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Annotation of OpenXM_contrib2/asir2000/gc5.3/solaris_threads.c, Revision 1.1

1.1     ! noro        1: /*
        !             2:  * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
        !             3:  *
        !             4:  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
        !             5:  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
        !             6:  *
        !             7:  * Permission is hereby granted to use or copy this program
        !             8:  * for any purpose,  provided the above notices are retained on all copies.
        !             9:  * Permission to modify the code and to distribute modified code is granted,
        !            10:  * provided the above notices are retained, and a notice that the code was
        !            11:  * modified is included with the above copyright notice.
        !            12:  */
        !            13: /*
        !            14:  * Support code for Solaris threads.  Provides functionality we wish Sun
        !            15:  * had provided.  Relies on some information we probably shouldn't rely on.
        !            16:  */
        !            17: /* Boehm, September 14, 1994 4:44 pm PDT */
        !            18:
        !            19: # if defined(SOLARIS_THREADS)
        !            20:
        !            21: # include "gc_priv.h"
        !            22: # include "solaris_threads.h"
        !            23: # include <thread.h>
        !            24: # include <synch.h>
        !            25: # include <signal.h>
        !            26: # include <fcntl.h>
        !            27: # include <sys/types.h>
        !            28: # include <sys/mman.h>
        !            29: # include <sys/time.h>
        !            30: # include <sys/resource.h>
        !            31: # include <sys/stat.h>
        !            32: # include <sys/syscall.h>
        !            33: # include <sys/procfs.h>
        !            34: # include <sys/lwp.h>
        !            35: # include <sys/reg.h>
        !            36: # define _CLASSIC_XOPEN_TYPES
        !            37: # include <unistd.h>
        !            38: # include <errno.h>
        !            39:
        !            40: /*
        !            41:  * This is the default size of the LWP arrays. If there are more LWPs
        !            42:  * than this when a stop-the-world GC happens, set_max_lwps will be
        !            43:  * called to cope.
        !            44:  * This must be higher than the number of LWPs at startup time.
        !            45:  * The threads library creates a thread early on, so the min. is 3
        !            46:  */
        !            47: # define DEFAULT_MAX_LWPS      4
        !            48:
        !            49: #undef thr_join
        !            50: #undef thr_create
        !            51: #undef thr_suspend
        !            52: #undef thr_continue
        !            53:
        !            54: cond_t GC_prom_join_cv;                /* Broadcast when any thread terminates */
        !            55: cond_t GC_create_cv;           /* Signalled when a new undetached      */
        !            56:                                /* thread starts.                       */
        !            57:
        !            58:
        !            59: #ifdef MMAP_STACKS
        !            60: static int GC_zfd;
        !            61: #endif /* MMAP_STACKS */
        !            62:
        !            63: /* We use the allocation lock to protect thread-related data structures. */
        !            64:
        !            65: /* We stop the world using /proc primitives.  This makes some  */
        !            66: /* minimal assumptions about the threads implementation.       */
        !            67: /* We don't play by the rules, since the rules make this       */
        !            68: /* impossible (as of Solaris 2.3).  Also note that as of       */
        !            69: /* Solaris 2.3 the various thread and lwp suspension           */
        !            70: /* primitives failed to stop threads by the time the request   */
        !            71: /* is completed.                                               */
        !            72:
        !            73:
        !            74: static sigset_t old_mask;
        !            75:
        !            76: /* Sleep for n milliseconds, n < 1000  */
        !            77: void GC_msec_sleep(int n)
        !            78: {
        !            79:     struct timespec ts;
        !            80:
        !            81:     ts.tv_sec = 0;
        !            82:     ts.tv_nsec = 1000000*n;
        !            83:     if (syscall(SYS_nanosleep, &ts, 0) < 0) {
        !            84:        ABORT("nanosleep failed");
        !            85:     }
        !            86: }
        !            87: /* Turn off preemption;  gross but effective.                  */
        !            88: /* Caller has allocation lock.                         */
        !            89: /* Actually this is not needed under Solaris 2.3 and   */
        !            90: /* 2.4, but hopefully that'll change.                  */
        !            91: void preempt_off()
        !            92: {
        !            93:     sigset_t set;
        !            94:
        !            95:     (void)sigfillset(&set);
        !            96:     sigdelset(&set, SIGABRT);
        !            97:     syscall(SYS_sigprocmask, SIG_SETMASK, &set, &old_mask);
        !            98: }
        !            99:
        !           100: void preempt_on()
        !           101: {
        !           102:     syscall(SYS_sigprocmask, SIG_SETMASK, &old_mask, NULL);
        !           103: }
        !           104:
        !           105: int GC_main_proc_fd = -1;
        !           106:
        !           107:
        !           108: struct lwp_cache_entry {
        !           109:     lwpid_t lc_id;
        !           110:     int lc_descr;      /* /proc file descriptor.       */
        !           111: }  GC_lwp_cache_default[DEFAULT_MAX_LWPS];
        !           112:
        !           113: static int max_lwps = DEFAULT_MAX_LWPS;
        !           114: static struct lwp_cache_entry *GC_lwp_cache = GC_lwp_cache_default;
        !           115:
        !           116: static prgregset_t GC_lwp_registers_default[DEFAULT_MAX_LWPS];
        !           117: static prgregset_t *GC_lwp_registers = GC_lwp_registers_default;
        !           118:
        !           119: /* Return a file descriptor for the /proc entry corresponding  */
        !           120: /* to the given lwp.  The file descriptor may be stale if the  */
        !           121: /* lwp exited and a new one was forked.                                */
        !           122: static int open_lwp(lwpid_t id)
        !           123: {
        !           124:     int result;
        !           125:     static int next_victim = 0;
        !           126:     register int i;
        !           127:
        !           128:     for (i = 0; i < max_lwps; i++) {
        !           129:        if (GC_lwp_cache[i].lc_id == id) return(GC_lwp_cache[i].lc_descr);
        !           130:     }
        !           131:     result = syscall(SYS_ioctl, GC_main_proc_fd, PIOCOPENLWP, &id);
        !           132:     /*
        !           133:      * If PIOCOPENLWP fails, try closing fds in the cache until it succeeds.
        !           134:      */
        !           135:     if (result < 0 && errno == EMFILE) {
        !           136:            for (i = 0; i < max_lwps; i++) {
        !           137:                if (GC_lwp_cache[i].lc_id != 0) {
        !           138:                        (void)syscall(SYS_close, GC_lwp_cache[i].lc_descr);
        !           139:                        result = syscall(SYS_ioctl, GC_main_proc_fd, PIOCOPENLWP, &id);
        !           140:                        if (result >= 0 || (result < 0 && errno != EMFILE))
        !           141:                                break;
        !           142:                }
        !           143:            }
        !           144:     }
        !           145:     if (result < 0) {
        !           146:        if (errno == EMFILE) {
        !           147:                ABORT("Too many open files");
        !           148:        }
        !           149:         return(-1) /* exited? */;
        !           150:     }
        !           151:     if (GC_lwp_cache[next_victim].lc_id != 0)
        !           152:         (void)syscall(SYS_close, GC_lwp_cache[next_victim].lc_descr);
        !           153:     GC_lwp_cache[next_victim].lc_id = id;
        !           154:     GC_lwp_cache[next_victim].lc_descr = result;
        !           155:     if (++next_victim >= max_lwps)
        !           156:        next_victim = 0;
        !           157:     return(result);
        !           158: }
        !           159:
        !           160: static void uncache_lwp(lwpid_t id)
        !           161: {
        !           162:     register int i;
        !           163:
        !           164:     for (i = 0; i < max_lwps; i++) {
        !           165:        if (GC_lwp_cache[i].lc_id == id) {
        !           166:            (void)syscall(SYS_close, GC_lwp_cache[id].lc_descr);
        !           167:            GC_lwp_cache[i].lc_id = 0;
        !           168:            break;
        !           169:        }
        !           170:     }
        !           171: }
        !           172:        /* Sequence of current lwp ids  */
        !           173: static lwpid_t GC_current_ids_default[DEFAULT_MAX_LWPS + 1];
        !           174: static lwpid_t *GC_current_ids = GC_current_ids_default;
        !           175:
        !           176:        /* Temporary used below (can be big if large number of LWPs) */
        !           177: static lwpid_t last_ids_default[DEFAULT_MAX_LWPS + 1];
        !           178: static lwpid_t *last_ids = last_ids_default;
        !           179:
        !           180:
        !           181: #define ROUNDUP(n)    WORDS_TO_BYTES(ROUNDED_UP_WORDS(n))
        !           182:
        !           183: static void set_max_lwps(GC_word n)
        !           184: {
        !           185:     char *mem;
        !           186:     char *oldmem;
        !           187:     int required_bytes = ROUNDUP(n * sizeof(struct lwp_cache_entry))
        !           188:        + ROUNDUP(n * sizeof(prgregset_t))
        !           189:        + ROUNDUP((n + 1) * sizeof(lwpid_t))
        !           190:        + ROUNDUP((n + 1) * sizeof(lwpid_t));
        !           191:
        !           192:     GC_expand_hp_inner(divHBLKSZ((word)required_bytes));
        !           193:     oldmem = mem = GC_scratch_alloc(required_bytes);
        !           194:     if (0 == mem) ABORT("No space for lwp data structures");
        !           195:
        !           196:     /*
        !           197:      * We can either flush the old lwp cache or copy it over. Do the latter.
        !           198:      */
        !           199:     memcpy(mem, GC_lwp_cache, max_lwps * sizeof(struct lwp_cache_entry));
        !           200:     GC_lwp_cache = (struct lwp_cache_entry*)mem;
        !           201:     mem += ROUNDUP(n * sizeof(struct lwp_cache_entry));
        !           202:
        !           203:     BZERO(GC_lwp_registers, max_lwps * sizeof(GC_lwp_registers[0]));
        !           204:     GC_lwp_registers = (prgregset_t *)mem;
        !           205:     mem += ROUNDUP(n * sizeof(prgregset_t));
        !           206:
        !           207:
        !           208:     GC_current_ids = (lwpid_t *)mem;
        !           209:     mem += ROUNDUP((n + 1) * sizeof(lwpid_t));
        !           210:
        !           211:     last_ids = (lwpid_t *)mem;
        !           212:     mem += ROUNDUP((n + 1)* sizeof(lwpid_t));
        !           213:
        !           214:     if (mem > oldmem + required_bytes)
        !           215:        ABORT("set_max_lwps buffer overflow");
        !           216:
        !           217:     max_lwps = n;
        !           218: }
        !           219:
        !           220:
        !           221: /* Stop all lwps in process.  Assumes preemption is off.       */
        !           222: /* Caller has allocation lock (and any other locks he may      */
        !           223: /* need).                                                      */
        !           224: static void stop_all_lwps()
        !           225: {
        !           226:     int lwp_fd;
        !           227:     char buf[30];
        !           228:     prstatus_t status;
        !           229:     register int i;
        !           230:     GC_bool changed;
        !           231:     lwpid_t me = _lwp_self();
        !           232:
        !           233:     if (GC_main_proc_fd == -1) {
        !           234:        sprintf(buf, "/proc/%d", getpid());
        !           235:        GC_main_proc_fd = syscall(SYS_open, buf, O_RDONLY);
        !           236:         if (GC_main_proc_fd < 0) {
        !           237:                if (errno == EMFILE)
        !           238:                        ABORT("/proc open failed: too many open files");
        !           239:                GC_printf1("/proc open failed: errno %d", errno);
        !           240:                abort();
        !           241:         }
        !           242:     }
        !           243:     BZERO(GC_lwp_registers, sizeof (prgregset_t) * max_lwps);
        !           244:     for (i = 0; i < max_lwps; i++)
        !           245:        last_ids[i] = 0;
        !           246:     for (;;) {
        !           247:     if (syscall(SYS_ioctl, GC_main_proc_fd, PIOCSTATUS, &status) < 0)
        !           248:        ABORT("Main PIOCSTATUS failed");
        !           249:        if (status.pr_nlwp < 1)
        !           250:                ABORT("Invalid number of lwps returned by PIOCSTATUS");
        !           251:        if (status.pr_nlwp >= max_lwps) {
        !           252:                set_max_lwps(status.pr_nlwp*2 + 10);
        !           253:                /*
        !           254:                 * The data in the old GC_current_ids and
        !           255:                 * GC_lwp_registers has been trashed. Cleaning out last_ids
        !           256:                 * will make sure every LWP gets re-examined.
        !           257:                 */
        !           258:                for (i = 0; i < max_lwps; i++)
        !           259:                        last_ids[i] = 0;
        !           260:                continue;
        !           261:     }
        !           262:         if (syscall(SYS_ioctl, GC_main_proc_fd, PIOCLWPIDS, GC_current_ids) < 0)
        !           263:             ABORT("PIOCLWPIDS failed");
        !           264:         changed = FALSE;
        !           265:         for (i = 0; GC_current_ids[i] != 0 && i < max_lwps; i++) {
        !           266:             if (GC_current_ids[i] != last_ids[i]) {
        !           267:                 changed = TRUE;
        !           268:                 if (GC_current_ids[i] != me) {
        !           269:                    /* PIOCSTOP doesn't work without a writable         */
        !           270:                    /* descriptor.  And that makes the process          */
        !           271:                    /* undebuggable.                                    */
        !           272:                     if (_lwp_suspend(GC_current_ids[i]) < 0) {
        !           273:                         /* Could happen if the lwp exited */
        !           274:                         uncache_lwp(GC_current_ids[i]);
        !           275:                         GC_current_ids[i] = me; /* ignore */
        !           276:                     }
        !           277:                 }
        !           278:             }
        !           279:         }
        !           280:         /*
        !           281:          * In the unlikely event something does a fork between the
        !           282:         * PIOCSTATUS and the PIOCLWPIDS.
        !           283:          */
        !           284:         if (i >= max_lwps)
        !           285:                continue;
        !           286:         /* All lwps in GC_current_ids != me have been suspended.  Note */
        !           287:         /* that _lwp_suspend is idempotent.                            */
        !           288:         for (i = 0; GC_current_ids[i] != 0; i++) {
        !           289:             if (GC_current_ids[i] != last_ids[i]) {
        !           290:                 if (GC_current_ids[i] != me) {
        !           291:                     lwp_fd = open_lwp(GC_current_ids[i]);
        !           292:                    if (lwp_fd == -1)
        !           293:                    {
        !           294:                            GC_current_ids[i] = me;
        !           295:                            continue;
        !           296:                    }
        !           297:                    /* LWP should be stopped.  Empirically it sometimes */
        !           298:                    /* isn't, and more frequently the PR_STOPPED flag   */
        !           299:                    /* is not set.  Wait for PR_STOPPED.                */
        !           300:                     if (syscall(SYS_ioctl, lwp_fd,
        !           301:                                 PIOCSTATUS, &status) < 0) {
        !           302:                        /* Possible if the descriptor was stale, or */
        !           303:                        /* we encountered the 2.3 _lwp_suspend bug. */
        !           304:                        uncache_lwp(GC_current_ids[i]);
        !           305:                         GC_current_ids[i] = me; /* handle next time. */
        !           306:                     } else {
        !           307:                         while (!(status.pr_flags & PR_STOPPED)) {
        !           308:                             GC_msec_sleep(1);
        !           309:                            if (syscall(SYS_ioctl, lwp_fd,
        !           310:                                        PIOCSTATUS, &status) < 0) {
        !           311:                                ABORT("Repeated PIOCSTATUS failed");
        !           312:                            }
        !           313:                            if (status.pr_flags & PR_STOPPED) break;
        !           314:
        !           315:                            GC_msec_sleep(20);
        !           316:                            if (syscall(SYS_ioctl, lwp_fd,
        !           317:                                        PIOCSTATUS, &status) < 0) {
        !           318:                                ABORT("Repeated PIOCSTATUS failed");
        !           319:                            }
        !           320:                         }
        !           321:                         if (status.pr_who !=  GC_current_ids[i]) {
        !           322:                                /* can happen if thread was on death row */
        !           323:                                uncache_lwp(GC_current_ids[i]);
        !           324:                                GC_current_ids[i] = me; /* handle next time. */
        !           325:                                continue;
        !           326:                         }
        !           327:                         /* Save registers where collector can */
        !           328:                        /* find them.                     */
        !           329:                            BCOPY(status.pr_reg, GC_lwp_registers[i],
        !           330:                                  sizeof (prgregset_t));
        !           331:                     }
        !           332:                 }
        !           333:             }
        !           334:         }
        !           335:         if (!changed) break;
        !           336:         for (i = 0; i < max_lwps; i++) last_ids[i] = GC_current_ids[i];
        !           337:     }
        !           338: }
        !           339:
        !           340: /* Restart all lwps in process.  Assumes preemption is off.    */
        !           341: static void restart_all_lwps()
        !           342: {
        !           343:     int lwp_fd;
        !           344:     register int i;
        !           345:     GC_bool changed;
        !           346:     lwpid_t me = _lwp_self();
        !           347: #   define PARANOID
        !           348:
        !           349:     for (i = 0; GC_current_ids[i] != 0; i++) {
        !           350: #      ifdef PARANOID
        !           351:          if (GC_current_ids[i] != me) {
        !           352:            int lwp_fd = open_lwp(GC_current_ids[i]);
        !           353:            prstatus_t status;
        !           354:
        !           355:            if (lwp_fd < 0) ABORT("open_lwp failed");
        !           356:            if (syscall(SYS_ioctl, lwp_fd,
        !           357:                        PIOCSTATUS, &status) < 0) {
        !           358:                 ABORT("PIOCSTATUS failed in restart_all_lwps");
        !           359:            }
        !           360:            if (memcmp(status.pr_reg, GC_lwp_registers[i],
        !           361:                       sizeof (prgregset_t)) != 0) {
        !           362:                    int j;
        !           363:
        !           364:                    for(j = 0; j < NGREG; j++)
        !           365:                    {
        !           366:                            GC_printf3("%i: %x -> %x\n", j,
        !           367:                                       GC_lwp_registers[i][j],
        !           368:                                       status.pr_reg[j]);
        !           369:                    }
        !           370:                ABORT("Register contents changed");
        !           371:            }
        !           372:            if (!status.pr_flags & PR_STOPPED) {
        !           373:                ABORT("lwp no longer stopped");
        !           374:            }
        !           375: #ifdef SPARC
        !           376:            {
        !           377:                    gwindows_t windows;
        !           378:              if (syscall(SYS_ioctl, lwp_fd,
        !           379:                        PIOCGWIN, &windows) < 0) {
        !           380:                 ABORT("PIOCSTATUS failed in restart_all_lwps");
        !           381:              }
        !           382:              if (windows.wbcnt > 0) ABORT("unsaved register windows");
        !           383:            }
        !           384: #endif
        !           385:          }
        !           386: #      endif /* PARANOID */
        !           387:        if (GC_current_ids[i] == me) continue;
        !           388:         if (_lwp_continue(GC_current_ids[i]) < 0) {
        !           389:             ABORT("Failed to restart lwp");
        !           390:         }
        !           391:     }
        !           392:     if (i >= max_lwps) ABORT("Too many lwps");
        !           393: }
        !           394:
        !           395: GC_bool GC_multithreaded = 0;
        !           396:
        !           397: void GC_stop_world()
        !           398: {
        !           399:     preempt_off();
        !           400:     if (GC_multithreaded)
        !           401:         stop_all_lwps();
        !           402: }
        !           403:
        !           404: void GC_start_world()
        !           405: {
        !           406:     if (GC_multithreaded)
        !           407:         restart_all_lwps();
        !           408:     preempt_on();
        !           409: }
        !           410:
        !           411: void GC_thr_init(void);
        !           412:
        !           413: GC_bool GC_thr_initialized = FALSE;
        !           414:
        !           415: size_t GC_min_stack_sz;
        !           416:
        !           417: size_t GC_page_sz;
        !           418:
        !           419: /*
        !           420:  * stack_head is stored at the top of free stacks
        !           421:  */
        !           422: struct stack_head {
        !           423:        struct stack_head       *next;
        !           424:        ptr_t                   base;
        !           425:        thread_t                owner;
        !           426: };
        !           427:
        !           428: # define N_FREE_LISTS 25
        !           429: struct stack_head *GC_stack_free_lists[N_FREE_LISTS] = { 0 };
        !           430:                /* GC_stack_free_lists[i] is free list for stacks of    */
        !           431:                /* size GC_min_stack_sz*2**i.                           */
        !           432:                /* Free lists are linked through stack_head stored      */                      /* at top of stack.                                     */
        !           433:
        !           434: /* Return a stack of size at least *stack_size.  *stack_size is        */
        !           435: /* replaced by the actual stack size.                          */
        !           436: /* Caller holds allocation lock.                               */
        !           437: ptr_t GC_stack_alloc(size_t * stack_size)
        !           438: {
        !           439:     register size_t requested_sz = *stack_size;
        !           440:     register size_t search_sz = GC_min_stack_sz;
        !           441:     register int index = 0;    /* = log2(search_sz/GC_min_stack_sz) */
        !           442:     register ptr_t base;
        !           443:     register struct stack_head *result;
        !           444:
        !           445:     while (search_sz < requested_sz) {
        !           446:         search_sz *= 2;
        !           447:         index++;
        !           448:     }
        !           449:     if ((result = GC_stack_free_lists[index]) == 0
        !           450:         && (result = GC_stack_free_lists[index+1]) != 0) {
        !           451:         /* Try next size up. */
        !           452:         search_sz *= 2; index++;
        !           453:     }
        !           454:     if (result != 0) {
        !           455:         base =  GC_stack_free_lists[index]->base;
        !           456:         GC_stack_free_lists[index] = GC_stack_free_lists[index]->next;
        !           457:     } else {
        !           458: #ifdef MMAP_STACKS
        !           459:         base = (ptr_t)mmap(0, search_sz + GC_page_sz,
        !           460:                             PROT_READ|PROT_WRITE, MAP_PRIVATE |MAP_NORESERVE,
        !           461:                             GC_zfd, 0);
        !           462:        if (base == (ptr_t)-1)
        !           463:        {
        !           464:                *stack_size = 0;
        !           465:                return NULL;
        !           466:        }
        !           467:
        !           468:        mprotect(base, GC_page_sz, PROT_NONE);
        !           469:        /* Should this use divHBLKSZ(search_sz + GC_page_sz) ? -- cf */
        !           470:        GC_is_fresh((struct hblk *)base, divHBLKSZ(search_sz));
        !           471:        base += GC_page_sz;
        !           472:
        !           473: #else
        !           474:         base = (ptr_t) GC_scratch_alloc(search_sz + 2*GC_page_sz);
        !           475:        if (base == NULL)
        !           476:        {
        !           477:                *stack_size = 0;
        !           478:                return NULL;
        !           479:        }
        !           480:
        !           481:         base = (ptr_t)(((word)base + GC_page_sz) & ~(GC_page_sz - 1));
        !           482:         /* Protect hottest page to detect overflow. */
        !           483: #      ifdef SOLARIS23_MPROTECT_BUG_FIXED
        !           484:             mprotect(base, GC_page_sz, PROT_NONE);
        !           485: #      endif
        !           486:         GC_is_fresh((struct hblk *)base, divHBLKSZ(search_sz));
        !           487:
        !           488:         base += GC_page_sz;
        !           489: #endif
        !           490:     }
        !           491:     *stack_size = search_sz;
        !           492:     return(base);
        !           493: }
        !           494:
        !           495: /* Caller holds  allocationlock.                                       */
        !           496: void GC_stack_free(ptr_t stack, size_t size)
        !           497: {
        !           498:     register int index = 0;
        !           499:     register size_t search_sz = GC_min_stack_sz;
        !           500:     register struct stack_head *head;
        !           501:
        !           502: #ifdef MMAP_STACKS
        !           503:     /* Zero pointers */
        !           504:     mmap(stack, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_NORESERVE|MAP_FIXED,
        !           505:         GC_zfd, 0);
        !           506: #endif
        !           507:     while (search_sz < size) {
        !           508:         search_sz *= 2;
        !           509:         index++;
        !           510:     }
        !           511:     if (search_sz != size) ABORT("Bad stack size");
        !           512:
        !           513:     head = (struct stack_head *)(stack + search_sz - sizeof(struct stack_head));
        !           514:     head->next = GC_stack_free_lists[index];
        !           515:     head->base = stack;
        !           516:     GC_stack_free_lists[index] = head;
        !           517: }
        !           518:
        !           519: void GC_my_stack_limits();
        !           520:
        !           521: /* Notify virtual dirty bit implementation that known empty parts of   */
        !           522: /* stacks do not contain useful data.                                  */
        !           523: /* Caller holds allocation lock.                                       */
        !           524: void GC_old_stacks_are_fresh()
        !           525: {
        !           526: /* No point in doing this for MMAP stacks - and pointers are zero'd out */
        !           527: /* by the mmap in GC_stack_free */
        !           528: #ifndef MMAP_STACKS
        !           529:     register int i;
        !           530:     register struct stack_head *s;
        !           531:     register ptr_t p;
        !           532:     register size_t sz;
        !           533:     register struct hblk * h;
        !           534:     int dummy;
        !           535:
        !           536:     for (i = 0, sz= GC_min_stack_sz; i < N_FREE_LISTS;
        !           537:          i++, sz *= 2) {
        !           538:          for (s = GC_stack_free_lists[i]; s != 0; s = s->next) {
        !           539:              p = s->base;
        !           540:              h = (struct hblk *)(((word)p + HBLKSIZE-1) & ~(HBLKSIZE-1));
        !           541:              if ((ptr_t)h == p) {
        !           542:                  GC_is_fresh((struct hblk *)p, divHBLKSZ(sz));
        !           543:              } else {
        !           544:                  GC_is_fresh((struct hblk *)p, divHBLKSZ(sz) - 1);
        !           545:                  BZERO(p, (ptr_t)h - p);
        !           546:              }
        !           547:          }
        !           548:     }
        !           549: #endif /* MMAP_STACKS */
        !           550:     GC_my_stack_limits();
        !           551: }
        !           552:
        !           553: /* The set of all known threads.  We intercept thread creation and     */
        !           554: /* joins.  We never actually create detached threads.  We allocate all         */
        !           555: /* new thread stacks ourselves.  These allow us to maintain this       */
        !           556: /* data structure.                                                     */
        !           557:
        !           558: # define THREAD_TABLE_SZ 128   /* Must be power of 2   */
        !           559: volatile GC_thread GC_threads[THREAD_TABLE_SZ];
        !           560:
        !           561: /* Add a thread to GC_threads.  We assume it wasn't already there.     */
        !           562: /* Caller holds allocation lock.                                       */
        !           563: GC_thread GC_new_thread(thread_t id)
        !           564: {
        !           565:     int hv = ((word)id) % THREAD_TABLE_SZ;
        !           566:     GC_thread result;
        !           567:     static struct GC_Thread_Rep first_thread;
        !           568:     static GC_bool first_thread_used = FALSE;
        !           569:
        !           570:     if (!first_thread_used) {
        !           571:        result = &first_thread;
        !           572:        first_thread_used = TRUE;
        !           573:        /* Dont acquire allocation lock, since we may already hold it. */
        !           574:     } else {
        !           575:         result = (struct GC_Thread_Rep *)
        !           576:                 GC_generic_malloc_inner(sizeof(struct GC_Thread_Rep), NORMAL);
        !           577:     }
        !           578:     if (result == 0) return(0);
        !           579:     result -> id = id;
        !           580:     result -> next = GC_threads[hv];
        !           581:     GC_threads[hv] = result;
        !           582:     /* result -> finished = 0; */
        !           583:     (void) cond_init(&(result->join_cv), USYNC_THREAD, 0);
        !           584:     return(result);
        !           585: }
        !           586:
        !           587: /* Delete a thread from GC_threads.  We assume it is there.    */
        !           588: /* (The code intentionally traps if it wasn't.)                        */
        !           589: /* Caller holds allocation lock.                               */
        !           590: void GC_delete_thread(thread_t id)
        !           591: {
        !           592:     int hv = ((word)id) % THREAD_TABLE_SZ;
        !           593:     register GC_thread p = GC_threads[hv];
        !           594:     register GC_thread prev = 0;
        !           595:
        !           596:     while (p -> id != id) {
        !           597:         prev = p;
        !           598:         p = p -> next;
        !           599:     }
        !           600:     if (prev == 0) {
        !           601:         GC_threads[hv] = p -> next;
        !           602:     } else {
        !           603:         prev -> next = p -> next;
        !           604:     }
        !           605: }
        !           606:
        !           607: /* Return the GC_thread correpsonding to a given thread_t.     */
        !           608: /* Returns 0 if it's not there.                                        */
        !           609: /* Caller holds  allocation lock.                              */
        !           610: GC_thread GC_lookup_thread(thread_t id)
        !           611: {
        !           612:     int hv = ((word)id) % THREAD_TABLE_SZ;
        !           613:     register GC_thread p = GC_threads[hv];
        !           614:
        !           615:     while (p != 0 && p -> id != id) p = p -> next;
        !           616:     return(p);
        !           617: }
        !           618:
        !           619: # define MAX_ORIG_STACK_SIZE (8 * 1024 * 1024)
        !           620:
        !           621: word GC_get_orig_stack_size() {
        !           622:     struct rlimit rl;
        !           623:     static int warned = 0;
        !           624:     int result;
        !           625:
        !           626:     if (getrlimit(RLIMIT_STACK, &rl) != 0) ABORT("getrlimit failed");
        !           627:     result = (word)rl.rlim_cur & ~(HBLKSIZE-1);
        !           628:     if (result > MAX_ORIG_STACK_SIZE) {
        !           629:        if (!warned) {
        !           630:            WARN("Large stack limit(%ld): only scanning 8 MB", result);
        !           631:            warned = 1;
        !           632:        }
        !           633:        result = MAX_ORIG_STACK_SIZE;
        !           634:     }
        !           635:     return result;
        !           636: }
        !           637:
        !           638: /* Notify dirty bit implementation of unused parts of my stack. */
        !           639: /* Caller holds allocation lock.                               */
        !           640: void GC_my_stack_limits()
        !           641: {
        !           642:     int dummy;
        !           643:     register ptr_t hottest = (ptr_t)((word)(&dummy) & ~(HBLKSIZE-1));
        !           644:     register GC_thread me = GC_lookup_thread(thr_self());
        !           645:     register size_t stack_size = me -> stack_size;
        !           646:     register ptr_t stack;
        !           647:
        !           648:     if (stack_size == 0) {
        !           649:       /* original thread */
        !           650:         /* Empirically, what should be the stack page with lowest      */
        !           651:         /* address is actually inaccessible.                           */
        !           652:         stack_size = GC_get_orig_stack_size() - GC_page_sz;
        !           653:         stack = GC_stackbottom - stack_size + GC_page_sz;
        !           654:     } else {
        !           655:         stack = me -> stack;
        !           656:     }
        !           657:     if (stack > hottest || stack + stack_size < hottest) {
        !           658:        ABORT("sp out of bounds");
        !           659:     }
        !           660:     GC_is_fresh((struct hblk *)stack, divHBLKSZ(hottest - stack));
        !           661: }
        !           662:
        !           663:
        !           664: /* We hold allocation lock.  Should do exactly the right thing if the  */
        !           665: /* world is stopped.  Should not fail if it isn't.                     */
        !           666: void GC_push_all_stacks()
        !           667: {
        !           668:     register int i;
        !           669:     register GC_thread p;
        !           670:     register ptr_t sp = GC_approx_sp();
        !           671:     register ptr_t bottom, top;
        !           672:     struct rlimit rl;
        !           673:
        !           674: #   define PUSH(bottom,top) \
        !           675:       if (GC_dirty_maintained) { \
        !           676:        GC_push_dirty((bottom), (top), GC_page_was_ever_dirty, \
        !           677:                      GC_push_all_stack); \
        !           678:       } else { \
        !           679:         GC_push_all_stack((bottom), (top)); \
        !           680:       }
        !           681:     GC_push_all_stack((ptr_t)GC_lwp_registers,
        !           682:                      (ptr_t)GC_lwp_registers
        !           683:                      + max_lwps * sizeof(GC_lwp_registers[0]));
        !           684:     for (i = 0; i < THREAD_TABLE_SZ; i++) {
        !           685:       for (p = GC_threads[i]; p != 0; p = p -> next) {
        !           686:         if (p -> stack_size != 0) {
        !           687:             bottom = p -> stack;
        !           688:             top = p -> stack + p -> stack_size;
        !           689:         } else {
        !           690:             /* The original stack. */
        !           691:             bottom = GC_stackbottom - GC_get_orig_stack_size() + GC_page_sz;
        !           692:             top = GC_stackbottom;
        !           693:         }
        !           694:         if ((word)sp > (word)bottom && (word)sp < (word)top) bottom = sp;
        !           695:         PUSH(bottom, top);
        !           696:       }
        !           697:     }
        !           698: }
        !           699:
        !           700:
        !           701: int GC_is_thread_stack(ptr_t addr)
        !           702: {
        !           703:     register int i;
        !           704:     register GC_thread p;
        !           705:     register ptr_t bottom, top;
        !           706:     struct rlimit rl;
        !           707:
        !           708:     for (i = 0; i < THREAD_TABLE_SZ; i++) {
        !           709:       for (p = GC_threads[i]; p != 0; p = p -> next) {
        !           710:         if (p -> stack_size != 0) {
        !           711:             if (p -> stack <= addr &&
        !           712:                addr < p -> stack + p -> stack_size)
        !           713:                    return 1;
        !           714:        }
        !           715:       }
        !           716:     }
        !           717: }
        !           718:
        !           719: /* The only thread that ever really performs a thr_join.       */
        !           720: void * GC_thr_daemon(void * dummy)
        !           721: {
        !           722:     void *status;
        !           723:     thread_t departed;
        !           724:     register GC_thread t;
        !           725:     register int i;
        !           726:     register int result;
        !           727:
        !           728:     for(;;) {
        !           729:       start:
        !           730:         result = thr_join((thread_t)0, &departed, &status);
        !           731:        LOCK();
        !           732:        if (result != 0) {
        !           733:            /* No more threads; wait for create. */
        !           734:            for (i = 0; i < THREAD_TABLE_SZ; i++) {
        !           735:                for (t = GC_threads[i]; t != 0; t = t -> next) {
        !           736:                     if (!(t -> flags & (DETACHED | FINISHED))) {
        !           737:                       UNLOCK();
        !           738:                       goto start; /* Thread started just before we */
        !           739:                                  /* acquired the lock.            */
        !           740:                     }
        !           741:                 }
        !           742:             }
        !           743:             cond_wait(&GC_create_cv, &GC_allocate_ml);
        !           744:             UNLOCK();
        !           745:        } else {
        !           746:            t = GC_lookup_thread(departed);
        !           747:            GC_multithreaded--;
        !           748:            if (!(t -> flags & CLIENT_OWNS_STACK)) {
        !           749:                GC_stack_free(t -> stack, t -> stack_size);
        !           750:            }
        !           751:            if (t -> flags & DETACHED) {
        !           752:                GC_delete_thread(departed);
        !           753:            } else {
        !           754:                t -> status = status;
        !           755:                t -> flags |= FINISHED;
        !           756:                cond_signal(&(t -> join_cv));
        !           757:                cond_broadcast(&GC_prom_join_cv);
        !           758:            }
        !           759:            UNLOCK();
        !           760:        }
        !           761:     }
        !           762: }
        !           763:
        !           764: /* We hold the allocation lock, or caller ensures that 2 instances     */
        !           765: /* cannot be invoked concurrently.                                     */
        !           766: void GC_thr_init(void)
        !           767: {
        !           768:     GC_thread t;
        !           769:     thread_t tid;
        !           770:
        !           771:     if (GC_thr_initialized)
        !           772:            return;
        !           773:     GC_thr_initialized = TRUE;
        !           774:     GC_min_stack_sz = ((thr_min_stack() + 32*1024 + HBLKSIZE-1)
        !           775:                       & ~(HBLKSIZE - 1));
        !           776:     GC_page_sz = sysconf(_SC_PAGESIZE);
        !           777: #ifdef MMAP_STACKS
        !           778:     GC_zfd = open("/dev/zero", O_RDONLY);
        !           779:     if (GC_zfd == -1)
        !           780:            ABORT("Can't open /dev/zero");
        !           781: #endif /* MMAP_STACKS */
        !           782:     cond_init(&GC_prom_join_cv, USYNC_THREAD, 0);
        !           783:     cond_init(&GC_create_cv, USYNC_THREAD, 0);
        !           784:     /* Add the initial thread, so we can stop it.      */
        !           785:       t = GC_new_thread(thr_self());
        !           786:       t -> stack_size = 0;
        !           787:       t -> flags = DETACHED | CLIENT_OWNS_STACK;
        !           788:     if (thr_create(0 /* stack */, 0 /* stack_size */, GC_thr_daemon,
        !           789:                   0 /* arg */, THR_DETACHED | THR_DAEMON,
        !           790:                   &tid /* thread_id */) != 0) {
        !           791:        ABORT("Cant fork daemon");
        !           792:     }
        !           793:     thr_setprio(tid, 126);
        !           794: }
        !           795:
        !           796: /* We acquire the allocation lock to prevent races with        */
        !           797: /* stopping/starting world.                                    */
        !           798: /* This is no more correct than the underlying Solaris 2.X     */
        !           799: /* implementation.  Under 2.3 THIS IS BROKEN.                  */
        !           800: int GC_thr_suspend(thread_t target_thread)
        !           801: {
        !           802:     GC_thread t;
        !           803:     int result;
        !           804:
        !           805:     LOCK();
        !           806:     result = thr_suspend(target_thread);
        !           807:     if (result == 0) {
        !           808:        t = GC_lookup_thread(target_thread);
        !           809:        if (t == 0) ABORT("thread unknown to GC");
        !           810:         t -> flags |= SUSPENDED;
        !           811:     }
        !           812:     UNLOCK();
        !           813:     return(result);
        !           814: }
        !           815:
        !           816: int GC_thr_continue(thread_t target_thread)
        !           817: {
        !           818:     GC_thread t;
        !           819:     int result;
        !           820:
        !           821:     LOCK();
        !           822:     result = thr_continue(target_thread);
        !           823:     if (result == 0) {
        !           824:        t = GC_lookup_thread(target_thread);
        !           825:        if (t == 0) ABORT("thread unknown to GC");
        !           826:         t -> flags &= ~SUSPENDED;
        !           827:     }
        !           828:     UNLOCK();
        !           829:     return(result);
        !           830: }
        !           831:
        !           832: int GC_thr_join(thread_t wait_for, thread_t *departed, void **status)
        !           833: {
        !           834:     register GC_thread t;
        !           835:     int result = 0;
        !           836:
        !           837:     LOCK();
        !           838:     if (wait_for == 0) {
        !           839:         register int i;
        !           840:         register GC_bool thread_exists;
        !           841:
        !           842:        for (;;) {
        !           843:          thread_exists = FALSE;
        !           844:          for (i = 0; i < THREAD_TABLE_SZ; i++) {
        !           845:            for (t = GC_threads[i]; t != 0; t = t -> next) {
        !           846:               if (!(t -> flags & DETACHED)) {
        !           847:                 if (t -> flags & FINISHED) {
        !           848:                   goto found;
        !           849:                 }
        !           850:                 thread_exists = TRUE;
        !           851:               }
        !           852:             }
        !           853:           }
        !           854:           if (!thread_exists) {
        !           855:               result = ESRCH;
        !           856:              goto out;
        !           857:           }
        !           858:           cond_wait(&GC_prom_join_cv, &GC_allocate_ml);
        !           859:         }
        !           860:     } else {
        !           861:         t = GC_lookup_thread(wait_for);
        !           862:        if (t == 0 || t -> flags & DETACHED) {
        !           863:            result = ESRCH;
        !           864:            goto out;
        !           865:        }
        !           866:        if (wait_for == thr_self()) {
        !           867:            result = EDEADLK;
        !           868:            goto out;
        !           869:        }
        !           870:        while (!(t -> flags & FINISHED)) {
        !           871:             cond_wait(&(t -> join_cv), &GC_allocate_ml);
        !           872:        }
        !           873:
        !           874:     }
        !           875:   found:
        !           876:     if (status) *status = t -> status;
        !           877:     if (departed) *departed = t -> id;
        !           878:     cond_destroy(&(t -> join_cv));
        !           879:     GC_delete_thread(t -> id);
        !           880:   out:
        !           881:     UNLOCK();
        !           882:     return(result);
        !           883: }
        !           884:
        !           885:
        !           886: int
        !           887: GC_thr_create(void *stack_base, size_t stack_size,
        !           888:               void *(*start_routine)(void *), void *arg, long flags,
        !           889:               thread_t *new_thread)
        !           890: {
        !           891:     int result;
        !           892:     GC_thread t;
        !           893:     thread_t my_new_thread;
        !           894:     word my_flags = 0;
        !           895:     void * stack = stack_base;
        !           896:
        !           897:     LOCK();
        !           898:     if (!GC_thr_initialized)
        !           899:     {
        !           900:     GC_thr_init();
        !           901:     }
        !           902:     GC_multithreaded++;
        !           903:     if (stack == 0) {
        !           904:        if (stack_size == 0) stack_size = 1024*1024;
        !           905:        stack = (void *)GC_stack_alloc(&stack_size);
        !           906:        if (stack == 0) {
        !           907:            GC_multithreaded--;
        !           908:            UNLOCK();
        !           909:            return(ENOMEM);
        !           910:        }
        !           911:     } else {
        !           912:        my_flags |= CLIENT_OWNS_STACK;
        !           913:     }
        !           914:     if (flags & THR_DETACHED) my_flags |= DETACHED;
        !           915:     if (flags & THR_SUSPENDED) my_flags |= SUSPENDED;
        !           916:     result = thr_create(stack, stack_size, start_routine,
        !           917:                        arg, flags & ~THR_DETACHED, &my_new_thread);
        !           918:     if (result == 0) {
        !           919:         t = GC_new_thread(my_new_thread);
        !           920:         t -> flags = my_flags;
        !           921:         if (!(my_flags & DETACHED)) cond_init(&(t -> join_cv), USYNC_THREAD, 0);
        !           922:         t -> stack = stack;
        !           923:         t -> stack_size = stack_size;
        !           924:         if (new_thread != 0) *new_thread = my_new_thread;
        !           925:         cond_signal(&GC_create_cv);
        !           926:     } else {
        !           927:        GC_multithreaded--;
        !           928:         if (!(my_flags & CLIENT_OWNS_STACK)) {
        !           929:            GC_stack_free(stack, stack_size);
        !           930:        }
        !           931:     }
        !           932:     UNLOCK();
        !           933:     return(result);
        !           934: }
        !           935:
        !           936: # else /* SOLARIS_THREADS */
        !           937:
        !           938: #ifndef LINT
        !           939:   int GC_no_sunOS_threads;
        !           940: #endif
        !           941: #endif

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