No empty .Rs/.Re

[netbsd-mini2440.git] / sys / compat / sa / compat_sa.c

/*      $NetBSD: compat_sa.c,v 1.11 2009/09/13 18:45:10 pooka Exp $     */

/*-
 * Copyright (c) 2001, 2004, 2005, 2006 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nathan J. Williams, and by Andrew Doran.
 *
 * 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 the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>

#include "opt_ktrace.h"
#include "opt_multiprocessor.h"
#include "opt_sa.h"
__KERNEL_RCSID(0, "$NetBSD: compat_sa.c,v 1.11 2009/09/13 18:45:10 pooka Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/cpu.h>
#include <sys/pool.h>
#include <sys/proc.h>
#include <sys/types.h>
#include <sys/ucontext.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/mount.h>
#include <sys/sa.h>
#include <sys/savar.h>
#include <sys/syscallargs.h>
#include <sys/ktrace.h>
#include <sys/sched.h>
#include <sys/sleepq.h>
#include <sys/atomic.h> /* for membar_producer() */

#include <uvm/uvm_extern.h>

/*
 * Now handle building with SA diabled. We always compile this file,
 * just if SA's disabled we merely build in stub routines for call
 * entry points we still need.
 */
#ifdef KERN_SA

/*
 * SA_CONCURRENCY is buggy can lead to kernel crashes.
 */
#ifdef SA_CONCURRENCY
#ifndef MULTIPROCESSOR
        #error "SA_CONCURRENCY is only valid on MULTIPROCESSOR kernels"
#endif
#endif

/*
 * memory pool for sadata structures
 */
static struct pool sadata_pool;

/*
 * memory pool for pending upcalls
 */
static struct pool saupcall_pool;

/*
 * memory pool for sastack structs
 */
static struct pool sastack_pool;

/*
 * memory pool for sadata_vp structures
 */
static struct pool savp_pool;

static struct sadata_vp *sa_newsavp(struct proc *);
static void sa_freevp(struct proc *, struct sadata *, struct sadata_vp *);
static inline int sa_stackused(struct sastack *, struct sadata *);
static inline void sa_setstackfree(struct sastack *, struct sadata *);
static struct sastack *sa_getstack(struct sadata *);
static inline struct sastack *sa_getstack0(struct sadata *);
static inline int sast_compare(struct sastack *, struct sastack *);
#ifdef SA_CONCURRENCY
static int sa_increaseconcurrency(struct lwp *, int);
#endif
static void sa_switchcall(void *);
static void sa_neverrun(void *);
static int sa_newcachelwp(struct lwp *, struct sadata_vp *);
static void sa_makeupcalls(struct lwp *, struct sadata_upcall *);

static inline int sa_pagefault(struct lwp *, ucontext_t *);

static void sa_upcall0(struct sadata_upcall *, int, struct lwp *, struct lwp *,
    size_t, void *, void (*)(void *));
static void sa_upcall_getstate(union sau_state *, struct lwp *, int);

void    sa_putcachelwp(struct proc *, struct lwp *);
struct lwp *sa_getcachelwp(struct proc *, struct sadata_vp *);
static void     sa_setrunning(struct lwp *);

#define SA_DEBUG

#ifdef SA_DEBUG
#define DPRINTF(x)      do { if (sadebug) printf_nolog x; } while (0)
#define DPRINTFN(n,x)   do { if (sadebug & (1<<(n-1))) printf_nolog x; } while (0)
int     sadebug = 0;
#else
#define DPRINTF(x)
#define DPRINTFN(n,x)
#endif

static syncobj_t sa_sobj = {
        SOBJ_SLEEPQ_FIFO,
        sleepq_unsleep,
        sleepq_changepri,
        sleepq_lendpri,
        syncobj_noowner,
};

static const char *sa_lwpcache_wmesg = "lwpcache";
static const char *sa_lwpwoken_wmesg = "lwpublk";

#define SA_LWP_STATE_LOCK(l, f) do {                            \
        (f) = ~(l)->l_pflag & LP_SA_NOBLOCK;                    \
        (l)->l_pflag |= LP_SA_NOBLOCK;                          \
} while (/*CONSTCOND*/ 0)

#define SA_LWP_STATE_UNLOCK(l, f) do {                          \
        (l)->l_pflag ^= (f);                                    \
} while (/*CONSTCOND*/ 0)

RB_PROTOTYPE(sasttree, sastack, sast_node, sast_compare);
RB_GENERATE(sasttree, sastack, sast_node, sast_compare);

kmutex_t        saupcall_mutex;
SIMPLEQ_HEAD(, sadata_upcall) saupcall_freelist;

void
sa_init(void)
{

        pool_init(&sadata_pool, sizeof(struct sadata), 0, 0, 0, "sadatapl",
            &pool_allocator_nointr, IPL_NONE);
        pool_init(&saupcall_pool, sizeof(struct sadata_upcall), 0, 0, 0,
            "saupcpl", &pool_allocator_nointr, IPL_NONE);
        pool_init(&sastack_pool, sizeof(struct sastack), 0, 0, 0, "sastackpl",
            &pool_allocator_nointr, IPL_NONE);
        pool_init(&savp_pool, sizeof(struct sadata_vp), 0, 0, 0, "savppl",
            &pool_allocator_nointr, IPL_NONE);
}

/*
 * sa_critpath API
 * permit other parts of the kernel to make SA_LWP_STATE_{UN,}LOCK calls.
 */
void
sa_critpath_enter(struct lwp *l1, sa_critpath_t *f1)
{
        SA_LWP_STATE_LOCK(l1, *f1);
}
void
sa_critpath_exit(struct lwp *l1, sa_critpath_t *f1)
{
        SA_LWP_STATE_UNLOCK(l1, *f1);
}


/*
 * sadata_upcall_alloc:
 *
 *      Allocate an sadata_upcall structure.
 */
struct sadata_upcall *
sadata_upcall_alloc(int waitok)
{
        struct sadata_upcall *sau;

        sau = NULL;
        if (waitok && !SIMPLEQ_EMPTY(&saupcall_freelist)) {
                mutex_enter(&saupcall_mutex);
                if ((sau = SIMPLEQ_FIRST(&saupcall_freelist)) != NULL)
                        SIMPLEQ_REMOVE_HEAD(&saupcall_freelist, sau_next);
                mutex_exit(&saupcall_mutex);
                if (sau != NULL && sau->sau_arg != NULL)
                        (*sau->sau_argfreefunc)(sau->sau_arg);
        }

        if (sau == NULL)
                sau = pool_get(&saupcall_pool, waitok ? PR_WAITOK : PR_NOWAIT);
        if (sau != NULL)
                sau->sau_arg = NULL;

        return sau;
}

/*
 * sadata_upcall_free:
 *
 *      Free an sadata_upcall structure and any associated argument data.
 */
void
sadata_upcall_free(struct sadata_upcall *sau)
{
        if (sau == NULL)
                return;

        /*
         * If our current synchronisation object is a sleep queue or
         * similar, we must not put the object back to the pool as
         * doing to could acquire sleep locks.  That could trigger
         * a recursive sleep.
         */
        if (curlwp->l_syncobj == &sched_syncobj) {
                if (sau->sau_arg)
                        (*sau->sau_argfreefunc)(sau->sau_arg);
                pool_put(&saupcall_pool, sau);
                sadata_upcall_drain();
        } else {
                mutex_enter(&saupcall_mutex);
                SIMPLEQ_INSERT_HEAD(&saupcall_freelist, sau, sau_next);
                mutex_exit(&saupcall_mutex);
        }
}

/*
 * sadata_upcall_drain:
 *
 *      Put freed upcall structures back to the pool.
 */
void
sadata_upcall_drain(void)
{
        struct sadata_upcall *sau;

        sau = SIMPLEQ_FIRST(&saupcall_freelist);
        while (sau != NULL) {
                mutex_enter(&saupcall_mutex);
                if ((sau = SIMPLEQ_FIRST(&saupcall_freelist)) != NULL)
                        SIMPLEQ_REMOVE_HEAD(&saupcall_freelist, sau_next);
                mutex_exit(&saupcall_mutex);
                if (sau != NULL) /* XXX sau_arg free needs a call! */
                        pool_put(&saupcall_pool, sau);
        }
}

/*
 * sa_newsavp
 *
 * Allocate a new virtual processor structure, do some simple
 * initialization and add it to the passed-in sa. Pre-allocate
 * an upcall event data structure for when the main thread on
 * this vp blocks.
 *
 * We lock ??? while manipulating the list of vp's.
 *
 * We allocate the lwp to run on this separately. In the case of the
 * first lwp/vp for a process, the lwp already exists. It's the
 * main (only) lwp of the process.
 */
static struct sadata_vp *
sa_newsavp(struct proc *p)
{
        struct sadata *sa = p->p_sa;
        struct sadata_vp *vp, *qvp;
        struct sadata_upcall *sau;

        /* Allocate virtual processor data structure */
        vp = pool_get(&savp_pool, PR_WAITOK);
        /* And preallocate an upcall data structure for sleeping */
        sau = sadata_upcall_alloc(1);
        /* Initialize. */
        memset(vp, 0, sizeof(*vp));
        /* Lock has to be IPL_SCHED, since we use it in the
         * hooks from the scheduler code */
        vp->savp_lwp = NULL;
        vp->savp_faultaddr = 0;
        vp->savp_ofaultaddr = 0;
        vp->savp_woken_count = 0;
        vp->savp_lwpcache_count = 0;
        vp->savp_pflags = 0;
        vp->savp_sleeper_upcall = sau;
        mutex_init(&vp->savp_mutex, MUTEX_DEFAULT, IPL_SCHED);
        sleepq_init(&vp->savp_lwpcache);
        sleepq_init(&vp->savp_woken);
        SIMPLEQ_INIT(&vp->savp_upcalls);

        /* We're writing sa_savps, so lock both locks */
        mutex_enter(p->p_lock);
        mutex_enter(&sa->sa_mutex);
        /* find first free savp_id and add vp to sorted slist */
        if (SLIST_EMPTY(&sa->sa_vps) ||
            SLIST_FIRST(&sa->sa_vps)->savp_id != 0) {
                vp->savp_id = 0;
                SLIST_INSERT_HEAD(&sa->sa_vps, vp, savp_next);
        } else {
                SLIST_FOREACH(qvp, &sa->sa_vps, savp_next) {
                        if (SLIST_NEXT(qvp, savp_next) == NULL ||
                            SLIST_NEXT(qvp, savp_next)->savp_id !=
                            qvp->savp_id + 1)
                                break;
                }
                vp->savp_id = qvp->savp_id + 1;
                SLIST_INSERT_AFTER(qvp, vp, savp_next);
        }
        mutex_exit(&sa->sa_mutex);
        mutex_exit(p->p_lock);

        DPRINTFN(1, ("sa_newsavp(%d) allocated vp %p\n", p->p_pid, vp));

        return (vp);
}

/*
 * sa_freevp:
 *
 *      Deallocate a vp. Must be called with no locks held.
 * Will lock and unlock p_lock.
 */
static void
sa_freevp(struct proc *p, struct sadata *sa, struct sadata_vp *vp)
{
        DPRINTFN(1, ("sa_freevp(%d) freeing vp %p\n", p->p_pid, vp));

        mutex_enter(p->p_lock);

        DPRINTFN(1, ("sa_freevp(%d) about to unlink in vp %p\n", p->p_pid, vp));
        SLIST_REMOVE(&sa->sa_vps, vp, sadata_vp, savp_next);
        DPRINTFN(1, ("sa_freevp(%d) done unlink in vp %p\n", p->p_pid, vp));

        if (vp->savp_sleeper_upcall) {
                sadata_upcall_free(vp->savp_sleeper_upcall);
                vp->savp_sleeper_upcall = NULL;
        }
        DPRINTFN(1, ("sa_freevp(%d) about to mut_det in vp %p\n", p->p_pid, vp));

        mutex_destroy(&vp->savp_mutex);

        mutex_exit(p->p_lock);

        pool_put(&savp_pool, vp);
}

/*
 *
 */
int sa_system_disabled = 1;

/*
 * sys_sa_register
 *      Handle copyin and copyout of info for registering the
 * upcall handler address.
 */
int
sys_sa_register(struct lwp *l, const struct sys_sa_register_args *uap,
    register_t *retval)
{
        int error;
        sa_upcall_t prev;

        error = dosa_register(l, SCARG(uap, new), &prev, SCARG(uap, flags),
            SCARG(uap, stackinfo_offset));
        if (error)
                return error;

        if (SCARG(uap, old))
                return copyout(&prev, SCARG(uap, old),
                    sizeof(prev));
        return 0;
}

/*
 * dosa_register
 *
 *      Change the upcall address for the process. If needed, allocate
 * an sadata structure (and initialize it) for the process. If initializing,
 * set the flags in the sadata structure to those passed in. Flags will
 * be ignored if the sadata structure already exists (dosa_regiister was
 * already called).
 *
 * Note: changing the upcall handler address for a process that has
 * concurrency greater than one can yield ambiguous results. The one
 * guarantee we can offer is that any upcalls generated on all CPUs
 * after this routine finishes will use the new upcall handler. Note
 * that any upcalls delivered upon return to user level by the
 * sys_sa_register() system call that called this routine will use the
 * new upcall handler. Note that any such upcalls will be delivered
 * before the old upcall handling address has been returned to
 * the application.
 */
int
dosa_register(struct lwp *l, sa_upcall_t new, sa_upcall_t *prev, int flags,
    ssize_t stackinfo_offset)
{
        struct proc *p = l->l_proc;
        struct sadata *sa;

        if (sa_system_disabled)
                return EINVAL;

        if (p->p_sa == NULL) {
                /* Allocate scheduler activations data structure */
                sa = pool_get(&sadata_pool, PR_WAITOK);
                memset(sa, 0, sizeof(*sa));

                /* WRS: not sure if need SCHED. need to audit lockers */
                mutex_init(&sa->sa_mutex, MUTEX_DEFAULT, IPL_SCHED);
                mutex_enter(p->p_lock);
                if ((p->p_sflag & PS_NOSA) != 0) {
                        mutex_exit(p->p_lock);
                        mutex_destroy(&sa->sa_mutex);
                        pool_put(&sadata_pool, sa);
                        return EINVAL;
                }

                /* Initialize. */
                sa->sa_flag = flags & SA_FLAG_ALL;
                sa->sa_maxconcurrency = 1;
                sa->sa_concurrency = 1;
                RB_INIT(&sa->sa_stackstree);
                sa->sa_stacknext = NULL;
                if (flags & SA_FLAG_STACKINFO)
                        sa->sa_stackinfo_offset = stackinfo_offset;
                else
                        sa->sa_stackinfo_offset = 0;
                sa->sa_nstacks = 0;
                sigemptyset(&sa->sa_sigmask);
                sigplusset(&l->l_sigmask, &sa->sa_sigmask);
                sigemptyset(&l->l_sigmask);
                SLIST_INIT(&sa->sa_vps);
                cv_init(&sa->sa_cv, "sawait");
                membar_producer();
                p->p_sa = sa;
                KASSERT(l->l_savp == NULL);
                mutex_exit(p->p_lock);
        }
        if (l->l_savp == NULL) {        /* XXXSMP */
                l->l_savp = sa_newsavp(p);
                sa_newcachelwp(l, NULL);
        }

        *prev = p->p_sa->sa_upcall;
        p->p_sa->sa_upcall = new;

        return (0);
}

void
sa_release(struct proc *p)
{
        struct sadata *sa;
        struct sastack *sast, *next;
        struct sadata_vp *vp;
        struct lwp *l;

        sa = p->p_sa;
        KASSERT(sa != NULL);
        KASSERT(p->p_nlwps <= 1);

        for (sast = RB_MIN(sasttree, &sa->sa_stackstree); sast != NULL;
             sast = next) {
                next = RB_NEXT(sasttree, &sa->sa_stackstree, sast);
                RB_REMOVE(sasttree, &sa->sa_stackstree, sast);
                pool_put(&sastack_pool, sast);
        }

        mutex_enter(p->p_lock);
        p->p_sflag = (p->p_sflag & ~PS_SA) | PS_NOSA;
        p->p_sa = NULL;
        l = LIST_FIRST(&p->p_lwps);
        if (l) {
                lwp_lock(l);
                KASSERT(LIST_NEXT(l, l_sibling) == NULL);
                l->l_savp = NULL;
                lwp_unlock(l);
        }
        mutex_exit(p->p_lock);

        while ((vp = SLIST_FIRST(&sa->sa_vps)) != NULL) {
                sa_freevp(p, sa, vp);
        }

        DPRINTFN(1, ("sa_release(%d) done vps\n", p->p_pid));

        mutex_destroy(&sa->sa_mutex);
        cv_destroy(&sa->sa_cv);
        pool_put(&sadata_pool, sa);

        DPRINTFN(1, ("sa_release(%d) put sa\n", p->p_pid));

        mutex_enter(p->p_lock);
        p->p_sflag &= ~PS_NOSA;
        mutex_exit(p->p_lock);
}

/*
 * sa_fetchstackgen
 *
 *      copyin the generation number for the stack in question.
 *
 * WRS: I think this routine needs the SA_LWP_STATE_LOCK() dance, either
 * here or in its caller.
 *
 * Must be called with sa_mutex locked.
 */
static int
sa_fetchstackgen(struct sastack *sast, struct sadata *sa, unsigned int *gen)
{
        int error;

        /* COMPAT_NETBSD32:  believe it or not, but the following is ok */
        mutex_exit(&sa->sa_mutex);
        error = copyin(&((struct sa_stackinfo_t *)
            ((char *)sast->sast_stack.ss_sp +
            sa->sa_stackinfo_offset))->sasi_stackgen, gen, sizeof(*gen));
        mutex_enter(&sa->sa_mutex);

        return error;
}

/*
 * sa_stackused
 *
 *      Convenience routine to determine if a given stack has been used
 * or not. We consider a stack to be unused if the kernel's concept
 * of its generation number matches that of userland.
 *      We kill the application with SIGILL if there is an error copying
 * in the userland generation number.
 */
static inline int
sa_stackused(struct sastack *sast, struct sadata *sa)
{
        unsigned int gen;

        KASSERT(mutex_owned(&sa->sa_mutex));

        if (sa_fetchstackgen(sast, sa, &gen)) {
                sigexit(curlwp, SIGILL);
                /* NOTREACHED */
        }
        return (sast->sast_gen != gen);
}

/*
 * sa_setstackfree
 *
 *      Convenience routine to mark a stack as unused in the kernel's
 * eyes. We do this by setting the kernel's generation number for the stack
 * to that of userland.
 *      We kill the application with SIGILL if there is an error copying
 * in the userland generation number.
 */
static inline void
sa_setstackfree(struct sastack *sast, struct sadata *sa)
{
        unsigned int gen;

        KASSERT(mutex_owned(&sa->sa_mutex));

        if (sa_fetchstackgen(sast, sa, &gen)) {
                sigexit(curlwp, SIGILL);
                /* NOTREACHED */
        }
        sast->sast_gen = gen;
}

/*
 * sa_getstack
 *
 * Find next free stack, starting at sa->sa_stacknext.  Must be called
 * with sa->sa_mutex held, and will release while checking for stack
 * availability.
 *
 * Caller should have set LP_SA_NOBLOCK for our thread. This is not the time
 * to go generating upcalls as we aren't in a position to deliver another one.
 */
static struct sastack *
sa_getstack(struct sadata *sa)
{
        struct sastack *sast;
        int chg;

        KASSERT(mutex_owned(&sa->sa_mutex));

        do {
                chg = sa->sa_stackchg;
                sast = sa->sa_stacknext;
                if (sast == NULL || sa_stackused(sast, sa))
                        sast = sa_getstack0(sa);
        } while (chg != sa->sa_stackchg);

        if (sast == NULL)
                return NULL;

        sast->sast_gen++;
        sa->sa_stackchg++;

        return sast;
}

/*
 * sa_getstack0 -- get the lowest numbered sa stack
 *
 *      We walk the splay tree in order and find the lowest-numbered
 * (as defined by SPLAY_MIN() and SPLAY_NEXT() ordering) stack that
 * is unused.
 */
static inline struct sastack *
sa_getstack0(struct sadata *sa)
{
        struct sastack *start;
        int chg;

        KASSERT(mutex_owned(&sa->sa_mutex));

 retry:
        chg = sa->sa_stackchg;
        if (sa->sa_stacknext == NULL) {
                sa->sa_stacknext = RB_MIN(sasttree, &sa->sa_stackstree);
                if (sa->sa_stacknext == NULL)
                        return NULL;
        }
        start = sa->sa_stacknext;

        while (sa_stackused(sa->sa_stacknext, sa)) {
                if (sa->sa_stackchg != chg)
                        goto retry;
                sa->sa_stacknext = RB_NEXT(sasttree, &sa->sa_stackstree,
                    sa->sa_stacknext);
                if (sa->sa_stacknext == NULL)
                        sa->sa_stacknext = RB_MIN(sasttree,
                            &sa->sa_stackstree);
                if (sa->sa_stacknext == start)
                        return NULL;
        }
        return sa->sa_stacknext;
}

/*
 * sast_compare - compare two sastacks
 *
 *      We sort stacks according to their userspace addresses.
 * Stacks are "equal" if their start + size overlap.
 */
static inline int
sast_compare(struct sastack *a, struct sastack *b)
{

        if ((vaddr_t)a->sast_stack.ss_sp + a->sast_stack.ss_size <=
            (vaddr_t)b->sast_stack.ss_sp)
                return (-1);
        if ((vaddr_t)a->sast_stack.ss_sp >=
            (vaddr_t)b->sast_stack.ss_sp + b->sast_stack.ss_size)
                return (1);
        return (0);
}

/*
 * sa_copyin_stack -- copyin a stack.
 */
static int
sa_copyin_stack(stack_t *stacks, int index, stack_t *dest)
{
        return copyin(stacks + index, dest, sizeof(stack_t));
}

/*
 * sys_sa_stacks -- the user level threading library is passing us stacks
 *
 * We copy in some arguments then call sa_stacks1() to do the main
 * work. NETBSD32 has its own front-end for this call.
 */
int
sys_sa_stacks(struct lwp *l, const struct sys_sa_stacks_args *uap,
        register_t *retval)
{
        return sa_stacks1(l, retval, SCARG(uap, num), SCARG(uap, stacks),
            sa_copyin_stack);
}

/*
 * sa_stacks1
 *      Process stacks passed-in by the user threading library. At
 * present we use the kernel lock to lock the SPLAY tree, which we
 * manipulate to load in the stacks.
 *
 *      It is an error to pass in a stack that we already know about
 * and which hasn't been used. Passing in a known-but-used one is fine.
 * We accept up to SA_MAXNUMSTACKS per desired vp (concurrency level).
 */
int
sa_stacks1(struct lwp *l, register_t *retval, int num, stack_t *stacks,
    sa_copyin_stack_t do_sa_copyin_stack)
{
        struct sadata *sa = l->l_proc->p_sa;
        struct sastack *sast, *new;
        int count, error, f, i, chg;

        /* We have to be using scheduler activations */
        if (sa == NULL)
                return (EINVAL);

        count = num;
        if (count < 0)
                return (EINVAL);

        SA_LWP_STATE_LOCK(l, f);

        error = 0;

        for (i = 0; i < count; i++) {
                new = pool_get(&sastack_pool, PR_WAITOK);
                error = do_sa_copyin_stack(stacks, i, &new->sast_stack);
                if (error) {
                        count = i;
                        break;
                }
                mutex_enter(&sa->sa_mutex);
         restart:
                chg = sa->sa_stackchg;
                sa_setstackfree(new, sa);
                sast = RB_FIND(sasttree, &sa->sa_stackstree, new);
                if (sast != NULL) {
                        DPRINTFN(9, ("sa_stacks(%d.%d) returning stack %p\n",
                                     l->l_proc->p_pid, l->l_lid,
                                     new->sast_stack.ss_sp));
                        if (sa_stackused(sast, sa) == 0) {
                                count = i;
                                error = EEXIST;
                                mutex_exit(&sa->sa_mutex);
                                pool_put(&sastack_pool, new);
                                break;
                        }
                        if (chg != sa->sa_stackchg)
                                goto restart;
                } else if (sa->sa_nstacks >=
                    SA_MAXNUMSTACKS * sa->sa_concurrency) {
                        DPRINTFN(9,
                            ("sa_stacks(%d.%d) already using %d stacks\n",
                            l->l_proc->p_pid, l->l_lid,
                            SA_MAXNUMSTACKS * sa->sa_concurrency));
                        count = i;
                        error = ENOMEM;
                        mutex_exit(&sa->sa_mutex);
                        pool_put(&sastack_pool, new);
                        break;
                } else {
                        DPRINTFN(9, ("sa_stacks(%d.%d) adding stack %p\n",
                                     l->l_proc->p_pid, l->l_lid,
                                     new->sast_stack.ss_sp));
                        RB_INSERT(sasttree, &sa->sa_stackstree, new);
                        sa->sa_nstacks++;
                        sa->sa_stackchg++;
                }
                mutex_exit(&sa->sa_mutex);
        }

        SA_LWP_STATE_UNLOCK(l, f);

        *retval = count;
        return (error);
}


/*
 * sys_sa_enable - throw the switch & enable SA
 *
 * Fairly simple. Make sure the sadata and vp've been set up for this
 * process, assign this thread to the vp and initiate the first upcall
 * (SA_UPCALL_NEWPROC).
 */
int
sys_sa_enable(struct lwp *l, const void *v, register_t *retval)
{
        struct proc *p = l->l_proc;
        struct sadata *sa = p->p_sa;
        struct sadata_vp *vp = l->l_savp;
        int error;

        DPRINTF(("sys_sa_enable(%d.%d)\n", l->l_proc->p_pid,
            l->l_lid));

        /* We have to be using scheduler activations */
        if (sa == NULL || vp == NULL)
                return (EINVAL);

        if (p->p_sflag & PS_SA) /* Already running! */
                return (EBUSY);

        error = sa_upcall(l, SA_UPCALL_NEWPROC, l, NULL, 0, NULL, NULL);
        if (error)
                return (error);

        /* Assign this LWP to the virtual processor */
        mutex_enter(p->p_lock);
        vp->savp_lwp = l;
        p->p_sflag |= PS_SA;
        lwp_lock(l);
        l->l_flag |= LW_SA; /* We are now an activation LWP */
        lwp_unlock(l);
        mutex_exit(p->p_lock);

        /*
         * This will return to the SA handler previously registered.
         */
        return (0);
}


/*
 * sa_increaseconcurrency
 *      Raise the process's maximum concurrency level to the
 * requested level. Does nothing if the current maximum councurrency
 * is greater than the requested.
 *      Must be called with sa_mutex locked. Will unlock and relock as
 * needed, and will lock p_lock. Will exit with sa_mutex locked.
 */
#ifdef SA_CONCURRENCY

static int
sa_increaseconcurrency(struct lwp *l, int concurrency)
{
        struct proc *p;
        struct lwp *l2;
        struct sadata *sa;
        struct sadata_vp *vp;
        struct sadata_upcall *sau;
        int addedconcurrency, error;

        p = l->l_proc;
        sa = p->p_sa;

        KASSERT(mutex_owned(&sa->sa_mutex));

        addedconcurrency = 0;
        while (sa->sa_maxconcurrency < concurrency) {
                sa->sa_maxconcurrency++;
                sa->sa_concurrency++;
                mutex_exit(&sa->sa_mutex);

                vp = sa_newsavp(p);
                error = sa_newcachelwp(l, vp);
                if (error) {
                        /* reset concurrency */
                        mutex_enter(&sa->sa_mutex);
                        sa->sa_maxconcurrency--;
                        sa->sa_concurrency--;
                        return (addedconcurrency);
                }
                mutex_enter(&vp->savp_mutex);
                l2 = sa_getcachelwp(p, vp);
                vp->savp_lwp = l2;

                sau = vp->savp_sleeper_upcall;
                vp->savp_sleeper_upcall = NULL;
                KASSERT(sau != NULL);

                cpu_setfunc(l2, sa_switchcall, sau);
                sa_upcall0(sau, SA_UPCALL_NEWPROC, NULL, NULL,
                    0, NULL, NULL);

                if (error) {
                        /* put l2 into l's VP LWP cache */
                        mutex_exit(&vp->savp_mutex);
                        lwp_lock(l2);
                        l2->l_savp = l->l_savp;
                        cpu_setfunc(l2, sa_neverrun, NULL);
                        lwp_unlock(l2);
                        mutex_enter(&l->l_savp->savp_mutex);
                        sa_putcachelwp(p, l2);
                        mutex_exit(&l->l_savp->savp_mutex);

                        /* Free new savp */
                        sa_freevp(p, sa, vp);

                        /* reset concurrency */
                        mutex_enter(&sa->sa_mutex);
                        sa->sa_maxconcurrency--;
                        sa->sa_concurrency--;
                        return (addedconcurrency);
                }
                /* Run the LWP, locked since its mutex is still savp_mutex */
                sa_setrunning(l2);
                mutex_exit(&vp->savp_mutex);

                mutex_enter(&sa->sa_mutex);
                addedconcurrency++;
        }

        return (addedconcurrency);
}
#endif

/*
 * sys_sa_setconcurrency
 *      The user threading library wants to increase the number
 * of active virtual CPUS we assign to it. We return the number of virt
 * CPUs we assigned to the process. We limit concurrency to the number
 * of CPUs in the system.
 *
 * WRS: at present, this system call serves two purposes. The first is
 * for an application to indicate that it wants a certain concurrency
 * level. The second is for the application to request that the kernel
 * reactivate previously allocated virtual CPUs.
 */
int
sys_sa_setconcurrency(struct lwp *l, const struct sys_sa_setconcurrency_args *uap,
        register_t *retval)
{
        struct proc *p = l->l_proc;
        struct sadata *sa = p->p_sa;
#ifdef SA_CONCURRENCY
        struct sadata_vp *vp = l->l_savp;
        struct lwp *l2;
        int ncpus;
        struct cpu_info *ci;
        CPU_INFO_ITERATOR cii;
#endif

        DPRINTFN(11,("sys_sa_concurrency(%d.%d)\n", p->p_pid,
                     l->l_lid));

        /* We have to be using scheduler activations */
        if (sa == NULL)
                return (EINVAL);

        if ((p->p_sflag & PS_SA) == 0)
                return (EINVAL);

        if (SCARG(uap, concurrency) < 1)
                return (EINVAL);

        *retval = 0;
        /*
         * Concurrency greater than the number of physical CPUs does
         * not make sense.
         * XXX Should we ever support hot-plug CPUs, this will need
         * adjustment.
         */
#ifdef SA_CONCURRENCY
        mutex_enter(&sa->sa_mutex);

        if (SCARG(uap, concurrency) > sa->sa_maxconcurrency) {
                ncpus = 0;
                for (CPU_INFO_FOREACH(cii, ci))
                        ncpus++;
                *retval += sa_increaseconcurrency(l,
                    min(SCARG(uap, concurrency), ncpus));
        }
#endif

        DPRINTFN(11,("sys_sa_concurrency(%d.%d) want %d, have %d, max %d\n",
                     p->p_pid, l->l_lid, SCARG(uap, concurrency),
                     sa->sa_concurrency, sa->sa_maxconcurrency));
#ifdef SA_CONCURRENCY
        if (SCARG(uap, concurrency) <= sa->sa_concurrency) {
                mutex_exit(&sa->sa_mutex);
                return 0;
        }
        SLIST_FOREACH(vp, &sa->sa_vps, savp_next) {
                l2 = vp->savp_lwp;
                lwp_lock(l2);
                if (l2->l_flag & LW_SA_IDLE) {
                        l2->l_flag &= ~(LW_SA_IDLE|LW_SA_YIELD|LW_SINTR);
                        lwp_unlock(l2);
                        DPRINTFN(11,("sys_sa_concurrency(%d.%d) NEWPROC vp %d\n",
                                     p->p_pid, l->l_lid, vp->savp_id));
                        sa->sa_concurrency++;
                        mutex_exit(&sa->sa_mutex);
                        /* error = */ sa_upcall(l2, SA_UPCALL_NEWPROC, NULL,
                            NULL, 0, NULL, NULL);
                        lwp_lock(l2);
                        /* lwp_unsleep() will unlock the LWP */
                        lwp_unsleep(vp->savp_lwp, true);
                        KASSERT((l2->l_flag & LW_SINTR) == 0);
                        (*retval)++;
                        mutex_enter(&sa->sa_mutex);
                } else
                        lwp_unlock(l2);
                if (sa->sa_concurrency == SCARG(uap, concurrency))
                        break;
        }
        mutex_exit(&sa->sa_mutex);
#endif
        return 0;
}

/*
 * sys_sa_yield
 *      application has nothing for this lwp to do, so let it linger in
 * the kernel.
 */
int
sys_sa_yield(struct lwp *l, const void *v, register_t *retval)
{
        struct proc *p = l->l_proc;

        mutex_enter(p->p_lock);
        if (p->p_sa == NULL || !(p->p_sflag & PS_SA)) {
                mutex_exit(p->p_lock);
                DPRINTFN(2,
                    ("sys_sa_yield(%d.%d) proc %p not SA (p_sa %p, flag %s)\n",
                    p->p_pid, l->l_lid, p, p->p_sa,
                    p->p_sflag & PS_SA ? "T" : "F"));
                return (EINVAL);
        }

        mutex_exit(p->p_lock);

        sa_yield(l);

        return (EJUSTRETURN);
}

/*
 * sa_yield
 *      This lwp has nothing to do, so hang around. Assuming we
 * are the lwp "on" our vp, sleep in "sawait" until there's something
 * to do.
 *
 *      Unfortunately some subsystems can't directly tell us if there's an
 * upcall going to happen when we get worken up. Work gets deferred to
 * userret() and that work may trigger an upcall. So we have to try
 * calling userret() (by calling upcallret()) and see if makeupcalls()
 * delivered an upcall. It will clear LW_SA_YIELD if it did.
 */
void
sa_yield(struct lwp *l)
{
        struct proc *p = l->l_proc;
        struct sadata *sa = p->p_sa;
        struct sadata_vp *vp = l->l_savp;
        int ret;

        lwp_lock(l);

        if (vp->savp_lwp != l) {
                lwp_unlock(l);

                /*
                 * We lost the VP on our way here, this happens for
                 * instance when we sleep in systrace.  This will end
                 * in an SA_UNBLOCKED_UPCALL in sa_unblock_userret().
                 */
                DPRINTFN(2,("sa_yield(%d.%d) lost VP\n",
                             p->p_pid, l->l_lid));
                KASSERT(l->l_flag & LW_SA_BLOCKING);
                return;
        }

        /*
         * If we're the last running LWP, stick around to receive
         * signals.
         */
        KASSERT((l->l_flag & LW_SA_YIELD) == 0);
        DPRINTFN(2,("sa_yield(%d.%d) going dormant\n",
                     p->p_pid, l->l_lid));
        /*
         * A signal will probably wake us up. Worst case, the upcall
         * happens and just causes the process to yield again.
         */
        KASSERT(vp->savp_lwp == l);

        /*
         * If we were told to make an upcall or exit already
         * make sure we process it (by returning and letting userret() do
         * the right thing). Otherwise set LW_SA_YIELD and go to sleep.
         */
        ret = 0;
        if (l->l_flag & LW_SA_UPCALL) {
                lwp_unlock(l);
                return;
        }
        l->l_flag |= LW_SA_YIELD;

        do {
                lwp_unlock(l);
                DPRINTFN(2,("sa_yield(%d.%d) really going dormant\n",
                             p->p_pid, l->l_lid));

                mutex_enter(&sa->sa_mutex);
                sa->sa_concurrency--;
                ret = cv_wait_sig(&sa->sa_cv, &sa->sa_mutex);
                sa->sa_concurrency++;
                mutex_exit(&sa->sa_mutex);
                DPRINTFN(2,("sa_yield(%d.%d) woke\n",
                             p->p_pid, l->l_lid));

                KASSERT(vp->savp_lwp == l || p->p_sflag & PS_WEXIT);

                /*
                 * We get woken in two different ways. Most code
                 * calls setrunnable() which clears LW_SA_IDLE,
                 * but leaves LW_SA_YIELD. Some call points
                 * (in this file) however also clear LW_SA_YIELD, mainly
                 * as the code knows there is an upcall to be delivered.
                 *
                 * As noted above, except in the cases where other code
                 * in this file cleared LW_SA_YIELD already, we have to
                 * try calling upcallret() & seeing if upcalls happen.
                 * if so, tell userret() NOT to deliver more upcalls on
                 * the way out!
                 */
                if (l->l_flag & LW_SA_YIELD) {
                        upcallret(l);
                        if (~l->l_flag & LW_SA_YIELD) {
                                /*
                                 * Ok, we made an upcall. We will exit. Tell
                                 * sa_upcall_userret() to NOT make any more
                                 * upcalls.
                                 */
                                vp->savp_pflags |= SAVP_FLAG_NOUPCALLS;
                                /*
                                 * Now force us to call into sa_upcall_userret()
                                 * which will clear SAVP_FLAG_NOUPCALLS
                                 */
                                lwp_lock(l);
                                l->l_flag |= LW_SA_UPCALL;
                                lwp_unlock(l);
                        }
                }

                lwp_lock(l);
        } while (l->l_flag & LW_SA_YIELD);

        DPRINTFN(2,("sa_yield(%d.%d) returned, ret %d\n",
                     p->p_pid, l->l_lid, ret));

        lwp_unlock(l);
}


/*
 * sys_sa_preempt - preempt a running thread
 *
 * Given an lwp id, send it a user upcall. This is a way for libpthread to
 * kick something into the upcall handler.
 */
int
sys_sa_preempt(struct lwp *l, const struct sys_sa_preempt_args *uap,
    register_t *retval)
{
/* Not yet ready */
#if 0
        struct proc             *p = l->l_proc;
        struct sadata           *sa = p->p_sa;
        struct lwp              *t;
        int                     target, error;

        DPRINTFN(11,("sys_sa_preempt(%d.%d)\n", l->l_proc->p_pid,
                     l->l_lid));

        /* We have to be using scheduler activations */
        if (sa == NULL)
                return (EINVAL);

        if ((p->p_sflag & PS_SA) == 0)
                return (EINVAL);

        if ((target = SCARG(uap, sa_id)) < 1)
                return (EINVAL);

        mutex_enter(p->p_lock);

        LIST_FOREACH(t, &l->l_proc->p_lwps, l_sibling)
                if (t->l_lid == target)
                        break;

        if (t == NULL) {
                error = ESRCH;
                goto exit_lock;
        }

        /* XXX WRS We really need all of this locking documented */
        mutex_exit(p->p_lock);

        error = sa_upcall(l, SA_UPCALL_USER | SA_UPCALL_DEFER_EVENT, l, NULL,
                0, NULL, NULL);
        if (error)
                return error;

        return 0;

exit_lock:
        mutex_exit(p->p_lock);

        return error;
#else
        /* Just return an error */
        return (sys_nosys(l, (const void *)uap, retval));
#endif
}


/* XXX Hm, naming collision. */
/*
 * sa_preempt(). In the 4.0 code, this routine is called when we 
 * are in preempt() and the caller informed us it does NOT
 * have more work to do (it's going to userland after we return).
 * If mi_switch() tells us we switched to another thread, we
 * generate a BLOCKED upcall. Since we are returning to userland
 * we then will immediately generate an UNBLOCKED upcall as well.
 *      The only place that actually didn't tell preempt() that
 * we had more to do was sys_sched_yield() (well, midi did too, but
 * that was a bug).
 *
 * For simplicitly, in 5.0+ code, just call this routine in
 * sys_sched_yield after we preempt(). The BLOCKED/UNBLOCKED
 * upcall sequence will get delivered when we return to userland
 * and will ensure that the SA scheduler has an opportunity to
 * effectively preempt the thread that was running in userland.
 *
 * Of course, it would be simpler for libpthread to just intercept
 * this call, but we do this to ensure binary compatability. Plus
 * it's not hard to do.
 *
 * We are called and return with no locks held.
 */
void
sa_preempt(struct lwp *l)
{
        struct proc *p = l->l_proc;
        struct sadata *sa = p->p_sa;

        /*
         * Defer saving the lwp's state because on some ports
         * preemption can occur between generating an unblocked upcall
         * and processing the upcall queue.
         */
        if (sa->sa_flag & SA_FLAG_PREEMPT)
                sa_upcall(l, SA_UPCALL_PREEMPTED | SA_UPCALL_DEFER_EVENT,
                    l, NULL, 0, NULL, NULL);
}


/*
 * Set up the user-level stack and trapframe to do an upcall.
 *
 * NOTE: This routine WILL FREE "arg" in the case of failure!  Callers
 * should not touch the "arg" pointer once calling sa_upcall().
 */
int
sa_upcall(struct lwp *l, int type, struct lwp *event, struct lwp *interrupted,
        size_t argsize, void *arg, void (*func)(void *))
{
        struct sadata_upcall *sau;
        struct sadata *sa = l->l_proc->p_sa;
        struct sadata_vp *vp = l->l_savp;
        struct sastack *sast;
        int f, error;

        KASSERT((type & (SA_UPCALL_LOCKED_EVENT | SA_UPCALL_LOCKED_INTERRUPTED))
                == 0);

        /* XXX prevent recursive upcalls if we sleep for memory */
        SA_LWP_STATE_LOCK(curlwp, f);
        sau = sadata_upcall_alloc(1);
        mutex_enter(&sa->sa_mutex);
        sast = sa_getstack(sa);
        mutex_exit(&sa->sa_mutex);
        SA_LWP_STATE_UNLOCK(curlwp, f);

        if (sau == NULL || sast == NULL) {
                if (sast != NULL) {
                        mutex_enter(&sa->sa_mutex);
                        sa_setstackfree(sast, sa);
                        mutex_exit(&sa->sa_mutex);
                }
                if (sau != NULL)
                        sadata_upcall_free(sau);
                return (ENOMEM);
        }
        DPRINTFN(9,("sa_upcall(%d.%d) using stack %p\n",
            l->l_proc->p_pid, l->l_lid, sast->sast_stack.ss_sp));

        if (l->l_proc->p_emul->e_sa->sae_upcallconv) {
                error = (*l->l_proc->p_emul->e_sa->sae_upcallconv)(l, type,
                    &argsize, &arg, &func);
                if (error) {
                        mutex_enter(&sa->sa_mutex);
                        sa_setstackfree(sast, sa);
                        mutex_exit(&sa->sa_mutex);
                        sadata_upcall_free(sau);
                        return error;
                }
        }

        sa_upcall0(sau, type, event, interrupted, argsize, arg, func);
        sau->sau_stack = sast->sast_stack;
        mutex_enter(&vp->savp_mutex);
        SIMPLEQ_INSERT_TAIL(&vp->savp_upcalls, sau, sau_next);
        lwp_lock(l);
        l->l_flag |= LW_SA_UPCALL;
        lwp_unlock(l);
        mutex_exit(&vp->savp_mutex);

        return (0);
}

static void
sa_upcall0(struct sadata_upcall *sau, int type, struct lwp *event,
    struct lwp *interrupted, size_t argsize, void *arg, void (*func)(void *))
{
        DPRINTFN(12,("sa_upcall0: event %p interrupted %p type %x\n",
            event, interrupted, type));

        KASSERT((event == NULL) || (event != interrupted));

        sau->sau_flags = 0;

        if (type & SA_UPCALL_DEFER_EVENT) {
                sau->sau_event.ss_deferred.ss_lwp = event;
                sau->sau_flags |= SAU_FLAG_DEFERRED_EVENT;
        } else
                sa_upcall_getstate(&sau->sau_event, event,
                        type & SA_UPCALL_LOCKED_EVENT);
        if (type & SA_UPCALL_DEFER_INTERRUPTED) {
                sau->sau_interrupted.ss_deferred.ss_lwp = interrupted;
                sau->sau_flags |= SAU_FLAG_DEFERRED_INTERRUPTED;
        } else
                sa_upcall_getstate(&sau->sau_interrupted, interrupted,
                        type & SA_UPCALL_LOCKED_INTERRUPTED);

        sau->sau_type = type & SA_UPCALL_TYPE_MASK;
        sau->sau_argsize = argsize;
        sau->sau_arg = arg;
        sau->sau_argfreefunc = func;
}

/*
 * sa_ucsp
 *      return the stack pointer (??) for a given context as
 * reported by the _UC_MACHINE_SP() macro.
 */
void *
sa_ucsp(void *arg)
{
        ucontext_t *uc = arg;

        return (void *)(uintptr_t)_UC_MACHINE_SP(uc);
}

/*
 * sa_upcall_getstate
 *      Fill in the given sau_state with info for the passed-in
 * lwp, and update the lwp accordingly.
 *      We set LW_SA_SWITCHING on the target lwp, and so we have to hold
 * l's lock in this call. l must be already locked, or it must be unlocked
 * and locking it must not cause deadlock.
 */
static void
sa_upcall_getstate(union sau_state *ss, struct lwp *l, int isLocked)
{
        uint8_t *sp;
        size_t ucsize;

        if (l) {
                if (isLocked == 0)
                        lwp_lock(l);
                l->l_flag |= LW_SA_SWITCHING;
                if (isLocked == 0)
                        lwp_unlock(l);
                (*l->l_proc->p_emul->e_sa->sae_getucontext)(l,
                    (void *)&ss->ss_captured.ss_ctx);
                if (isLocked == 0)
                        lwp_lock(l);
                l->l_flag &= ~LW_SA_SWITCHING;
                if (isLocked == 0)
                        lwp_unlock(l);
                sp = (*l->l_proc->p_emul->e_sa->sae_ucsp)
                    (&ss->ss_captured.ss_ctx);
                /* XXX COMPAT_NETBSD32: _UC_UCONTEXT_ALIGN */
                sp = STACK_ALIGN(sp, ~_UC_UCONTEXT_ALIGN);
                ucsize = roundup(l->l_proc->p_emul->e_sa->sae_ucsize,
                    (~_UC_UCONTEXT_ALIGN) + 1);
                ss->ss_captured.ss_sa.sa_context =
                    (ucontext_t *)STACK_ALLOC(sp, ucsize);
                ss->ss_captured.ss_sa.sa_id = l->l_lid;
                ss->ss_captured.ss_sa.sa_cpu = l->l_savp->savp_id;
        } else
                ss->ss_captured.ss_sa.sa_context = NULL;
}


/*
 * sa_pagefault
 *
 * Detect double pagefaults and pagefaults on upcalls.
 * - double pagefaults are detected by comparing the previous faultaddr
 *   against the current faultaddr
 * - pagefaults on upcalls are detected by checking if the userspace
 *   thread is running on an upcall stack
 */
static inline int
sa_pagefault(struct lwp *l, ucontext_t *l_ctx)
{
        struct proc *p;
        struct sadata *sa;
        struct sadata_vp *vp;
        struct sastack sast;
        int found;

        p = l->l_proc;
        sa = p->p_sa;
        vp = l->l_savp;

        KASSERT(mutex_owned(&sa->sa_mutex));
        KASSERT(vp->savp_lwp == l);

        if (vp->savp_faultaddr == vp->savp_ofaultaddr) {
                DPRINTFN(10,("sa_pagefault(%d.%d) double page fault\n",
                             p->p_pid, l->l_lid));
                return 1;
        }

        sast.sast_stack.ss_sp = (*p->p_emul->e_sa->sae_ucsp)(l_ctx);
        sast.sast_stack.ss_size = 1;
        found = (RB_FIND(sasttree, &sa->sa_stackstree, &sast) != NULL);

        if (found) {
                DPRINTFN(10,("sa_pagefault(%d.%d) upcall page fault\n",
                             p->p_pid, l->l_lid));
                return 1;
        }

        vp->savp_ofaultaddr = vp->savp_faultaddr;
        return 0;
}


/*
 * sa_switch
 *
 * Called by sleepq_block() when it wants to call mi_switch().
 * Block current LWP and switch to another.
 *
 * WE ARE NOT ALLOWED TO SLEEP HERE!  WE ARE CALLED FROM WITHIN
 * SLEEPQ_BLOCK() ITSELF!  We are called with sched_lock held, and must
 * hold it right through the mi_switch() call.
 *
 * We return with the scheduler unlocked.
 *
 * We are called in one of three conditions:
 *
 * 1:           We are an sa_yield thread. If there are any UNBLOCKED
 *      upcalls to deliver, deliver them (by exiting) instead of sleeping.
 * 2:           We are the main lwp (we're the lwp on our vp). Trigger
 *      delivery of a BLOCKED upcall.
 * 3:           We are not the main lwp on our vp. Chances are we got
 *      woken up but the sleeper turned around and went back to sleep.
 *      It seems that select and poll do this a lot. So just go back to sleep.
 */

void
sa_switch(struct lwp *l)
{
        struct proc *p = l->l_proc;
        struct sadata_vp *vp = l->l_savp;
        struct sadata_upcall *sau = NULL;
        struct lwp *l2;

        KASSERT(lwp_locked(l, NULL));

        DPRINTFN(4,("sa_switch(%d.%d VP %d)\n", p->p_pid, l->l_lid,
            vp->savp_lwp ? vp->savp_lwp->l_lid : 0));

        if ((l->l_flag & LW_WEXIT) || (p->p_sflag & (PS_WCORE | PS_WEXIT))) {
                mi_switch(l);
                return;
        }

        /*
         * We need to hold two locks from here on out. Since you can
         * sleepq_block() on ANY lock, there really can't be a locking
         * hierarcy relative to savp_mutex. So if we can't get the mutex,
         * drop the lwp lock, get the mutex, and carry on.
         *
         * Assumes the lwp lock can never be a sleeping mutex.
         *
         * We do however try hard to never not get savp_mutex. The only
         * times we lock it are either when we are the blessed lwp for
         * our vp, or when a blocked lwp is adding itself to the savp_worken
         * list. So contention should be rare.
         */
        if (!mutex_tryenter(&vp->savp_mutex)) {
                lwp_unlock(l);
                mutex_enter(&vp->savp_mutex);
                lwp_lock(l);
        }
        if (l->l_stat == LSONPROC) {
                /* Oops! We woke before we got to sleep. Ok, back we go! */
                lwp_unlock(l);
                mutex_exit(&vp->savp_mutex);
                return;
        }

        if (l->l_flag & LW_SA_YIELD) {
                /*
                 * Case 0: we're blocking in sa_yield
                 */
                DPRINTFN(4,("sa_switch(%d.%d) yield, flags %x pflag %x\n",
                    p->p_pid, l->l_lid, l->l_flag, l->l_pflag));
                if (vp->savp_woken_count == 0 && p->p_timerpend == 0) {
                        DPRINTFN(4,("sa_switch(%d.%d) setting idle\n",
                            p->p_pid, l->l_lid));
                        l->l_flag |= LW_SA_IDLE;
                        mutex_exit(&vp->savp_mutex);
                        mi_switch(l);
                } else {
                        /*
                         * Make us running again. lwp_unsleep() will
                         * release the lock.
                         */
                        mutex_exit(&vp->savp_mutex);
                        lwp_unsleep(l, true);
                }
                return;
        }

        if (vp->savp_lwp == l) {
                if (vp->savp_pflags & SAVP_FLAG_DELIVERING) {
                        /*
                         * We've exited sa_switchcall() but NOT
                         * made it into a new systemcall. Don't make
                         * a BLOCKED upcall.
                         */
                        mutex_exit(&vp->savp_mutex);
                        mi_switch(l);
                        return;
                }
                /*
                 * Case 1: we're blocking for the first time; generate
                 * a SA_BLOCKED upcall and allocate resources for the
                 * UNBLOCKED upcall.
                 */
                if (vp->savp_sleeper_upcall) {
                        sau = vp->savp_sleeper_upcall;
                        vp->savp_sleeper_upcall = NULL;
                }

                if (sau == NULL) {
#ifdef DIAGNOSTIC
                        printf("sa_switch(%d.%d): no upcall data.\n",
                            p->p_pid, l->l_lid);
#endif
                        panic("Oops! Don't have a sleeper!\n");
                        /* XXXWRS Shouldn't we just kill the app here? */
                        mutex_exit(&vp->savp_mutex);
                        mi_switch(l);
                        return;
                }

                /*
                 * The process of allocating a new LWP could cause
                 * sleeps. We're called from inside sleep, so that
                 * would be Bad. Therefore, we must use a cached new
                 * LWP. The first thing that this new LWP must do is
                 * allocate another LWP for the cache.
                 */
                l2 = sa_getcachelwp(p, vp);
                if (l2 == NULL) {
                        /* XXXSMP */
                        /* No upcall for you! */
                        /* XXX The consequences of this are more subtle and
                         * XXX the recovery from this situation deserves
                         * XXX more thought.
                         */

                        /* XXXUPSXXX Should only happen with concurrency > 1 */
                        mutex_exit(&vp->savp_mutex);
                        mi_switch(l);
                        sadata_upcall_free(sau);
                        return;
                }

                cpu_setfunc(l2, sa_switchcall, sau);
                sa_upcall0(sau, SA_UPCALL_BLOCKED | SA_UPCALL_LOCKED_EVENT, l,
                        NULL, 0, NULL, NULL);

                /*
                 * Perform the double/upcall pagefault check.
                 * We do this only here since we need l's ucontext to
                 * get l's userspace stack. sa_upcall0 above has saved
                 * it for us.
                 * The LP_SA_PAGEFAULT flag is set in the MD
                 * pagefault code to indicate a pagefault.  The MD
                 * pagefault code also saves the faultaddr for us.
                 *
                 * If the double check is true, turn this into a non-upcall
                 * block.
                 */
                if ((l->l_flag & LP_SA_PAGEFAULT) && sa_pagefault(l,
                        &sau->sau_event.ss_captured.ss_ctx) != 0) {
                        cpu_setfunc(l2, sa_neverrun, NULL);
                        sa_putcachelwp(p, l2);
                        mutex_exit(&vp->savp_mutex);
                        DPRINTFN(4,("sa_switch(%d.%d) Pagefault\n",
                            p->p_pid, l->l_lid));
                        mi_switch(l);
                        /*
                         * WRS Not sure how vp->savp_sleeper_upcall != NULL
                         * but be careful none the less
                         */
                        if (vp->savp_sleeper_upcall == NULL)
                                vp->savp_sleeper_upcall = sau;
                        else
                                sadata_upcall_free(sau);
                        DPRINTFN(10,("sa_switch(%d.%d) page fault resolved\n",
                                     p->p_pid, l->l_lid));
                        mutex_enter(&vp->savp_mutex);
                        if (vp->savp_faultaddr == vp->savp_ofaultaddr)
                                vp->savp_ofaultaddr = -1;
                        mutex_exit(&vp->savp_mutex);
                        return;
                }

                DPRINTFN(8,("sa_switch(%d.%d) blocked upcall %d\n",
                             p->p_pid, l->l_lid, l2->l_lid));

                l->l_flag |= LW_SA_BLOCKING;
                vp->savp_blocker = l;
                vp->savp_lwp = l2;

                sa_setrunning(l2);

                KASSERT(l2 != l);
        } else if (vp->savp_lwp != NULL) {

                /*
                 * Case 2: We've been woken up while another LWP was
                 * on the VP, but we're going back to sleep without
                 * having returned to userland and delivering the
                 * SA_UNBLOCKED upcall (select and poll cause this
                 * kind of behavior a lot).
                 */
                l2 = NULL;
        } else {
                /* NOTREACHED */
                mutex_exit(&vp->savp_mutex);
                lwp_unlock(l);
                panic("sa_vp empty");
        }

        DPRINTFN(4,("sa_switch(%d.%d) switching to LWP %d.\n",
            p->p_pid, l->l_lid, l2 ? l2->l_lid : 0));
        /* WRS need to add code to make sure we switch to l2 */
        mutex_exit(&vp->savp_mutex);
        mi_switch(l);
        DPRINTFN(4,("sa_switch(%d.%d flag %x) returned.\n",
            p->p_pid, l->l_lid, l->l_flag));
        KASSERT(l->l_wchan == 0);
}

/*
 * sa_neverrun
 *
 *      Routine for threads that have never run. Calls lwp_exit.
 * New, never-run cache threads get pointed at this routine, which just runs
 * and calls lwp_exit().
 */
static void
sa_neverrun(void *arg)
{
        struct lwp *l;

        l = curlwp;

        DPRINTFN(1,("sa_neverrun(%d.%d %x) exiting\n", l->l_proc->p_pid,
            l->l_lid, l->l_flag));

        lwp_exit(l);
}

/*
 * sa_switchcall
 *
 * We need to pass an upcall to userland. We are now
 * running on a spare stack and need to allocate a new
 * one. Also, if we are passed an sa upcall, we need to dispatch
 * it to the app.
 */
static void
sa_switchcall(void *arg)
{
        struct lwp *l, *l2;
        struct proc *p;
        struct sadata_vp *vp;
        struct sadata_upcall *sau;
        struct sastack *sast;
        struct sadata *sa;

        l2 = curlwp;
        p = l2->l_proc;
        vp = l2->l_savp;
        sau = arg;
        sa = p->p_sa;

        lwp_lock(l2);
        KASSERT(vp->savp_lwp == l2);
        if ((l2->l_flag & LW_WEXIT) || (p->p_sflag & (PS_WCORE | PS_WEXIT))) {
                lwp_unlock(l2);
                sadata_upcall_free(sau);
                lwp_exit(l2);
        }

        KASSERT(vp->savp_lwp == l2);
        DPRINTFN(6,("sa_switchcall(%d.%d)\n", p->p_pid, l2->l_lid));

        l2->l_flag |= LW_SA;
        lwp_unlock(l2);
        l2->l_pflag |= LP_SA_NOBLOCK;

        if (vp->savp_lwpcache_count == 0) {
                /* Allocate the next cache LWP */
                DPRINTFN(6,("sa_switchcall(%d.%d) allocating LWP\n",
                    p->p_pid, l2->l_lid));
                sa_newcachelwp(l2, NULL);
        }

        if (sau) {
                mutex_enter(&sa->sa_mutex);
                sast = sa_getstack(p->p_sa);
                mutex_exit(&sa->sa_mutex);
                mutex_enter(&vp->savp_mutex);
                l = vp->savp_blocker;
                if (sast) {
                        sau->sau_stack = sast->sast_stack;
                        SIMPLEQ_INSERT_TAIL(&vp->savp_upcalls, sau, sau_next);
                        mutex_exit(&vp->savp_mutex);
                        lwp_lock(l2);
                        l2->l_flag |= LW_SA_UPCALL;
                        lwp_unlock(l2);
                } else {
                        /*
                         * Oops! We're in trouble. The app hasn't
                         * passed us in any stacks on which to deliver
                         * the upcall.
                         *
                         * WRS: I think this code is wrong. If we can't
                         * get a stack, we are dead. We either need
                         * to block waiting for one (assuming there's a
                         * live vp still in userland so it can hand back
                         * stacks, or we should just kill the process
                         * as we're deadlocked.
                         */
                        if (vp->savp_sleeper_upcall == NULL)
                                vp->savp_sleeper_upcall = sau;
                        else
                                sadata_upcall_free(sau);

                        sa_putcachelwp(p, l2); /* sets LW_SA */
                        mutex_exit(&vp->savp_mutex);
                        lwp_lock(l);
                        vp->savp_lwp = l;
                        l->l_flag &= ~LW_SA_BLOCKING;
                        lwp_unlock(l);
                        //mutex_enter(p->p_lock);       /* XXXAD */
                        //p->p_nrlwps--;
                        //mutex_exit(p->p_lock);
                        lwp_lock(l2);
                        mi_switch(l2);
                        /* mostly NOTREACHED */
                        lwp_exit(l2);
                }
        }

        upcallret(l2);

        /*
         * Ok, clear LP_SA_NOBLOCK. However it'd be VERY BAD to generate
         * a blocked upcall before this upcall makes it to libpthread.
         * So disable BLOCKED upcalls until this vp enters a syscall.
         */
        l2->l_pflag &= ~LP_SA_NOBLOCK;
        vp->savp_pflags |= SAVP_FLAG_DELIVERING;
}

/*
 * sa_newcachelwp
 *      Allocate a new lwp, attach it to either the given vp or to l's vp,
 * and add it to its vp's idle cache.
 *      Assumes no locks (other than kernel lock) on entry and exit.
 * Locks scheduler lock during operation.
 *      Returns 0 on success or if process is exiting. Returns ENOMEM
 * if it is unable to allocate a new uarea.
 */
static int
sa_newcachelwp(struct lwp *l, struct sadata_vp *targ_vp)
{
        struct proc *p;
        struct lwp *l2;
        struct sadata_vp *vp;
        vaddr_t uaddr;
        int error;

        p = l->l_proc;
        if (p->p_sflag & (PS_WCORE | PS_WEXIT))
                return (0);

        uaddr = uvm_uarea_alloc();
        if (__predict_false(uaddr == 0))
                return ENOMEM;

        error = lwp_create(l, p, uaddr, 0, NULL, 0,
            sa_neverrun, NULL, &l2, l->l_class);
        if (error) {
                uvm_uarea_free(uaddr);
                return error;
        }

        /* We don't want this LWP on the process's main LWP list, but
         * newlwp helpfully puts it there. Unclear if newlwp should
         * be tweaked.
         */
        mutex_enter(p->p_lock);
        p->p_nrlwps++;
        mutex_exit(p->p_lock);

        vp = (targ_vp) ? targ_vp : l->l_savp;
        mutex_enter(&vp->savp_mutex);
        l2->l_savp = vp;
        sa_putcachelwp(p, l2);
        mutex_exit(&vp->savp_mutex);

        return 0;
}

/*
 * sa_putcachelwp
 *      Take a normal process LWP and place it in the SA cache.
 * LWP must not be running, or it must be our caller.
 *      sadat_vp::savp_mutex held on entry and exit.
 *
 *      Previous NetBSD versions removed queued lwps from the list of
 * visible lwps. This made ps cleaner, and hid implementation details.
 * At present, this implementation no longer does that.
 */
void
sa_putcachelwp(struct proc *p, struct lwp *l)
{
        struct sadata_vp *vp;
        sleepq_t        *sq;

        vp = l->l_savp;
        sq = &vp->savp_lwpcache;

        KASSERT(mutex_owned(&vp->savp_mutex));

#if 0 /* not now, leave lwp visible to all */
        LIST_REMOVE(l, l_sibling);
        p->p_nlwps--;
        l->l_prflag |= LPR_DETACHED;
#endif
        l->l_flag |= LW_SA;
        membar_producer();
        DPRINTFN(5,("sa_putcachelwp(%d.%d) Adding LWP %d to cache\n",
            p->p_pid, curlwp->l_lid, l->l_lid));

        /*
         * Hand-rolled call of the form:
         * sleepq_enter(&vp->savp_woken, l, &vp->savp_mutex);
         * adapted to take into account the fact that (1) l and the mutex
         * we want to lend it are both locked, and (2) we don't have
         * any other locks.
         */
        l->l_mutex = &vp->savp_mutex;

        /*
         * XXXWRS: Following is a hand-rolled call of the form:
         * sleepq_enqueue(sq, (void *)sq, "lwpcache", sa_sobj); but
         * hand-done since l might not be curlwp.
         */

        l->l_syncobj = &sa_sobj;
        l->l_wchan = sq;
        l->l_sleepq = sq;
        l->l_wmesg = sa_lwpcache_wmesg;
        l->l_slptime = 0;
        l->l_stat = LSSLEEP;
        l->l_sleeperr = 0;
         
        vp->savp_lwpcache_count++;
        sleepq_insert(sq, l, &sa_sobj);
}

/*
 * sa_getcachelwp
 *      Fetch a LWP from the cache.
 * Called with savp_mutex held.
 */
struct lwp *
sa_getcachelwp(struct proc *p, struct sadata_vp *vp)
{
        struct lwp      *l;
        sleepq_t        *sq = &vp->savp_lwpcache;

        KASSERT(mutex_owned(&vp->savp_mutex));
        KASSERT(vp->savp_lwpcache_count > 0);

        vp->savp_lwpcache_count--;
        l= TAILQ_FIRST(sq);

        /*
         * Now we have a hand-unrolled version of part of sleepq_remove.
         * The main issue is we do NOT want to make the lwp runnable yet
         * since we need to set up the upcall first (we know our caller(s)).
         */

        TAILQ_REMOVE(sq, l, l_sleepchain);
        l->l_syncobj = &sched_syncobj;
        l->l_wchan = NULL;
        l->l_sleepq = NULL;
        l->l_flag &= ~LW_SINTR;

#if 0 /* Not now, for now leave lwps in lwp list */
        LIST_INSERT_HEAD(&p->p_lwps, l, l_sibling);
#endif
        DPRINTFN(5,("sa_getcachelwp(%d.%d) Got LWP %d from cache.\n",
                p->p_pid, curlwp->l_lid, l->l_lid));
        return l;
}

/*
 * sa_setrunning:
 *
 *      Make an lwp we pulled out of the cache, with sa_getcachelwp()
 * above. This routine and sa_getcachelwp() must perform all the work
 * of sleepq_remove().
 */
static void
sa_setrunning(struct lwp *l)
{
        struct schedstate_percpu *spc;
        struct cpu_info *ci;

        KASSERT(mutex_owned(&l->l_savp->savp_mutex));

        /* Update sleep time delta, call the wake-up handler of scheduler */
        l->l_slpticksum += (hardclock_ticks - l->l_slpticks);
        sched_wakeup(l);

        /*
         * Since l was on the sleep queue, we locked it
         * when we locked savp_mutex. Now set it running.
         * This is the second-part of sleepq_remove().
         */
        l->l_priority = MAXPRI_USER; /* XXX WRS needs thought, used to be l_usrpri */
        /* Look for a CPU to wake up */
        l->l_cpu = sched_takecpu(l);
        ci = l->l_cpu;
        spc = &ci->ci_schedstate;

        spc_lock(ci);
        lwp_setlock(l, spc->spc_mutex);
        sched_setrunnable(l);
        l->l_stat = LSRUN;
        l->l_slptime = 0;
        sched_enqueue(l, true);
        spc_unlock(ci);
}

/*
 * sa_upcall_userret
 *      We are about to exit the kernel and return to userland, and
 * userret() noticed we have upcalls pending. So deliver them.
 *
 *      This is the place where unblocking upcalls get generated. We
 * allocate the stack & upcall event here. We may block doing so, but
 * we lock our LWP state (clear LW_SA for the moment) while doing so.
 *
 *      In the case of delivering multiple upcall events, we will end up
 * writing multiple stacks out to userland at once. The last one we send
 * out will be the first one run, then it will notice the others and
 * run them.
 *
 * No locks held on entry or exit. We lock varied processing.
 */
void
sa_upcall_userret(struct lwp *l)
{
        struct lwp *l2;
        struct proc *p;
        struct sadata *sa;
        struct sadata_vp *vp;
        struct sadata_upcall *sau;
        struct sastack *sast;
        sleepq_t *sq;
        int f;

        p = l->l_proc;
        sa = p->p_sa;
        vp = l->l_savp;

        if (vp->savp_pflags & SAVP_FLAG_NOUPCALLS) {
                int     do_clear = 0;
                /*
                 * We made upcalls in sa_yield() (otherwise we would
                 * still be in the loop there!). Don't do it again.
                 * Clear LW_SA_UPCALL, unless there are upcalls to deliver.
                 * they will get delivered next time we return to user mode.
                 */
                vp->savp_pflags &= ~SAVP_FLAG_NOUPCALLS;
                mutex_enter(&vp->savp_mutex);
                if ((vp->savp_woken_count == 0)
                    && SIMPLEQ_EMPTY(&vp->savp_upcalls)) {
                        do_clear = 1;
                }
                mutex_exit(&vp->savp_mutex);
                if (do_clear) {
                        lwp_lock(l);
                        l->l_flag &= ~LW_SA_UPCALL;
                        lwp_unlock(l);
                }
                DPRINTFN(7,("sa_upcall_userret(%d.%d %x) skipping processing\n",
                    p->p_pid, l->l_lid, l->l_flag));
                return;
        }

        SA_LWP_STATE_LOCK(l, f);

        DPRINTFN(7,("sa_upcall_userret(%d.%d %x) empty %d, woken %d\n",
            p->p_pid, l->l_lid, l->l_flag, SIMPLEQ_EMPTY(&vp->savp_upcalls),
            vp->savp_woken_count));

        KASSERT((l->l_flag & LW_SA_BLOCKING) == 0);

        mutex_enter(&vp->savp_mutex);
        sast = NULL;
        if (SIMPLEQ_EMPTY(&vp->savp_upcalls) &&
            vp->savp_woken_count != 0) {
                mutex_exit(&vp->savp_mutex);
                mutex_enter(&sa->sa_mutex);
                sast = sa_getstack(sa);
                mutex_exit(&sa->sa_mutex);
                if (sast == NULL) {
                        lwp_lock(l);
                        SA_LWP_STATE_UNLOCK(l, f);
                        lwp_unlock(l);
                        preempt();
                        return;
                }
                mutex_enter(&vp->savp_mutex);
        }
        if (SIMPLEQ_EMPTY(&vp->savp_upcalls) &&
            vp->savp_woken_count != 0 && sast != NULL) {
                /*
                 * Invoke an "unblocked" upcall. We create a message
                 * with the first unblock listed here, and then
                 * string along a number of other unblocked stacks when
                 * we deliver the call.
                 */
                l2 = TAILQ_FIRST(&vp->savp_woken);
                TAILQ_REMOVE(&vp->savp_woken, l2, l_sleepchain);
                vp->savp_woken_count--;
                mutex_exit(&vp->savp_mutex);

                DPRINTFN(9,("sa_upcall_userret(%d.%d) using stack %p\n",
                    l->l_proc->p_pid, l->l_lid, sast->sast_stack.ss_sp));

                if ((l->l_flag & LW_WEXIT)
                    || (p->p_sflag & (PS_WCORE | PS_WEXIT))) {
                        lwp_exit(l);
                        /* NOTREACHED */
                }

                DPRINTFN(8,("sa_upcall_userret(%d.%d) unblocking %d\n",
                    p->p_pid, l->l_lid, l2->l_lid));

                sau = sadata_upcall_alloc(1);
                if ((l->l_flag & LW_WEXIT)
                    || (p->p_sflag & (PS_WCORE | PS_WEXIT))) {
                        sadata_upcall_free(sau);
                        lwp_exit(l);
                        /* NOTREACHED */
                }

                sa_upcall0(sau, SA_UPCALL_UNBLOCKED, l2, l, 0, NULL, NULL);
                sau->sau_stack = sast->sast_stack;
                mutex_enter(&vp->savp_mutex);
                SIMPLEQ_INSERT_TAIL(&vp->savp_upcalls, sau, sau_next);
                l2->l_flag &= ~LW_SA_BLOCKING;

                /* Now return l2 to the cache. Mutex already set */
                sq = &vp->savp_lwpcache;
                l2->l_wchan = sq;
                l2->l_wmesg = sa_lwpcache_wmesg;
                vp->savp_lwpcache_count++;
                sleepq_insert(sq, l2, &sa_sobj);

        } else if (sast)
                sa_setstackfree(sast, sa);

        KASSERT(vp->savp_lwp == l);

        while ((sau = SIMPLEQ_FIRST(&vp->savp_upcalls)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(&vp->savp_upcalls, sau_next);
                mutex_exit(&vp->savp_mutex);
                sa_makeupcalls(l, sau);
                mutex_enter(&vp->savp_mutex);
        }
        mutex_exit(&vp->savp_mutex);

        lwp_lock(l);

        if (vp->savp_woken_count == 0) {
                l->l_flag &= ~LW_SA_UPCALL;
        }

        lwp_unlock(l);

        SA_LWP_STATE_UNLOCK(l, f);

        return;
}

#define SACOPYOUT(sae, type, kp, up) \
        (((sae)->sae_sacopyout != NULL) ? \
        (*(sae)->sae_sacopyout)((type), (kp), (void *)(up)) : \
        copyout((kp), (void *)(up), sizeof(*(kp))))

/*
 * sa_makeupcalls
 *      We're delivering the first upcall on lwp l, so
 * copy everything out. We assigned the stack for this upcall
 * when we enqueued it.
 *
 * SA_LWP_STATE should be locked (LP_SA_NOBLOCK set).
 *
 *      If the enqueued event was DEFERRED, this is the time when we set
 * up the upcall event's state.
 */
static void
sa_makeupcalls(struct lwp *l, struct sadata_upcall *sau)
{
        struct lwp *l2;
        struct proc *p;
        const struct sa_emul *sae;
        struct sadata *sa;
        struct sadata_vp *vp;
        sleepq_t *sq;
        uintptr_t sapp, sap;
        struct sa_t self_sa;
        struct sa_t *sas[3];
        struct sa_t **ksapp = NULL;
        void *stack, *ap;
        union sau_state *e_ss;
        ucontext_t *kup, *up;
        size_t sz, ucsize;
        int i, nint, nevents, type, error;

        p = l->l_proc;
        sae = p->p_emul->e_sa;
        sa = p->p_sa;
        vp = l->l_savp;
        ucsize = sae->sae_ucsize;

        if (sau->sau_flags & SAU_FLAG_DEFERRED_EVENT)
                sa_upcall_getstate(&sau->sau_event,
                    sau->sau_event.ss_deferred.ss_lwp, 0);
        if (sau->sau_flags & SAU_FLAG_DEFERRED_INTERRUPTED)
                sa_upcall_getstate(&sau->sau_interrupted,
                    sau->sau_interrupted.ss_deferred.ss_lwp, 0);

#ifdef __MACHINE_STACK_GROWS_UP
        stack = sau->sau_stack.ss_sp;
#else
        stack = (char *)sau->sau_stack.ss_sp + sau->sau_stack.ss_size;
#endif
        stack = STACK_ALIGN(stack, ALIGNBYTES);

        self_sa.sa_id = l->l_lid;
        self_sa.sa_cpu = vp->savp_id;
        sas[0] = &self_sa;
        nevents = 0;
        nint = 0;
        if (sau->sau_event.ss_captured.ss_sa.sa_context != NULL) {
                if (copyout(&sau->sau_event.ss_captured.ss_ctx,
                    sau->sau_event.ss_captured.ss_sa.sa_context,
                    ucsize) != 0) {
                        sigexit(l, SIGILL);
                        /* NOTREACHED */
                }
                sas[1] = &sau->sau_event.ss_captured.ss_sa;
                nevents = 1;
        }
        if (sau->sau_interrupted.ss_captured.ss_sa.sa_context != NULL) {
                KASSERT(sau->sau_interrupted.ss_captured.ss_sa.sa_context !=
                    sau->sau_event.ss_captured.ss_sa.sa_context);
                if (copyout(&sau->sau_interrupted.ss_captured.ss_ctx,
                    sau->sau_interrupted.ss_captured.ss_sa.sa_context,
                    ucsize) != 0) {
                        sigexit(l, SIGILL);
                        /* NOTREACHED */
                }
                sas[2] = &sau->sau_interrupted.ss_captured.ss_sa;
                nint = 1;
        }
#if 0
        /* For now, limit ourselves to one unblock at once. */
        if (sau->sau_type == SA_UPCALL_UNBLOCKED) {
                mutex_enter(&vp->savp_mutex);
                nevents += vp->savp_woken_count;
                mutex_exit(&vp->savp_mutex);
                /* XXX WRS Need to limit # unblocks we copy out at once! */
        }
#endif

        /* Copy out the activation's ucontext */
        up = (void *)STACK_ALLOC(stack, ucsize);
        stack = STACK_GROW(stack, ucsize);
        kup = kmem_zalloc(sizeof(*kup), KM_SLEEP);
        KASSERT(kup != NULL);
        kup->uc_stack = sau->sau_stack;
        kup->uc_flags = _UC_STACK;
        error = SACOPYOUT(sae, SAOUT_UCONTEXT, kup, up);
        kmem_free(kup, sizeof(*kup));
        if (error) {
                sadata_upcall_free(sau);
                sigexit(l, SIGILL);
                /* NOTREACHED */
        }
        sas[0]->sa_context = up;

        /* Next, copy out the sa_t's and pointers to them. */

        sz = (1 + nevents + nint) * sae->sae_sasize;
        sap = (uintptr_t)STACK_ALLOC(stack, sz);
        sap += sz;
        stack = STACK_GROW(stack, sz);

        sz = (1 + nevents + nint) * sae->sae_sapsize;
        sapp = (uintptr_t)STACK_ALLOC(stack, sz);
        sapp += sz;
        stack = STACK_GROW(stack, sz);

        if (KTRPOINT(p, KTR_SAUPCALL))
                ksapp = kmem_alloc(sizeof(struct sa_t *) * (nevents + nint + 1),
                    KM_SLEEP);

        KASSERT(nint <= 1);
        e_ss = NULL;
        for (i = nevents + nint; i >= 0; i--) {
                struct sa_t *sasp;

                sap -= sae->sae_sasize;
                sapp -= sae->sae_sapsize;
                error = 0;
                if (i == 1 + nevents)   /* interrupted sa */
                        sasp = sas[2];
                else if (i <= 1)        /* self_sa and event sa */
                        sasp = sas[i];
                else {                  /* extra sas */
                        KASSERT(sau->sau_type == SA_UPCALL_UNBLOCKED);

                        if (e_ss == NULL) {
                                e_ss = kmem_alloc(sizeof(*e_ss), KM_SLEEP);
                        }
                        /* Lock vp and all savp_woken lwps */
                        mutex_enter(&vp->savp_mutex);
                        sq = &vp->savp_woken;
                        KASSERT(vp->savp_woken_count > 0);
                        l2 = TAILQ_FIRST(sq);
                        KASSERT(l2 != NULL);
                        TAILQ_REMOVE(sq, l2, l_sleepchain);
                        vp->savp_woken_count--;

                        DPRINTFN(8,
                            ("sa_makeupcalls(%d.%d) unblocking extra %d\n",
                            p->p_pid, l->l_lid, l2->l_lid));
                        /*
                         * Since l2 was on savp_woken, we locked it when
                         * we locked savp_mutex
                         */
                        sa_upcall_getstate(e_ss, l2, 1);
                        l2->l_flag &= ~LW_SA_BLOCKING;

                        /* Now return l2 to the cache. Mutex already set */
                        sq = &vp->savp_lwpcache;
                        l2->l_wchan = sq;
                        l2->l_wmesg = sa_lwpcache_wmesg;
                        vp->savp_lwpcache_count++;
                        sleepq_insert(sq, l2, &sa_sobj);
                        mutex_exit(&vp->savp_mutex);

                        error = copyout(&e_ss->ss_captured.ss_ctx,
                            e_ss->ss_captured.ss_sa.sa_context, ucsize);
                        sasp = &e_ss->ss_captured.ss_sa;
                }
                if (error != 0 ||
                    SACOPYOUT(sae, SAOUT_SA_T, sasp, sap) ||
                    SACOPYOUT(sae, SAOUT_SAP_T, &sap, sapp)) {
                        /* Copying onto the stack didn't work. Die. */
                        sadata_upcall_free(sau);
                        if (e_ss != NULL) {
                                kmem_free(e_ss, sizeof(*e_ss));
                        }
                        goto fail;
                }
                if (KTRPOINT(p, KTR_SAUPCALL))
                        ksapp[i] = sasp;
        }
        if (e_ss != NULL) {
                kmem_free(e_ss, sizeof(*e_ss));
        }

        /* Copy out the arg, if any */
        /* xxx assume alignment works out; everything so far has been
         * a structure, so...
         */
        if (sau->sau_arg) {
                ap = STACK_ALLOC(stack, sau->sau_argsize);
                stack = STACK_GROW(stack, sau->sau_argsize);
                if (copyout(sau->sau_arg, ap, sau->sau_argsize) != 0) {
                        /* Copying onto the stack didn't work. Die. */
                        sadata_upcall_free(sau);
                        goto fail;
                }
        } else {
                ap = NULL;
#ifdef __hppa__
                stack = STACK_ALIGN(stack, HPPA_FRAME_SIZE);
#endif
        }
        type = sau->sau_type;

        if (vp->savp_sleeper_upcall == NULL)
                vp->savp_sleeper_upcall = sau;
        else
                sadata_upcall_free(sau);

        DPRINTFN(7,("sa_makeupcalls(%d.%d): type %d\n", p->p_pid,
            l->l_lid, type));

        if (KTRPOINT(p, KTR_SAUPCALL)) {
                ktrsaupcall(l, type, nevents, nint, (void *)sapp, ap, ksapp);
                kmem_free(ksapp, sizeof(struct sa_t *) * (nevents + nint + 1));
        }

        (*sae->sae_upcall)(l, type, nevents, nint, (void *)sapp, ap, stack,
            sa->sa_upcall);

        lwp_lock(l);
        l->l_flag &= ~LW_SA_YIELD;
        lwp_unlock(l);
        return;

fail:
        if (KTRPOINT(p, KTR_SAUPCALL))
                kmem_free(ksapp, sizeof(struct sa_t) * (nevents + nint + 1));
        sigexit(l, SIGILL);
        /* NOTREACHED */
}

/*
 * sa_unblock_userret:
 *
 *      Our lwp is in the process of returning to userland, and
 * userret noticed LW_SA_BLOCKING is set for us. This indicates that
 * we were at one time the blessed lwp for our vp and we blocked.
 * An upcall was delivered to our process indicating that we blocked.
 *      Since then, we have unblocked in the kernel, and proceeded
 * to finish whatever work needed to be done. For instance, pages
 * have been faulted in for a trap or system call results have been
 * saved out for a systemcall.
 *      We now need to simultaneously do two things. First, we have to
 * cause an UNBLOCKED upcall to be generated. Second, we actually
 * have to STOP executing. When the blocked upcall was generated, a
 * new lwp was given to our application. Thus if we simply returned,
 * we would be exceeding our concurrency.
 *       So we put ourself on our vp's savp_woken list and take
 * steps to make sure the blessed lwp will notice us. Note: we maintain
 * loose concurrency controls, so the blessed lwp for our vp could in
 * fact be running on another cpu in the system.
 */
void
sa_unblock_userret(struct lwp *l)
{
        struct lwp *l2, *vp_lwp;
        struct proc *p;
        struct sadata *sa;
        struct sadata_vp *vp;

        p = l->l_proc;
        sa = p->p_sa;
        vp = l->l_savp;

        if ((l->l_flag & LW_WEXIT) || (p->p_sflag & (PS_WCORE | PS_WEXIT)))
                return;

        if ((l->l_flag & LW_SA_BLOCKING) == 0)
                return;

        DPRINTFN(7,("sa_unblock_userret(%d.%d %x) \n", p->p_pid, l->l_lid,
            l->l_flag));

        p = l->l_proc;
        sa = p->p_sa;
        vp = l->l_savp;
        vp_lwp = vp->savp_lwp;
        l2 = NULL;

        KASSERT(vp_lwp != NULL);
        DPRINTFN(3,("sa_unblock_userret(%d.%d) woken, flags %x, vp %d\n",
                     l->l_proc->p_pid, l->l_lid, l->l_flag,
                     vp_lwp->l_lid));

#if notyet
        if (vp_lwp->l_flag & LW_SA_IDLE) {
                KASSERT((vp_lwp->l_flag & LW_SA_UPCALL) == 0);
                KASSERT(vp->savp_wokenq_head == NULL);
                DPRINTFN(3,
                    ("sa_unblock_userret(%d.%d) repossess: idle vp_lwp %d state %d\n",
                    l->l_proc->p_pid, l->l_lid,
                    vp_lwp->l_lid, vp_lwp->l_stat));
                vp_lwp->l_flag &= ~LW_SA_IDLE;
                return;
        }
#endif

        DPRINTFN(3,(
            "sa_unblock_userret(%d.%d) put on wokenq: vp_lwp %d state %d flags %x\n",
                     l->l_proc->p_pid, l->l_lid, vp_lwp->l_lid,
                     vp_lwp->l_stat, vp_lwp->l_flag));

        lwp_lock(vp_lwp);

        if (!mutex_tryenter(&vp->savp_mutex)) {
                lwp_unlock(vp_lwp);
                mutex_enter(&vp->savp_mutex);
                /* savp_lwp may have changed. We'll be ok even if it did */
                vp_lwp = vp->savp_lwp;
                lwp_lock(vp_lwp);
        }
        

        switch (vp_lwp->l_stat) {
        case LSONPROC:
                if (vp_lwp->l_flag & LW_SA_UPCALL)
                        break;
                vp_lwp->l_flag |= LW_SA_UPCALL;
                if (vp_lwp->l_flag & LW_SA_YIELD)
                        break;
                spc_lock(vp_lwp->l_cpu);
                cpu_need_resched(vp_lwp->l_cpu, RESCHED_IMMED);
                spc_unlock(vp_lwp->l_cpu);
                break;
        case LSSLEEP:
                if (vp_lwp->l_flag & LW_SA_IDLE) {
                        vp_lwp->l_flag &= ~(LW_SA_IDLE|LW_SA_YIELD|LW_SINTR);
                        vp_lwp->l_flag |= LW_SA_UPCALL;
                        /* lwp_unsleep() will unlock the LWP */
                        lwp_unsleep(vp_lwp, true);
                        DPRINTFN(3,(
                            "sa_unblock_userret(%d.%d) woke vp: %d state %d\n",
                             l->l_proc->p_pid, l->l_lid, vp_lwp->l_lid,
                             vp_lwp->l_stat));
                        vp_lwp = NULL;
                        break;
                }
                vp_lwp->l_flag |= LW_SA_UPCALL;
                break;
        case LSSUSPENDED:
                break;
        case LSSTOP:
                vp_lwp->l_flag |= LW_SA_UPCALL;
                break;
        case LSRUN:
                if (vp_lwp->l_flag & LW_SA_UPCALL)
                        break;
                vp_lwp->l_flag |= LW_SA_UPCALL;
                if (vp_lwp->l_flag & LW_SA_YIELD)
                        break;
#if 0
                if (vp_lwp->l_slptime > 1) {
                        void updatepri(struct lwp *);
                        updatepri(vp_lwp);
                }
#endif
                vp_lwp->l_slptime = 0;
                if (vp_lwp->l_cpu == curcpu())
                        l2 = vp_lwp;
                else {
                        /*
                         * don't need to spc_lock the other cpu
                         * as runable lwps have the cpu as their
                         * mutex.
                         */
                        /* spc_lock(vp_lwp->l_cpu); */
                        cpu_need_resched(vp_lwp->l_cpu, 0);
                        /* spc_unlock(vp_lwp->l_cpu); */
                }
                break;
        default:
                panic("sa_vp LWP not sleeping/onproc/runnable");
        }

        if (vp_lwp != NULL)
                lwp_unlock(vp_lwp);

        /*
         * Add ourselves to the savp_woken queue. Still on p_lwps.
         *
         * We now don't unlock savp_mutex since it now is l's mutex,
         * and it will be released in mi_switch().
         */
        sleepq_enter(&vp->savp_woken, l, &vp->savp_mutex);
        sleepq_enqueue(&vp->savp_woken, &vp->savp_woken, sa_lwpwoken_wmesg,
            &sa_sobj);
        vp->savp_woken_count++;
        //l->l_stat = LSSUSPENDED;
        mi_switch(l);

        /*
         * We suspended ourself and put ourself on the savp_woken
         * list. The only way we come back from mi_switch() to this
         * routine is if we were put back on the run queues, which only
         * happens if the process is exiting. So just exit.
         *
         * In the normal lwp lifecycle, cpu_setfunc() will make this lwp
         * run in a different routine by the time we next run.
         */
        lwp_exit(l);
        /* NOTREACHED */
}



#ifdef DEBUG
int debug_print_sa(struct proc *);
int debug_print_proc(int);

int
debug_print_proc(int pid)
{
        struct proc *p;

        p = pfind(pid);
        if (p == NULL)
                printf("No process %d\n", pid);
        else
                debug_print_sa(p);

        return 0;
}

int
debug_print_sa(struct proc *p)
{
        struct sadata *sa;
        struct sadata_vp *vp;

        printf("Process %d (%s), state %d, address %p, flags %x\n",
            p->p_pid, p->p_comm, p->p_stat, p, p->p_sflag);
        printf("LWPs: %d (%d running, %d zombies)\n", p->p_nlwps, p->p_nrlwps,
            p->p_nzlwps);
        sa = p->p_sa;
        if (sa) {
                SLIST_FOREACH(vp, &sa->sa_vps, savp_next) {
                        if (vp->savp_lwp)
                                printf("SA VP: %d %s\n", vp->savp_lwp->l_lid,
                                    vp->savp_lwp->l_flag & LW_SA_YIELD ?
                                    (vp->savp_lwp->l_flag & LW_SA_IDLE ?
                                        "idle" : "yielding") : "");
                        printf("SAs: %d cached LWPs\n",
                                        vp->savp_lwpcache_count);
                        printf("SAs: %d woken LWPs\n",
                                        vp->savp_woken_count);
                }
        }

        return 0;
}

#endif

#endif /* KERN_SA */