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[netbsd-mini2440.git] / sys / kern / kern_proc.c

/*      $NetBSD: kern_proc.c,v 1.158 2009/11/26 00:19:11 matt Exp $     */

/*-
 * Copyright (c) 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center, 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.
 *
 * 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.
 */

/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993
 *      The Regents of the University of California.  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. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 *
 *      @(#)kern_proc.c 8.7 (Berkeley) 2/14/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.158 2009/11/26 00:19:11 matt Exp $");

#include "opt_kstack.h"
#include "opt_maxuprc.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/buf.h>
#include <sys/acct.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <ufs/ufs/quota.h>
#include <sys/uio.h>
#include <sys/pool.h>
#include <sys/pset.h>
#include <sys/mbuf.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/signalvar.h>
#include <sys/ras.h>
#include <sys/sa.h>
#include <sys/savar.h>
#include <sys/filedesc.h>
#include "sys/syscall_stats.h"
#include <sys/kauth.h>
#include <sys/sleepq.h>
#include <sys/atomic.h>
#include <sys/kmem.h>

#include <uvm/uvm.h>
#include <uvm/uvm_extern.h>

/*
 * Other process lists
 */

struct proclist allproc;
struct proclist zombproc;       /* resources have been freed */

kmutex_t        *proc_lock;

/*
 * pid to proc lookup is done by indexing the pid_table array.
 * Since pid numbers are only allocated when an empty slot
 * has been found, there is no need to search any lists ever.
 * (an orphaned pgrp will lock the slot, a session will lock
 * the pgrp with the same number.)
 * If the table is too small it is reallocated with twice the
 * previous size and the entries 'unzipped' into the two halves.
 * A linked list of free entries is passed through the pt_proc
 * field of 'free' items - set odd to be an invalid ptr.
 */

struct pid_table {
        struct proc     *pt_proc;
        struct pgrp     *pt_pgrp;
};
#if 1   /* strongly typed cast - should be a noop */
static inline uint p2u(struct proc *p) { return (uint)(uintptr_t)p; }
#else
#define p2u(p) ((uint)p)
#endif
#define P_VALID(p) (!(p2u(p) & 1))
#define P_NEXT(p) (p2u(p) >> 1)
#define P_FREE(pid) ((struct proc *)(uintptr_t)((pid) << 1 | 1))

#define INITIAL_PID_TABLE_SIZE  (1 << 5)
static struct pid_table *pid_table;
static uint pid_tbl_mask = INITIAL_PID_TABLE_SIZE - 1;
static uint pid_alloc_lim;      /* max we allocate before growing table */
static uint pid_alloc_cnt;      /* number of allocated pids */

/* links through free slots - never empty! */
static uint next_free_pt, last_free_pt;
static pid_t pid_max = PID_MAX;         /* largest value we allocate */

/* Components of the first process -- never freed. */

extern struct emul emul_netbsd; /* defined in kern_exec.c */

struct session session0 = {
        .s_count = 1,
        .s_sid = 0,
};
struct pgrp pgrp0 = {
        .pg_members = LIST_HEAD_INITIALIZER(&pgrp0.pg_members),
        .pg_session = &session0,
};
filedesc_t filedesc0;
struct cwdinfo cwdi0 = {
        .cwdi_cmask = CMASK,            /* see cmask below */
        .cwdi_refcnt = 1,
};
struct plimit limit0;
struct pstats pstat0;
struct vmspace vmspace0;
struct sigacts sigacts0;
struct turnstile turnstile0;
struct proc proc0 = {
        .p_lwps = LIST_HEAD_INITIALIZER(&proc0.p_lwps),
        .p_sigwaiters = LIST_HEAD_INITIALIZER(&proc0.p_sigwaiters),
        .p_nlwps = 1,
        .p_nrlwps = 1,
        .p_nlwpid = 1,          /* must match lwp0.l_lid */
        .p_pgrp = &pgrp0,
        .p_comm = "system",
        /*
         * Set P_NOCLDWAIT so that kernel threads are reparented to init(8)
         * when they exit.  init(8) can easily wait them out for us.
         */
        .p_flag = PK_SYSTEM | PK_NOCLDWAIT,
        .p_stat = SACTIVE,
        .p_nice = NZERO,
        .p_emul = &emul_netbsd,
        .p_cwdi = &cwdi0,
        .p_limit = &limit0,
        .p_fd = &filedesc0,
        .p_vmspace = &vmspace0,
        .p_stats = &pstat0,
        .p_sigacts = &sigacts0,
};
struct lwp lwp0 __aligned(MIN_LWP_ALIGNMENT) = {
#ifdef LWP0_CPU_INFO
        .l_cpu = LWP0_CPU_INFO,
#endif
        .l_proc = &proc0,
        .l_lid = 1,
        .l_flag = LW_SYSTEM,
        .l_stat = LSONPROC,
        .l_ts = &turnstile0,
        .l_syncobj = &sched_syncobj,
        .l_refcnt = 1,
        .l_priority = PRI_USER + NPRI_USER - 1,
        .l_inheritedprio = -1,
        .l_class = SCHED_OTHER,
        .l_psid = PS_NONE,
        .l_pi_lenders = SLIST_HEAD_INITIALIZER(&lwp0.l_pi_lenders),
        .l_name = __UNCONST("swapper"),
        .l_fd = &filedesc0,
};
kauth_cred_t cred0;

int nofile = NOFILE;
int maxuprc = MAXUPRC;
int cmask = CMASK;

MALLOC_DEFINE(M_EMULDATA, "emuldata", "Per-process emulation data");
MALLOC_DEFINE(M_SUBPROC, "subproc", "Proc sub-structures");

/*
 * The process list descriptors, used during pid allocation and
 * by sysctl.  No locking on this data structure is needed since
 * it is completely static.
 */
const struct proclist_desc proclists[] = {
        { &allproc      },
        { &zombproc     },
        { NULL          },
};

static struct pgrp *    pg_remove(pid_t);
static void             pg_delete(pid_t);
static void             orphanpg(struct pgrp *);

static specificdata_domain_t proc_specificdata_domain;

static pool_cache_t proc_cache;

static kauth_listener_t proc_listener;

static int
proc_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        struct proc *p;
        int result;

        result = KAUTH_RESULT_DEFER;
        p = arg0;

        switch (action) {
        case KAUTH_PROCESS_CANSEE: {
                enum kauth_process_req req;

                req = (enum kauth_process_req)arg1;

                switch (req) {
                case KAUTH_REQ_PROCESS_CANSEE_ARGS:
                case KAUTH_REQ_PROCESS_CANSEE_ENTRY:
                case KAUTH_REQ_PROCESS_CANSEE_OPENFILES:
                        result = KAUTH_RESULT_ALLOW;

                        break;

                case KAUTH_REQ_PROCESS_CANSEE_ENV:
                        if (kauth_cred_getuid(cred) !=
                            kauth_cred_getuid(p->p_cred) ||
                            kauth_cred_getuid(cred) !=
                            kauth_cred_getsvuid(p->p_cred))
                                break;

                        result = KAUTH_RESULT_ALLOW;

                        break;

                default:
                        break;
                }

                break;
                }

        case KAUTH_PROCESS_FORK: {
                int lnprocs = (int)(unsigned long)arg2;

                /*
                 * Don't allow a nonprivileged user to use the last few
                 * processes. The variable lnprocs is the current number of
                 * processes, maxproc is the limit.
                 */
                if (__predict_false((lnprocs >= maxproc - 5)))
                        break;

                result = KAUTH_RESULT_ALLOW;

                break;
                }

        case KAUTH_PROCESS_CORENAME:
        case KAUTH_PROCESS_STOPFLAG:
                if (proc_uidmatch(cred, p->p_cred) == 0)
                        result = KAUTH_RESULT_ALLOW;

                break;

        default:
                break;
        }

        return result;
}

/*
 * Initialize global process hashing structures.
 */
void
procinit(void)
{
        const struct proclist_desc *pd;
        u_int i;
#define LINK_EMPTY ((PID_MAX + INITIAL_PID_TABLE_SIZE) & ~(INITIAL_PID_TABLE_SIZE - 1))

        for (pd = proclists; pd->pd_list != NULL; pd++)
                LIST_INIT(pd->pd_list);

        proc_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
        pid_table = kmem_alloc(INITIAL_PID_TABLE_SIZE
            * sizeof(struct pid_table), KM_SLEEP);

        /* Set free list running through table...
           Preset 'use count' above PID_MAX so we allocate pid 1 next. */
        for (i = 0; i <= pid_tbl_mask; i++) {
                pid_table[i].pt_proc = P_FREE(LINK_EMPTY + i + 1);
                pid_table[i].pt_pgrp = 0;
        }
        /* slot 0 is just grabbed */
        next_free_pt = 1;
        /* Need to fix last entry. */
        last_free_pt = pid_tbl_mask;
        pid_table[last_free_pt].pt_proc = P_FREE(LINK_EMPTY);
        /* point at which we grow table - to avoid reusing pids too often */
        pid_alloc_lim = pid_tbl_mask - 1;
#undef LINK_EMPTY

        proc_specificdata_domain = specificdata_domain_create();
        KASSERT(proc_specificdata_domain != NULL);

        proc_cache = pool_cache_init(sizeof(struct proc), 0, 0, 0,
            "procpl", NULL, IPL_NONE, NULL, NULL, NULL);

        proc_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS,
            proc_listener_cb, NULL);
}

/*
 * Initialize process 0.
 */
void
proc0_init(void)
{
        struct proc *p;
        struct pgrp *pg;
        struct lwp *l;
        rlim_t lim;
        int i;

        p = &proc0;
        pg = &pgrp0;
        l = &lwp0;

        KASSERT((void *)uvm_lwp_getuarea(l) != NULL);
        KASSERT(l->l_lid == p->p_nlwpid);

        mutex_init(&p->p_stmutex, MUTEX_DEFAULT, IPL_HIGH);
        mutex_init(&p->p_auxlock, MUTEX_DEFAULT, IPL_NONE);
        p->p_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);

        rw_init(&p->p_reflock);
        cv_init(&p->p_waitcv, "wait");
        cv_init(&p->p_lwpcv, "lwpwait");

        LIST_INSERT_HEAD(&p->p_lwps, l, l_sibling);

        pid_table[0].pt_proc = p;
        LIST_INSERT_HEAD(&allproc, p, p_list);
        LIST_INSERT_HEAD(&alllwp, l, l_list);

        pid_table[0].pt_pgrp = pg;
        LIST_INSERT_HEAD(&pg->pg_members, p, p_pglist);

#ifdef __HAVE_SYSCALL_INTERN
        (*p->p_emul->e_syscall_intern)(p);
#endif

        callout_init(&l->l_timeout_ch, CALLOUT_MPSAFE);
        callout_setfunc(&l->l_timeout_ch, sleepq_timeout, l);
        cv_init(&l->l_sigcv, "sigwait");

        /* Create credentials. */
        cred0 = kauth_cred_alloc();
        p->p_cred = cred0;
        kauth_cred_hold(cred0);
        l->l_cred = cred0;

        /* Create the CWD info. */
        rw_init(&cwdi0.cwdi_lock);

        /* Create the limits structures. */
        mutex_init(&limit0.pl_lock, MUTEX_DEFAULT, IPL_NONE);
        for (i = 0; i < __arraycount(limit0.pl_rlimit); i++)
                limit0.pl_rlimit[i].rlim_cur =   
                    limit0.pl_rlimit[i].rlim_max = RLIM_INFINITY;

        limit0.pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
        limit0.pl_rlimit[RLIMIT_NOFILE].rlim_cur =
            maxfiles < nofile ? maxfiles : nofile;

        limit0.pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
        limit0.pl_rlimit[RLIMIT_NPROC].rlim_cur =
            maxproc < maxuprc ? maxproc : maxuprc;

        lim = ptoa(uvmexp.free);
        limit0.pl_rlimit[RLIMIT_RSS].rlim_max = lim;
        limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_max = lim;
        limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = lim / 3;
        limit0.pl_corename = defcorename;        
        limit0.pl_refcnt = 1;    
        limit0.pl_sv_limit = NULL;

        /* Configure virtual memory system, set vm rlimits. */
        uvm_init_limits(p);

        /* Initialize file descriptor table for proc0. */
        fd_init(&filedesc0);

        /*
         * Initialize proc0's vmspace, which uses the kernel pmap.
         * All kernel processes (which never have user space mappings)
         * share proc0's vmspace, and thus, the kernel pmap.
         */
        uvmspace_init(&vmspace0, pmap_kernel(), round_page(VM_MIN_ADDRESS),
            trunc_page(VM_MAX_ADDRESS));

        /* Initialize signal state for proc0. XXX IPL_SCHED */
        mutex_init(&p->p_sigacts->sa_mutex, MUTEX_DEFAULT, IPL_SCHED);
        siginit(p);

        proc_initspecific(p);
        lwp_initspecific(l);

        SYSCALL_TIME_LWP_INIT(l);
}

/*
 * Session reference counting.
 */

void
proc_sesshold(struct session *ss)
{

        KASSERT(mutex_owned(proc_lock));
        ss->s_count++;
}

void
proc_sessrele(struct session *ss)
{

        KASSERT(mutex_owned(proc_lock));
        /*
         * We keep the pgrp with the same id as the session in order to
         * stop a process being given the same pid.  Since the pgrp holds
         * a reference to the session, it must be a 'zombie' pgrp by now.
         */
        if (--ss->s_count == 0) {
                struct pgrp *pg;

                pg = pg_remove(ss->s_sid);
                mutex_exit(proc_lock);

                kmem_free(pg, sizeof(struct pgrp));
                kmem_free(ss, sizeof(struct session));
        } else {
                mutex_exit(proc_lock);
        }
}

/*
 * Check that the specified process group is in the session of the
 * specified process.
 * Treats -ve ids as process ids.
 * Used to validate TIOCSPGRP requests.
 */
int
pgid_in_session(struct proc *p, pid_t pg_id)
{
        struct pgrp *pgrp;
        struct session *session;
        int error;

        mutex_enter(proc_lock);
        if (pg_id < 0) {
                struct proc *p1 = p_find(-pg_id, PFIND_LOCKED | PFIND_UNLOCK_FAIL);
                if (p1 == NULL)
                        return EINVAL;
                pgrp = p1->p_pgrp;
        } else {
                pgrp = pg_find(pg_id, PFIND_LOCKED | PFIND_UNLOCK_FAIL);
                if (pgrp == NULL)
                        return EINVAL;
        }
        session = pgrp->pg_session;
        if (session != p->p_pgrp->pg_session)
                error = EPERM;
        else
                error = 0;
        mutex_exit(proc_lock);

        return error;
}

/*
 * p_inferior: is p an inferior of q?
 */
static inline bool
p_inferior(struct proc *p, struct proc *q)
{

        KASSERT(mutex_owned(proc_lock));

        for (; p != q; p = p->p_pptr)
                if (p->p_pid == 0)
                        return false;
        return true;
}

/*
 * Locate a process by number
 */
struct proc *
p_find(pid_t pid, uint flags)
{
        struct proc *p;
        char stat;

        if (!(flags & PFIND_LOCKED))
                mutex_enter(proc_lock);

        p = pid_table[pid & pid_tbl_mask].pt_proc;

        /* Only allow live processes to be found by pid. */
        /* XXXSMP p_stat */
        if (P_VALID(p) && p->p_pid == pid && ((stat = p->p_stat) == SACTIVE ||
            stat == SSTOP || ((flags & PFIND_ZOMBIE) &&
            (stat == SZOMB || stat == SDEAD || stat == SDYING)))) {
                if (flags & PFIND_UNLOCK_OK)
                         mutex_exit(proc_lock);
                return p;
        }
        if (flags & PFIND_UNLOCK_FAIL)
                mutex_exit(proc_lock);
        return NULL;
}


/*
 * Locate a process group by number
 */
struct pgrp *
pg_find(pid_t pgid, uint flags)
{
        struct pgrp *pg;

        if (!(flags & PFIND_LOCKED))
                mutex_enter(proc_lock);
        pg = pid_table[pgid & pid_tbl_mask].pt_pgrp;
        /*
         * Can't look up a pgrp that only exists because the session
         * hasn't died yet (traditional)
         */
        if (pg == NULL || pg->pg_id != pgid || LIST_EMPTY(&pg->pg_members)) {
                if (flags & PFIND_UNLOCK_FAIL)
                         mutex_exit(proc_lock);
                return NULL;
        }

        if (flags & PFIND_UNLOCK_OK)
                mutex_exit(proc_lock);
        return pg;
}

static void
expand_pid_table(void)
{
        size_t pt_size, tsz;
        struct pid_table *n_pt, *new_pt;
        struct proc *proc;
        struct pgrp *pgrp;
        pid_t pid;
        u_int i;

        pt_size = pid_tbl_mask + 1;
        tsz = pt_size * 2 * sizeof(struct pid_table);
        new_pt = kmem_alloc(tsz, KM_SLEEP);

        mutex_enter(proc_lock);
        if (pt_size != pid_tbl_mask + 1) {
                /* Another process beat us to it... */
                mutex_exit(proc_lock);
                kmem_free(new_pt, tsz);
                return;
        }

        /*
         * Copy entries from old table into new one.
         * If 'pid' is 'odd' we need to place in the upper half,
         * even pid's to the lower half.
         * Free items stay in the low half so we don't have to
         * fixup the reference to them.
         * We stuff free items on the front of the freelist
         * because we can't write to unmodified entries.
         * Processing the table backwards maintains a semblance
         * of issueing pid numbers that increase with time.
         */
        i = pt_size - 1;
        n_pt = new_pt + i;
        for (; ; i--, n_pt--) {
                proc = pid_table[i].pt_proc;
                pgrp = pid_table[i].pt_pgrp;
                if (!P_VALID(proc)) {
                        /* Up 'use count' so that link is valid */
                        pid = (P_NEXT(proc) + pt_size) & ~pt_size;
                        proc = P_FREE(pid);
                        if (pgrp)
                                pid = pgrp->pg_id;
                } else
                        pid = proc->p_pid;

                /* Save entry in appropriate half of table */
                n_pt[pid & pt_size].pt_proc = proc;
                n_pt[pid & pt_size].pt_pgrp = pgrp;

                /* Put other piece on start of free list */
                pid = (pid ^ pt_size) & ~pid_tbl_mask;
                n_pt[pid & pt_size].pt_proc =
                                    P_FREE((pid & ~pt_size) | next_free_pt);
                n_pt[pid & pt_size].pt_pgrp = 0;
                next_free_pt = i | (pid & pt_size);
                if (i == 0)
                        break;
        }

        /* Save old table size and switch tables */
        tsz = pt_size * sizeof(struct pid_table);
        n_pt = pid_table;
        pid_table = new_pt;
        pid_tbl_mask = pt_size * 2 - 1;

        /*
         * pid_max starts as PID_MAX (= 30000), once we have 16384
         * allocated pids we need it to be larger!
         */
        if (pid_tbl_mask > PID_MAX) {
                pid_max = pid_tbl_mask * 2 + 1;
                pid_alloc_lim |= pid_alloc_lim << 1;
        } else
                pid_alloc_lim <<= 1;    /* doubles number of free slots... */

        mutex_exit(proc_lock);
        kmem_free(n_pt, tsz);
}

struct proc *
proc_alloc(void)
{
        struct proc *p;
        int nxt;
        pid_t pid;
        struct pid_table *pt;

        p = pool_cache_get(proc_cache, PR_WAITOK);
        p->p_stat = SIDL;                       /* protect against others */

        proc_initspecific(p);
        /* allocate next free pid */

        for (;;expand_pid_table()) {
                if (__predict_false(pid_alloc_cnt >= pid_alloc_lim))
                        /* ensure pids cycle through 2000+ values */
                        continue;
                mutex_enter(proc_lock);
                pt = &pid_table[next_free_pt];
#ifdef DIAGNOSTIC
                if (__predict_false(P_VALID(pt->pt_proc) || pt->pt_pgrp))
                        panic("proc_alloc: slot busy");
#endif
                nxt = P_NEXT(pt->pt_proc);
                if (nxt & pid_tbl_mask)
                        break;
                /* Table full - expand (NB last entry not used....) */
                mutex_exit(proc_lock);
        }

        /* pid is 'saved use count' + 'size' + entry */
        pid = (nxt & ~pid_tbl_mask) + pid_tbl_mask + 1 + next_free_pt;
        if ((uint)pid > (uint)pid_max)
                pid &= pid_tbl_mask;
        p->p_pid = pid;
        next_free_pt = nxt & pid_tbl_mask;

        /* Grab table slot */
        pt->pt_proc = p;
        pid_alloc_cnt++;

        mutex_exit(proc_lock);

        return p;
}

/*
 * Free a process id - called from proc_free (in kern_exit.c)
 *
 * Called with the proc_lock held.
 */
void
proc_free_pid(struct proc *p)
{
        pid_t pid = p->p_pid;
        struct pid_table *pt;

        KASSERT(mutex_owned(proc_lock));

        pt = &pid_table[pid & pid_tbl_mask];
#ifdef DIAGNOSTIC
        if (__predict_false(pt->pt_proc != p))
                panic("proc_free: pid_table mismatch, pid %x, proc %p",
                        pid, p);
#endif
        /* save pid use count in slot */
        pt->pt_proc = P_FREE(pid & ~pid_tbl_mask);

        if (pt->pt_pgrp == NULL) {
                /* link last freed entry onto ours */
                pid &= pid_tbl_mask;
                pt = &pid_table[last_free_pt];
                pt->pt_proc = P_FREE(P_NEXT(pt->pt_proc) | pid);
                last_free_pt = pid;
                pid_alloc_cnt--;
        }

        atomic_dec_uint(&nprocs);
}

void
proc_free_mem(struct proc *p)
{

        pool_cache_put(proc_cache, p);
}

/*
 * proc_enterpgrp: move p to a new or existing process group (and session).
 *
 * If we are creating a new pgrp, the pgid should equal
 * the calling process' pid.
 * If is only valid to enter a process group that is in the session
 * of the process.
 * Also mksess should only be set if we are creating a process group
 *
 * Only called from sys_setsid and sys_setpgid.
 */
int
proc_enterpgrp(struct proc *curp, pid_t pid, pid_t pgid, bool mksess)
{
        struct pgrp *new_pgrp, *pgrp;
        struct session *sess;
        struct proc *p;
        int rval;
        pid_t pg_id = NO_PGID;

        sess = mksess ? kmem_alloc(sizeof(*sess), KM_SLEEP) : NULL;

        /* Allocate data areas we might need before doing any validity checks */
        mutex_enter(proc_lock);         /* Because pid_table might change */
        if (pid_table[pgid & pid_tbl_mask].pt_pgrp == 0) {
                mutex_exit(proc_lock);
                new_pgrp = kmem_alloc(sizeof(*new_pgrp), KM_SLEEP);
                mutex_enter(proc_lock);
        } else
                new_pgrp = NULL;
        rval = EPERM;   /* most common error (to save typing) */

        /* Check pgrp exists or can be created */
        pgrp = pid_table[pgid & pid_tbl_mask].pt_pgrp;
        if (pgrp != NULL && pgrp->pg_id != pgid)
                goto done;

        /* Can only set another process under restricted circumstances. */
        if (pid != curp->p_pid) {
                /* must exist and be one of our children... */
                if ((p = p_find(pid, PFIND_LOCKED)) == NULL ||
                    !p_inferior(p, curp)) {
                        rval = ESRCH;
                        goto done;
                }
                /* ... in the same session... */
                if (sess != NULL || p->p_session != curp->p_session)
                        goto done;
                /* ... existing pgid must be in same session ... */
                if (pgrp != NULL && pgrp->pg_session != p->p_session)
                        goto done;
                /* ... and not done an exec. */
                if (p->p_flag & PK_EXEC) {
                        rval = EACCES;
                        goto done;
                }
        } else {
                /* ... setsid() cannot re-enter a pgrp */
                if (mksess && (curp->p_pgid == curp->p_pid ||
                    pg_find(curp->p_pid, PFIND_LOCKED)))
                        goto done;
                p = curp;
        }

        /* Changing the process group/session of a session
           leader is definitely off limits. */
        if (SESS_LEADER(p)) {
                if (sess == NULL && p->p_pgrp == pgrp)
                        /* unless it's a definite noop */
                        rval = 0;
                goto done;
        }

        /* Can only create a process group with id of process */
        if (pgrp == NULL && pgid != pid)
                goto done;

        /* Can only create a session if creating pgrp */
        if (sess != NULL && pgrp != NULL)
                goto done;

        /* Check we allocated memory for a pgrp... */
        if (pgrp == NULL && new_pgrp == NULL)
                goto done;

        /* Don't attach to 'zombie' pgrp */
        if (pgrp != NULL && LIST_EMPTY(&pgrp->pg_members))
                goto done;

        /* Expect to succeed now */
        rval = 0;

        if (pgrp == p->p_pgrp)
                /* nothing to do */
                goto done;

        /* Ok all setup, link up required structures */

        if (pgrp == NULL) {
                pgrp = new_pgrp;
                new_pgrp = NULL;
                if (sess != NULL) {
                        sess->s_sid = p->p_pid;
                        sess->s_leader = p;
                        sess->s_count = 1;
                        sess->s_ttyvp = NULL;
                        sess->s_ttyp = NULL;
                        sess->s_flags = p->p_session->s_flags & ~S_LOGIN_SET;
                        memcpy(sess->s_login, p->p_session->s_login,
                            sizeof(sess->s_login));
                        p->p_lflag &= ~PL_CONTROLT;
                } else {
                        sess = p->p_pgrp->pg_session;
                        proc_sesshold(sess);
                }
                pgrp->pg_session = sess;
                sess = NULL;

                pgrp->pg_id = pgid;
                LIST_INIT(&pgrp->pg_members);
#ifdef DIAGNOSTIC
                if (__predict_false(pid_table[pgid & pid_tbl_mask].pt_pgrp))
                        panic("enterpgrp: pgrp table slot in use");
                if (__predict_false(mksess && p != curp))
                        panic("enterpgrp: mksession and p != curproc");
#endif
                pid_table[pgid & pid_tbl_mask].pt_pgrp = pgrp;
                pgrp->pg_jobc = 0;
        }

        /*
         * Adjust eligibility of affected pgrps to participate in job control.
         * Increment eligibility counts before decrementing, otherwise we
         * could reach 0 spuriously during the first call.
         */
        fixjobc(p, pgrp, 1);
        fixjobc(p, p->p_pgrp, 0);

        /* Interlock with ttread(). */
        mutex_spin_enter(&tty_lock);

        /* Move process to requested group. */
        LIST_REMOVE(p, p_pglist);
        if (LIST_EMPTY(&p->p_pgrp->pg_members))
                /* defer delete until we've dumped the lock */
                pg_id = p->p_pgrp->pg_id;
        p->p_pgrp = pgrp;
        LIST_INSERT_HEAD(&pgrp->pg_members, p, p_pglist);

        /* Done with the swap; we can release the tty mutex. */
        mutex_spin_exit(&tty_lock);

    done:
        if (pg_id != NO_PGID) {
                /* Releases proc_lock. */
                pg_delete(pg_id);
        } else {
                mutex_exit(proc_lock);
        }
        if (sess != NULL)
                kmem_free(sess, sizeof(*sess));
        if (new_pgrp != NULL)
                kmem_free(new_pgrp, sizeof(*new_pgrp));
#ifdef DEBUG_PGRP
        if (__predict_false(rval))
                printf("enterpgrp(%d,%d,%d), curproc %d, rval %d\n",
                        pid, pgid, mksess, curp->p_pid, rval);
#endif
        return rval;
}

/*
 * proc_leavepgrp: remove a process from its process group.
 *  => must be called with the proc_lock held, which will be released;
 */
void
proc_leavepgrp(struct proc *p)
{
        struct pgrp *pgrp;

        KASSERT(mutex_owned(proc_lock));

        /* Interlock with ttread() */
        mutex_spin_enter(&tty_lock);
        pgrp = p->p_pgrp;
        LIST_REMOVE(p, p_pglist);
        p->p_pgrp = NULL;
        mutex_spin_exit(&tty_lock);

        if (LIST_EMPTY(&pgrp->pg_members)) {
                /* Releases proc_lock. */
                pg_delete(pgrp->pg_id);
        } else {
                mutex_exit(proc_lock);
        }
}

/*
 * pg_remove: remove a process group from the table.
 *  => must be called with the proc_lock held;
 *  => returns process group to free;
 */
static struct pgrp *
pg_remove(pid_t pg_id)
{
        struct pgrp *pgrp;
        struct pid_table *pt;

        KASSERT(mutex_owned(proc_lock));

        pt = &pid_table[pg_id & pid_tbl_mask];
        pgrp = pt->pt_pgrp;

        KASSERT(pgrp != NULL);
        KASSERT(pgrp->pg_id == pg_id);
        KASSERT(LIST_EMPTY(&pgrp->pg_members));

        pt->pt_pgrp = NULL;

        if (!P_VALID(pt->pt_proc)) {
                /* Orphaned pgrp, put slot onto free list. */
                KASSERT((P_NEXT(pt->pt_proc) & pid_tbl_mask) == 0);
                pg_id &= pid_tbl_mask;
                pt = &pid_table[last_free_pt];
                pt->pt_proc = P_FREE(P_NEXT(pt->pt_proc) | pg_id);
                last_free_pt = pg_id;
                pid_alloc_cnt--;
        }
        return pgrp;
}

/*
 * pg_delete: delete and free a process group.
 *  => must be called with the proc_lock held, which will be released.
 */
static void
pg_delete(pid_t pg_id)
{
        struct pgrp *pg;
        struct tty *ttyp;
        struct session *ss;

        KASSERT(mutex_owned(proc_lock));

        pg = pid_table[pg_id & pid_tbl_mask].pt_pgrp;
        if (pg == NULL || pg->pg_id != pg_id || !LIST_EMPTY(&pg->pg_members)) {
                mutex_exit(proc_lock);
                return;
        }

        ss = pg->pg_session;

        /* Remove reference (if any) from tty to this process group */
        mutex_spin_enter(&tty_lock);
        ttyp = ss->s_ttyp;
        if (ttyp != NULL && ttyp->t_pgrp == pg) {
                ttyp->t_pgrp = NULL;
                KASSERT(ttyp->t_session == ss);
        }
        mutex_spin_exit(&tty_lock);

        /*
         * The leading process group in a session is freed by proc_sessrele(),
         * if last reference.  Note: proc_sessrele() releases proc_lock.
         */
        pg = (ss->s_sid != pg->pg_id) ? pg_remove(pg_id) : NULL;
        proc_sessrele(ss);

        if (pg != NULL) {
                /* Free it, if was not done by proc_sessrele(). */
                kmem_free(pg, sizeof(struct pgrp));
        }
}

/*
 * Adjust pgrp jobc counters when specified process changes process group.
 * We count the number of processes in each process group that "qualify"
 * the group for terminal job control (those with a parent in a different
 * process group of the same session).  If that count reaches zero, the
 * process group becomes orphaned.  Check both the specified process'
 * process group and that of its children.
 * entering == 0 => p is leaving specified group.
 * entering == 1 => p is entering specified group.
 *
 * Call with proc_lock held.
 */
void
fixjobc(struct proc *p, struct pgrp *pgrp, int entering)
{
        struct pgrp *hispgrp;
        struct session *mysession = pgrp->pg_session;
        struct proc *child;

        KASSERT(mutex_owned(proc_lock));

        /*
         * Check p's parent to see whether p qualifies its own process
         * group; if so, adjust count for p's process group.
         */
        hispgrp = p->p_pptr->p_pgrp;
        if (hispgrp != pgrp && hispgrp->pg_session == mysession) {
                if (entering) {
                        pgrp->pg_jobc++;
                        p->p_lflag &= ~PL_ORPHANPG;
                } else if (--pgrp->pg_jobc == 0)
                        orphanpg(pgrp);
        }

        /*
         * Check this process' children to see whether they qualify
         * their process groups; if so, adjust counts for children's
         * process groups.
         */
        LIST_FOREACH(child, &p->p_children, p_sibling) {
                hispgrp = child->p_pgrp;
                if (hispgrp != pgrp && hispgrp->pg_session == mysession &&
                    !P_ZOMBIE(child)) {
                        if (entering) {
                                child->p_lflag &= ~PL_ORPHANPG;
                                hispgrp->pg_jobc++;
                        } else if (--hispgrp->pg_jobc == 0)
                                orphanpg(hispgrp);
                }
        }
}

/*
 * A process group has become orphaned;
 * if there are any stopped processes in the group,
 * hang-up all process in that group.
 *
 * Call with proc_lock held.
 */
static void
orphanpg(struct pgrp *pg)
{
        struct proc *p;

        KASSERT(mutex_owned(proc_lock));

        LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                if (p->p_stat == SSTOP) {
                        p->p_lflag |= PL_ORPHANPG;
                        psignal(p, SIGHUP);
                        psignal(p, SIGCONT);
                }
        }
}

#ifdef DDB
#include <ddb/db_output.h>
void pidtbl_dump(void);
void
pidtbl_dump(void)
{
        struct pid_table *pt;
        struct proc *p;
        struct pgrp *pgrp;
        int id;

        db_printf("pid table %p size %x, next %x, last %x\n",
                pid_table, pid_tbl_mask+1,
                next_free_pt, last_free_pt);
        for (pt = pid_table, id = 0; id <= pid_tbl_mask; id++, pt++) {
                p = pt->pt_proc;
                if (!P_VALID(p) && !pt->pt_pgrp)
                        continue;
                db_printf("  id %x: ", id);
                if (P_VALID(p))
                        db_printf("proc %p id %d (0x%x) %s\n",
                                p, p->p_pid, p->p_pid, p->p_comm);
                else
                        db_printf("next %x use %x\n",
                                P_NEXT(p) & pid_tbl_mask,
                                P_NEXT(p) & ~pid_tbl_mask);
                if ((pgrp = pt->pt_pgrp)) {
                        db_printf("\tsession %p, sid %d, count %d, login %s\n",
                            pgrp->pg_session, pgrp->pg_session->s_sid,
                            pgrp->pg_session->s_count,
                            pgrp->pg_session->s_login);
                        db_printf("\tpgrp %p, pg_id %d, pg_jobc %d, members %p\n",
                            pgrp, pgrp->pg_id, pgrp->pg_jobc,
                            LIST_FIRST(&pgrp->pg_members));
                        LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
                                db_printf("\t\tpid %d addr %p pgrp %p %s\n",
                                    p->p_pid, p, p->p_pgrp, p->p_comm);
                        }
                }
        }
}
#endif /* DDB */

#ifdef KSTACK_CHECK_MAGIC

#define KSTACK_MAGIC    0xdeadbeaf

/* XXX should be per process basis? */
static int      kstackleftmin = KSTACK_SIZE;
static int      kstackleftthres = KSTACK_SIZE / 8;

void
kstack_setup_magic(const struct lwp *l)
{
        uint32_t *ip;
        uint32_t const *end;

        KASSERT(l != NULL);
        KASSERT(l != &lwp0);

        /*
         * fill all the stack with magic number
         * so that later modification on it can be detected.
         */
        ip = (uint32_t *)KSTACK_LOWEST_ADDR(l);
        end = (uint32_t *)((char *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
        for (; ip < end; ip++) {
                *ip = KSTACK_MAGIC;
        }
}

void
kstack_check_magic(const struct lwp *l)
{
        uint32_t const *ip, *end;
        int stackleft;

        KASSERT(l != NULL);

        /* don't check proc0 */ /*XXX*/
        if (l == &lwp0)
                return;

#ifdef __MACHINE_STACK_GROWS_UP
        /* stack grows upwards (eg. hppa) */
        ip = (uint32_t *)((void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
        end = (uint32_t *)KSTACK_LOWEST_ADDR(l);
        for (ip--; ip >= end; ip--)
                if (*ip != KSTACK_MAGIC)
                        break;

        stackleft = (void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE - (void *)ip;
#else /* __MACHINE_STACK_GROWS_UP */
        /* stack grows downwards (eg. i386) */
        ip = (uint32_t *)KSTACK_LOWEST_ADDR(l);
        end = (uint32_t *)((char *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
        for (; ip < end; ip++)
                if (*ip != KSTACK_MAGIC)
                        break;

        stackleft = ((const char *)ip) - (const char *)KSTACK_LOWEST_ADDR(l);
#endif /* __MACHINE_STACK_GROWS_UP */

        if (kstackleftmin > stackleft) {
                kstackleftmin = stackleft;
                if (stackleft < kstackleftthres)
                        printf("warning: kernel stack left %d bytes"
                            "(pid %u:lid %u)\n", stackleft,
                            (u_int)l->l_proc->p_pid, (u_int)l->l_lid);
        }

        if (stackleft <= 0) {
                panic("magic on the top of kernel stack changed for "
                    "pid %u, lid %u: maybe kernel stack overflow",
                    (u_int)l->l_proc->p_pid, (u_int)l->l_lid);
        }
}
#endif /* KSTACK_CHECK_MAGIC */

int
proclist_foreach_call(struct proclist *list,
    int (*callback)(struct proc *, void *arg), void *arg)
{
        struct proc marker;
        struct proc *p;
        int ret = 0;

        marker.p_flag = PK_MARKER;
        mutex_enter(proc_lock);
        for (p = LIST_FIRST(list); ret == 0 && p != NULL;) {
                if (p->p_flag & PK_MARKER) {
                        p = LIST_NEXT(p, p_list);
                        continue;
                }
                LIST_INSERT_AFTER(p, &marker, p_list);
                ret = (*callback)(p, arg);
                KASSERT(mutex_owned(proc_lock));
                p = LIST_NEXT(&marker, p_list);
                LIST_REMOVE(&marker, p_list);
        }
        mutex_exit(proc_lock);

        return ret;
}

int
proc_vmspace_getref(struct proc *p, struct vmspace **vm)
{

        /* XXXCDC: how should locking work here? */

        /* curproc exception is for coredump. */

        if ((p != curproc && (p->p_sflag & PS_WEXIT) != 0) ||
            (p->p_vmspace->vm_refcnt < 1)) { /* XXX */
                return EFAULT;
        }

        uvmspace_addref(p->p_vmspace);
        *vm = p->p_vmspace;

        return 0;
}

/*
 * Acquire a write lock on the process credential.
 */
void 
proc_crmod_enter(void)
{
        struct lwp *l = curlwp;
        struct proc *p = l->l_proc;
        struct plimit *lim;
        kauth_cred_t oc;
        char *cn;

        /* Reset what needs to be reset in plimit. */
        if (p->p_limit->pl_corename != defcorename) {
                lim_privatise(p, false);
                lim = p->p_limit;
                mutex_enter(&lim->pl_lock);
                cn = lim->pl_corename;
                lim->pl_corename = defcorename;
                mutex_exit(&lim->pl_lock);
                if (cn != defcorename)
                        free(cn, M_TEMP);
        }

        mutex_enter(p->p_lock);

        /* Ensure the LWP cached credentials are up to date. */
        if ((oc = l->l_cred) != p->p_cred) {
                kauth_cred_hold(p->p_cred);
                l->l_cred = p->p_cred;
                kauth_cred_free(oc);
        }

}

/*
 * Set in a new process credential, and drop the write lock.  The credential
 * must have a reference already.  Optionally, free a no-longer required
 * credential.  The scheduler also needs to inspect p_cred, so we also
 * briefly acquire the sched state mutex.
 */
void
proc_crmod_leave(kauth_cred_t scred, kauth_cred_t fcred, bool sugid)
{
        struct lwp *l = curlwp, *l2;
        struct proc *p = l->l_proc;
        kauth_cred_t oc;

        KASSERT(mutex_owned(p->p_lock));

        /* Is there a new credential to set in? */
        if (scred != NULL) {
                p->p_cred = scred;
                LIST_FOREACH(l2, &p->p_lwps, l_sibling) {
                        if (l2 != l)
                                l2->l_prflag |= LPR_CRMOD;
                }

                /* Ensure the LWP cached credentials are up to date. */
                if ((oc = l->l_cred) != scred) {
                        kauth_cred_hold(scred);
                        l->l_cred = scred;
                }
        } else
                oc = NULL;      /* XXXgcc */

        if (sugid) {
                /*
                 * Mark process as having changed credentials, stops
                 * tracing etc.
                 */
                p->p_flag |= PK_SUGID;
        }

        mutex_exit(p->p_lock);

        /* If there is a credential to be released, free it now. */
        if (fcred != NULL) {
                KASSERT(scred != NULL);
                kauth_cred_free(fcred);
                if (oc != scred)
                        kauth_cred_free(oc);
        }
}

/*
 * proc_specific_key_create --
 *      Create a key for subsystem proc-specific data.
 */
int
proc_specific_key_create(specificdata_key_t *keyp, specificdata_dtor_t dtor)
{

        return (specificdata_key_create(proc_specificdata_domain, keyp, dtor));
}

/*
 * proc_specific_key_delete --
 *      Delete a key for subsystem proc-specific data.
 */
void
proc_specific_key_delete(specificdata_key_t key)
{

        specificdata_key_delete(proc_specificdata_domain, key);
}

/*
 * proc_initspecific --
 *      Initialize a proc's specificdata container.
 */
void
proc_initspecific(struct proc *p)
{
        int error;

        error = specificdata_init(proc_specificdata_domain, &p->p_specdataref);
        KASSERT(error == 0);
}

/*
 * proc_finispecific --
 *      Finalize a proc's specificdata container.
 */
void
proc_finispecific(struct proc *p)
{

        specificdata_fini(proc_specificdata_domain, &p->p_specdataref);
}

/*
 * proc_getspecific --
 *      Return proc-specific data corresponding to the specified key.
 */
void *
proc_getspecific(struct proc *p, specificdata_key_t key)
{

        return (specificdata_getspecific(proc_specificdata_domain,
                                         &p->p_specdataref, key));
}

/*
 * proc_setspecific --
 *      Set proc-specific data corresponding to the specified key.
 */
void
proc_setspecific(struct proc *p, specificdata_key_t key, void *data)
{

        specificdata_setspecific(proc_specificdata_domain,
                                 &p->p_specdataref, key, data);
}

int
proc_uidmatch(kauth_cred_t cred, kauth_cred_t target)
{
        int r = 0;

        if (kauth_cred_getuid(cred) != kauth_cred_getuid(target) ||
            kauth_cred_getuid(cred) != kauth_cred_getsvuid(target)) {
                /*
                 * suid proc of ours or proc not ours
                 */
                r = EPERM;
        } else if (kauth_cred_getgid(target) != kauth_cred_getsvgid(target)) {
                /*
                 * sgid proc has sgid back to us temporarily
                 */
                r = EPERM;
        } else {
                /*
                 * our rgid must be in target's group list (ie,
                 * sub-processes started by a sgid process)
                 */
                int ismember = 0;

                if (kauth_cred_ismember_gid(cred,
                    kauth_cred_getgid(target), &ismember) != 0 ||
                    !ismember)
                        r = EPERM;
        }

        return (r);
}