sys/compat/linux/linux_futex.c

   1 /*      $NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu 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 __FBSDID("$FreeBSD$");
  36 #if 0
  37 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $");
  38 #endif
  39
  40 #include "opt_compat.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/types.h>
  44 #include <sys/time.h>
  45 #include <sys/systm.h>
  46 #include <sys/proc.h>
  47 #include <sys/queue.h>
  48 #include <sys/lock.h>
  49 #include <sys/mutex.h>
  50 #include <sys/sx.h>
  51 #include <sys/malloc.h>
  52
  53 #ifdef COMPAT_LINUX32
  54 #include <machine/../linux32/linux.h>
  55 #include <machine/../linux32/linux32_proto.h>
  56 #else
  57 #include <machine/../linux/linux.h>
  58 #include <machine/../linux/linux_proto.h>
  59 #endif
  60 #include <compat/linux/linux_futex.h>
  61
  62 struct futex;
  63
  64 struct waiting_proc {
  65         struct thread *wp_t;
  66         struct futex *wp_new_futex;
  67         TAILQ_ENTRY(waiting_proc) wp_list;
  68 };
  69 struct futex {
  70         void   *f_uaddr;
  71         int     f_refcount;
  72         LIST_ENTRY(futex) f_list;
  73         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
  74 };
  75
  76 LIST_HEAD(futex_list, futex) futex_list;
  77 struct sx futex_sx;             /* this protects the LIST of futexes */
  78
  79 #define FUTEX_LOCK sx_xlock(&futex_sx)
  80 #define FUTEX_UNLOCK sx_xunlock(&futex_sx)
  81
  82 #define FUTEX_LOCKED    1
  83 #define FUTEX_UNLOCKED  0
  84
  85 #define FUTEX_SYSTEM_LOCK mtx_lock(&Giant)
  86 #define FUTEX_SYSTEM_UNLOCK mtx_unlock(&Giant)
  87
  88 static struct futex     *futex_get(void *, int);
  89 static void futex_put(struct futex *);
  90 static int futex_sleep(struct futex *, struct thread *, unsigned long);
  91 static int futex_wake(struct futex *, int, struct futex *, int);
  92 static int futex_atomic_op(struct thread *td, int encoded_op, caddr_t uaddr);
  93
  94 /* support.s */
  95 int futex_xchgl(int oparg, caddr_t uaddr, int *oldval);
  96 int futex_addl(int oparg, caddr_t uaddr, int *oldval);
  97 int futex_orl(int oparg, caddr_t uaddr, int *oldval);
  98 int futex_andl(int oparg, caddr_t uaddr, int *oldval);
  99 int futex_xorl(int oparg, caddr_t uaddr, int *oldval);
 100
 101 int
 102 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
 103 {
 104         int val;
 105         int ret;
 106         struct l_timespec timeout = {0, 0};
 107         int error = 0;
 108         struct futex *f;
 109         struct futex *newf;
 110         int timeout_hz;
 111         struct timeval tv = {0, 0};
 112         struct futex *f2;
 113         int op_ret;
 114
 115 #ifdef  DEBUG
 116         if (ldebug(sys_futex))
 117                 printf(ARGS(futex, "%p, %i, %i, *, %p, %i"), args->uaddr, args->op,
 118                     args->val, args->uaddr2, args->val3);
 119 #endif
 120
 121         /*
 122          * Our implementation provides only privates futexes. Most of the apps
 123          * should use private futexes but don't claim so. Therefore we treat
 124          * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works
 125          * in most cases (ie. when futexes are not shared on file descriptor
 126          * or between different processes.).
 127          */
 128         args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG);
 129
 130         switch (args->op) {
 131         case LINUX_FUTEX_WAIT:
 132                 FUTEX_SYSTEM_LOCK;
 133
 134                 if ((error = copyin(args->uaddr,
 135                     &val, sizeof(val))) != 0) {
 136                         FUTEX_SYSTEM_UNLOCK;
 137                         return error;
 138                 }
 139
 140                 if (val != args->val) {
 141                         FUTEX_SYSTEM_UNLOCK;
 142                         return EWOULDBLOCK;
 143                 }
 144
 145                 if (args->timeout != NULL) {
 146                         if ((error = copyin(args->timeout,
 147                             &timeout, sizeof(timeout))) != 0) {
 148                                 FUTEX_SYSTEM_UNLOCK;
 149                                 return error;
 150                         }
 151                 }
 152
 153 #ifdef DEBUG
 154                 if (ldebug(sys_futex))
 155                         printf("FUTEX_WAIT %d: val = %d, uaddr = %p, "
 156                             "*uaddr = %d, timeout = %d.%09lu\n",
 157                             td->td_proc->p_pid, args->val,
 158                             args->uaddr, val, timeout.tv_sec,
 159                             (unsigned long)timeout.tv_nsec);
 160 #endif
 161                 tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000;
 162                 timeout_hz = tvtohz(&tv);
 163
 164                 if (timeout.tv_sec == 0 && timeout.tv_nsec == 0)
 165                         timeout_hz = 0;
 166                 /*
 167                  * If the user process requests a non null timeout,
 168                  * make sure we do not turn it into an infinite
 169                  * timeout because timeout_hz gets null.
 170                  *
 171                  * We use a minimal timeout of 1/hz. Maybe it would
 172                  * make sense to just return ETIMEDOUT without sleeping.
 173                  */
 174                 if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) &&
 175                     (timeout_hz == 0))
 176                         timeout_hz = 1;
 177
 178
 179                 f = futex_get(args->uaddr, FUTEX_UNLOCKED);
 180                 ret = futex_sleep(f, td, timeout_hz);
 181                 futex_put(f);
 182
 183 #ifdef DEBUG
 184                 if (ldebug(sys_futex))
 185                         printf("FUTEX_WAIT %d: uaddr = %p, "
 186                             "ret = %d\n", td->td_proc->p_pid, args->uaddr, ret);
 187 #endif
 188
 189                 FUTEX_SYSTEM_UNLOCK;
 190                 switch (ret) {
 191                 case EWOULDBLOCK:       /* timeout */
 192                         return ETIMEDOUT;
 193                         break;
 194                 case EINTR:             /* signal */
 195                         return EINTR;
 196                         break;
 197                 case 0:         /* FUTEX_WAKE received */
 198 #ifdef DEBUG
 199                         if (ldebug(sys_futex))
 200                                 printf("FUTEX_WAIT %d: uaddr = %p, "
 201                                     "got FUTEX_WAKE\n",
 202                                     td->td_proc->p_pid, args->uaddr);
 203 #endif
 204                         return 0;
 205                         break;
 206                 default:
 207 #ifdef DEBUG
 208                         if (ldebug(sys_futex))
 209                                 printf("FUTEX_WAIT: unexpected ret = %d\n",
 210                                     ret);
 211 #endif
 212                         break;
 213                 }
 214
 215                 /* NOTREACHED */
 216                 break;
 217
 218         case LINUX_FUTEX_WAKE:
 219                 FUTEX_SYSTEM_LOCK;
 220
 221                 /*
 222                  * XXX: Linux is able to cope with different addresses
 223                  * corresponding to the same mapped memory in the sleeping
 224                  * and waker process(es).
 225                  */
 226 #ifdef DEBUG
 227                 if (ldebug(sys_futex))
 228                         printf("FUTEX_WAKE %d: uaddr = %p, val = %d\n",
 229                             td->td_proc->p_pid, args->uaddr, args->val);
 230 #endif
 231                 f = futex_get(args->uaddr, FUTEX_UNLOCKED);
 232                 td->td_retval[0] = futex_wake(f, args->val, NULL, 0);
 233                 futex_put(f);
 234
 235                 FUTEX_SYSTEM_UNLOCK;
 236                 break;
 237
 238         case LINUX_FUTEX_CMP_REQUEUE:
 239                 FUTEX_SYSTEM_LOCK;
 240
 241                 if ((error = copyin(args->uaddr,
 242                     &val, sizeof(val))) != 0) {
 243                         FUTEX_SYSTEM_UNLOCK;
 244                         return error;
 245                 }
 246
 247                 if (val != args->val3) {
 248                         FUTEX_SYSTEM_UNLOCK;
 249                         return EAGAIN;
 250                 }
 251
 252                 f = futex_get(args->uaddr, FUTEX_UNLOCKED);
 253                 newf = futex_get(args->uaddr2, FUTEX_UNLOCKED);
 254                 td->td_retval[0] = futex_wake(f, args->val, newf,
 255                     (int)(unsigned long)args->timeout);
 256                 futex_put(f);
 257                 futex_put(newf);
 258
 259                 FUTEX_SYSTEM_UNLOCK;
 260                 break;
 261
 262         case LINUX_FUTEX_REQUEUE:
 263                 FUTEX_SYSTEM_LOCK;
 264
 265                 f = futex_get(args->uaddr, FUTEX_UNLOCKED);
 266                 newf = futex_get(args->uaddr2, FUTEX_UNLOCKED);
 267                 td->td_retval[0] = futex_wake(f, args->val, newf,
 268                     (int)(unsigned long)args->timeout);
 269                 futex_put(f);
 270                 futex_put(newf);
 271
 272                 FUTEX_SYSTEM_UNLOCK;
 273                 break;
 274
 275         case LINUX_FUTEX_FD:
 276 #ifdef DEBUG
 277                 printf("linux_sys_futex: unimplemented op %d\n",
 278                     args->op);
 279 #endif
 280                 return (ENOSYS);
 281
 282         case LINUX_FUTEX_WAKE_OP:
 283                 FUTEX_SYSTEM_LOCK;
 284 #ifdef DEBUG
 285                 if (ldebug(sys_futex))
 286                         printf("FUTEX_WAKE_OP: %d: uaddr = %p, op = %d, "
 287                             "val = %x, uaddr2 = %p, val3 = %x\n",
 288                             td->td_proc->p_pid, args->uaddr, args->op,
 289                             args->val, args->uaddr2, args->val3);
 290 #endif
 291                 f = futex_get(args->uaddr, FUTEX_UNLOCKED);
 292                 f2 = futex_get(args->uaddr2, FUTEX_UNLOCKED);
 293
 294                 /*
 295                  * This function returns positive number as results and
 296                  * negative as errors
 297                  */
 298                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
 299 #ifdef DEBUG
 300                 if (ldebug(sys_futex))
 301                         printf("futex_atomic_op ret %d\n", op_ret);
 302 #endif
 303                 if (op_ret < 0) {
 304                         /* XXX: We don't handle the EFAULT yet. */
 305                         if (op_ret != -EFAULT) {
 306                                 futex_put(f);
 307                                 futex_put(f2);
 308                                 FUTEX_SYSTEM_UNLOCK;
 309                                 return (-op_ret);
 310                         }
 311
 312                         futex_put(f);
 313                         futex_put(f2);
 314
 315                         FUTEX_SYSTEM_UNLOCK;
 316                         return (EFAULT);
 317                 }
 318
 319                 ret = futex_wake(f, args->val, NULL, 0);
 320                 futex_put(f);
 321                 if (op_ret > 0) {
 322                         op_ret = 0;
 323                         /*
 324                          * Linux abuses the address of the timespec parameter
 325                          * as the number of retries.
 326                          */
 327                         op_ret += futex_wake(f2,
 328                             (int)(unsigned long)args->timeout, NULL, 0);
 329                         ret += op_ret;
 330                 }
 331                 futex_put(f2);
 332                 td->td_retval[0] = ret;
 333
 334                 FUTEX_SYSTEM_UNLOCK;
 335                 break;
 336
 337         case LINUX_FUTEX_LOCK_PI:
 338                 /* not yet implemented */
 339                 return (ENOSYS);
 340
 341         case LINUX_FUTEX_UNLOCK_PI:
 342                 /* not yet implemented */
 343                 return (ENOSYS);
 344
 345         case LINUX_FUTEX_TRYLOCK_PI:
 346                 /* not yet implemented */
 347                 return (ENOSYS);
 348
 349         default:
 350                 printf("linux_sys_futex: unknown op %d\n",
 351                     args->op);
 352                 return (ENOSYS);
 353         }
 354         return (0);
 355 }
 356
 357 static struct futex *
 358 futex_get(void *uaddr, int locked)
 359 {
 360         struct futex *f;
 361
 362         if (locked == FUTEX_UNLOCKED)
 363                 FUTEX_LOCK;
 364         LIST_FOREACH(f, &futex_list, f_list) {
 365                 if (f->f_uaddr == uaddr) {
 366                         f->f_refcount++;
 367                         if (locked == FUTEX_UNLOCKED)
 368                                 FUTEX_UNLOCK;
 369                         return f;
 370                 }
 371         }
 372
 373         f = malloc(sizeof(*f), M_LINUX, M_WAITOK);
 374         f->f_uaddr = uaddr;
 375         f->f_refcount = 1;
 376         TAILQ_INIT(&f->f_waiting_proc);
 377         LIST_INSERT_HEAD(&futex_list, f, f_list);
 378         if (locked == FUTEX_UNLOCKED)
 379                 FUTEX_UNLOCK;
 380
 381         return f;
 382 }
 383
 384 static void
 385 futex_put(f)
 386         struct futex *f;
 387 {
 388         FUTEX_LOCK;
 389         f->f_refcount--;
 390         if (f->f_refcount == 0) {
 391                 LIST_REMOVE(f, f_list);
 392                 free(f, M_LINUX);
 393         }
 394         FUTEX_UNLOCK;
 395
 396         return;
 397 }
 398
 399 static int
 400 futex_sleep(struct futex *f, struct thread *td, unsigned long timeout)
 401 {
 402         struct waiting_proc *wp;
 403         int ret;
 404
 405         wp = malloc(sizeof(*wp), M_LINUX, M_WAITOK);
 406         wp->wp_t = td;
 407         wp->wp_new_futex = NULL;
 408         FUTEX_LOCK;
 409         TAILQ_INSERT_TAIL(&f->f_waiting_proc, wp, wp_list);
 410         FUTEX_UNLOCK;
 411
 412 #ifdef DEBUG
 413         if (ldebug(sys_futex))
 414                 printf("FUTEX --> %d tlseep timeout = %ld\n",
 415                     td->td_proc->p_pid, timeout);
 416 #endif
 417         ret = tsleep(wp, PCATCH | PZERO, "linuxfutex", timeout);
 418 #ifdef DEBUG
 419         if (ldebug(sys_futex))
 420                 printf("FUTEX -> %d tsleep returns %d\n",
 421                     td->td_proc->p_pid, ret);
 422 #endif
 423
 424         FUTEX_LOCK;
 425         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 426         FUTEX_UNLOCK;
 427
 428         /* if we got woken up in futex_wake */
 429         if ((ret == 0) && (wp->wp_new_futex != NULL)) {
 430                 /* suspend us on the new futex */
 431                 ret = futex_sleep(wp->wp_new_futex, td, timeout);
 432                 /* and release the old one */
 433                 futex_put(wp->wp_new_futex);
 434         }
 435
 436         free(wp, M_LINUX);
 437
 438         return ret;
 439 }
 440
 441 static int
 442 futex_wake(struct futex *f, int n, struct futex *newf, int n2)
 443 {
 444         struct waiting_proc *wp;
 445         int count;
 446
 447         /*
 448          * Linux is very strange it wakes up N threads for
 449          * all operations BUT requeue ones where its N+1
 450          * mimic this.
 451          */
 452         count = newf ? 0 : 1;
 453
 454         FUTEX_LOCK;
 455         TAILQ_FOREACH(wp, &f->f_waiting_proc, wp_list) {
 456                 if (count <= n) {
 457                         wakeup_one(wp);
 458                         count++;
 459                 } else {
 460                         if (newf != NULL) {
 461                                 /* futex_put called after tsleep */
 462                                 wp->wp_new_futex = futex_get(newf->f_uaddr,
 463                                     FUTEX_LOCKED);
 464                                 wakeup_one(wp);
 465                                 if (count - n >= n2)
 466                                         break;
 467                         }
 468                 }
 469         }
 470         FUTEX_UNLOCK;
 471
 472         return count;
 473 }
 474
 475 static int
 476 futex_atomic_op(struct thread *td, int encoded_op, caddr_t uaddr)
 477 {
 478         int op = (encoded_op >> 28) & 7;
 479         int cmp = (encoded_op >> 24) & 15;
 480         int oparg = (encoded_op << 8) >> 20;
 481         int cmparg = (encoded_op << 20) >> 20;
 482         int oldval = 0, ret;
 483
 484         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 485                 oparg = 1 << oparg;
 486
 487 #ifdef DEBUG
 488         if (ldebug(sys_futex))
 489                 printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
 490                        "cmparg = %x, uaddr = %p\n",
 491                        op, cmp, oparg, cmparg, uaddr);
 492 #endif
 493         /* XXX: linux verifies access here and returns EFAULT */
 494
 495         switch (op) {
 496         case FUTEX_OP_SET:
 497                 ret = futex_xchgl(oparg, uaddr, &oldval);
 498                 break;
 499         case FUTEX_OP_ADD:
 500                 ret = futex_addl(oparg, uaddr, &oldval);
 501                 break;
 502         case FUTEX_OP_OR:
 503                 ret = futex_orl(oparg, uaddr, &oldval);
 504                 break;
 505         case FUTEX_OP_ANDN:
 506                 ret = futex_andl(~oparg, uaddr, &oldval);
 507                 break;
 508         case FUTEX_OP_XOR:
 509                 ret = futex_xorl(oparg, uaddr, &oldval);
 510                 break;
 511         default:
 512                 ret = -ENOSYS;
 513                 break;
 514         }
 515
 516         if (ret)
 517                 return (ret);
 518
 519         switch (cmp) {
 520         case FUTEX_OP_CMP_EQ:
 521                 return (oldval == cmparg);
 522         case FUTEX_OP_CMP_NE:
 523                 return (oldval != cmparg);
 524         case FUTEX_OP_CMP_LT:
 525                 return (oldval < cmparg);
 526         case FUTEX_OP_CMP_GE:
 527                 return (oldval >= cmparg);
 528         case FUTEX_OP_CMP_LE:
 529                 return (oldval <= cmparg);
 530         case FUTEX_OP_CMP_GT:
 531                 return (oldval > cmparg);
 532         default:
 533                 return (-ENOSYS);
 534         }
 535 }