drm/i915: Set GPU freq to idle_freq initially

[dragonfly.git] / lib / libc_r / uthread / pthread_private.h

/*
 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by John Birrell.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Private thread definitions for the uthread kernel.
 *
 * $FreeBSD: src/lib/libc_r/uthread/pthread_private.h,v 1.36.2.21 2002/10/22 14:44:02 fjoe Exp $
 */

#ifndef _PTHREAD_PRIVATE_H
#define _PTHREAD_PRIVATE_H

/*
 * Evaluate the storage class specifier.
 */
#ifdef GLOBAL_PTHREAD_PRIVATE
#define SCLASS
#else
#define SCLASS extern
#endif

/*
 * Include files.
 */
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/cdefs.h>
#include <sys/sched.h>
#include <spinlock.h>
#include <pthread_np.h>

#include <machine/tls.h>

/*
 * Define machine dependent macros to get and set the stack pointer
 * from the supported contexts.  Also define a macro to set the return
 * address in a jmp_buf context.
 *
 * XXX - These need to be moved into architecture dependent support files.
 */
#if defined(__x86_64__)
#define GET_STACK_JB(jb)        ((unsigned long)((jb)[0]._jb[2]))
#define GET_STACK_SJB(sjb)      ((unsigned long)((sjb)[0]._sjb[2]))
#define GET_STACK_UC(ucp)       ((unsigned long)((ucp)->uc_mcontext.mc_rsp))
#define SET_STACK_JB(jb, stk)   (jb)[0]._jb[2] = (long)(stk)
#define SET_STACK_SJB(sjb, stk) (sjb)[0]._sjb[2] = (long)(stk)
#define SET_STACK_UC(ucp, stk)  (ucp)->uc_mcontext.mc_rsp = (long)(stk)
#define FP_SAVE_UC(ucp)         do {                    \
        char    *fdata;                                 \
        fdata = (char *) (ucp)->uc_mcontext.mc_fpstate; \
        __asm__("fxsave %0": :"m"(*fdata));             \
} while (0)
#define FP_RESTORE_UC(ucp)      do {                    \
        char    *fdata;                                 \
        fdata = (char *) (ucp)->uc_mcontext.mc_fpstate; \
        __asm__("fxrstor %0": :"m"(*fdata));            \
} while (0)
#define SET_RETURN_ADDR_JB(jb, ra)      (jb)[0]._jb[0] = (long)(ra)
#else
#error "Don't recognize this architecture!"
#endif

/*
 * Kernel fatal error handler macro.
 */
#define PANIC(string)   _thread_exit(__FILE__,__LINE__,string)


/* Output debug messages like this: */
#define stdout_debug(args...)   do {            \
        char buf[128];                          \
        snprintf(buf, sizeof(buf), ##args);     \
        __sys_extpwrite(1, buf, strlen(buf), O_FBLOCKING, -1);  \
} while (0)
#define stderr_debug(args...)   do {            \
        char buf[128];                          \
        snprintf(buf, sizeof(buf), ##args);     \
        __sys_extpwrite(2, buf, strlen(buf), O_FBLOCKING, -1);  \
} while (0)



/*
 * Priority queue manipulation macros (using pqe link):
 */
#define PTHREAD_PRIOQ_INSERT_HEAD(thrd) _pq_insert_head(&_readyq,thrd)
#define PTHREAD_PRIOQ_INSERT_TAIL(thrd) _pq_insert_tail(&_readyq,thrd)
#define PTHREAD_PRIOQ_REMOVE(thrd)      _pq_remove(&_readyq,thrd)
#define PTHREAD_PRIOQ_FIRST()           _pq_first(&_readyq)

/*
 * Waiting queue manipulation macros (using pqe link):
 */
#define PTHREAD_WAITQ_REMOVE(thrd)      _waitq_remove(thrd)
#define PTHREAD_WAITQ_INSERT(thrd)      _waitq_insert(thrd)

#if defined(_PTHREADS_INVARIANTS)
#define PTHREAD_WAITQ_CLEARACTIVE()     _waitq_clearactive()
#define PTHREAD_WAITQ_SETACTIVE()       _waitq_setactive()
#else
#define PTHREAD_WAITQ_CLEARACTIVE()
#define PTHREAD_WAITQ_SETACTIVE()
#endif

/*
 * Work queue manipulation macros (using qe link):
 */
#define PTHREAD_WORKQ_INSERT(thrd) do {                                 \
        TAILQ_INSERT_TAIL(&_workq,thrd,qe);                             \
        (thrd)->flags |= PTHREAD_FLAGS_IN_WORKQ;                        \
} while (0)
#define PTHREAD_WORKQ_REMOVE(thrd) do {                                 \
        TAILQ_REMOVE(&_workq,thrd,qe);                                  \
        (thrd)->flags &= ~PTHREAD_FLAGS_IN_WORKQ;                       \
} while (0)


/*
 * State change macro without scheduling queue change:
 */
#define PTHREAD_SET_STATE(thrd, newstate) do {                          \
        (thrd)->state = newstate;                                       \
        (thrd)->fname = __FILE__;                                       \
        (thrd)->lineno = __LINE__;                                      \
} while (0)

/*
 * State change macro with scheduling queue change - This must be
 * called with preemption deferred (see thread_kern_sched_[un]defer).
 */
#if defined(_PTHREADS_INVARIANTS)
#include <assert.h>
#define PTHREAD_ASSERT(cond, msg) do {  \
        if (!(cond))                    \
                PANIC(msg);             \
} while (0)
#define PTHREAD_ASSERT_NOT_IN_SYNCQ(thrd) \
        PTHREAD_ASSERT((((thrd)->flags & PTHREAD_FLAGS_IN_SYNCQ) == 0), \
            "Illegal call from signal handler");
#define PTHREAD_NEW_STATE(thrd, newstate) do {                          \
        if (_thread_kern_new_state != 0)                                \
                PANIC("Recursive PTHREAD_NEW_STATE");                   \
        _thread_kern_new_state = 1;                                     \
        if ((thrd)->state != newstate) {                                \
                if ((thrd)->state == PS_RUNNING) {                      \
                        PTHREAD_PRIOQ_REMOVE(thrd);                     \
                        PTHREAD_SET_STATE(thrd, newstate);              \
                        PTHREAD_WAITQ_INSERT(thrd);                     \
                } else if (newstate == PS_RUNNING) {                    \
                        PTHREAD_WAITQ_REMOVE(thrd);                     \
                        PTHREAD_SET_STATE(thrd, newstate);              \
                        PTHREAD_PRIOQ_INSERT_TAIL(thrd);                \
                }                                                       \
        }                                                               \
        _thread_kern_new_state = 0;                                     \
} while (0)
#else
#define PTHREAD_ASSERT(cond, msg)
#define PTHREAD_ASSERT_NOT_IN_SYNCQ(thrd)
#define PTHREAD_NEW_STATE(thrd, newstate) do {                          \
        if ((thrd)->state != newstate) {                                \
                if ((thrd)->state == PS_RUNNING) {                      \
                        PTHREAD_PRIOQ_REMOVE(thrd);                     \
                        PTHREAD_WAITQ_INSERT(thrd);                     \
                } else if (newstate == PS_RUNNING) {                    \
                        PTHREAD_WAITQ_REMOVE(thrd);                     \
                        PTHREAD_PRIOQ_INSERT_TAIL(thrd);                \
                }                                                       \
        }                                                               \
        PTHREAD_SET_STATE(thrd, newstate);                              \
} while (0)
#endif

/*
 * Define the signals to be used for scheduling.
 */
#if defined(_PTHREADS_COMPAT_SCHED)
#define _ITIMER_SCHED_TIMER     ITIMER_VIRTUAL
#define _SCHED_SIGNAL           SIGVTALRM
#else
#define _ITIMER_SCHED_TIMER     ITIMER_PROF
#define _SCHED_SIGNAL           SIGPROF
#endif

/*
 * Priority queues.
 *
 * XXX It'd be nice if these were contained in uthread_priority_queue.[ch].
 */
typedef struct pq_list {
        TAILQ_HEAD(, pthread)   pl_head; /* list of threads at this priority */
        TAILQ_ENTRY(pq_list)    pl_link; /* link for queue of priority lists */
        int                     pl_prio; /* the priority of this list */
        int                     pl_queued; /* is this in the priority queue */
} pq_list_t;

typedef struct pq_queue {
        TAILQ_HEAD(, pq_list)    pq_queue; /* queue of priority lists */
        pq_list_t               *pq_lists; /* array of all priority lists */
        int                      pq_size;  /* number of priority lists */
} pq_queue_t;


/*
 * TailQ initialization values.
 */
#define TAILQ_INITIALIZER       { NULL, NULL }

/* 
 * Mutex definitions.
 */
union pthread_mutex_data {
        void    *m_ptr;
        int     m_count;
};

struct pthread_mutex {
        enum pthread_mutextype          m_type;
        int                             m_protocol;
        TAILQ_HEAD(mutex_head, pthread) m_queue;
        struct pthread                  *m_owner;
        union pthread_mutex_data        m_data;
        long                            m_flags;
        int                             m_refcount;

        /*
         * Used for priority inheritence and protection.
         *
         *   m_prio       - For priority inheritence, the highest active
         *                  priority (threads locking the mutex inherit
         *                  this priority).  For priority protection, the
         *                  ceiling priority of this mutex.
         *   m_saved_prio - mutex owners inherited priority before
         *                  taking the mutex, restored when the owner
         *                  unlocks the mutex.
         */
        int                             m_prio;
        int                             m_saved_prio;

        /*
         * Link for list of all mutexes a thread currently owns.
         */
        TAILQ_ENTRY(pthread_mutex)      m_qe;

        /*
         * Lock for accesses to this structure.
         */
        spinlock_t                      lock;
};

/*
 * Flags for mutexes. 
 */
#define MUTEX_FLAGS_PRIVATE     0x01
#define MUTEX_FLAGS_INITED      0x02
#define MUTEX_FLAGS_BUSY        0x04

/*
 * Static mutex initialization values. 
 */
#define PTHREAD_MUTEX_STATIC_INITIALIZER   \
        { PTHREAD_MUTEX_DEFAULT, PTHREAD_PRIO_NONE, TAILQ_INITIALIZER, \
        NULL, { NULL }, MUTEX_FLAGS_PRIVATE, 0, 0, 0, TAILQ_INITIALIZER, \
        _SPINLOCK_INITIALIZER }

struct pthread_mutex_attr {
        enum pthread_mutextype  m_type;
        int                     m_protocol;
        int                     m_ceiling;
        long                    m_flags;
};

/* 
 * Condition variable definitions.
 */
enum pthread_cond_type {
        COND_TYPE_FAST,
        COND_TYPE_MAX
};

struct pthread_cond {
        enum pthread_cond_type          c_type;
        TAILQ_HEAD(cond_head, pthread)  c_queue;
        pthread_mutex_t                 c_mutex;
        void                            *c_data;
        long                            c_flags;
        int                             c_seqno;

        /*
         * Lock for accesses to this structure.
         */
        spinlock_t                      lock;
};

struct pthread_cond_attr {
        enum pthread_cond_type  c_type;
        long                    c_flags;
};

/*
 * Flags for condition variables.
 */
#define COND_FLAGS_PRIVATE      0x01
#define COND_FLAGS_INITED       0x02
#define COND_FLAGS_BUSY         0x04

/*
 * Static cond initialization values. 
 */
#define PTHREAD_COND_STATIC_INITIALIZER    \
        { COND_TYPE_FAST, TAILQ_INITIALIZER, NULL, NULL, \
        0, 0, _SPINLOCK_INITIALIZER }

/*
 * Semaphore definitions.
 */
struct sem {
#define SEM_MAGIC       ((u_int32_t) 0x09fa4012)
        u_int32_t       magic;
        pthread_mutex_t lock;
        pthread_cond_t  gtzero;
        u_int32_t       count;
        u_int32_t       nwaiters;
};

/*
 * Cleanup definitions.
 */
struct pthread_cleanup {
        struct pthread_cleanup  *next;
        void                    (*routine)(void *);
        void                    *routine_arg;
};

struct pthread_atfork {
        TAILQ_ENTRY(pthread_atfork) qe;
        void (*prepare)(void);
        void (*parent)(void);
        void (*child)(void);
};

struct pthread_attr {
        int     sched_policy;
        int     sched_inherit;
        int     sched_interval;
        int     prio;
        int     suspend;
        int     flags;
        void    *arg_attr;
        void    (*cleanup_attr)(void *);
        void    *stackaddr_attr;
        size_t  stacksize_attr;
};

/*
 * Thread creation state attributes.
 */
#define PTHREAD_CREATE_RUNNING                  0
#define PTHREAD_CREATE_SUSPENDED                1

/*
 * Miscellaneous definitions.
 */
#define PTHREAD_STACK_DEFAULT                   65536
/*
 * Size of red zone at the end of each stack.  In actuality, this "red zone" is
 * merely an unmapped region, except in the case of the initial stack.  Since
 * mmap() makes it possible to specify the maximum growth of a MAP_STACK region,
 * an unmapped gap between thread stacks achieves the same effect as explicitly
 * mapped red zones.
 */
#define PTHREAD_STACK_GUARD                     PAGE_SIZE

/*
 * Maximum size of initial thread's stack.  This perhaps deserves to be larger
 * than the stacks of other threads, since many applications are likely to run
 * almost entirely on this stack.
 */
#define PTHREAD_STACK_INITIAL                   0x100000

/* Size of the scheduler stack: */
#define SCHED_STACK_SIZE                        PAGE_SIZE

/*
 * Define the different priority ranges.  All applications have thread
 * priorities constrained within 0-31.  The threads library raises the
 * priority when delivering signals in order to ensure that signal
 * delivery happens (from the POSIX spec) "as soon as possible".
 * In the future, the threads library will also be able to map specific
 * threads into real-time (cooperating) processes or kernel threads.
 * The RT and SIGNAL priorities will be used internally and added to
 * thread base priorities so that the scheduling queue can handle both
 * normal and RT priority threads with and without signal handling.
 *
 * The approach taken is that, within each class, signal delivery
 * always has priority over thread execution.
 */
#define PTHREAD_DEFAULT_PRIORITY                15
#define PTHREAD_MIN_PRIORITY                    0
#define PTHREAD_MAX_PRIORITY                    31      /* 0x1F */
#define PTHREAD_SIGNAL_PRIORITY                 32      /* 0x20 */
#define PTHREAD_RT_PRIORITY                     64      /* 0x40 */
#define PTHREAD_FIRST_PRIORITY                  PTHREAD_MIN_PRIORITY
#define PTHREAD_LAST_PRIORITY   \
        (PTHREAD_MAX_PRIORITY + PTHREAD_SIGNAL_PRIORITY + PTHREAD_RT_PRIORITY)
#define PTHREAD_BASE_PRIORITY(prio)     ((prio) & PTHREAD_MAX_PRIORITY)

/*
 * Clock resolution in microseconds.
 */
#define CLOCK_RES_USEC                          10000
#define CLOCK_RES_USEC_MIN                      1000

/*
 * Time slice period in microseconds.
 */
#define TIMESLICE_USEC                          20000

/*
 * Define a thread-safe macro to get the current time of day
 * which is updated at regular intervals by the scheduling signal
 * handler.
 */
#define GET_CURRENT_TOD(tv)                             \
        do {                                            \
                tv.tv_sec = _sched_tod.tv_sec;          \
                tv.tv_usec = _sched_tod.tv_usec;        \
        } while (tv.tv_sec != _sched_tod.tv_sec)


struct pthread_key {
        spinlock_t      lock;
        volatile int    allocated;
        volatile int    count;
        void            (*destructor)(void *);
};

struct pthread_rwlockattr {
        int             pshared;
};

struct pthread_rwlock {
        pthread_mutex_t lock;   /* monitor lock */
        int             state;  /* 0 = idle  >0 = # of readers  -1 = writer */
        pthread_cond_t  read_signal;
        pthread_cond_t  write_signal;
        int             blocked_writers;
};

/*
 * Thread states.
 */
enum pthread_state {
        PS_RUNNING,
        PS_SIGTHREAD,
        PS_MUTEX_WAIT,
        PS_COND_WAIT,
        PS_FDLR_WAIT,
        PS_FDLW_WAIT,
        PS_FDR_WAIT,
        PS_FDW_WAIT,
        PS_POLL_WAIT,
        PS_SELECT_WAIT,
        PS_SLEEP_WAIT,
        PS_WAIT_WAIT,
        PS_SIGSUSPEND,
        PS_SIGWAIT,
        PS_SPINBLOCK,
        PS_JOIN,
        PS_SUSPENDED,
        PS_DEAD,
        PS_DEADLOCK,
        PS_STATE_MAX
};


/*
 * File descriptor locking definitions.
 */
#define FD_READ             0x1
#define FD_WRITE            0x2
#define FD_RDWR             (FD_READ | FD_WRITE)

/*
 * File descriptor table structure.
 */
struct fd_table_entry {
        /*
         * Lock for accesses to this file descriptor table
         * entry. This is passed to _spinlock() to provide atomic
         * access to this structure. It does *not* represent the
         * state of the lock on the file descriptor.
         */
        spinlock_t              lock;
        TAILQ_HEAD(, pthread)   r_queue;        /* Read queue.                        */
        TAILQ_HEAD(, pthread)   w_queue;        /* Write queue.                       */
        struct pthread          *r_owner;       /* Ptr to thread owning read lock.    */
        struct pthread          *w_owner;       /* Ptr to thread owning write lock.   */
        char                    *r_fname;       /* Ptr to read lock source file name  */
        int                     r_lineno;       /* Read lock source line number.      */
        char                    *w_fname;       /* Ptr to write lock source file name */
        int                     w_lineno;       /* Write lock source line number.     */
        int                     r_lockcount;    /* Count for FILE read locks.         */
        int                     w_lockcount;    /* Count for FILE write locks.        */
        int                     flags;          /* Flags used in open.                */
};

struct pthread_poll_data {
        int     nfds;
        struct pollfd *fds;
};

union pthread_wait_data {
        pthread_mutex_t mutex;
        pthread_cond_t  cond;
        const sigset_t  *sigwait;       /* Waiting on a signal in sigwait */
        struct {
                short   fd;             /* Used when thread waiting on fd */
                short   branch;         /* Line number, for debugging.    */
                char    *fname;         /* Source file name for debugging.*/
        } fd;
        FILE            *fp;
        struct pthread_poll_data *poll_data;
        spinlock_t      *spinlock;
        struct pthread  *thread;
};

/*
 * Define a continuation routine that can be used to perform a
 * transfer of control:
 */
typedef void    (*thread_continuation_t) (void *);

struct pthread_signal_frame;

struct pthread_state_data {
        struct pthread_signal_frame *psd_curframe;
        sigset_t                psd_sigmask;
        struct timespec         psd_wakeup_time;
        union pthread_wait_data psd_wait_data;
        enum pthread_state      psd_state;
        int                     psd_flags;
        int                     psd_interrupted;
        int                     psd_longjmp_val;
        int                     psd_sigmask_seqno;
        int                     psd_signo;
        int                     psd_sig_defer_count;
        /* XXX - What about thread->timeout and/or thread->error? */
};

struct join_status {
        struct pthread  *thread;
        void            *ret;
        int             error;
};

/*
 * The frame that is added to the top of a threads stack when setting up
 * up the thread to run a signal handler.
 */
struct pthread_signal_frame {
        /*
         * This stores the threads state before the signal.
         */
        struct pthread_state_data saved_state;

        /*
         * Threads return context; we use only jmp_buf's for now.
         */
        union {
                jmp_buf         jb;
                ucontext_t      uc;
        } ctx;
        int                     signo;  /* signal, arg 1 to sighandler */
        int                     sig_has_args;   /* use signal args if true */
        ucontext_t              uc;
        siginfo_t               siginfo;
};

/*
 * Thread structure.
 */
struct pthread {
        /*
         * Magic value to help recognize a valid thread structure
         * from an invalid one:
         */
#define PTHREAD_MAGIC           ((u_int32_t) 0xd09ba115)
        u_int32_t               magic;
        char                    *name;
        u_int64_t               uniqueid; /* for gdb */
        struct tls_tcb          *tcb;

        /*
         * Lock for accesses to this thread structure.
         */
        spinlock_t              lock;

        /* Queue entry for list of all threads: */
        TAILQ_ENTRY(pthread)    tle;

        /* Queue entry for list of dead threads: */
        TAILQ_ENTRY(pthread)    dle;

        /*
         * Thread start routine, argument, stack pointer and thread
         * attributes.
         */
        void                    *(*start_routine)(void *);
        void                    *arg;
        void                    *stack;
        struct pthread_attr     attr;

        /*
         * Threads return context; we use only jmp_buf's for now.
         */
        union {
                jmp_buf         jb;
                ucontext_t      uc;
        } ctx;

        /*
         * Used for tracking delivery of signal handlers.
         */
        struct pthread_signal_frame     *curframe;

        /*
         * Cancelability flags - the lower 2 bits are used by cancel
         * definitions in pthread.h
         */
#define PTHREAD_AT_CANCEL_POINT         0x0004
#define PTHREAD_CANCELLING              0x0008
#define PTHREAD_CANCEL_NEEDED           0x0010
        int     cancelflags;

        thread_continuation_t   continuation;

        /*
         * Current signal mask and pending signals.
         */
        sigset_t        sigmask;
        sigset_t        sigpend;
        int             sigmask_seqno;
        int             check_pending;

        /* Thread state: */
        enum pthread_state      state;

        /* Scheduling clock when this thread was last made active. */
        long    last_active;

        /* Scheduling clock when this thread was last made inactive. */
        long    last_inactive;

        /*
         * Number of microseconds accumulated by this thread when
         * time slicing is active.
         */
        long    slice_usec;

        /*
         * Time to wake up thread. This is used for sleeping threads and
         * for any operation which may time out (such as select).
         */
        struct timespec wakeup_time;

        /* TRUE if operation has timed out. */
        int     timeout;

        /*
         * The joiner is the thread that is joining to this thread.  The
         * join status keeps track of a join operation to another thread.
         */
        struct pthread          *joiner;
        struct join_status      join_status;

        /*
         * The current thread can belong to only one scheduling queue at
         * a time (ready or waiting queue).  It can also belong to:
         *
         *   o A queue of threads waiting for a mutex
         *   o A queue of threads waiting for a condition variable
         *   o A queue of threads waiting for a file descriptor lock
         *   o A queue of threads needing work done by the kernel thread
         *     (waiting for a spinlock or file I/O)
         *
         * A thread can also be joining a thread (the joiner field above).
         *
         * It must not be possible for a thread to belong to any of the
         * above queues while it is handling a signal.  Signal handlers
         * may longjmp back to previous stack frames circumventing normal
         * control flow.  This could corrupt queue integrity if the thread
         * retains membership in the queue.  Therefore, if a thread is a
         * member of one of these queues when a signal handler is invoked,
         * it must remove itself from the queue before calling the signal
         * handler and reinsert itself after normal return of the handler.
         *
         * Use pqe for the scheduling queue link (both ready and waiting),
         * sqe for synchronization (mutex and condition variable) queue
         * links, and qe for all other links.
         */
        TAILQ_ENTRY(pthread)    pqe;    /* priority queue link */
        TAILQ_ENTRY(pthread)    sqe;    /* synchronization queue link */
        TAILQ_ENTRY(pthread)    qe;     /* all other queues link */

        /* Wait data. */
        union pthread_wait_data data;

        /*
         * Allocated for converting select into poll.
         */
        struct pthread_poll_data poll_data;

        /*
         * Set to TRUE if a blocking operation was
         * interrupted by a signal:
         */
        int             interrupted;

        /* Signal number when in state PS_SIGWAIT: */
        int             signo;

        /*
         * Set to non-zero when this thread has deferred signals.
         * We allow for recursive deferral.
         */
        int             sig_defer_count;

        /*
         * Set to TRUE if this thread should yield after undeferring
         * signals.
         */
        int             yield_on_sig_undefer;

        /* Miscellaneous flags; only set with signals deferred. */
        int             flags;
#define PTHREAD_FLAGS_PRIVATE   0x0001
#define PTHREAD_EXITING         0x0002
#define PTHREAD_FLAGS_IN_WAITQ  0x0004  /* in waiting queue using pqe link */
#define PTHREAD_FLAGS_IN_PRIOQ  0x0008  /* in priority queue using pqe link */
#define PTHREAD_FLAGS_IN_WORKQ  0x0010  /* in work queue using qe link */
#define PTHREAD_FLAGS_IN_FILEQ  0x0020  /* in file lock queue using qe link */
#define PTHREAD_FLAGS_IN_FDQ    0x0040  /* in fd lock queue using qe link */
#define PTHREAD_FLAGS_IN_CONDQ  0x0080  /* in condition queue using sqe link*/
#define PTHREAD_FLAGS_IN_MUTEXQ 0x0100  /* in mutex queue using sqe link */
#define PTHREAD_FLAGS_SUSPENDED 0x0200  /* thread is suspended */
#define PTHREAD_FLAGS_TRACE     0x0400  /* for debugging purposes */
#define PTHREAD_FLAGS_IN_SYNCQ  \
    (PTHREAD_FLAGS_IN_CONDQ | PTHREAD_FLAGS_IN_MUTEXQ)

        /*
         * Base priority is the user setable and retrievable priority
         * of the thread.  It is only affected by explicit calls to
         * set thread priority and upon thread creation via a thread
         * attribute or default priority.
         */
        char            base_priority;

        /*
         * Inherited priority is the priority a thread inherits by
         * taking a priority inheritence or protection mutex.  It
         * is not affected by base priority changes.  Inherited
         * priority defaults to and remains 0 until a mutex is taken
         * that is being waited on by any other thread whose priority
         * is non-zero.
         */
        char            inherited_priority;

        /*
         * Active priority is always the maximum of the threads base
         * priority and inherited priority.  When there is a change
         * in either the base or inherited priority, the active
         * priority must be recalculated.
         */
        char            active_priority;

        /* Number of priority ceiling or protection mutexes owned. */
        int             priority_mutex_count;

        /*
         * Queue of currently owned mutexes.
         */
        TAILQ_HEAD(, pthread_mutex)     mutexq;

        void            *ret;
        const void      **specific_data;
        int             specific_data_count;

        /* Cleanup handlers Link List */
        struct pthread_cleanup *cleanup;
        char                    *fname; /* Ptr to source file name  */
        int                     lineno; /* Source line number.      */
};

/* Spare thread stack. */
struct stack {
        SLIST_ENTRY(stack)      qe; /* Queue entry for this stack. */
};

/*
 * Global variables for the uthread kernel.
 */

SCLASS void *_usrstack
#ifdef GLOBAL_PTHREAD_PRIVATE
= (void *) USRSTACK;
#else
;
#endif

/* Kernel thread structure used when there are no running threads: */
SCLASS struct pthread   _thread_kern_thread;

/* Ptr to the thread structure for the running thread: */
SCLASS struct pthread   * volatile _thread_run
#ifdef GLOBAL_PTHREAD_PRIVATE
= &_thread_kern_thread;
#else
;
#endif

/* Ptr to the thread structure for the last user thread to run: */
SCLASS struct pthread   * volatile _last_user_thread
#ifdef GLOBAL_PTHREAD_PRIVATE
= &_thread_kern_thread;
#else
;
#endif

/* List of all threads: */
SCLASS TAILQ_HEAD(, pthread)    _thread_list
#ifdef GLOBAL_PTHREAD_PRIVATE
= TAILQ_HEAD_INITIALIZER(_thread_list);
#else
;
#endif

/*
 * Array of kernel pipe file descriptors that are used to ensure that
 * no signals are missed in calls to _select.
 */
SCLASS int              _thread_kern_pipe[2]
#ifdef GLOBAL_PTHREAD_PRIVATE
= {
        -1,
        -1
};
#else
;
#endif
SCLASS int              volatile _queue_signals
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0;
#else
;
#endif
SCLASS int              _thread_kern_in_sched
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0;
#else
;
#endif

SCLASS int              _sig_in_handler
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0;
#else
;
#endif

/* Time of day at last scheduling timer signal: */
SCLASS struct timeval volatile  _sched_tod
#ifdef GLOBAL_PTHREAD_PRIVATE
= { 0, 0 };
#else
;
#endif

/*
 * Current scheduling timer ticks; used as resource usage.
 */
SCLASS unsigned int volatile    _sched_ticks
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0;
#else
;
#endif

/* Dead threads: */
SCLASS TAILQ_HEAD(, pthread) _dead_list
#ifdef GLOBAL_PTHREAD_PRIVATE
= TAILQ_HEAD_INITIALIZER(_dead_list);
#else
;
#endif

/* Initial thread: */
SCLASS struct pthread *_thread_initial
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL;
#else
;
#endif

SCLASS TAILQ_HEAD(atfork_head, pthread_atfork) _atfork_list;
SCLASS pthread_mutex_t          _atfork_mutex;

/* Default thread attributes: */
SCLASS struct pthread_attr pthread_attr_default
#ifdef GLOBAL_PTHREAD_PRIVATE
= { SCHED_RR, 0, TIMESLICE_USEC, PTHREAD_DEFAULT_PRIORITY, PTHREAD_CREATE_RUNNING,
        PTHREAD_CREATE_JOINABLE, NULL, NULL, NULL, PTHREAD_STACK_DEFAULT };
#else
;
#endif

/* Default mutex attributes: */
SCLASS struct pthread_mutex_attr pthread_mutexattr_default
#ifdef GLOBAL_PTHREAD_PRIVATE
= { PTHREAD_MUTEX_DEFAULT, PTHREAD_PRIO_NONE, 0, 0 };
#else
;
#endif

/* Default condition variable attributes: */
SCLASS struct pthread_cond_attr pthread_condattr_default
#ifdef GLOBAL_PTHREAD_PRIVATE
= { COND_TYPE_FAST, 0 };
#else
;
#endif

/*
 * Standard I/O file descriptors need special flag treatment since
 * setting one to non-blocking does all on *BSD. Sigh. This array
 * is used to store the initial flag settings.
 */
SCLASS int      _pthread_stdio_flags[3];

/* File table information: */
SCLASS struct fd_table_entry **_thread_fd_table
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL;
#else
;
#endif

/* Table for polling file descriptors: */
SCLASS struct pollfd *_thread_pfd_table
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL;
#else
;
#endif

SCLASS const int dtablecount
#ifdef GLOBAL_PTHREAD_PRIVATE
= 4096/sizeof(struct fd_table_entry);
#else
;
#endif
SCLASS int    _thread_dtablesize        /* Descriptor table size.           */
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0;
#else
;
#endif

SCLASS int    _clock_res_usec           /* Clock resolution in usec.    */
#ifdef GLOBAL_PTHREAD_PRIVATE
= CLOCK_RES_USEC;
#else
;
#endif

/* Garbage collector mutex and condition variable. */
SCLASS  pthread_mutex_t _gc_mutex
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL
#endif
;
SCLASS  pthread_cond_t  _gc_cond
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL
#endif
;

/*
 * Array of signal actions for this process.
 */
SCLASS struct  sigaction _thread_sigact[NSIG];

/*
 * Array of counts of dummy handlers for SIG_DFL signals.  This is used to
 * assure that there is always a dummy signal handler installed while there is a
 * thread sigwait()ing on the corresponding signal.
 */
SCLASS int      _thread_dfl_count[NSIG];

/*
 * Pending signals and mask for this process:
 */
SCLASS sigset_t _process_sigpending;
SCLASS sigset_t _process_sigmask
#ifdef GLOBAL_PTHREAD_PRIVATE
= { {0, 0, 0, 0} }
#endif
;

/*
 * Scheduling queues:
 */
SCLASS pq_queue_t               _readyq;
SCLASS TAILQ_HEAD(, pthread)    _waitingq;

/*
 * Work queue:
 */
SCLASS TAILQ_HEAD(, pthread)    _workq;

/* Tracks the number of threads blocked while waiting for a spinlock. */
SCLASS  volatile int    _spinblock_count
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0
#endif
;

/* Used to maintain pending and active signals: */
struct sigstatus {
        int             pending;        /* Is this a pending signal? */
        int             blocked;        /*
                                         * A handler is currently active for
                                         * this signal; ignore subsequent
                                         * signals until the handler is done.
                                         */
        int             signo;          /* arg 1 to signal handler */
        siginfo_t       siginfo;        /* arg 2 to signal handler */
        ucontext_t      uc;             /* arg 3 to signal handler */
};

SCLASS struct sigstatus _thread_sigq[NSIG];

/* Indicates that the signal queue needs to be checked. */
SCLASS  volatile int    _sigq_check_reqd
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0
#endif
;

/* Thread switch hook. */
SCLASS pthread_switch_routine_t _sched_switch_hook
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL
#endif
;

/*
 * Spare stack queue.  Stacks of default size are cached in order to reduce
 * thread creation time.  Spare stacks are used in LIFO order to increase cache
 * locality.
 */
SCLASS SLIST_HEAD(, stack)      _stackq;

/*
 * Base address of next unallocated default-size {stack, red zone}.  Stacks are
 * allocated contiguously, starting below the bottom of the main stack.  When a
 * new stack is created, a red zone is created (actually, the red zone is simply
 * left unmapped) below the bottom of the stack, such that the stack will not be
 * able to grow all the way to the top of the next stack.  This isn't
 * fool-proof.  It is possible for a stack to grow by a large amount, such that
 * it grows into the next stack, and as long as the memory within the red zone
 * is never accessed, nothing will prevent one thread stack from trouncing all
 * over the next.
 */
SCLASS void *   _next_stack
#ifdef GLOBAL_PTHREAD_PRIVATE
/* main stack top   - main stack size       - stack size            - (red zone + main stack red zone) */
= (void *) USRSTACK - PTHREAD_STACK_INITIAL - PTHREAD_STACK_DEFAULT - (2 * PTHREAD_STACK_GUARD)
#endif
;

/*
 * Declare the kernel scheduler jump buffer and stack:
 */
SCLASS jmp_buf  _thread_kern_sched_jb;

SCLASS void *   _thread_kern_sched_stack
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL
#endif
;


/* Used for _PTHREADS_INVARIANTS checking. */
SCLASS int      _thread_kern_new_state
#ifdef GLOBAL_PTHREAD_PRIVATE
= 0
#endif
;

/* Undefine the storage class specifier: */
#undef  SCLASS

#ifdef  _LOCK_DEBUG
#define _FD_LOCK(_fd,_type,_ts)         _thread_fd_lock_debug(_fd, _type, \
                                                _ts, __FILE__, __LINE__)
#define _FD_UNLOCK(_fd,_type)           _thread_fd_unlock_debug(_fd, _type, \
                                                __FILE__, __LINE__)
#else
#define _FD_LOCK(_fd,_type,_ts)         _thread_fd_lock(_fd, _type, _ts)
#define _FD_UNLOCK(_fd,_type)           _thread_fd_unlock(_fd, _type)
#endif

/*
 * Function prototype definitions.
 */
__BEGIN_DECLS
int     _close(int);
char    *__ttyname_basic(int);
void    _cond_wait_backout(pthread_t);
void    _fd_lock_backout(pthread_t);
int     _find_thread(pthread_t);
struct pthread *_get_curthread(void);
void    _set_curthread(struct pthread *);
void    _flockfile_backout(struct pthread *);
void    _funlock_owned(struct pthread *);
int     _thread_create(pthread_t *,const pthread_attr_t *,void *(*start_routine)(void *),void *,pthread_t);
int     _mutex_cv_lock(pthread_mutex_t *);
int     _mutex_cv_unlock(pthread_mutex_t *);
void    _mutex_lock_backout(pthread_t);
void    _mutex_notify_priochange(pthread_t);
int     _mutex_reinit(pthread_mutex_t *);
void    _mutex_unlock_private(pthread_t);
int     _cond_reinit(pthread_cond_t *);
int     _pq_alloc(struct pq_queue *, int, int);
int     _pq_init(struct pq_queue *);
void    _pq_remove(struct pq_queue *pq, struct pthread *);
void    _pq_insert_head(struct pq_queue *pq, struct pthread *);
void    _pq_insert_tail(struct pq_queue *pq, struct pthread *);
struct pthread *_pq_first(struct pq_queue *pq);
void    *_pthread_getspecific(pthread_key_t);
int     _pthread_key_create(pthread_key_t *, void (*) (void *));
int     _pthread_key_delete(pthread_key_t);
int     _pthread_mutex_destroy(pthread_mutex_t *);
int     _pthread_mutex_init(pthread_mutex_t *, const pthread_mutexattr_t *);
int     _pthread_mutex_lock(pthread_mutex_t *);
int     _pthread_mutex_trylock(pthread_mutex_t *);
int     _pthread_mutex_unlock(pthread_mutex_t *);
int     _pthread_once(pthread_once_t *, void (*) (void));
int     _pthread_setspecific(pthread_key_t, const void *);
int     _pthread_cond_init(pthread_cond_t *, const pthread_condattr_t *);
int     _pthread_cond_destroy(pthread_cond_t *);
int     _pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
int     _pthread_cond_timedwait(pthread_cond_t *, pthread_mutex_t *,
            const struct timespec *);
int     _pthread_cond_signal(pthread_cond_t *);
int     _pthread_cond_broadcast(pthread_cond_t *);
void    _waitq_insert(pthread_t pthread);
void    _waitq_remove(pthread_t pthread);
#if defined(_PTHREADS_INVARIANTS)
void    _waitq_setactive(void);
void    _waitq_clearactive(void);
#endif
void    _thread_exit(char *, int, char *);
void    _thread_exit_cleanup(void);
int     _thread_fd_getflags(int);
int     _thread_fd_lock(int, int, struct timespec *);
int     _thread_fd_lock_debug(int, int, struct timespec *,char *fname,int lineno);
void    _thread_fd_setflags(int, int);
int     _thread_fd_table_init(int fd);
void    _thread_fd_unlock(int, int);
void    _thread_fd_unlock_debug(int, int, char *, int);
void    _thread_fd_unlock_owned(pthread_t);
void    *_thread_cleanup(pthread_t);
void    _thread_cleanupspecific(void);
void    _thread_dump_info(void);
void    _thread_init(void);
void    _thread_kern_sched(ucontext_t *);
void    _thread_kern_scheduler(void);
void    _thread_kern_sched_frame(struct pthread_signal_frame *psf);
void    _thread_kern_sched_sig(void);
void    _thread_kern_sched_state(enum pthread_state, char *fname, int lineno);
void    _thread_kern_sched_state_unlock(enum pthread_state state,
            spinlock_t *lock, char *fname, int lineno);
void    _thread_kern_set_timeout(const struct timespec *);
void    _thread_kern_sig_defer(void);
void    _thread_kern_sig_undefer(void);
void    _thread_mksigpipe(void);
void    _thread_sig_handler(int, siginfo_t *, ucontext_t *);
void    _thread_sig_check_pending(struct pthread *pthread);
void    _thread_sig_handle_pending(void);
void    _thread_sig_send(struct pthread *pthread, int sig);
void    _thread_sig_wrapper(void);
void    _thread_sigframe_restore(struct pthread *thread,
            struct pthread_signal_frame *psf);
void    _thread_start(void);
pthread_addr_t _thread_gc(pthread_addr_t);
void    _thread_enter_cancellation_point(void);
void    _thread_leave_cancellation_point(void);
void    _thread_cancellation_point(void);

/* #include <aio.h> */
#ifdef _SYS_AIO_H_
int     __sys_aio_suspend(const struct aiocb * const[], int, const struct timespec *);
#endif

/* #include <sys/event.h> */
#ifdef _SYS_EVENT_H_
int     __sys_kevent(int, const struct kevent *, int, struct kevent *,
            int, const struct timespec *);
int     __sys_kqueue(void);
#endif

/* #include <sys/ioctl.h> */
#ifdef _SYS_IOCTL_H_
int     __sys_ioctl(int, unsigned long, ...);
#endif

/* #include <sys/mman.h> */
#ifdef _SYS_MMAN_H_
int     __sys_msync(void *, size_t, int);
#endif

/* #include <sys/mount.h> */
#ifdef _SYS_MOUNT_H_
int     __sys_fstatfs(int, struct statfs *);
#endif

/* #include <sys/socket.h> */
#ifdef _SYS_SOCKET_H_
int     __sys_accept(int, struct sockaddr *, socklen_t *);
int     __sys_extaccept(int, int, struct sockaddr *, socklen_t *);
int     __sys_bind(int, const struct sockaddr *, socklen_t);
int     __sys_connect(int, const struct sockaddr *, socklen_t);
int     __sys_extconnect(int, int, const struct sockaddr *, socklen_t);
int     __sys_getpeername(int, struct sockaddr *, socklen_t *);
int     __sys_getsockname(int, struct sockaddr *, socklen_t *);
int     __sys_getsockopt(int, int, int, void *, socklen_t *);
int     __sys_listen(int, int);
ssize_t __sys_recvfrom(int, void *, size_t, int, struct sockaddr *, socklen_t *);
ssize_t __sys_recvmsg(int, struct msghdr *, int);
int     __sys_sendfile(int, int, off_t, size_t, struct sf_hdtr *, off_t *, int);
ssize_t __sys_sendmsg(int, const struct msghdr *, int);
ssize_t __sys_sendto(int, const void *,size_t, int, const struct sockaddr *, socklen_t);
int     __sys_setsockopt(int, int, int, const void *, socklen_t);
int     __sys_shutdown(int, int);
int     __sys_socket(int, int, int);
int     __sys_socketpair(int, int, int, int *);
#endif

/* #include <sys/stat.h> */
#ifdef _SYS_STAT_H_
int     __sys_fchflags(int, u_long);
int     __sys_fchmod(int, mode_t);
int     __sys_fchmodat(int, const char *, mode_t, int);
int     __sys_fstat(int, struct stat *);
int     __sys_fstatat(int, const char *, struct stat *, int);
#endif

/* #include <sys/uio.h> */
#ifdef _SYS_UIO_H_
ssize_t __sys_readv(int, const struct iovec *, int);
ssize_t __sys_writev(int, const struct iovec *, int);
ssize_t __sys_extpreadv(int, const struct iovec *, int, int, off_t);
ssize_t __sys_extpwritev(int, const struct iovec *, int, int, off_t);
#endif

/* #include <sys/wait.h> */
#ifdef WNOHANG
pid_t   __sys_wait4(pid_t, int *, int, struct rusage *);
#endif

/* #include <dirent.h> */
#ifdef _DIRENT_H_
int     __sys_getdirentries(int, char *, int, long *);
#endif

/* #include <fcntl.h> */
#ifdef _SYS_FCNTL_H_
int     __sys_fcntl(int, int, ...);
int     __sys_flock(int, int);
int     __sys_open(const char *, int, ...);
int     __sys_openat(int, const char *, int, ...);
#endif

/* #include <poll.h> */
#ifdef _SYS_POLL_H_
int     __sys_poll(struct pollfd *, unsigned, int);
#endif

/* #include <signal.h> */
#ifdef _SIGNAL_H_
int     __sys_sigaction(int, const struct sigaction *, struct sigaction *);
int     __sys_sigprocmask(int, const sigset_t *, sigset_t *);
int     __sys_sigreturn(ucontext_t *);
#endif

/* #include <unistd.h> */
#ifdef _UNISTD_H_
void    __sys_exit(int);
int     __sys_close(int);
int     __sys_closefrom(int);
int     __sys_dup(int);
int     __sys_dup2(int, int);
int     __sys_execve(const char *, char * const *, char * const *);
int     __sys_faccessat(int, const char *, int, int);
int     __sys_fchown(int, uid_t, gid_t);
int     __sys_fchownat(int, const char *, uid_t, gid_t, int);
long    __sys_fpathconf(int, int);
int     __sys_fsync(int);
int     __sys_pipe(int *);
ssize_t __sys_read(int, void *, size_t);
ssize_t __sys_extpread(int, void *, size_t, int, off_t);
ssize_t __sys_write(int, const void *, size_t);
ssize_t __sys_extpwrite(int, const void *, size_t, int, off_t);
int     __sys_unlinkat(int, const char *, int);
#endif

/* #include <setjmp.h> */
#ifdef _SETJMP_H_
extern void     __siglongjmp(sigjmp_buf, int) __dead2;
extern void     __longjmp(jmp_buf, int) __dead2;
extern void     ___longjmp(jmp_buf, int) __dead2;
#endif
__END_DECLS

#endif  /* !_PTHREAD_PRIVATE_H */