/* * Copyright (c) 1988 University of Utah. * Copyright (c) 1991 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. 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: Utah Hdr: vm_mmap.c 1.3 90/01/21 * from: @(#)vm_mmap.c 7.5 (Berkeley) 6/28/91 * $Id: vm_mmap.c,v 1.25 1994/05/04 01:39:05 cgd Exp $ */ /* * Mapped file (mmap) interface to VM */ #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DEBUG int mmapdebug = 0; #define MDB_FOLLOW 0x01 #define MDB_SYNC 0x02 #define MDB_MAPIT 0x04 #endif static boolean_t vm_map_is_allocated __P((vm_map_t, vm_offset_t, vm_offset_t, boolean_t)); /* ARGSUSED */ int getpagesize(p, uap, retval) struct proc *p; void *uap; int *retval; { *retval = NBPG * CLSIZE; return (0); } struct sbrk_args { int incr; }; /* ARGSUSED */ int sbrk(p, uap, retval) struct proc *p; struct sbrk_args *uap; int *retval; { /* Not yet implemented */ return (EOPNOTSUPP); } struct sstk_args { int incr; }; /* ARGSUSED */ int sstk(p, uap, retval) struct proc *p; struct sstk_args *uap; int *retval; { /* Not yet implemented */ return (EOPNOTSUPP); } struct mmap_args { caddr_t addr; int len; int prot; int flags; int fd; int pad; off_t pos; }; int mmap(p, uap, retval) struct proc *p; register struct mmap_args *uap; int *retval; { register struct filedesc *fdp = p->p_fd; register struct file *fp; struct vnode *vp; vm_offset_t addr; vm_size_t size; vm_prot_t prot; vm_prot_t maxprot; caddr_t handle; int error; int flags = uap->flags; #ifdef DEBUG if (mmapdebug & MDB_FOLLOW) printf("mmap(%d): addr %x len %x pro %x flg %x fd %d pos %qx\n", p->p_pid, uap->addr, uap->len, uap->prot, flags, uap->fd, uap->pos); #endif if (uap->pos > (quad_t)0x07fffffff || uap->pos < -(quad_t)0x080000000) return (EINVAL); /* XXX */ /* * Address (if FIXED) must be page aligned. * Size is implicitly rounded to a page boundary. */ addr = (vm_offset_t) uap->addr; if ((flags & MAP_FIXED) && (addr & PAGE_MASK) || uap->len < 0) return(EINVAL); size = (vm_size_t) round_page(uap->len); if ((flags & MAP_FIXED) && (addr + size > VM_MAXUSER_ADDRESS)) return(EINVAL); /* * XXX if no hint provided for a non-fixed mapping place it after * the end of the largest possible heap. * * There should really be a pmap call to determine a reasonable * location. */ if (addr == 0 && (flags & MAP_FIXED) == 0) addr = round_page(p->p_vmspace->vm_daddr + MAXDSIZ); /* * Mapping file or named anonymous, get fp for validation */ if ((flags & MAP_ANON) == 0 || uap->fd != -1) { if (((unsigned)uap->fd) >= fdp->fd_nfiles || (fp = fdp->fd_ofiles[uap->fd]) == NULL) return(EBADF); } /* * Map current protections to MACH style */ prot = VM_PROT_NONE; if (uap->prot & PROT_READ) prot |= VM_PROT_READ; if (uap->prot & PROT_WRITE) prot |= VM_PROT_WRITE; if (uap->prot & PROT_EXEC) prot |= VM_PROT_EXECUTE; /* * If we are mapping a file we need to check various * file/vnode related things. */ if ((flags & MAP_ANON) == 0) { /* * Obtain vnode and make sure it is of appropriate type */ if (fp->f_type != DTYPE_VNODE) return(EINVAL); vp = (struct vnode *)fp->f_data; if (vp->v_type != VREG && vp->v_type != VCHR) return(EINVAL); /* * Set the maximum protection according to the file * protection. */ maxprot = VM_PROT_NONE; if (fp->f_flag & FREAD) maxprot |= VM_PROT_READ|VM_PROT_EXECUTE; if (flags & MAP_SHARED) { if (fp->f_flag & FWRITE) maxprot |= VM_PROT_WRITE; } else maxprot |= VM_PROT_WRITE; /* * Ensure that the maximum protection (based on the file * protection) and the desired protection are compatible. */ if ((maxprot & prot) != prot) return(EACCES); handle = (caddr_t)vp; } else if (uap->fd != -1) { maxprot = VM_PROT_ALL; handle = (caddr_t)fp; } else { maxprot = VM_PROT_ALL; handle = NULL; } error = vm_mmap(&p->p_vmspace->vm_map, &addr, size, prot, maxprot, flags, handle, (vm_offset_t)uap->pos); if (error == 0) *retval = (int) addr; return(error); } #if defined(COMPAT_43) || defined(COMPAT_SUNOS) struct ommap_args { caddr_t addr; int len; int prot; int flags; int fd; long pos; }; int ommap(p, uap, retval) struct proc *p; register struct ommap_args *uap; int *retval; { struct mmap_args ma; ma.len = uap->len; /* prot and flags below */ ma.fd = uap->fd; ma.pos = uap->pos; #define OPROT_EXEC 0x01 #define OPROT_WRITE 0x02 #define OPROT_READ 0x04 ma.prot = 0; if (uap->prot & OPROT_EXEC) ma.prot |= PROT_EXEC; if (uap->prot & OPROT_WRITE) ma.prot |= PROT_WRITE; if (uap->prot & OPROT_READ) ma.prot |= PROT_READ; #define OMAP_ANON 0x0002 #define OMAP_SHARED 0x0010 #define OMAP_COPY 0x0020 #define OMAP_FIXED 0x0100 #define OMAP_NOEXTEND 0x0200 #define OMAP_HASSEMAPHORE 0x0400 #define OMAP_INHERIT 0x0800 ma.addr = uap->addr; ma.flags = 0; if (uap->flags & OMAP_ANON) ma.flags |= MAP_ANON; /* else MAP_FILE, the default */ if (uap->flags & OMAP_COPY) ma.flags |= MAP_COPY; else if (uap->flags & OMAP_SHARED) ma.flags |= MAP_SHARED; else ma.flags |= MAP_PRIVATE; if (uap->flags & OMAP_FIXED) ma.flags |= MAP_FIXED; if (uap->flags & OMAP_NOEXTEND) ma.flags |= MAP_NOEXTEND; if (uap->flags & OMAP_HASSEMAPHORE) ma.flags |= MAP_HASSEMAPHORE; if (uap->flags & OMAP_INHERIT) ma.flags |= MAP_INHERIT; return(mmap(p, &ma, retval)); } #endif /* defined(COMPAT_43) || defined(COMPAT_SUNOS) */ struct msync_args { caddr_t addr; int len; }; int msync(p, uap, retval) struct proc *p; struct msync_args *uap; int *retval; { vm_offset_t addr, objoff, oaddr; vm_size_t size, osize; vm_prot_t prot, mprot; vm_inherit_t inherit; vm_object_t object; boolean_t shared; int rv; #ifdef DEBUG if (mmapdebug & (MDB_FOLLOW|MDB_SYNC)) printf("msync(%d): addr %x len %x\n", p->p_pid, uap->addr, uap->len); #endif if (((int)uap->addr & PAGE_MASK) || uap->len < 0) return(EINVAL); addr = oaddr = (vm_offset_t)uap->addr; osize = (vm_size_t)uap->len; /* * Region must be entirely contained in a single entry */ if (!vm_map_is_allocated(&p->p_vmspace->vm_map, addr, addr+osize, TRUE)) return(EINVAL); /* * Determine the object associated with that entry * (object is returned locked on KERN_SUCCESS) */ rv = vm_region(&p->p_vmspace->vm_map, &addr, &size, &prot, &mprot, &inherit, &shared, &object, &objoff); if (rv != KERN_SUCCESS) return(EINVAL); #ifdef DEBUG if (mmapdebug & MDB_SYNC) printf("msync: region: object %x addr %x size %d objoff %d\n", object, addr, size, objoff); #endif /* * Do not msync non-vnoded backed objects. */ if ((object->flags & OBJ_INTERNAL) || object->pager == NULL || object->pager->pg_type != PG_VNODE) { vm_object_unlock(object); return(EINVAL); } objoff += oaddr - addr; if (osize == 0) osize = size; #ifdef DEBUG if (mmapdebug & MDB_SYNC) printf("msync: cleaning/flushing object range [%x-%x)\n", objoff, objoff+osize); #endif if (prot & VM_PROT_WRITE) vm_object_page_clean(object, objoff, objoff+osize); /* * (XXX) * Bummer, gotta flush all cached pages to ensure * consistency with the file system cache. */ vm_object_page_remove(object, objoff, objoff+osize); vm_object_unlock(object); return(0); } struct munmap_args { caddr_t addr; int len; }; int munmap(p, uap, retval) register struct proc *p; register struct munmap_args *uap; int *retval; { vm_offset_t addr; vm_size_t size; #ifdef DEBUG if (mmapdebug & MDB_FOLLOW) printf("munmap(%d): addr %x len %x\n", p->p_pid, uap->addr, uap->len); #endif addr = (vm_offset_t) uap->addr; if ((addr & PAGE_MASK) || uap->len < 0) return(EINVAL); size = (vm_size_t) round_page(uap->len); if (size == 0) return(0); if (addr + size >= VM_MAXUSER_ADDRESS) return(EINVAL); if (!vm_map_is_allocated(&p->p_vmspace->vm_map, addr, addr+size, FALSE)) return(EINVAL); /* returns nothing but KERN_SUCCESS anyway */ (void) vm_map_remove(&p->p_vmspace->vm_map, addr, addr+size); return(0); } void munmapfd(p, fd) register struct proc *p; int fd; { #ifdef DEBUG if (mmapdebug & MDB_FOLLOW) printf("munmapfd(%d): fd %d\n", p->p_pid, fd); #endif /* * XXX -- should vm_deallocate any regions mapped to this file */ p->p_fd->fd_ofileflags[fd] &= ~UF_MAPPED; } struct mprotect_args { caddr_t addr; int len; int prot; }; int mprotect(p, uap, retval) struct proc *p; struct mprotect_args *uap; int *retval; { vm_offset_t addr; vm_size_t size; register vm_prot_t prot; #ifdef DEBUG if (mmapdebug & MDB_FOLLOW) printf("mprotect(%d): addr %x len %x prot %d\n", p->p_pid, uap->addr, uap->len, uap->prot); #endif addr = (vm_offset_t) uap->addr; if ((addr & PAGE_MASK) || uap->len < 0) return(EINVAL); size = (vm_size_t) uap->len; /* * Map protections */ prot = VM_PROT_NONE; if (uap->prot & PROT_READ) prot |= VM_PROT_READ; if (uap->prot & PROT_WRITE) prot |= VM_PROT_WRITE; if (uap->prot & PROT_EXEC) prot |= VM_PROT_EXECUTE; switch (vm_map_protect(&p->p_vmspace->vm_map, addr, addr+size, prot, FALSE)) { case KERN_SUCCESS: return (0); case KERN_PROTECTION_FAILURE: return (EACCES); } return(EINVAL); } struct madvise_args { caddr_t addr; int len; int behav; }; /* ARGSUSED */ int madvise(p, uap, retval) struct proc *p; struct madvise_args *uap; int *retval; { /* Not yet implemented */ return (EOPNOTSUPP); } struct mincore_args { caddr_t addr; int len; char *vec; }; /* ARGSUSED */ int mincore(p, uap, retval) struct proc *p; struct mincore_args *uap; int *retval; { /* Not yet implemented */ return (EOPNOTSUPP); } /* * Internal version of mmap. * Currently used by mmap, exec, and sys5 shared memory. * Handle is: * MAP_FILE: a vnode pointer * MAP_ANON: NULL or a file pointer */ int vm_mmap(map, addr, size, prot, maxprot, flags, handle, foff) register vm_map_t map; register vm_offset_t *addr; register vm_size_t size; vm_prot_t prot; vm_prot_t maxprot; register int flags; caddr_t handle; /* XXX should be vp */ vm_offset_t foff; { register vm_pager_t pager; boolean_t fitit; vm_object_t object; struct vnode *vp; int type; int rv = KERN_SUCCESS; if (size == 0) return (0); if ((flags & MAP_FIXED) == 0) { fitit = TRUE; *addr = round_page(*addr); } else { fitit = FALSE; (void) vm_deallocate(map, *addr, size); } /* * Lookup/allocate pager. All except an unnamed anonymous lookup * gain a reference to ensure continued existance of the object. * (XXX the exception is to appease the pageout daemon) */ if (flags & MAP_ANON) type = PG_DFLT; else { vp = (struct vnode *)handle; if (vp->v_type == VCHR) { type = PG_DEVICE; handle = (caddr_t)(long)vp->v_rdev; } else type = PG_VNODE; } pager = vm_pager_allocate(type, handle, size, prot, foff); if (pager == NULL) return (type == PG_DEVICE ? EINVAL : ENOMEM); /* * Find object and release extra reference gained by lookup */ object = vm_object_lookup(pager); vm_object_deallocate(object); /* * Anonymous memory. */ if (flags & MAP_ANON) { rv = vm_allocate_with_pager(map, addr, size, fitit, pager, (vm_offset_t)foff, TRUE); if (rv != KERN_SUCCESS) { if (handle == NULL) vm_pager_deallocate(pager); else vm_object_deallocate(object); goto out; } /* * The object of unnamed anonymous regions was just created * find it for pager_cache. */ if (handle == NULL) object = vm_object_lookup(pager); /* * Don't cache anonymous objects. * Loses the reference gained by vm_pager_allocate. */ (void) pager_cache(object, FALSE); #ifdef DEBUG if (mmapdebug & MDB_MAPIT) printf("vm_mmap(%d): ANON *addr %x size %x pager %x\n", curproc->p_pid, *addr, size, pager); #endif } /* * Must be type MAP_FILE. * Distinguish between character special and regular files. */ else if (vp->v_type == VCHR) { rv = vm_allocate_with_pager(map, addr, size, fitit, pager, (vm_offset_t)foff, FALSE); /* * Uncache the object and lose the reference gained * by vm_pager_allocate(). If the call to * vm_allocate_with_pager() was sucessful, then we * gained an additional reference ensuring the object * will continue to exist. If the call failed then * the deallocate call below will terminate the * object which is fine. */ (void) pager_cache(object, FALSE); if (rv != KERN_SUCCESS) goto out; } /* * A regular file */ else { #ifdef DEBUG if (object == NULL) printf("vm_mmap: no object: vp %x, pager %x\n", vp, pager); #endif /* * Map it directly. * Allows modifications to go out to the vnode. */ if (flags & MAP_SHARED) { rv = vm_allocate_with_pager(map, addr, size, fitit, pager, (vm_offset_t)foff, FALSE); if (rv != KERN_SUCCESS) { vm_object_deallocate(object); goto out; } /* * Don't cache the object. This is the easiest way * of ensuring that data gets back to the filesystem * because vnode_pager_deallocate() will fsync the * vnode. pager_cache() will lose the extra ref. */ if (prot & VM_PROT_WRITE) pager_cache(object, FALSE); else vm_object_deallocate(object); } /* * Copy-on-write of file. Two flavors. * MAP_COPY is true COW, you essentially get a snapshot of * the region at the time of mapping. MAP_PRIVATE means only * that your changes are not reflected back to the object. * Changes made by others will be seen. */ else { vm_map_t tmap; vm_offset_t off; /* locate and allocate the target address space */ rv = vm_map_find(map, NULL, (vm_offset_t)0, addr, size, fitit); if (rv != KERN_SUCCESS) { vm_object_deallocate(object); goto out; } tmap = vm_map_create(pmap_create(size), VM_MIN_ADDRESS, VM_MIN_ADDRESS+size, TRUE); off = VM_MIN_ADDRESS; rv = vm_allocate_with_pager(tmap, &off, size, TRUE, pager, (vm_offset_t)foff, FALSE); if (rv != KERN_SUCCESS) { vm_object_deallocate(object); vm_map_deallocate(tmap); goto out; } /* * (XXX) * MAP_PRIVATE implies that we see changes made by * others. To ensure that we need to guarentee that * no copy object is created (otherwise original * pages would be pushed to the copy object and we * would never see changes made by others). We * totally sleeze it right now by marking the object * internal temporarily. */ if ((flags & MAP_COPY) == 0) object->flags |= OBJ_INTERNAL; rv = vm_map_copy(map, tmap, *addr, size, off, FALSE, FALSE); object->flags &= ~OBJ_INTERNAL; /* * (XXX) * My oh my, this only gets worse... * Force creation of a shadow object so that * vm_map_fork will do the right thing. */ if ((flags & MAP_COPY) == 0) { vm_map_t tmap; vm_map_entry_t tentry; vm_object_t tobject; vm_offset_t toffset; vm_prot_t tprot; boolean_t twired, tsu; tmap = map; vm_map_lookup(&tmap, *addr, VM_PROT_WRITE, &tentry, &tobject, &toffset, &tprot, &twired, &tsu); vm_map_lookup_done(tmap, tentry); } /* * (XXX) * Map copy code cannot detect sharing unless a * sharing map is involved. So we cheat and write * protect everything ourselves. */ vm_object_pmap_copy(object, (vm_offset_t)foff, (vm_offset_t)foff+size); vm_object_deallocate(object); vm_map_deallocate(tmap); if (rv != KERN_SUCCESS) goto out; } #ifdef DEBUG if (mmapdebug & MDB_MAPIT) printf("vm_mmap(%d): FILE *addr %x size %x pager %x\n", curproc->p_pid, *addr, size, pager); #endif } /* * We only need to set max_protection in case it's * unequal to its default, which is VM_PROT_DEFAULT. */ if (maxprot != VM_PROT_DEFAULT) { rv = vm_map_protect(map, *addr, *addr+size, maxprot, TRUE); if (rv != KERN_SUCCESS) { (void) vm_deallocate(map, *addr, size); goto out; } } /* * We only need to set the current protection if it's different * from the maximum. If it is equal to the maximum, then the * vm_map_protect() above would have set it. */ if (prot != maxprot) { rv = vm_map_protect(map, *addr, *addr+size, prot, FALSE); if (rv != KERN_SUCCESS) { (void) vm_deallocate(map, *addr, size); goto out; } } /* * Shared memory is also shared with children. */ if (flags & MAP_SHARED) { rv = vm_inherit(map, *addr, size, VM_INHERIT_SHARE); if (rv != KERN_SUCCESS) { (void) vm_deallocate(map, *addr, size); goto out; } } out: #ifdef DEBUG if (mmapdebug & MDB_MAPIT) printf("vm_mmap: rv %d\n", rv); #endif switch (rv) { case KERN_SUCCESS: return (0); case KERN_INVALID_ADDRESS: case KERN_NO_SPACE: return (ENOMEM); case KERN_PROTECTION_FAILURE: return (EACCES); default: return (EINVAL); } } /* * Internal bastardized version of MACHs vm_region system call. * Given address and size it returns map attributes as well * as the (locked) object mapped at that location. */ int vm_region(map, addr, size, prot, max_prot, inheritance, shared, object, objoff) vm_map_t map; vm_offset_t *addr; /* IN/OUT */ vm_size_t *size; /* OUT */ vm_prot_t *prot; /* OUT */ vm_prot_t *max_prot; /* OUT */ vm_inherit_t *inheritance; /* OUT */ boolean_t *shared; /* OUT */ vm_object_t *object; /* OUT */ vm_offset_t *objoff; /* OUT */ { vm_map_entry_t tmp_entry; register vm_map_entry_t entry; register vm_offset_t tmp_offset; vm_offset_t start; if (map == NULL) return(KERN_INVALID_ARGUMENT); start = *addr; vm_map_lock_read(map); if (!vm_map_lookup_entry(map, start, &tmp_entry)) { if ((entry = tmp_entry->next) == &map->header) { vm_map_unlock_read(map); return(KERN_NO_SPACE); } start = entry->start; *addr = start; } else entry = tmp_entry; *prot = entry->protection; *max_prot = entry->max_protection; *inheritance = entry->inheritance; tmp_offset = entry->offset + (start - entry->start); *size = (entry->end - start); if (entry->is_a_map) { register vm_map_t share_map; vm_size_t share_size; share_map = entry->object.share_map; vm_map_lock_read(share_map); (void) vm_map_lookup_entry(share_map, tmp_offset, &tmp_entry); if ((share_size = (tmp_entry->end - tmp_offset)) < *size) *size = share_size; vm_object_lock(tmp_entry->object); *object = tmp_entry->object.vm_object; *objoff = tmp_entry->offset + (tmp_offset - tmp_entry->start); *shared = (share_map->ref_count != 1); vm_map_unlock_read(share_map); } else { vm_object_lock(entry->object); *object = entry->object.vm_object; *objoff = tmp_offset; *shared = FALSE; } vm_map_unlock_read(map); return(KERN_SUCCESS); } /* * Yet another bastard routine. */ int vm_allocate_with_pager(map, addr, size, fitit, pager, poffset, internal) register vm_map_t map; register vm_offset_t *addr; register vm_size_t size; boolean_t fitit; vm_pager_t pager; vm_offset_t poffset; boolean_t internal; { register vm_object_t object; register int result; if (map == NULL) return(KERN_INVALID_ARGUMENT); *addr = trunc_page(*addr); size = round_page(size); /* * Lookup the pager/paging-space in the object cache. * If it's not there, then create a new object and cache * it. */ object = vm_object_lookup(pager); cnt.v_lookups++; if (object == NULL) { object = vm_object_allocate(size); /* * From Mike Hibler: "unnamed anonymous objects should never * be on the hash list ... For now you can just change * vm_allocate_with_pager to not do vm_object_enter if this * is an internal object ..." */ if (!internal) vm_object_enter(object, pager); } else cnt.v_hits++; if (internal) object->flags |= OBJ_INTERNAL; else object->flags &= ~OBJ_INTERNAL; result = vm_map_find(map, object, poffset, addr, size, fitit); if (result != KERN_SUCCESS) vm_object_deallocate(object); else if (pager != NULL) vm_object_setpager(object, pager, (vm_offset_t) 0, TRUE); return(result); } /* * XXX: this routine belongs in vm_map.c. * * Returns TRUE if the range [start - end) is allocated in either * a single entry (single_entry == TRUE) or multiple contiguous * entries (single_entry == FALSE). * * start and end should be page aligned. */ static boolean_t vm_map_is_allocated(map, start, end, single_entry) vm_map_t map; vm_offset_t start, end; boolean_t single_entry; { vm_map_entry_t mapent; register vm_offset_t nend; vm_map_lock_read(map); /* * Start address not in any entry */ if (!vm_map_lookup_entry(map, start, &mapent)) { vm_map_unlock_read(map); return (FALSE); } /* * Find the maximum stretch of contiguously allocated space */ nend = mapent->end; if (!single_entry) { mapent = mapent->next; while (mapent != &map->header && mapent->start == nend) { nend = mapent->end; mapent = mapent->next; } } vm_map_unlock_read(map); return (end <= nend); }