vm_unix.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988 University of Utah.
 * 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 Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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.
 *
 * from: Utah $Hdr: vm_unix.c 1.1 89/11/07$
 */

/*
 * Traditional sbrk/grow interface to VM
 */

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/systm.h>
#if defined(__amd64__) || defined(__i386__) /* for i386_read_exec */
#include <machine/md_var.h>
#endif

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>

#ifndef _SYS_SYSPROTO_H_
struct break_args {
	char *nsize;
};
#endif
int
sys_break(struct thread *td, struct break_args *uap)
{
#if !defined(__aarch64__) && !defined(__riscv)
	uintptr_t addr;
	int error;

	addr = (uintptr_t)uap->nsize;
	error = kern_break(td, &addr);
	if (error == 0)
		td->td_retval[0] = addr;
	return (error);
#else /* defined(__aarch64__) || defined(__riscv) */
	return (ENOSYS);
#endif /* defined(__aarch64__) || defined(__riscv) */
}

int
kern_break(struct thread *td, uintptr_t *addr)
{
	struct vmspace *vm = td->td_proc->p_vmspace;
	vm_map_t map = &vm->vm_map;
	vm_offset_t new, old, base;
	rlim_t datalim, lmemlim, vmemlim;
	int prot, rv;
	int error = 0;

	datalim = lim_cur(td, RLIMIT_DATA);
	lmemlim = lim_cur(td, RLIMIT_MEMLOCK);
	vmemlim = lim_cur(td, RLIMIT_VMEM);

	new = round_page(*addr);
	vm_map_lock(map);

	base = round_page((vm_offset_t) vm->vm_daddr);
	old = base + ctob(vm->vm_dsize);
	if (new > base) {
		/*
		 * Check the resource limit, but allow a process to reduce
		 * its usage, even if it remains over the limit.
		 */
		if (new - base > datalim && new > old) {
			error = ENOMEM;
			goto done;
		}
		if (new > vm_map_max(map)) {
			error = ENOMEM;
			goto done;
		}
	} else if (new < base) {
		/*
		 * Simply return the current break address without
		 * modifying any state.  This is an ad-hoc interface
		 * used by libc to determine the initial break address,
		 * avoiding a dependency on magic features in the system
		 * linker.
		 */
		new = old;
		goto done;
	}

	if (new > old) {
		if (!old_mlock && map->flags & MAP_WIREFUTURE) {
			if (ptoa(pmap_wired_count(map->pmap)) +
			    (new - old) > lmemlim) {
				error = ENOMEM;
				goto done;
			}
		}
		if (map->size + (new - old) > vmemlim) {
			error = ENOMEM;
			goto done;
		}
#ifdef RACCT
		if (racct_enable) {
			PROC_LOCK(td->td_proc);
			error = racct_set(td->td_proc, RACCT_DATA, new - base);
			if (error != 0) {
				PROC_UNLOCK(td->td_proc);
				error = ENOMEM;
				goto done;
			}
			error = racct_set(td->td_proc, RACCT_VMEM,
			    map->size + (new - old));
			if (error != 0) {
				racct_set_force(td->td_proc, RACCT_DATA,
				    old - base);
				PROC_UNLOCK(td->td_proc);
				error = ENOMEM;
				goto done;
			}
			if (!old_mlock && map->flags & MAP_WIREFUTURE) {
				error = racct_set(td->td_proc, RACCT_MEMLOCK,
				    ptoa(pmap_wired_count(map->pmap)) +
				    (new - old));
				if (error != 0) {
					racct_set_force(td->td_proc, RACCT_DATA,
					    old - base);
					racct_set_force(td->td_proc, RACCT_VMEM,
					    map->size);
					PROC_UNLOCK(td->td_proc);
					error = ENOMEM;
					goto done;
				}
			}
			PROC_UNLOCK(td->td_proc);
		}
#endif
		prot = VM_PROT_RW;
#if (defined(COMPAT_FREEBSD32) && defined(__amd64__)) || defined(__i386__)
		if (i386_read_exec && SV_PROC_FLAG(td->td_proc, SV_ILP32))
			prot |= VM_PROT_EXECUTE;
#endif
		rv = vm_map_insert(map, NULL, 0, old, new, prot, VM_PROT_ALL,
		    0);
		if (rv == KERN_SUCCESS && (map->flags & MAP_WIREFUTURE) != 0) {
			rv = vm_map_wire_locked(map, old, new,
			    VM_MAP_WIRE_USER | VM_MAP_WIRE_NOHOLES);
			if (rv != KERN_SUCCESS)
				(void)vm_map_delete(map, old, new);
		}
		if (rv != KERN_SUCCESS) {
#ifdef RACCT
			if (racct_enable) {
				PROC_LOCK(td->td_proc);
				racct_set_force(td->td_proc,
				    RACCT_DATA, old - base);
				racct_set_force(td->td_proc,
				    RACCT_VMEM, map->size);
				if (!old_mlock && map->flags & MAP_WIREFUTURE) {
					racct_set_force(td->td_proc,
					    RACCT_MEMLOCK,
					    ptoa(pmap_wired_count(map->pmap)));
				}
				PROC_UNLOCK(td->td_proc);
			}
#endif
			error = ENOMEM;
			goto done;
		}
		vm->vm_dsize += btoc(new - old);
	} else if (new < old) {
		rv = vm_map_delete(map, new, old);
		if (rv != KERN_SUCCESS) {
			error = ENOMEM;
			goto done;
		}
		vm->vm_dsize -= btoc(old - new);
#ifdef RACCT
		if (racct_enable) {
			PROC_LOCK(td->td_proc);
			racct_set_force(td->td_proc, RACCT_DATA, new - base);
			racct_set_force(td->td_proc, RACCT_VMEM, map->size);
			if (!old_mlock && map->flags & MAP_WIREFUTURE) {
				racct_set_force(td->td_proc, RACCT_MEMLOCK,
				    ptoa(pmap_wired_count(map->pmap)));
			}
			PROC_UNLOCK(td->td_proc);
		}
#endif
	}
done:
	vm_map_unlock(map);

	if (error == 0)
		*addr = new;

	return (error);
}

#ifdef COMPAT_FREEBSD11
int
freebsd11_vadvise(struct thread *td, struct freebsd11_vadvise_args *uap)
{

	return (EINVAL);
}
#endif