_entry(l, &next_entry, &entry->next, &next_pi); |
| 783 | |
| 784 | if (entry != pending) |
| 785 | if (handle_futex_death((char *)entry + futex_offset, |
| 786 | l->l_lid, pi)) |
| 787 | return; |
| 788 | |
| 789 | if (rc) |
| 790 | return; |
| 791 | |
| 792 | entry = next_entry; |
| 793 | pi = next_pi; |
| 794 | |
| 795 | if (!--limit) |
| 796 | break; |
| 797 | |
| 798 | yield(); /* XXX why? */ |
| 799 | } |
| 800 | |
| 801 | if (pending) |
| 802 | handle_futex_death((char *)pending + futex_offset, |
| 803 | l->l_lid, pip); |
| 804 | } |
| 805 | |