solaris_threads.c

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/* 
 * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */
/*
 * Support code for Solaris threads.  Provides functionality we wish Sun
 * had provided.  Relies on some information we probably shouldn't rely on.
 */
/* Boehm, September 14, 1994 4:44 pm PDT */

# include "private/gc_priv.h"

# if defined(GC_SOLARIS_THREADS) || defined(GC_SOLARIS_PTHREADS)
# include "private/solaris_threads.h"
# include <thread.h>
# include <synch.h>
# include <signal.h>
# include <fcntl.h>
# include <sys/types.h>
# include <sys/mman.h>
# include <sys/time.h>
# include <sys/resource.h>
# include <sys/stat.h>
# include <sys/syscall.h>
# include <sys/procfs.h>
# include <sys/lwp.h>
# include <sys/reg.h>
# define _CLASSIC_XOPEN_TYPES
# include <unistd.h>
# include <errno.h>

#ifdef HANDLE_FORK
  --> Not yet supported.  Try porting the code from linux_threads.c.
#endif

/*
 * This is the default size of the LWP arrays. If there are more LWPs
 * than this when a stop-the-world GC happens, set_max_lwps will be
 * called to cope.
 * This must be higher than the number of LWPs at startup time.
 * The threads library creates a thread early on, so the min. is 3
 */
# define DEFAULT_MAX_LWPS	4

#undef thr_join
#undef thr_create
#undef thr_suspend
#undef thr_continue

cond_t GC_prom_join_cv;		/* Broadcast when any thread terminates	*/
cond_t GC_create_cv;		/* Signalled when a new undetached	*/
				/* thread starts.			*/
				

#ifdef MMAP_STACKS
static int GC_zfd;
#endif /* MMAP_STACKS */

/* We use the allocation lock to protect thread-related data structures. */

/* We stop the world using /proc primitives.  This makes some	*/
/* minimal assumptions about the threads implementation.	*/
/* We don't play by the rules, since the rules make this	*/
/* impossible (as of Solaris 2.3).  Also note that as of	*/
/* Solaris 2.3 the various thread and lwp suspension		*/
/* primitives failed to stop threads by the time the request	*/
/* is completed.						*/


static sigset_t old_mask;

/* Sleep for n milliseconds, n < 1000	*/
void GC_msec_sleep(int n)
{
    struct timespec ts;
                            
    ts.tv_sec = 0;
    ts.tv_nsec = 1000000*n;
    if (syscall(SYS_nanosleep, &ts, 0) < 0) {
	ABORT("nanosleep failed");
    }
}
/* Turn off preemption;  gross but effective.  		*/
/* Caller has allocation lock.				*/
/* Actually this is not needed under Solaris 2.3 and	*/
/* 2.4, but hopefully that'll change.			*/
void preempt_off()
{
    sigset_t set;

    (void)sigfillset(&set);
    sigdelset(&set, SIGABRT);
    syscall(SYS_sigprocmask, SIG_SETMASK, &set, &old_mask);
}

void preempt_on()
{
    syscall(SYS_sigprocmask, SIG_SETMASK, &old_mask, NULL);
}

int GC_main_proc_fd = -1;


struct lwp_cache_entry {
    lwpid_t lc_id;
    int lc_descr;	/* /proc file descriptor.	*/
}  GC_lwp_cache_default[DEFAULT_MAX_LWPS];

static int max_lwps = DEFAULT_MAX_LWPS;
static struct lwp_cache_entry *GC_lwp_cache = GC_lwp_cache_default;

static prgregset_t GC_lwp_registers_default[DEFAULT_MAX_LWPS];
static prgregset_t *GC_lwp_registers = GC_lwp_registers_default;

/* Return a file descriptor for the /proc entry corresponding	*/
/* to the given lwp.  The file descriptor may be stale if the	*/
/* lwp exited and a new one was forked.				*/
static int open_lwp(lwpid_t id)
{
    int result;
    static int next_victim = 0;
    register int i;
    
    for (i = 0; i < max_lwps; i++) {
    	if (GC_lwp_cache[i].lc_id == id) return(GC_lwp_cache[i].lc_descr);
    }
    result = syscall(SYS_ioctl, GC_main_proc_fd, PIOCOPENLWP, &id);
    /*
     * If PIOCOPENLWP fails, try closing fds in the cache until it succeeds.
     */
    if (result < 0 && errno == EMFILE) {
	    for (i = 0; i < max_lwps; i++) {
		if (GC_lwp_cache[i].lc_id != 0) {
        		(void)syscall(SYS_close, GC_lwp_cache[i].lc_descr);
			result = syscall(SYS_ioctl, GC_main_proc_fd, PIOCOPENLWP, &id);
			if (result >= 0 || (result < 0 && errno != EMFILE))
				break;
		}
	    }
    }
    if (result < 0) {
	if (errno == EMFILE) {
		ABORT("Too many open files");
	}
        return(-1) /* exited? */;
    }
    if (GC_lwp_cache[next_victim].lc_id != 0)
        (void)syscall(SYS_close, GC_lwp_cache[next_victim].lc_descr);
    GC_lwp_cache[next_victim].lc_id = id;
    GC_lwp_cache[next_victim].lc_descr = result;
    if (++next_victim >= max_lwps)
	next_victim = 0;
    return(result);
}

static void uncache_lwp(lwpid_t id)
{
    register int i;
    
    for (i = 0; i < max_lwps; i++) {
    	if (GC_lwp_cache[i].lc_id == id) {
    	    (void)syscall(SYS_close, GC_lwp_cache[id].lc_descr);
    	    GC_lwp_cache[i].lc_id = 0;
    	    break;
    	}
    }
}
	/* Sequence of current lwp ids	*/
static lwpid_t GC_current_ids_default[DEFAULT_MAX_LWPS + 1];
static lwpid_t *GC_current_ids = GC_current_ids_default;

	/* Temporary used below (can be big if large number of LWPs) */
static lwpid_t last_ids_default[DEFAULT_MAX_LWPS + 1];
static lwpid_t *last_ids = last_ids_default;


#define ROUNDUP(n)    WORDS_TO_BYTES(ROUNDED_UP_WORDS(n))

static void set_max_lwps(GC_word n)
{
    char *mem;
    char *oldmem;
    int required_bytes = ROUNDUP(n * sizeof(struct lwp_cache_entry))
	+ ROUNDUP(n * sizeof(prgregset_t))
	+ ROUNDUP((n + 1) * sizeof(lwpid_t))
	+ ROUNDUP((n + 1) * sizeof(lwpid_t));

    GC_expand_hp_inner(divHBLKSZ((word)required_bytes));
    oldmem = mem = GC_scratch_alloc(required_bytes);
    if (0 == mem) ABORT("No space for lwp data structures");

    /*
     * We can either flush the old lwp cache or copy it over. Do the latter.
     */
    memcpy(mem, GC_lwp_cache, max_lwps * sizeof(struct lwp_cache_entry));
    GC_lwp_cache = (struct lwp_cache_entry*)mem;
    mem += ROUNDUP(n * sizeof(struct lwp_cache_entry));

    BZERO(GC_lwp_registers, max_lwps * sizeof(GC_lwp_registers[0]));
    GC_lwp_registers = (prgregset_t *)mem;
    mem += ROUNDUP(n * sizeof(prgregset_t));


    GC_current_ids = (lwpid_t *)mem;
    mem += ROUNDUP((n + 1) * sizeof(lwpid_t));

    last_ids = (lwpid_t *)mem;
    mem += ROUNDUP((n + 1)* sizeof(lwpid_t));

    if (mem > oldmem + required_bytes)
	ABORT("set_max_lwps buffer overflow");

    max_lwps = n;
}


/* Stop all lwps in process.  Assumes preemption is off.	*/
/* Caller has allocation lock (and any other locks he may	*/
/* need).							*/
static void stop_all_lwps()
{
    int lwp_fd;
    char buf[30];
    prstatus_t status;
    register int i;
    GC_bool changed;
    lwpid_t me = _lwp_self();

    if (GC_main_proc_fd == -1) {
    	sprintf(buf, "/proc/%d", getpid());
    	GC_main_proc_fd = syscall(SYS_open, buf, O_RDONLY);
        if (GC_main_proc_fd < 0) {
		if (errno == EMFILE)
			ABORT("/proc open failed: too many open files");
		GC_printf1("/proc open failed: errno %d", errno);
		abort();
        }
    }
    BZERO(GC_lwp_registers, sizeof (prgregset_t) * max_lwps);
    for (i = 0; i < max_lwps; i++)
	last_ids[i] = 0;
    for (;;) {
        if (syscall(SYS_ioctl, GC_main_proc_fd, PIOCSTATUS, &status) < 0)
    	    ABORT("Main PIOCSTATUS failed");
    	if (status.pr_nlwp < 1)
    		ABORT("Invalid number of lwps returned by PIOCSTATUS");
    	if (status.pr_nlwp >= max_lwps) {
    		set_max_lwps(status.pr_nlwp*2 + 10);
		/*
		 * The data in the old GC_current_ids and
		 * GC_lwp_registers has been trashed. Cleaning out last_ids
		 * will make sure every LWP gets re-examined.
		 */
        	for (i = 0; i < max_lwps; i++)
			last_ids[i] = 0;
		continue;
    	}
        if (syscall(SYS_ioctl, GC_main_proc_fd, PIOCLWPIDS, GC_current_ids) < 0)
            ABORT("PIOCLWPIDS failed");
        changed = FALSE;
        for (i = 0; GC_current_ids[i] != 0 && i < max_lwps; i++) {
            if (GC_current_ids[i] != last_ids[i]) {
                changed = TRUE;
                if (GC_current_ids[i] != me) {
		    /* PIOCSTOP doesn't work without a writable		*/
		    /* descriptor.  And that makes the process		*/
		    /* undebuggable.					*/
                    if (_lwp_suspend(GC_current_ids[i]) < 0) {
                        /* Could happen if the lwp exited */
                        uncache_lwp(GC_current_ids[i]);
                        GC_current_ids[i] = me; /* ignore */
                    }
                }
            }
        }
        /*
         * In the unlikely event something does a fork between the
	 * PIOCSTATUS and the PIOCLWPIDS. 
         */
        if (i >= max_lwps)
		continue;
        /* All lwps in GC_current_ids != me have been suspended.  Note	*/
        /* that _lwp_suspend is idempotent.				*/
        for (i = 0; GC_current_ids[i] != 0; i++) {
            if (GC_current_ids[i] != last_ids[i]) {
                if (GC_current_ids[i] != me) {
                    lwp_fd = open_lwp(GC_current_ids[i]);
		    if (lwp_fd == -1)
		    {
			    GC_current_ids[i] = me;
			    continue;
		    }
		    /* LWP should be stopped.  Empirically it sometimes	*/
		    /* isn't, and more frequently the PR_STOPPED flag	*/
		    /* is not set.  Wait for PR_STOPPED.		*/
                    if (syscall(SYS_ioctl, lwp_fd,
                                PIOCSTATUS, &status) < 0) {
			/* Possible if the descriptor was stale, or */
			/* we encountered the 2.3 _lwp_suspend bug. */
			uncache_lwp(GC_current_ids[i]);
                        GC_current_ids[i] = me; /* handle next time. */
                    } else {
                        while (!(status.pr_flags & PR_STOPPED)) {
                            GC_msec_sleep(1);
			    if (syscall(SYS_ioctl, lwp_fd,
				    	PIOCSTATUS, &status) < 0) {
                            	ABORT("Repeated PIOCSTATUS failed");
			    }
			    if (status.pr_flags & PR_STOPPED) break;
			    
			    GC_msec_sleep(20);
			    if (syscall(SYS_ioctl, lwp_fd,
				    	PIOCSTATUS, &status) < 0) {
                            	ABORT("Repeated PIOCSTATUS failed");
			    }
                        }
                        if (status.pr_who !=  GC_current_ids[i]) {
				/* can happen if thread was on death row */
				uncache_lwp(GC_current_ids[i]);
				GC_current_ids[i] = me; /* handle next time. */
				continue;	
                        }
                        /* Save registers where collector can */
			/* find them.			  */
			    BCOPY(status.pr_reg, GC_lwp_registers[i],
				  sizeof (prgregset_t));
                    }
                }
            }
        }
        if (!changed) break;
        for (i = 0; i < max_lwps; i++) last_ids[i] = GC_current_ids[i];
    }
}

/* Restart all lwps in process.  Assumes preemption is off.	*/
static void restart_all_lwps()
{
    int lwp_fd;
    register int i;
    GC_bool changed;
    lwpid_t me = _lwp_self();
#   define PARANOID

    for (i = 0; GC_current_ids[i] != 0; i++) {
#	ifdef PARANOID
	  if (GC_current_ids[i] != me) {
	    int lwp_fd = open_lwp(GC_current_ids[i]);
	    prstatus_t status;
	    
	    if (lwp_fd < 0) ABORT("open_lwp failed");
	    if (syscall(SYS_ioctl, lwp_fd,
			PIOCSTATUS, &status) < 0) {
                ABORT("PIOCSTATUS failed in restart_all_lwps");
	    }
	    if (memcmp(status.pr_reg, GC_lwp_registers[i],
		       sizeof (prgregset_t)) != 0) {
		    int j;

		    for(j = 0; j < NPRGREG; j++)
		    {
			    GC_printf3("%i: %x -> %x\n", j,
				       GC_lwp_registers[i][j],
				       status.pr_reg[j]);
		    }
		ABORT("Register contents changed");
	    }
	    if (!status.pr_flags & PR_STOPPED) {
	    	ABORT("lwp no longer stopped");
	    }
#ifdef SPARC
	    {
		    gwindows_t windows;
	      if (syscall(SYS_ioctl, lwp_fd,
			PIOCGWIN, &windows) < 0) {
                ABORT("PIOCSTATUS failed in restart_all_lwps");
	      }
	      if (windows.wbcnt > 0) ABORT("unsaved register windows");
	    }
#endif
	  }
#	endif /* PARANOID */
	if (GC_current_ids[i] == me) continue;
        if (_lwp_continue(GC_current_ids[i]) < 0) {
            ABORT("Failed to restart lwp");
        }
    }
    if (i >= max_lwps) ABORT("Too many lwps");
}

GC_bool GC_multithreaded = 0;

void GC_stop_world()
{
    preempt_off();
    if (GC_multithreaded)
        stop_all_lwps();
}

void GC_start_world()
{
    if (GC_multithreaded)
        restart_all_lwps();
    preempt_on();
}

void GC_thr_init(void);

GC_bool GC_thr_initialized = FALSE;

size_t GC_min_stack_sz;


/*
 * stack_head is stored at the top of free stacks
 */
struct stack_head {
	struct stack_head	*next;
	ptr_t			base;
	thread_t		owner;
};

# define N_FREE_LISTS 25
struct stack_head *GC_stack_free_lists[N_FREE_LISTS] = { 0 };
		/* GC_stack_free_lists[i] is free list for stacks of 	*/
		/* size GC_min_stack_sz*2**i.				*/
		/* Free lists are linked through stack_head stored	*/			/* at top of stack.					*/

/* Return a stack of size at least *stack_size.  *stack_size is	*/
/* replaced by the actual stack size.				*/
/* Caller holds allocation lock.				*/
ptr_t GC_stack_alloc(size_t * stack_size)
{
    register size_t requested_sz = *stack_size;
    register size_t search_sz = GC_min_stack_sz;
    register int index = 0;	/* = log2(search_sz/GC_min_stack_sz) */
    register ptr_t base;
    register struct stack_head *result;
    
    while (search_sz < requested_sz) {
        search_sz *= 2;
        index++;
    }
    if ((result = GC_stack_free_lists[index]) == 0
        && (result = GC_stack_free_lists[index+1]) != 0) {
        /* Try next size up. */
        search_sz *= 2; index++;
    }
    if (result != 0) {
        base =  GC_stack_free_lists[index]->base;
        GC_stack_free_lists[index] = GC_stack_free_lists[index]->next;
    } else {
#ifdef MMAP_STACKS
        base = (ptr_t)mmap(0, search_sz + GC_page_size,
			     PROT_READ|PROT_WRITE, MAP_PRIVATE |MAP_NORESERVE,
			     GC_zfd, 0);
	if (base == (ptr_t)-1)
	{
		*stack_size = 0;
		return NULL;
	}

	mprotect(base, GC_page_size, PROT_NONE);
	/* Should this use divHBLKSZ(search_sz + GC_page_size) ? -- cf */
	GC_is_fresh((struct hblk *)base, divHBLKSZ(search_sz));
	base += GC_page_size;

#else
        base = (ptr_t) GC_scratch_alloc(search_sz + 2*GC_page_size);
	if (base == NULL)
	{
		*stack_size = 0;