xref: /src/sys/uvm/uvm_glue.c

/*	$NetBSD: uvm_glue.c,v 1.4 1998/02/07 11:08:33 mrg Exp $	*/

/*
 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
 *         >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
 */
/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * 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 Charles D. Cranor,
 *      Washington University, 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.
 *
 *	@(#)vm_glue.c	8.6 (Berkeley) 1/5/94
 * from: Id: uvm_glue.c,v 1.1.2.8 1998/02/07 01:16:54 chs Exp
 *
 *
 * 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 (at) 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.
 */

/*
 * uvm_glue.c: glue functions
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/buf.h>
#include <sys/user.h>
#ifdef SYSVSHM
#include <sys/shm.h>
#endif

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>

#include <uvm/uvm.h>

#include <machine/cpu.h>

UVMHIST_DECL(maphist);

/*
 * local prototypes
 */

static void uvm_swapout __P((struct proc *));

/*
 * XXXCDC: do these really belong here?
 */

unsigned maxdmap = MAXDSIZ;	/* kern_resource.c: RLIMIT_DATA max */
unsigned maxsmap = MAXSSIZ;	/* kern_resource.c: RLIMIT_STACK max */

int readbuffers = 0;		/* allow KGDB to read kern buffer pool */
				/* XXX: see uvm_kernacc */


/*
 * uvm_kernacc: can the kernel access a region of memory
 *
 * - called from malloc [DIAGNOSTIC], and /dev/kmem driver (mem.c)
 */

boolean_t uvm_kernacc(addr, len, rw)

caddr_t addr;
int len, rw;

{
  boolean_t rv;
  vm_offset_t saddr, eaddr;
  vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;

  saddr = trunc_page(addr);
  eaddr = round_page(addr+len);
  vm_map_lock_read(kernel_map);
  rv = uvm_map_checkprot(kernel_map, saddr, eaddr, prot);
  vm_map_unlock_read(kernel_map);

  /*
   * XXX there are still some things (e.g. the buffer cache) that
   * are managed behind the VM system's back so even though an
   * address is accessible in the mind of the VM system, there may
   * not be physical pages where the VM thinks there is.  This can
   * lead to bogus allocation of pages in the kernel address space
   * or worse, inconsistencies at the pmap level.  We only worry
   * about the buffer cache for now.
   */
  if (!readbuffers && rv && (eaddr > (vm_offset_t)buffers &&
			     saddr < (vm_offset_t)buffers + MAXBSIZE * nbuf))
    rv = FALSE;
  return(rv);
}

/*
 * uvm_useracc: can the user access it?
 *
 * - called from physio() and sys___sysctl().
 */

boolean_t uvm_useracc(addr, len, rw)

caddr_t addr;
int len, rw;

{
  boolean_t rv;
  vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;

#if defined(i386) || defined(pc532)
  /*
   * XXX - specially disallow access to user page tables - they are
   * in the map.  This is here until i386 & pc532 pmaps are fixed...
   */
  if ((vm_offset_t) addr >= VM_MAXUSER_ADDRESS
      || (vm_offset_t) addr + len > VM_MAXUSER_ADDRESS
      || (vm_offset_t) addr + len <= (vm_offset_t) addr)
    return (FALSE);
#endif

  rv = uvm_map_checkprot(&curproc->p_vmspace->vm_map,
			trunc_page(addr), round_page(addr+len), prot);
  return(rv);
}

#ifdef KGDB
/*
 * Change protections on kernel pages from addr to addr+len
 * (presumably so debugger can plant a breakpoint).
 *
 * We force the protection change at the pmap level.  If we were
 * to use vm_map_protect a change to allow writing would be lazily-
 * applied meaning we would still take a protection fault, something
 * we really don't want to do.  It would also fragment the kernel
 * map unnecessarily.  We cannot use pmap_protect since it also won't
 * enforce a write-enable request.  Using pmap_enter is the only way
 * we can ensure the change takes place properly.
 */
void uvm_chgkprot(addr, len, rw)

register caddr_t addr;
int len, rw;

{
  vm_prot_t prot;
  vm_offset_t pa, sva, eva;

  prot = rw == B_READ ? VM_PROT_READ : VM_PROT_READ|VM_PROT_WRITE;
  eva = round_page(addr + len);
  for (sva = trunc_page(addr); sva < eva; sva += PAGE_SIZE) {
    /*
     * Extract physical address for the page.
     * We use a cheezy hack to differentiate physical
     * page 0 from an invalid mapping, not that it
     * really matters...
     */
    pa = pmap_extract(pmap_kernel(), sva|1);
    if (pa == 0)
      panic("chgkprot: invalid page");
    pmap_enter(pmap_kernel(), sva, pa&~1, prot, TRUE);
  }
}
#endif

/*
 * vslock: wire user memory for I/O
 *
 * - called from physio and sys___sysctl
 * - XXXCDC: consider nuking this (or making it a macro?)
 */

void uvm_vslock(addr, len)

caddr_t	addr;
u_int	len;

{
  uvm_fault_wire(&curproc->p_vmspace->vm_map, trunc_page(addr),
    round_page(addr+len));
}

/*
 * vslock: wire user memory for I/O
 *
 * - called from physio and sys___sysctl
 * - XXXCDC: consider nuking this (or making it a macro?)
 */

void uvm_vsunlock(addr, len)

caddr_t	addr;
u_int	len;

{
  uvm_fault_unwire(curproc->p_vmspace->vm_map.pmap, trunc_page(addr),
    round_page(addr+len));
}

/*
 * uvm_fork: fork a virtual address space
 *
 * - the address space is copied as per parent map's inherit values
 * - a new "user" structure is allocated for the child process
 *	[filled in by MD layer...]
 * - NOTE: the kernel stack may be at a different location in the child
 *	process, and thus addresses of automatic variables may be invalid
 *	after cpu_fork returns in the child process.  We do nothing here
 *	after cpu_fork returns.
 * - XXXCDC: we need a way for this to return a failure value rather
 *   than just hang
 */
void uvm_fork(p1, p2, shared)

struct proc *p1, *p2;
boolean_t shared;

{
  register struct user *up;
  vm_offset_t addr;
  int rv;

  if (shared == TRUE)
    uvmspace_share(p1, p2);				/* share vmspace */
  else
    p2->p_vmspace = uvmspace_fork(p1->p_vmspace);	/* fork vmspace */

#if !defined(vax)
  /*
   * Allocate a wired-down (for now) pcb and kernel stack for the process
   * "wired" state is stored in p->p_flag's P_INMEM bit rather than in
   * vm_map_entry's wired count to prevent kernel_map fragmentation.
   */
  addr = uvm_km_valloc(kernel_map, USPACE);
  if (addr == 0)
    panic("uvm_fork: no more kernel virtual memory");
  rv = uvm_fault_wire(kernel_map, addr, addr + USPACE);
  if (rv != KERN_SUCCESS)
    panic("uvm_fork: uvm_fault_wire failed: %d\n", rv);
#else
  /*
   * XXXCDC: Why does VAX need this?
   *
   * XXX somehow, on 386, ocassionally pageout removes active, wired down
   * kstack and pagetables, WITHOUT going thru vm_page_unwire! Why this
   * appears to work is not yet clear, yet it does...
   */
  addr = uvm_km_alloc(kernel_map, USPACE);
  if (addr == 0)
    panic("uvm_fork: no more kernel virtual memory");
#endif
  up = (struct user *)addr;
  p2->p_addr = up;

  /*
   * p_stats and p_sigacts currently point at fields in the user
   * struct but not at &u, instead at p_addr.  Copy p_sigacts and
   * parts of p_stats; zero the rest of p_stats (statistics).
   */
  p2->p_stats = &up->u_stats;
  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 kernel stack and pcb, and make
   * the child ready to run.  The child will exit directly to user
   * mode on its first time slice, and will not return here.
   */
  cpu_fork(p1, p2);
}

/*
 * uvm_init_limit: init per-process VM limits
 *
 * - called for process 0 and then inherited by all others.
 */
void uvm_init_limits(p)

struct proc *p;

{
    /*
     * Set up the initial limits on process VM.  Set the maximum
     * resident set size to be all of (reasonably) available memory.
     * This causes any single, large process to start random page
     * replacement once it fills memory.
     */

  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;
  p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(uvmexp.free);
}

#ifdef DEBUG
int	enableswap = 1;
int	swapdebug = 0;
#define	SDB_FOLLOW	1
#define SDB_SWAPIN	2
#define SDB_SWAPOUT	4
#endif

/*
 * uvm_swapin: swap in a process's u-area.
 */

void uvm_swapin(p)

struct proc *p;

{
  vm_offset_t addr;
  int s;

  addr = (vm_offset_t)p->p_addr;
  uvm_fault_wire(kernel_map, addr, addr + USPACE);	/* make P_INMEM true */
  /*
   * Some architectures need to be notified when the user area has
   * moved to new physical page(s) (e.g.  see mips/mips/vm_machdep.c).
   */
  cpu_swapin(p);
  s = splstatclock();
  if (p->p_stat == SRUN)
    setrunqueue(p);
  p->p_flag |= P_INMEM;
  splx(s);
  p->p_swtime = 0;
  ++uvmexp.swapins;
}

/*
 * uvm_scheduler: process zero main loop
 *
 * - attempt to swapin every swaped-out, runnable process in order of
 *	priority.
 * - if not enough memory, wake the pagedaemon and let it clear space.
 */

void uvm_scheduler()

{
  register struct proc *p;
  register int pri;
  struct proc *pp;
  int ppri;
  UVMHIST_FUNC("uvm_scheduler"); UVMHIST_CALLED(maphist);

loop:
#ifdef DEBUG
  while (!enableswap)
    tsleep((caddr_t)&proc0, PVM, "noswap", 0);
#endif
  pp = NULL;		/* process to choose */
  ppri = INT_MIN;	/* its priority */
  for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {

    /* is it a runnable swapped out process? */
    if (p->p_stat == SRUN && (p->p_flag & P_INMEM) == 0) {
      pri = p->p_swtime + p->p_slptime	- (p->p_nice - NZERO) * 8;
      if (pri > ppri) {   /* higher priority?  remember it. */
	pp = p;
	ppri = pri;
      }
    }

  }

#ifdef DEBUG
  if (swapdebug & SDB_FOLLOW)
    printf("scheduler: running, procp %p pri %d\n", pp, ppri);
#endif
  /*
   * Nothing to do, back to sleep
   */
  if ((p = pp) == NULL) {
    tsleep((caddr_t)&proc0, PVM, "scheduler", 0);
    goto loop;
  }

  /*
   * we have found swapped out process which we would like to bring
   * back in.
   *
   * XXX: this part is really bogus cuz we could deadlock on memory
   * despite our feeble check
   */
  if (uvmexp.free > atop(USPACE)) {
#ifdef DEBUG
    if (swapdebug & SDB_SWAPIN)
      printf("swapin: pid %d(%s)@%p, pri %d free %d\n",
	     p->p_pid, p->p_comm, p->p_addr, ppri, uvmexp.free);
#endif
    uvm_swapin(p);
    goto loop;
  }
  /*
   * not enough memory, jab the pageout daemon and wait til the coast is clear
   */
#ifdef DEBUG
  if (swapdebug & SDB_FOLLOW)
    printf("scheduler: no room for pid %d(%s), free %d\n",
	   p->p_pid, p->p_comm, uvmexp.free);
#endif
  printf("scheduler: no room for pid %d(%s), free %d\n",
	   p->p_pid, p->p_comm, uvmexp.free);/*XXXCDC: HIGHLY BOGUS */
  (void) splhigh();
  uvm_wait("schedpwait");
  (void) spl0();
#ifdef DEBUG
  if (swapdebug & SDB_FOLLOW)
    printf("scheduler: room again, free %d\n", uvmexp.free);
#endif
  goto loop;
}

/*
 * swappable: is process "p" swappable?
 */

#define	swappable(p)							\
	(((p)->p_flag & (P_SYSTEM | P_INMEM | P_WEXIT)) == P_INMEM &&	\
	 (p)->p_holdcnt == 0)

/*
 * swapout_threads: find threads that can be swapped and unwire their
 *	u-areas.
 *
 * - called by the pagedaemon
 * - try and swap at least one processs
 * - processes that are sleeping or stopped for maxslp or more seconds
 *   are swapped... otherwise the longest-sleeping or stopped process
 *   is swapped, otherwise the longest resident process...
 */
void uvm_swapout_threads()

{
  register struct proc *p;
  struct proc *outp, *outp2;
  int outpri, outpri2;
  int didswap = 0;
  extern int maxslp;
  /* XXXCDC: should move off to uvmexp. or uvm., also in uvm_meter */

#ifdef DEBUG
  if (!enableswap)
    return;
#endif

  /*
   * outp/outpri  : stop/sleep process with largest sleeptime < maxslp
   * outp2/outpri2: the longest resident process (its swap time)
   */
  outp = outp2 = NULL;
  outpri = outpri2 = 0;
  for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    if (!swappable(p))
      continue;
    switch (p->p_stat) {
    case SRUN:
      if (p->p_swtime > outpri2) {
	outp2 = p;
	outpri2 = p->p_swtime;
      }
      continue;

    case SSLEEP:
    case SSTOP:
      if (p->p_slptime >= maxslp) {
	uvm_swapout(p);			/* zap! */
	didswap++;
      } else if (p->p_slptime > outpri) {
	outp = p;
	outpri = p->p_slptime;
      }
      continue;
    }
  }

  /*
   * If we didn't get rid of any real duds, toss out the next most
   * likely sleeping/stopped or running candidate.  We only do this
   * if we are real low on memory since we don't gain much by doing
   * it (USPACE bytes).
   */
  if (didswap == 0 && uvmexp.free <= atop(round_page(USPACE))) {
    if ((p = outp) == NULL)
      p = outp2;
#ifdef DEBUG
    if (swapdebug & SDB_SWAPOUT)
      printf("swapout_threads: no duds, try procp %p\n", p);
#endif
    if (p)
      uvm_swapout(p);
  }
}

/*
 * uvm_swapout: swap out process "p"
 *
 * - currently "swapout" means "unwire U-area" and "pmap_collect()"
 *   the pmap.
 * - XXXCDC: should deactivate all process' private anonymous memory
 */

static void uvm_swapout(p)

register struct proc *p;

{
  vm_offset_t addr;
  int s;

#ifdef DEBUG
  if (swapdebug & SDB_SWAPOUT)
    printf("swapout: pid %d(%s)@%p, stat %x pri %d free %d\n",
	   p->p_pid, p->p_comm, p->p_addr, p->p_stat,
	   p->p_slptime, uvmexp.free);
#endif

  /*
   * Do any machine-specific actions necessary before swapout.
   * This can include saving floating point state, etc.
   */
  cpu_swapout(p);

  /*
   * Unwire the to-be-swapped process's user struct and kernel stack.
   */
  addr = (vm_offset_t)p->p_addr;
  uvm_fault_unwire(kernel_map->pmap, addr, addr + USPACE); /* !P_INMEM */
  pmap_collect(vm_map_pmap(&p->p_vmspace->vm_map));

  /*
   * Mark it as (potentially) swapped out.
   */
  s = splstatclock();
  p->p_flag &= ~P_INMEM;
  if (p->p_stat == SRUN)
    remrunqueue(p);
  splx(s);
  p->p_swtime = 0;
  ++uvmexp.swapouts;
}