uvm_glue.c

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/*	$NetBSD: uvm_glue.c,v 1.43 2000/11/25 06:27:59 chs Exp $	*/

/* 
 * 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  [e-mail]
 *  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.
 */

#include "opt_uvmhist.h"
#include "opt_sysv.h"

/*
 * 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 <uvm/uvm.h>

#include <machine/cpu.h>

/*
 * 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;
	size_t len;
	int rw;
{
	boolean_t rv;
	vaddr_t saddr, eaddr;
	vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;

	saddr = trunc_page((vaddr_t)addr);
	eaddr = round_page((vaddr_t)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 > (vaddr_t)buffers &&
			     saddr < (vaddr_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;
	size_t len;
	int rw;
{
	vm_map_t map;
	boolean_t rv;
	vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;

	/* XXX curproc */
	map = &curproc->p_vmspace->vm_map;

	vm_map_lock_read(map);
	rv = uvm_map_checkprot(map, trunc_page((vaddr_t)addr),
	    round_page((vaddr_t)addr + len), prot);
	vm_map_unlock_read(map);

	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)
	caddr_t addr;
	size_t len;
	int rw;
{
	vm_prot_t prot;
	paddr_t pa;
	vaddr_t sva, eva;

	prot = rw == B_READ ? VM_PROT_READ : VM_PROT_READ|VM_PROT_WRITE;
	eva = round_page((vaddr_t)addr + len);
	for (sva = trunc_page((vaddr_t)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...
		 */
		if (pmap_extract(pmap_kernel(), sva, &pa) == FALSE)
			panic("chgkprot: invalid page");
		pmap_enter(pmap_kernel(), sva, pa, prot, PMAP_WIRED);
	}
}
#endif

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

int
uvm_vslock(p, addr, len, access_type)
	struct proc *p;
	caddr_t	addr;
	size_t	len;
	vm_prot_t access_type;
{
	vm_map_t map;
	vaddr_t start, end;
	int rv;

	map = &p->p_vmspace->vm_map;
	start = trunc_page((vaddr_t)addr);
	end = round_page((vaddr_t)addr + len);

	rv = uvm_fault_wire(map, start, end, access_type);

	return (rv);
}

/*
 * 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(p, addr, len)
	struct proc *p;
	caddr_t	addr;
	size_t	len;
{
	uvm_fault_unwire(&p->p_vmspace->vm_map, trunc_page((vaddr_t)addr),
		round_page((vaddr_t)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...]
 * - if specified, the child gets a new user stack described by
 *	stack and stacksize
 * - 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, stack, stacksize, func, arg)
	struct proc *p1, *p2;
	boolean_t shared;
	void *stack;
	size_t stacksize;
	void (*func) __P((void *));
	void *arg;
{
	struct user *up = p2->p_addr;
	int rv;

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

	/*
	 * Wire down the U-area for the process, which contains the PCB
	 * and the kernel stack.  Wired state is stored in p->p_flag's
	 * P_INMEM bit rather than in the vm_map_entry's wired count
	 * to prevent kernel_map fragmentation.
	 *
	 * Note the kernel stack gets read/write accesses right off
	 * the bat.
	 */
	rv = uvm_fault_wire(kernel_map, (vaddr_t)up,
	    (vaddr_t)up + USPACE, VM_PROT_READ | VM_PROT_WRITE);
	if (rv != KERN_SUCCESS)
		panic("uvm_fork: uvm_fault_wire failed: %d", rv);

	/*
	 * p_stats currently points at a field in the user struct.  Copy
	 * parts of p_stats, and zero out the rest.
	 */
	p2->p_stats = &up->u_stats;
	memset(&up->u_stats.pstat_startzero, 0,
	       ((caddr_t)&up->u_stats.pstat_endzero -
		(caddr_t)&up->u_stats.pstat_startzero));
	memcpy(&up->u_stats.pstat_startcopy, &p1->p_stats->pstat_startcopy,
	       ((caddr_t)&up->u_stats.pstat_endcopy -
		(caddr_t)&up->u_stats.pstat_startcopy));
	
	/*