text: /*
   * Copyright (c) 1991, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * The Mach Operating System project at Carnegie-Mellon University.
   *
   * 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 University of
   *	California, Berkeley and its contributors.
   * 4. 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.
   *
   *	from: @(#)vm_glue.c	8.6 (Berkeley) 1/5/94
   *
   *
   * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   * All rights reserved.
   *
   * Permission to use, copy, modify and distribute this software and
   * its documentation is hereby granted, provided that both the copyright
   * notice and this permission notice appear in all copies of the
   * software, derivative works or modified versions, and any portions
   * thereof, and that both notices appear in supporting documentation.
   *
   * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   *
   * Carnegie Mellon requests users of this software to return to
   *
   *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   *  School of Computer Science
   *  Carnegie Mellon University
   *  Pittsburgh PA 15213-3890
   *
   * any improvements or extensions that they make and grant Carnegie the
   * rights to redistribute these changes.
   *
   * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94 1999/12/06 04:53:08 luoqi Exp $
   */
  
  #include "opt_rlimit.h"
  #include "opt_vm.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/proc.h>
  #include <sys/resourcevar.h>
  #include <sys/buf.h>
  #include <sys/shm.h>
  #include <sys/vmmeter.h>
  #include <sys/sysctl.h>
  
  #include <sys/kernel.h>
  #include <sys/unistd.h>
  
  #include <machine/limits.h>
  
  #include <vm/vm.h>
  #include <vm/vm_param.h>
  #include <sys/lock.h>
  #include <vm/pmap.h>
  #include <vm/vm_map.h>
  #include <vm/vm_page.h>
  #include <vm/vm_pageout.h>
  #include <vm/vm_kern.h>
  #include <vm/vm_extern.h>
  
  #include <sys/user.h>
  
  /*
   * System initialization
   *
   * Note: proc0 from proc.h
   */
  
  static void vm_init_limits __P((void *));
  SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0)
  
  /*
   * THIS MUST BE THE LAST INITIALIZATION ITEM!!!
   *
   * Note: run scheduling should be divorced from the vm system.
   */
  static void scheduler __P((void *));
  SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL)
  
  
  static void swapout __P((struct proc *));
  
  int
  kernacc(addr, len, rw)
  	caddr_t addr;
  	int len, rw;
  {
  	boolean_t rv;
  	vm_offset_t saddr, eaddr;
  	vm_prot_t prot;
  
  	KASSERT((rw & (~VM_PROT_ALL)) == 0,
  	    ("illegal ``rw'' argument to kernacc (%x)\n", rw));
  	prot = rw;
  	saddr = trunc_page((vm_offset_t)addr);
  	eaddr = round_page((vm_offset_t)addr + len);
  	vm_map_lock_read(kernel_map);
  	rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
  	vm_map_unlock_read(kernel_map);
  	return (rv == TRUE);
  }
  
  int
  useracc(addr, len, rw)
  	caddr_t addr;
  	int len, rw;
  {
  	boolean_t rv;
  	vm_prot_t prot;
  	vm_map_t map;
  	vm_map_entry_t save_hint;
  
  	KASSERT((rw & (~VM_PROT_ALL)) == 0,
  	    ("illegal ``rw'' argument to useracc (%x)\n", rw));
  	prot = rw;
  	/*
  	 * XXX - check separately to disallow access to user area and user
  	 * page tables - they are in the map.
  	 *
  	 * XXX - VM_MAXUSER_ADDRESS is an end address, not a max.  It was once
  	 * only used (as an end address) in trap.c.  Use it as an end address
  	 * here too.  This bogusness has spread.  I just fixed where it was
  	 * used as a max in vm_mmap.c.
  	 */
  	if ((vm_offset_t) addr + len > /* XXX */ VM_MAXUSER_ADDRESS
  	    || (vm_offset_t) addr + len < (vm_offset_t) addr) {
  		return (FALSE);
  	}
  	map = &curproc->p_vmspace->vm_map;
  	vm_map_lock_read(map);
  	/*
  	 * We save the map hint, and restore it.  Useracc appears to distort
  	 * the map hint unnecessarily.
  	 */
  	save_hint = map->hint;
  	rv = vm_map_check_protection(map,
  	    trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), prot);
  	map->hint = save_hint;
  	vm_map_unlock_read(map);
  	
  	return (rv == TRUE);
  }
  
  void
  vslock(addr, len)
  	caddr_t addr;
  	u_int len;
  {
  	vm_map_pageable(&curproc->p_vmspace->vm_map, trunc_page((vm_offset_t)addr),
  	    round_page((vm_offset_t)addr + len), FALSE);
  }
  
  void
  vsunlock(addr, len, dirtied)
  	caddr_t addr;
  	u_int len;
  	int dirtied;
  {
  #ifdef	lint
  	dirtied++;
  #endif	/* lint */
  	vm_map_pageable(&curproc->p_vmspace->vm_map, trunc_page((vm_offset_t)addr),
  	    round_page((vm_offset_t)addr + len), TRUE);
  }
  
  /*
   * Implement fork's actions on an address space.
   * Here we arrange for the address space to be copied or referenced,
   * allocate a user struct (pcb and kernel stack), then call the
   * machine-dependent layer to fill those in and make the new process
   * ready to run.  The new process is set up so that it returns directly
   * to user mode to avoid stack copying and relocation problems.
   */
  void
  vm_fork(p1, p2, flags)
  	register struct proc *p1, *p2;
  	int flags;
  {
  	register struct user *up;
  
  	if ((flags & RFPROC) == 0) {
  		/*
  		 * Divorce the memory, if it is shared, essentially
  		 * this changes shared memory amongst threads, into
  		 * COW locally.
  		 */
  		if ((flags & RFMEM) == 0) {
  			if (p1->p_vmspace->vm_refcnt > 1) {
  				vmspace_unshare(p1);
  			}
  		}
  		cpu_fork(p1, p2, flags);
  		return;
  	}
  
  	if (flags & RFMEM) {
  		p2->p_vmspace = p1->p_vmspace;
  		p1->p_vmspace->vm_refcnt++;
  	}
  
  	while (vm_page_count_severe()) {
  		VM_WAIT;
  	}
  
  	if ((flags & RFMEM) == 0) {
  		p2->p_vmspace = vmspace_fork(p1->p_vmspace);
  
  		pmap_pinit2(vmspace_pmap(p2->p_vmspace));
  
  		if (p1->p_vmspace->vm_shm)
  			shmfork(p1, p2);
  	}
  
  	pmap_new_proc(p2);
  
  	up = p2->p_addr;
  
  	/*
  	 * p_stats currently points at fields in the user struct
  	 * but not at &u, instead at p_addr. Copy parts of
  	 * p_stats; zero the rest of p_stats (statistics).
  	 *
  	 * If procsig->ps_refcnt is 1 and p2->p_sigacts is NULL we dont' need
  	 * to share sigacts, so we use the up->u_sigacts.
  	 */
  	p2->p_stats = &up->u_stats;
  	if (p2->p_sigacts == NULL) {
  		if (p2->p_procsig->ps_refcnt != 1)
  			printf ("PID:%d NULL sigacts with refcnt not 1!\n",p2->p_pid);
  		p2->p_sigacts = &up->u_sigacts;
  		up->u_sigacts = *p1->p_sigacts;
  	}
  
  	bzero(&up->u_stats.pstat_startzero,
  	    (unsigned) ((caddr_t) &up->u_stats.pstat_endzero -
  		(caddr_t) &up->u_stats.pstat_startzero));
  	bcopy(&p1->p_stats->pstat_startcopy, &up->u_stats.pstat_startcopy,
  	    ((caddr_t) &up->u_stats.pstat_endcopy -
  		(caddr_t) &up->u_stats.pstat_startcopy));
  
  
  	/*
  	 * cpu_fork will copy and update the pcb, set up the kernel stack,
  	 * and make the child ready to run.
  	 */
  	cpu_fork(p1, p2, flags);
  }
  
  /*
   * Set default limits for VM system.
   * Called for proc 0, and then inherited by all others.
   *
   * XXX should probably act directly on proc0.
   */
  static void
  vm_init_limits(udata)
  	void *udata;
  {
  	register struct proc *p = udata;
  	int rss_limit;
  
  	/*
  	 * Set up the initial limits on process VM. Set the maximum resident
  	 * set size to be half of (reasonably) available memory.  Since this
  	 * is a soft limit, it comes into effect only when the system is out
  	 * of memory - half of main memory helps to favor smaller processes,
  	 * and reduces thrashing of the object cache.
  	 */
  	p->p_rlimit[RLIMIT_STACK].rlim_cur = DFLSSIZ;
  	p->p_rlimit[RLIMIT_STACK].rlim_max = MAXSSIZ;
  	p->p_rlimit[RLIMIT_DATA].rlim_cur = DFLDSIZ;
  	p->p_rlimit[RLIMIT_DATA].rlim_max = MAXDSIZ;
  	/* limit the limit to no less than 2MB */
  	rss_limit = max(cnt.v_free_count, 512);
  	p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit);
  	p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY;
  }
  
  void
  faultin(p)
  	struct proc *p;
  {
  	int s;
  
  	if ((p->p_flag & P_INMEM) == 0) {
  
  		++p->p_lock;
  
  		pmap_swapin_proc(p);
  
  		s = splhigh();
  
  		if (p->p_stat == SRUN)
  			setrunqueue(p);
  
  		p->p_flag |= P_INMEM;
  
  		/* undo the effect of setting SLOCK above */
  		--p->p_lock;
  		splx(s);
  
  	}
  }
  
  /*
   * This swapin algorithm attempts to swap-in processes only if there
   * is enough space for them.  Of course, if a process waits for a long
   * time, it will be swapped in anyway.
   */
  /* ARGSUSED*/
  static void
  scheduler(dummy)
  	void *dummy;
  {
  	register struct proc *p;
  	register int pri;
  	struct proc *pp;
  	int ppri;
  
  loop:
  	if (vm_page_count_min()) {
  		VM_WAIT;
  		goto loop;
  	}
  
  	pp = NULL;
  	ppri = INT_MIN;
  	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
  		if (p->p_stat == SRUN &&
  			(p->p_flag & (P_INMEM | P_SWAPPING)) == 0) {
  
  			pri = p->p_swtime + p->p_slptime;
  			if ((p->p_flag & P_SWAPINREQ) == 0) {
  				pri -= p->p_nice * 8;
  			}
  
  			/*
  			 * if this process is higher priority and there is
  			 * enough space, then select this process instead of
  			 * the previous selection.
  			 */
  			if (pri > ppri) {
  				pp = p;
  				ppri = pri;
  			}
  		}
  	}
  
  	/*
  	 * Nothing to do, back to sleep.
  	 */
  	if ((p = pp) == NULL) {
  		tsleep(&proc0, PVM, "sched", 0);
  		goto loop;
  	}
  	p->p_flag &= ~P_SWAPINREQ;
  
  	/*
  	 * We would like to bring someone in. (only if there is space).
  	 */
  	faultin(p);
  	p->p_swtime = 0;
  	goto loop;
  }
  
  #ifndef NO_SWAPPING
  
  #define	swappable(p) \
  	(((p)->p_lock == 0) && \
  		((p)->p_flag & (P_TRACED|P_SYSTEM|P_INMEM|P_WEXIT|P_SWAPPING)) == P_INMEM)
  
  
  /*
   * Swap_idle_threshold1 is the guaranteed swapped in time for a process
   */
  static int swap_idle_threshold1 = 2;
  SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1,
  	CTLFLAG_RW, &swap_idle_threshold1, 0, "");
  
  /*
   * Swap_idle_threshold2 is the time that a process can be idle before
   * it will be swapped out, if idle swapping is enabled.
   */
  static int swap_idle_threshold2 = 10;
  SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2,
  	CTLFLAG_RW, &swap_idle_threshold2, 0, "");
  
  /*
   * Swapout is driven by the pageout daemon.  Very simple, we find eligible
   * procs and unwire their u-areas.  We try to always "swap" at least one
   * process in case we need the room for a swapin.
   * If any procs have been sleeping/stopped for at least maxslp seconds,
   * they are swapped.  Else, we swap the longest-sleeping or stopped process,
   * if any, otherwise the longest-resident process.
   */
  void
  swapout_procs(action)
  int action;
  {
  	register struct proc *p;
  	struct proc *outp, *outp2;
  	int outpri, outpri2;
  	int didswap = 0;
  
  	outp = outp2 = NULL;
  	outpri = outpri2 = INT_MIN;
  retry:
  	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
  		struct vmspace *vm;
  		if (!swappable(p))
  			continue;
  
  		vm = p->p_vmspace;
  
  		switch (p->p_stat) {
  		default:
  			continue;
  
  		case SSLEEP:
  		case SSTOP:
  			/*
  			 * do not swapout a realtime process
  			 */
  			if (RTP_PRIO_IS_REALTIME(p->p_rtprio.type))
  				continue;
  
  			/*
  			 * Do not swapout a process waiting on a critical
  			 * event of some kind.  Also guarantee swap_idle_threshold1
  			 * time in memory.
  			 */
  			if (((p->p_priority & 0x7f) < PSOCK) ||
  				(p->p_slptime < swap_idle_threshold1))
  				continue;
  
  			/*
  			 * If the system is under memory stress, or if we are swapping
  			 * idle processes >= swap_idle_threshold2, then swap the process
  			 * out.
  			 */
  			if (((action & VM_SWAP_NORMAL) == 0) &&
  				(((action & VM_SWAP_IDLE) == 0) ||
  				  (p->p_slptime < swap_idle_threshold2)))
  				continue;
  
  			++vm->vm_refcnt;
  			/*
  			 * do not swapout a process that is waiting for VM
  			 * data structures there is a possible deadlock.
  			 */
  			if (lockmgr(&vm->vm_map.lock,
  					LK_EXCLUSIVE | LK_NOWAIT,
  					(void *)0, curproc)) {
  				vmspace_free(vm);
  				continue;
  			}
  			vm_map_unlock(&vm->vm_map);
  			/*
  			 * If the process has been asleep for awhile and had
  			 * most of its pages taken away already, swap it out.
  			 */
  			if ((action & VM_SWAP_NORMAL) ||
  				((action & VM_SWAP_IDLE) &&
  				 (p->p_slptime > swap_idle_threshold2))) {
  				swapout(p);
  				vmspace_free(vm);
  				didswap++;
  				goto retry;
  			}
  		}
  	}
  	/*
  	 * If we swapped something out, and another process needed memory,
  	 * then wakeup the sched process.
  	 */
  	if (didswap)
  		wakeup(&proc0);
  }
  
  static void
  swapout(p)
  	register struct proc *p;
  {
  
  #if defined(SWAP_DEBUG)
  	printf("swapping out %d\n", p->p_pid);
  #endif
  	++p->p_stats->p_ru.ru_nswap;
  	/*
  	 * remember the process resident count
  	 */
  	p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
  
  	(void) splhigh();
  	p->p_flag &= ~P_INMEM;
  	p->p_flag |= P_SWAPPING;
  	if (p->p_stat == SRUN)
  		remrunqueue(p);
  	(void) spl0();
  
  	pmap_swapout_proc(p);
  
  	p->p_flag &= ~P_SWAPPING;
  	p->p_swtime = 0;
  }
  #endif /* !NO_SWAPPING */
  