vm_unix.c

Go to the documentation of this file.

/*-
 * 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 $Hdr: vm_unix.c 1.1 89/11/07$
 *
 *      @(#)vm_unix.c   8.1 (Berkeley) 6/11/93
 */
 
/*
 * Traditional sbrk/grow interface to VM
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#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