src/runtime/bsd-os.c

   1 /*
   2  * OS-dependent routines for BSD-ish systems
   3  *
   4  * This file (along with os.h) exports an OS-independent interface to
   5  * the operating system VM facilities. This interface looks a lot like
   6  * the Mach interface (but simpler in some places). For some operating
   7  * systems, a subset of these functions will have to be emulated.
   8  */
   9
  10 /*
  11  * This software is part of the SBCL system. See the README file for
  12  * more information.
  13  *
  14  * This software is derived from the CMU CL system, which was
  15  * written at Carnegie Mellon University and released into the
  16  * public domain. The software is in the public domain and is
  17  * provided with absolutely no warranty. See the COPYING and CREDITS
  18  * files for more information.
  19  */
  20
  21 #include <stdio.h>
  22 #include <sys/param.h>
  23 #include <sys/file.h>
  24 #include <unistd.h>
  25 #include <utime.h>
  26 #include <assert.h>
  27 #include <errno.h>
  28 #include "sbcl.h"
  29 #include "./signal.h"
  30 #include "os.h"
  31 #include "arch.h"
  32 #include "globals.h"
  33 #include "interrupt.h"
  34 #include "interr.h"
  35 #include "lispregs.h"
  36 #include "thread.h"
  37 #include "runtime.h"
  38 #include "genesis/static-symbols.h"
  39 #include "genesis/fdefn.h"
  40
  41 #include <sys/types.h>
  42 #include <signal.h>
  43 /* #include <sys/sysinfo.h> */
  44 #include "validate.h"
  45 #if defined LISP_FEATURE_GENCGC
  46 #include "gencgc-internal.h"
  47 #endif
  48
  49 #if defined(LISP_FEATURE_SB_WTIMER) && !defined(LISP_FEATURE_DARWIN)
  50 # include <sys/event.h>
  51 #endif
  52
  53 \f
  54 os_vm_size_t os_vm_page_size;
  55
  56 #ifdef __NetBSD__
  57 #include <sys/resource.h>
  58 #include <sys/sysctl.h>
  59 #include <string.h>
  60 #include <sys/stat.h> /* For the stat-family wrappers. */
  61 #include <dirent.h>   /* For the opendir()/readdir() wrappers */
  62 #include <sys/socket.h> /* For the socket() wrapper */
  63 static void netbsd_init();
  64 static os_vm_size_t max_allocation_size;
  65 #endif /* __NetBSD__ */
  66
  67 #if defined LISP_FEATURE_FREEBSD
  68 #include <sys/sysctl.h>
  69 #if defined(LISP_FEATURE_SB_THREAD) && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
  70 #include <sys/umtx.h>
  71 #endif
  72
  73 static void freebsd_init();
  74 #endif /* __FreeBSD__ */
  75
  76 #ifdef __DragonFly__
  77 #include <sys/sysctl.h>
  78
  79 static void dragonfly_init();
  80 #endif /* __DragonFly__ */
  81
  82 #ifdef __OpenBSD__
  83 #include <sys/types.h>
  84 #include <sys/resource.h>
  85 #include <sys/stat.h>
  86 #include <sys/sysctl.h>
  87 #include <dlfcn.h>
  88 #ifdef LISP_FEATURE_X86
  89 #include <machine/cpu.h>
  90 #endif
  91
  92 static void openbsd_init();
  93 #endif
  94
  95 void
  96 os_init(char *argv[], char *envp[])
  97 {
  98     os_vm_page_size = BACKEND_PAGE_BYTES;
  99
 100 #ifdef __NetBSD__
 101     netbsd_init();
 102 #elif defined(LISP_FEATURE_FREEBSD)
 103     freebsd_init();
 104 #elif defined(__OpenBSD__)
 105     openbsd_init();
 106 #elif defined(LISP_FEATURE_DARWIN)
 107     darwin_init();
 108 #elif defined(__DragonFly__)
 109     dragonfly_init();
 110 #endif
 111 }
 112
 113 sigset_t *
 114 os_context_sigmask_addr(os_context_t *context)
 115 {
 116     /* (Unlike most of the other context fields that we access, the
 117      * signal mask field is a field of the basic, outermost context
 118      * struct itself both in FreeBSD 4.0 and in OpenBSD 2.6.) */
 119 #if defined(LISP_FEATURE_FREEBSD) || defined(__NetBSD__) || defined(LISP_FEATURE_DARWIN) \
 120     || defined(__DragonFly__)
 121     return &context->uc_sigmask;
 122 #elif defined (__OpenBSD__)
 123     return &context->sc_mask;
 124 #else
 125 #error unsupported BSD variant
 126 #endif
 127 }
 128
 129 os_vm_address_t
 130 os_validate(os_vm_address_t addr, os_vm_size_t len)
 131 {
 132     int flags = MAP_PRIVATE | MAP_ANON;
 133
 134     if (addr)
 135         flags |= MAP_FIXED;
 136
 137 #ifdef __NetBSD__
 138     if (addr) {
 139         os_vm_address_t curaddr = addr;
 140
 141         while (len > 0) {
 142             os_vm_address_t resaddr;
 143             os_vm_size_t curlen = MIN(max_allocation_size, len);
 144
 145             resaddr = mmap(curaddr, curlen, OS_VM_PROT_ALL, flags, -1, 0);
 146
 147             if (resaddr == (os_vm_address_t) - 1) {
 148                 perror("mmap");
 149
 150                 while (curaddr > addr) {
 151                     curaddr -= max_allocation_size;
 152                     munmap(curaddr, max_allocation_size);
 153                 }
 154
 155                 return NULL;
 156             }
 157
 158             curaddr += curlen;
 159             len -= curlen;
 160         }
 161     } else {
 162 #endif
 163      addr = mmap(addr, len, OS_VM_PROT_ALL, flags, -1, 0);
 164 #ifdef __NetBSD__
 165     }
 166 #endif
 167
 168     if (addr == MAP_FAILED) {
 169         perror("mmap");
 170         return NULL;
 171     }
 172
 173     return addr;
 174 }
 175
 176 void
 177 os_invalidate(os_vm_address_t addr, os_vm_size_t len)
 178 {
 179     if (munmap(addr, len) == -1)
 180         perror("munmap");
 181 }
 182
 183 os_vm_address_t
 184 os_map(int fd, int offset, os_vm_address_t addr, os_vm_size_t len)
 185 {
 186     addr = mmap(addr, len,
 187                 OS_VM_PROT_ALL,
 188                 MAP_PRIVATE | MAP_FILE | MAP_FIXED,
 189                 fd, (off_t) offset);
 190
 191     if (addr == MAP_FAILED) {
 192         perror("mmap");
 193         lose("unexpected mmap(..) failure\n");
 194     }
 195
 196     return addr;
 197 }
 198
 199 void
 200 os_protect(os_vm_address_t address, os_vm_size_t length, os_vm_prot_t prot)
 201 {
 202     if (mprotect(address, length, prot) == -1) {
 203         perror("mprotect");
 204     }
 205 }
 206 \f
 207 static boolean
 208 in_range_p(os_vm_address_t a, lispobj sbeg, size_t slen)
 209 {
 210     char* beg = (char*) sbeg;
 211     char* end = (char*) sbeg + slen;
 212     char* adr = (char*) a;
 213     return (adr >= beg && adr < end);
 214 }
 215
 216 boolean
 217 is_valid_lisp_addr(os_vm_address_t addr)
 218 {
 219     struct thread *th;
 220
 221     if (in_range_p(addr, READ_ONLY_SPACE_START, READ_ONLY_SPACE_SIZE) ||
 222         in_range_p(addr, STATIC_SPACE_START, STATIC_SPACE_SIZE) ||
 223         in_range_p(addr, DYNAMIC_SPACE_START, dynamic_space_size))
 224         return 1;
 225     for_each_thread(th) {
 226         if (((os_vm_address_t)th->control_stack_start <= addr) &&
 227             (addr < (os_vm_address_t)th->control_stack_end))
 228             return 1;
 229         if (in_range_p(addr, (lispobj) th->binding_stack_start,
 230                        BINDING_STACK_SIZE))
 231             return 1;
 232     }
 233     return 0;
 234 }
 235 \f
 236 /*
 237  * any OS-dependent special low-level handling for signals
 238  */
 239
 240 #if defined LISP_FEATURE_GENCGC
 241
 242 /*
 243  * The GENCGC needs to be hooked into whatever signal is raised for
 244  * page fault on this OS.
 245  */
 246
 247 void
 248 memory_fault_handler(int signal, siginfo_t *siginfo, os_context_t *context)
 249 {
 250     void *fault_addr = arch_get_bad_addr(signal, siginfo, context);
 251
 252 #if defined(LISP_FEATURE_RESTORE_TLS_SEGMENT_REGISTER_FROM_CONTEXT)
 253     FSHOW_SIGNAL((stderr, "/ TLS: restoring fs: %p in memory_fault_handler\n",
 254                   *CONTEXT_ADDR_FROM_STEM(fs)));
 255     os_restore_tls_segment_register(context);
 256 #endif
 257
 258     FSHOW((stderr, "Memory fault at: %p, PC: %p\n", fault_addr, *os_context_pc_addr(context)));
 259
 260 #ifdef LISP_FEATURE_SB_SAFEPOINT
 261     if (!handle_safepoint_violation(context, fault_addr))
 262 #endif
 263
 264     if (!gencgc_handle_wp_violation(fault_addr))
 265         if(!handle_guard_page_triggered(context,fault_addr))
 266             lisp_memory_fault_error(context, fault_addr);
 267 }
 268
 269 #if defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 270 void
 271 mach_error_memory_fault_handler(int signal, siginfo_t *siginfo,
 272                                 os_context_t *context) {
 273     lose("Unhandled memory fault. Exiting.");
 274 }
 275 #endif
 276
 277 void
 278 os_install_interrupt_handlers(void)
 279 {
 280     SHOW("os_install_interrupt_handlers()/bsd-os/defined(GENCGC)");
 281 #if defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 282     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 283                                                  mach_error_memory_fault_handler);
 284 #else
 285     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 286 #if defined(LISP_FEATURE_FREEBSD) && !defined(__GLIBC__)
 287                                                  (__siginfohandler_t *)
 288 #endif
 289                                                  memory_fault_handler);
 290 #endif
 291
 292 #ifdef LISP_FEATURE_SB_THREAD
 293 # ifdef LISP_FEATURE_SB_SAFEPOINT
 294 #  ifdef LISP_FEATURE_SB_THRUPTION
 295     undoably_install_low_level_interrupt_handler(SIGPIPE, thruption_handler);
 296 #  endif
 297 # else
 298     undoably_install_low_level_interrupt_handler(SIG_STOP_FOR_GC,
 299                                                  sig_stop_for_gc_handler);
 300 # endif
 301 #endif
 302     SHOW("leaving os_install_interrupt_handlers()");
 303 }
 304
 305 #else /* Currently PPC/Darwin/Cheney only */
 306
 307 static void
 308 sigsegv_handler(int signal, siginfo_t *info, os_context_t *context)
 309 {
 310 #if 0
 311     unsigned int pc =  (unsigned int *)(*os_context_pc_addr(context));
 312 #endif
 313     os_vm_address_t addr;
 314
 315     addr = arch_get_bad_addr(signal, info, context);
 316     if (!cheneygc_handle_wp_violation(context, addr))
 317         if (!handle_guard_page_triggered(context, addr))
 318             interrupt_handle_now(signal, info, context);
 319 }
 320
 321 void
 322 os_install_interrupt_handlers(void)
 323 {
 324     SHOW("os_install_interrupt_handlers()/bsd-os/!defined(GENCGC)");
 325     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 326                                                  sigsegv_handler);
 327 }
 328
 329 #endif /* defined GENCGC */
 330
 331 #ifdef __NetBSD__
 332 static void netbsd_init()
 333 {
 334     struct rlimit rl;
 335     int mib[2], osrev;
 336     size_t len;
 337
 338     /* Are we running on a sufficiently functional kernel? */
 339     mib[0] = CTL_KERN;
 340     mib[1] = KERN_OSREV;
 341
 342     len = sizeof(osrev);
 343     sysctl(mib, 2, &osrev, &len, NULL, 0);
 344
 345     /* If we're older than 2.0... */
 346     if (osrev < 200000000) {
 347         fprintf(stderr, "osrev = %d (needed at least 200000000).\n", osrev);
 348         lose("NetBSD kernel too old to run sbcl.\n");
 349     }
 350
 351     /* NetBSD counts mmap()ed space against the process's data size limit,
 352      * so yank it up. This might be a nasty thing to do? */
 353     getrlimit (RLIMIT_DATA, &rl);
 354     if (rl.rlim_cur < rl.rlim_max) {
 355         rl.rlim_cur = rl.rlim_max;
 356         if (setrlimit (RLIMIT_DATA, &rl) < 0) {
 357             fprintf (stderr,
 358                      "RUNTIME WARNING: unable to raise process data size limit:\n\
 359 %s.\n\
 360 The system may fail to start.\n",
 361                      strerror(errno));
 362         }
 363     }
 364     max_allocation_size = (os_vm_size_t)((rl.rlim_cur / 2) &
 365       ~(32 * 1024 * 1024));
 366
 367 #ifdef LISP_FEATURE_X86
 368     {
 369         size_t len;
 370         int sse;
 371
 372         len = sizeof(sse);
 373         if (sysctlbyname("machdep.sse", &sse, &len,
 374                          NULL, 0) == 0 && sse != 0) {
 375             /* Use the SSE detector */
 376             fast_bzero_pointer = fast_bzero_detect;
 377         }
 378      }
 379 #endif /* LISP_FEATURE_X86 */
 380 }
 381
 382 /* Various routines in NetBSD's C library are compatibility wrappers
 383    for old versions. Programs must be processed by the C toolchain in
 384    order to get up-to-date definitions of such routines. */
 385 /* The stat-family, opendir, and readdir are used only in sb-posix, as
 386    of 2007-01-16. -- RMK */
 387 int
 388 _stat(const char *path, struct stat *sb)
 389 {
 390     return stat(path, sb);
 391 }
 392 int
 393 _lstat(const char *path, struct stat *sb)
 394 {
 395     return lstat(path, sb);
 396 }
 397 int
 398 _fstat(int fd, struct stat *sb)
 399 {
 400     return fstat(fd, sb);
 401 }
 402
 403 DIR *
 404 _opendir(const char *filename)
 405 {
 406     return opendir(filename);
 407 }
 408 struct dirent *
 409 _readdir(DIR *dirp)
 410 {
 411     return readdir(dirp);
 412 }
 413
 414 int
 415 _utime(const char *file, const struct utimbuf *timep)
 416 {
 417     return utime(file, timep);
 418 }
 419
 420 /* Used in sb-bsd-sockets. */
 421 int
 422 _socket(int domain, int type, int protocol)
 423 {
 424     return socket(domain, type, protocol);
 425 }
 426 #endif /* __NetBSD__ */
 427
 428 #if defined(LISP_FEATURE_FREEBSD)
 429 #ifndef __GLIBC__
 430 extern int getosreldate(void);
 431 #endif
 432
 433 int sig_memory_fault;
 434
 435 static void freebsd_init()
 436 {
 437     /* Memory fault signal on FreeBSD was changed from SIGBUS to
 438      * SIGSEGV. */
 439 #ifdef __GLIBC__
 440         sig_memory_fault = SIGSEGV;
 441 #else
 442     if (getosreldate() < 700004)
 443         sig_memory_fault = SIGBUS;
 444     else
 445         sig_memory_fault = SIGSEGV;
 446 #endif
 447
 448     /* Quote from sbcl-devel (NIIMI Satoshi): "Some OSes, like FreeBSD
 449      * 4.x with GENERIC kernel, does not enable SSE support even on
 450      * SSE capable CPUs". Detect this situation and skip the
 451      * fast_bzero sse/base selection logic that's normally done in
 452      * x86-assem.S.
 453      */
 454 #ifdef LISP_FEATURE_X86
 455     {
 456         size_t len;
 457         int instruction_sse;
 458
 459         len = sizeof(instruction_sse);
 460         if (sysctlbyname("hw.instruction_sse", &instruction_sse, &len,
 461                          NULL, 0) == 0 && instruction_sse != 0) {
 462             /* Use the SSE detector */
 463             fast_bzero_pointer = fast_bzero_detect;
 464         }
 465     }
 466 #endif /* LISP_FEATURE_X86 */
 467 }
 468
 469 #if defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_SB_FUTEX) \
 470     && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
 471 int
 472 futex_wait(int *lock_word, long oldval, long sec, unsigned long usec)
 473 {
 474     struct timespec timeout;
 475     int ret;
 476
 477     if (sec < 0)
 478         ret = umtx_wait((void *)lock_word, oldval, NULL);
 479     else {
 480         timeout.tv_sec = sec;
 481         timeout.tv_nsec = usec * 1000;
 482         ret = umtx_wait((void *)lock_word, oldval, &timeout);
 483     }
 484
 485     switch (ret) {
 486     case 0:
 487         return 0;
 488     case ETIMEDOUT:
 489         return 1;
 490     case EINTR:
 491         return 2;
 492     default:
 493         /* EWOULDBLOCK and others, need to check the lock */
 494         return -1;
 495     }
 496 }
 497
 498 int
 499 futex_wake(int *lock_word, int n)
 500 {
 501     return umtx_wake((void *)lock_word, n);
 502 }
 503 #endif
 504 #endif /* __FreeBSD__ */
 505
 506 #ifdef __DragonFly__
 507 static void dragonfly_init()
 508 {
 509 #ifdef LISP_FEATURE_X86
 510     size_t len;
 511     int instruction_sse;
 512
 513     len = sizeof(instruction_sse);
 514     if (sysctlbyname("hw.instruction_sse", &instruction_sse, &len,
 515                      NULL, 0) == 0 && instruction_sse != 0) {
 516         /* Use the SSE detector */
 517         fast_bzero_pointer = fast_bzero_detect;
 518     }
 519 #endif /* LISP_FEATURE_X86 */
 520 }
 521
 522
 523 #if defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_SB_FUTEX) \
 524     && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
 525 int
 526 futex_wait(int *lock_word, long oldval, long sec, unsigned long usec)
 527 {
 528     int ret;
 529
 530     if (sec < 0)
 531         ret = umtx_sleep(lock_word, oldval, 0);
 532     else {
 533         int count = usec + 1000000 * sec;
 534         ret = umtx_sleep(lock_word, oldval, count);
 535     }
 536
 537     if (ret == 0) return 0;
 538     else {
 539         switch (errno) {
 540         case EWOULDBLOCK: // Operation timed out
 541             return 1;
 542         case EINTR:
 543             return 2;
 544         default: // Such as EINVAL or EBUSY
 545             return -1;
 546         }
 547     }
 548 }
 549
 550 int
 551 futex_wake(int *lock_word, int n)
 552 {
 553     return umtx_wakeup(lock_word, n);
 554 }
 555 #endif
 556 #endif /* __DragonFly__ */
 557
 558 #ifdef LISP_FEATURE_DARWIN
 559 /* defined in ppc-darwin-os.c instead */
 560 #elif defined(LISP_FEATURE_FREEBSD)
 561 #ifndef KERN_PROC_PATHNAME
 562 #define KERN_PROC_PATHNAME 12
 563 #endif
 564
 565 char *
 566 os_get_runtime_executable_path(int external)
 567 {
 568     char path[PATH_MAX + 1];
 569
 570 #ifndef __GLIBC__
 571     if (getosreldate() >= 600024) {
 572 #endif
 573         /* KERN_PROC_PATHNAME is available */
 574         size_t len = PATH_MAX + 1;
 575         int mib[4];
 576
 577         mib[0] = CTL_KERN;
 578         mib[1] = KERN_PROC;
 579         mib[2] = KERN_PROC_PATHNAME;
 580         mib[3] = -1;
 581         if (sysctl(mib, 4, &path, &len, NULL, 0) != 0)
 582             return NULL;
 583 #ifndef __GLIBC__
 584     } else {
 585         int size;
 586         size = readlink("/proc/curproc/file", path, sizeof(path) - 1);
 587         if (size < 0)
 588             return NULL;
 589         path[size] = '\0';
 590     }
 591 #endif
 592     if (strcmp(path, "unknown") == 0)
 593         return NULL;
 594     return copied_string(path);
 595 }
 596 #elif defined(LISP_FEATURE_DRAGONFLY)
 597 char *
 598 os_get_runtime_executable_path(int external)
 599 {
 600     char path[PATH_MAX + 1];
 601     int size = readlink("/proc/curproc/file", path, sizeof(path) - 1);
 602     if (size < 0)
 603         return NULL;
 604     path[size] = '\0';
 605
 606     if (strcmp(path, "unknown") == 0)
 607         return NULL;
 608     return copied_string(path);
 609 }
 610 #elif defined(LISP_FEATURE_NETBSD) || defined(LISP_FEATURE_OPENBSD)
 611 char *
 612 os_get_runtime_executable_path(int external)
 613 {
 614     struct stat sb;
 615     if (!external && stat("/proc/curproc/file", &sb) == 0)
 616         return copied_string("/proc/curproc/file");
 617     return NULL;
 618 }
 619 #else /* Not DARWIN or FREEBSD or NETBSD or OPENBSD or DragonFly */
 620 char *
 621 os_get_runtime_executable_path(int external)
 622 {
 623     return NULL;
 624 }
 625 #endif
 626
 627 #ifdef __OpenBSD__
 628
 629 int openbsd_use_fxsave = 0;
 630
 631 void
 632 openbsd_init()
 633 {
 634 #ifdef LISP_FEATURE_X86
 635     int mib[2];
 636     size_t size;
 637 #endif
 638     /*
 639      * Show a warning if it looks like the memory available after
 640      * allocating the spaces won't be at least this much.
 641      */
 642 #ifdef LISP_FEATURE_X86_64
 643     const int wantfree = 64 * 1024 * 1024;
 644 #else
 645     const int wantfree = 32 * 1024 * 1024;
 646 #endif
 647     struct rlimit rl;
 648
 649 #ifdef LISP_FEATURE_X86
 650     /* Save the machdep.osfxsr sysctl for use by os_restore_fp_control() */
 651     mib[0] = CTL_MACHDEP;
 652     mib[1] = CPU_OSFXSR;
 653     size = sizeof (openbsd_use_fxsave);
 654     sysctl(mib, 2, &openbsd_use_fxsave, &size, NULL, 0);
 655 #endif
 656
 657     /* OpenBSD, like NetBSD, counts mmap()ed space against the
 658      * process's data size limit. If the soft limit is lower than the
 659      * hard limit then try to yank it up, this lets users in the
 660      * "staff" or "daemon" login classes run sbcl with larger dynamic
 661      * space sizes.
 662      */
 663     getrlimit (RLIMIT_DATA, &rl);
 664     if (rl.rlim_cur < rl.rlim_max) {
 665         rl.rlim_cur = rl.rlim_max;
 666         if (setrlimit (RLIMIT_DATA, &rl) < 0) {
 667             fprintf (stderr,
 668                      "RUNTIME WARNING: unable to raise process data size limit:\n\
 669   %s.\n\
 670 The system may fail to start.\n",
 671                      strerror(errno));
 672         }
 673     }
 674
 675     /*
 676      * Display a (hopefully) helpful warning if it looks like we won't
 677      * be able to allocate enough memory.
 678      */
 679     getrlimit (RLIMIT_DATA, &rl);
 680     if (dynamic_space_size + READ_ONLY_SPACE_SIZE + STATIC_SPACE_SIZE +
 681         LINKAGE_TABLE_SPACE_SIZE + wantfree > rl.rlim_cur)
 682         fprintf (stderr,
 683                  "RUNTIME WARNING: data size resource limit may be too low,\n"
 684                  "  try decreasing the dynamic space size with --dynamic-space-size\n"
 685                  "  or raising the datasize or datasize-max limits in /etc/login.conf\n");
 686 }
 687
 688 /* OpenBSD's dlsym() relies on the gcc bulitin
 689  * __builtin_return_address(0) returning an address in the
 690  * executable's text segment, but when called from lisp it will return
 691  * an address in the dynamic space.  Work around this by calling this
 692  * wrapper function instead. Note that tail-call optimization will
 693  * defeat this, disable it by saving the dlsym() return value in a
 694  * volatile variable.
 695 */
 696 void *
 697 os_dlsym(void *handle, const char *symbol)
 698 {
 699     void * volatile ret = dlsym(handle, symbol);
 700     return ret;
 701 }
 702
 703 #endif
 704
 705 #if defined(LISP_FEATURE_SB_WTIMER) && !defined(LISP_FEATURE_DARWIN)
 706 /*
 707  * Waitable timer implementation for the safepoint-based (SIGALRM-free)
 708  * timer facility using kqueue.
 709  */
 710 int
 711 os_create_wtimer()
 712 {
 713     int kq = kqueue();
 714     if (kq == -1)
 715         lose("os_create_wtimer: kqueue");
 716     return kq;
 717 }
 718
 719 int
 720 os_wait_for_wtimer(int kq)
 721 {
 722     struct kevent ev;
 723     int n;
 724     if ( (n = kevent(kq, 0, 0, &ev, 1, 0)) == -1) {
 725         if (errno != EINTR)
 726             lose("os_wtimer_listen failed");
 727         n = 0;
 728     }
 729     return n != 1;
 730 }
 731
 732 void
 733 os_close_wtimer(int kq)
 734 {
 735     if (close(kq) == -1)
 736         lose("os_close_wtimer failed");
 737 }
 738
 739 void
 740 os_set_wtimer(int kq, int sec, int nsec)
 741 {
 742     long long msec
 743         = ((long long) sec) * 1000 + (long long) (nsec+999999) / 1000000;
 744     if (msec > INT_MAX) msec = INT_MAX;
 745
 746     struct kevent ev;
 747     EV_SET(&ev, 1, EVFILT_TIMER, EV_ADD|EV_ENABLE|EV_ONESHOT, 0, (int)msec, 0);
 748     if (kevent(kq, &ev, 1, 0, 0, 0) == -1)
 749         perror("os_set_wtimer: kevent");
 750 }
 751
 752 void
 753 os_cancel_wtimer(int kq)
 754 {
 755     struct kevent ev;
 756     EV_SET(&ev, 1, EVFILT_TIMER, EV_DISABLE, 0, 0, 0);
 757     if (kevent(kq, &ev, 1, 0, 0, 0) == -1 && errno != ENOENT)
 758         perror("os_cancel_wtimer: kevent");
 759 }
 760 #endif