/* * mm/mmap.c * * Written by obz. * * Address space accounting code <alan@redhat.com> */ #include <linux/slab.h> #include <linux/shm.h> #include <linux/mman.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <linux/init.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/personality.h> #include <linux/security.h> #include <linux/hugetlb.h> #include <linux/profile.h> #include <asm/uaccess.h> #include <asm/pgalloc.h> #include <asm/tlb.h> /* * WARNING: the debugging will use recursive algorithms so never enable this * unless you know what you are doing. */ #undef DEBUG_MM_RB /* description of effects of mapping type and prot in current implementation. * this is due to the limited x86 page protection hardware. The expected * behavior is in parens: * * map_type prot * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes * w: (no) no w: (no) no w: (yes) yes w: (no) no * x: (no) no x: (no) yes x: (no) yes x: (yes) yes * * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes * w: (no) no w: (no) no w: (copy) copy w: (no) no * x: (no) no x: (no) yes x: (no) yes x: (yes) yes * */ pgprot_t protection_map[16] = { __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 }; int sysctl_overcommit_memory = 0; /* default is heuristic overcommit */ int sysctl_overcommit_ratio = 50; /* default is 50% */ atomic_t vm_committed_space = ATOMIC_INIT(0); inline void vm_unacct_memory(long pages) { atomic_sub(pages, &vm_committed_space); } /* * Check that a process has enough memory to allocate a new virtual * mapping. 1 means there is enough memory for the allocation to * succeed and 0 implies there is not. * * We currently support three overcommit policies, which are set via the * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-acounting * * Strict overcommit modes added 2002 Feb 26 by Alan Cox. * Additional code 2002 Jul 20 by Robert Love. */ int vm_enough_memory(long pages) { unsigned long free, allowed; atomic_add(pages, &vm_committed_space); /* * Sometimes we want to use more memory than we have */ if (sysctl_overcommit_memory == 1) return 1; if (sysctl_overcommit_memory == 0) { free = get_page_cache_size(); free += nr_free_pages(); free += nr_swap_pages; /* * This double-counts: the nrpages are both in the * page-cache and in the swapper space. At the same time, * this compensates for the swap-space over-allocation * (ie "nr_swap_pages" being too small). */ free += total_swapcache_pages; /* * The code below doesn't account for free space in the * inode and dentry slab cache, slab cache fragmentation, * inodes and dentries which will become freeable under * VM load, etc. Lets just hope all these (complex) * factors balance out... */ free += (dentry_stat.nr_unused * sizeof(struct dentry)) >> PAGE_SHIFT; free += (inodes_stat.nr_unused * sizeof(struct inode)) >> PAGE_SHIFT; if (free > pages) return 1; vm_unacct_memory(pages); return 0; } allowed = totalram_pages * sysctl_overcommit_ratio / 100; allowed += total_swap_pages; if (atomic_read(&vm_committed_space) < allowed) return 1; vm_unacct_memory(pages); return 0; } /* * Requires inode->i_mapping->i_shared_sem */ static inline void __remove_shared_vm_struct(struct vm_area_struct *vma, struct inode *inode) { if (inode) { if (vma->vm_flags & VM_DENYWRITE) atomic_inc(&inode->i_writecount); list_del_init(&vma->shared); } } /* * Remove one vm structure from the inode's i_mapping address space. */ static void remove_shared_vm_struct(struct vm_area_struct *vma) { struct file *file = vma->vm_file; if (file) { struct inode *inode = file->f_dentry->d_inode; down(&inode->i_mapping->i_shared_sem); __remove_shared_vm_struct(vma, inode); up(&inode->i_mapping->i_shared_sem); } } /* * sys_brk() for the most part doesn't need the global kernel * lock, except when an application is doing something nasty * like trying to un-brk an area that has already been mapped * to a regular file. in this case, the unmapping will need * to invoke file system routines that need the global lock. */ asmlinkage unsigned long sys_brk(unsigned long brk) { unsigned long rlim, retval; unsigned long newbrk, oldbrk; struct mm_struct *mm = current->mm; down_write(&mm->mmap_sem); if (brk < mm->end_code) goto out; newbrk = PAGE_ALIGN(brk); oldbrk = PAGE_ALIGN(mm->brk); if (oldbrk == newbrk) goto set_brk; /* Always allow shrinking brk. */ if (brk <= mm->brk) { if (!do_munmap(mm, newbrk, oldbrk-newbrk)) goto set_brk; goto out; } /* Check against rlimit.. */ rlim = current->rlim[RLIMIT_DATA].rlim_cur; if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) goto out; /* Check against existing mmap mappings. */ if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) goto out; /* Ok, looks good - let it rip. */ if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) goto out; set_brk: mm->brk = brk; out: retval = mm->brk; up_write(&mm->mmap_sem); return retval; } /* Combine the mmap "prot" and "flags" argument into one "vm_flags" used * internally. Essentially, translate the "PROT_xxx" and "MAP_xxx" bits * into "VM_xxx". */ static inline unsigned long calc_vm_flags(unsigned long prot, unsigned long flags) { #define _trans(x,bit1,bit2) \ ((bit1==bit2)?(x&bit1):(x&bit1)?bit2:0) unsigned long prot_bits, flag_bits; prot_bits = _trans(prot, PROT_READ, VM_READ) | _trans(prot, PROT_WRITE, VM_WRITE) | _trans(prot, PROT_EXEC, VM_EXEC); flag_bits = _trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN) | _trans(flags, MAP_DENYWRITE, VM_DENYWRITE) | _trans(flags, MAP_EXECUTABLE, VM_EXECUTABLE); return prot_bits | flag_bits; #undef _trans } #ifdef DEBUG_MM_RB static int browse_rb(struct rb_node * rb_node) { int i = 0; if (rb_node) { i++; i += browse_rb(rb_node->rb_left); i += browse_rb(rb_node->rb_right); } return i; } static void validate_mm(struct mm_struct * mm) { int bug = 0; int i = 0; struct vm_area_struct * tmp = mm->mmap; while (tmp) { tmp = tmp->vm_next; i++; } if (i != mm->map_count) printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; i = browse_rb(mm->mm_rb.rb_node); if (i != mm->map_count) printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; if (bug) BUG(); } #else #define validate_mm(mm) do { } while (0) #endif static struct vm_area_struct * find_vma_prepare(struct mm_struct *mm, unsigned long addr, struct vm_area_struct **pprev, struct rb_node ***rb_link, struct rb_node ** rb_parent) { struct vm_area_struct * vma; struct rb_node ** __rb_link, * __rb_parent, * rb_prev; __rb_link = &mm->mm_rb.rb_node; rb_prev = __rb_parent = NULL; vma = NULL; while (*__rb_link) { struct vm_area_struct *vma_tmp; __rb_parent = *__rb_link; vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); if (vma_tmp->vm_end > addr) { vma = vma_tmp; if (vma_tmp->vm_start <= addr) return vma; __rb_link = &__rb_parent->rb_left; } else { rb_prev = __rb_parent; __rb_link = &__rb_parent->rb_right; } } *pprev = NULL; if (rb_prev) *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); *rb_link = __rb_link; *rb_parent = __rb_parent; return vma; } static inline void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, struct rb_node *rb_parent) { if (prev) { vma->vm_next = prev->vm_next; prev->vm_next = vma; } else { mm->mmap = vma; if (rb_parent) vma->vm_next = rb_entry(rb_parent, struct vm_area_struct, vm_rb); else vma->vm_next = NULL; } } static void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, struct rb_node **rb_link, struct rb_node *rb_parent) { rb_link_node(&vma->vm_rb, rb_parent, rb_link); rb_insert_color(&vma->vm_rb, &mm->mm_rb); } static inline void __vma_link_file(struct vm_area_struct *vma) { struct file * file; file = vma->vm_file; if (file) { struct inode * inode = file->f_dentry->d_inode; struct address_space *mapping = inode->i_mapping; if (vma->vm_flags & VM_DENYWRITE) atomic_dec(&inode->i_writecount); if (vma->vm_flags & VM_SHARED) list_add_tail(&vma->shared, &mapping->i_mmap_shared); else list_add_tail(&vma->shared, &mapping->i_mmap); } } static void __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, struct rb_node **rb_link, struct rb_node *rb_parent) { __vma_link_list(mm, vma, prev, rb_parent); __vma_link_rb(mm, vma, rb_link, rb_parent); __vma_link_file(vma); } static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, struct rb_node **rb_link, struct rb_node *rb_parent) { struct address_space *mapping = NULL; if (vma->vm_file) mapping = vma->vm_file->f_dentry->d_inode->i_mapping; if (mapping) down(&mapping->i_shared_sem); spin_lock(&mm->page_table_lock); __vma_link(mm, vma, prev, rb_link, rb_parent); spin_unlock(&mm->page_table_lock); if (mapping) up(&mapping->i_shared_sem); mark_mm_hugetlb(mm, vma); mm->map_count++; validate_mm(mm); } /* * Return true if we can merge this (vm_flags,file,vm_pgoff,size) * in front of (at a lower virtual address and file offset than) the vma. * * We don't check here for the merged mmap wrapping around the end of pagecache * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which * wrap, nor mmaps which cover the final page at index -1UL. */ static int can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, struct file *file, unsigned long vm_pgoff, unsigned long size) { if (vma->vm_file == file && vma->vm_flags == vm_flags) { if (!file) return 1; /* anon mapping */ if (vma->vm_pgoff == vm_pgoff + size) return 1; } return 0; } /* * Return true if we can merge this (vm_flags,file,vm_pgoff) * beyond (at a higher virtual address and file offset than) the vma. */ static int can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, struct file *file, unsigned long vm_pgoff) { if (vma->vm_file == file && vma->vm_flags == vm_flags) { unsigned long vma_size; if (!file) return 1; /* anon mapping */ vma_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; if (vma->vm_pgoff + vma_size == vm_pgoff) return 1; } return 0; } /* * Given a new mapping request (addr,end,vm_flags,file,pgoff), figure out * whether that can be merged with its predecessor or its successor. Or * both (it neatly fills a hole). */ static int vma_merge(struct mm_struct *mm, struct vm_area_struct *prev, struct rb_node *rb_parent, unsigned long addr, unsigned long end, unsigned long vm_flags, struct file *file, unsigned long pgoff) { spinlock_t * lock = &mm->page_table_lock; if (!prev) { prev = rb_entry(rb_parent, struct vm_area_struct, vm_rb); goto merge_next; } /* * Can it merge with the predecessor? */ if (prev->vm_end == addr && can_vma_merge_after(prev, vm_flags, file, pgoff)) { struct vm_area_struct *next; struct inode *inode = file ? file->f_dentry->d_inode : NULL; int need_up = 0; if (unlikely(file && prev->vm_next && prev->vm_next->vm_file == file)) { down(&inode->i_mapping->i_shared_sem); need_up = 1; } spin_lock(lock); prev->vm_end = end; /* * OK, it did. Can we now merge in the successor as well? */ next = prev->vm_next; if (next && prev->vm_end == next->vm_start && can_vma_merge_before(next, vm_flags, file, pgoff, (end - addr) >> PAGE_SHIFT)) { prev->vm_end = next->vm_end; __vma_unlink(mm, next, prev); __remove_shared_vm_struct(next, inode); spin_unlock(lock); if (need_up) up(&inode->i_mapping->i_shared_sem); mm->map_count--; kmem_cache_free(vm_area_cachep, next); return 1; } spin_unlock(lock); if (need_up) up(&inode->i_mapping->i_shared_sem); return 1; } /* * Can this new request be merged in front of prev->vm_next? */ prev = prev->vm_next; if (prev) { merge_next: if (!can_vma_merge_before(prev, vm_flags, file, pgoff, (end - addr) >> PAGE_SHIFT)) return 0; if (end == prev->vm_start) { spin_lock(lock); prev->vm_start = addr; prev->vm_pgoff -= (end - addr) >> PAGE_SHIFT; spin_unlock(lock); return 1; } } return 0; } /* * The caller must hold down_write(current->mm->mmap_sem). */ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long pgoff) { struct mm_struct * mm = current->mm; struct vm_area_struct * vma, * prev; struct inode *inode; unsigned int vm_flags; int correct_wcount = 0; int error; struct rb_node ** rb_link, * rb_parent; unsigned long charged = 0; if (file && (!file->f_op || !file->f_op->mmap)) return -ENODEV; if (!len) return addr; if (len > TASK_SIZE) return -EINVAL; len = PAGE_ALIGN(len); /* offset overflow? */ if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) return -EINVAL; /* Too many mappings? */ if (mm->map_count > MAX_MAP_COUNT) return -ENOMEM; /* Obtain the address to map to. we verify (or select) it and ensure * that it represents a valid section of the address space. */ addr = get_unmapped_area(file, addr, len, pgoff, flags); if (addr & ~PAGE_MASK) return addr; /* Do simple checking here so the lower-level routines won't have * to. we assume access permissions have been handled by the open * of the memory object, so we don't do any here. */ vm_flags = calc_vm_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; if (flags & MAP_LOCKED) { if (!capable(CAP_IPC_LOCK)) return -EPERM; vm_flags |= VM_LOCKED; } /* mlock MCL_FUTURE? */ if (vm_flags & VM_LOCKED) { unsigned long locked = mm->locked_vm << PAGE_SHIFT; locked += len; if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur) return -EAGAIN; } inode = file ? file->f_dentry->d_inode : NULL; if (file) { switch (flags & MAP_TYPE) { case MAP_SHARED: if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) return -EACCES; /* * Make sure we don't allow writing to an append-only * file.. */ if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) return -EACCES; /* * Make sure there are no mandatory locks on the file. */ if (locks_verify_locked(inode)) return -EAGAIN; vm_flags |= VM_SHARED | VM_MAYSHARE; if (!(file->f_mode & FMODE_WRITE)) vm_flags &= ~(VM_MAYWRITE | VM_SHARED); /* fall through */ case MAP_PRIVATE: if (!(file->f_mode & FMODE_READ)) return -EACCES; break; default: return -EINVAL; } } else { vm_flags |= VM_SHARED | VM_MAYSHARE; switch (flags & MAP_TYPE) { default: return -EINVAL; case MAP_PRIVATE: vm_flags &= ~(VM_SHARED | VM_MAYSHARE); /* fall through */ case MAP_SHARED: break; } } error = security_file_mmap(file, prot, flags); if (error) return error; /* Clear old maps */ error = -ENOMEM; munmap_back: vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); if (vma && vma->vm_start < addr + len) { if (do_munmap(mm, addr, len)) return -ENOMEM; goto munmap_back; } /* Check against address space limit. */ if ((mm->total_vm << PAGE_SHIFT) + len > current->rlim[RLIMIT_AS].rlim_cur) return -ENOMEM; if (!(flags & MAP_NORESERVE) || sysctl_overcommit_memory > 1) { if (vm_flags & VM_SHARED) { /* Check memory availability in shmem_file_setup? */ vm_flags |= VM_ACCOUNT; } else if (vm_flags & VM_WRITE) { /* * Private writable mapping: check memory availability */ charged = len >> PAGE_SHIFT; if (!vm_enough_memory(charged)) return -ENOMEM; vm_flags |= VM_ACCOUNT; } } /* Can we just expand an old anonymous mapping? */ if (!file && !(vm_flags & VM_SHARED) && rb_parent) if (vma_merge(mm, prev, rb_parent, addr, addr + len, vm_flags, NULL, 0)) goto out; /* * Determine the object being mapped and call the appropriate * specific mapper. the address has already been validated, but * not unmapped, but the maps are removed from the list. */ vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); error = -ENOMEM; if (!vma) goto unacct_error; vma->vm_mm = mm; vma->vm_start = addr; vma->vm_end = addr + len; vma->vm_flags = vm_flags; vma->vm_page_prot = protection_map[vm_flags & 0x0f]; vma->vm_ops = NULL; vma->vm_pgoff = pgoff; vma->vm_file = NULL; vma->vm_private_data = NULL; INIT_LIST_HEAD(&vma->shared); if (file) { error = -EINVAL; if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) goto free_vma; if (vm_flags & VM_DENYWRITE) { error = deny_write_access(file); if (error) goto free_vma; correct_wcount = 1; } vma->vm_file = file; get_file(file); error = file->f_op->mmap(file, vma); if (error) goto unmap_and_free_vma; } else if (vm_flags & VM_SHARED) { error = shmem_zero_setup(vma); if (error) goto free_vma; } /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) * that memory reservation must be checked; but that reservation * belongs to shared memory object, not to vma: so now clear it. */ if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) vma->vm_flags &= ~VM_ACCOUNT; /* Can addr have changed?? * * Answer: Yes, several device drivers can do it in their * f_op->mmap method. -DaveM */ addr = vma->vm_start; if (!file || !rb_parent || !vma_merge(mm, prev, rb_parent, addr, addr + len, vma->vm_flags, file, pgoff)) { vma_link(mm, vma, prev, rb_link, rb_parent); if (correct_wcount) atomic_inc(&inode->i_writecount); } else { if (file) { if (correct_wcount) atomic_inc(&inode->i_writecount); fput(file); } kmem_cache_free(vm_area_cachep, vma); } out: mm->total_vm += len >> PAGE_SHIFT; if (vm_flags & VM_LOCKED) { mm->locked_vm += len >> PAGE_SHIFT; make_pages_present(addr, addr + len); } if (flags & MAP_POPULATE) { up_write(&mm->mmap_sem); sys_remap_file_pages(addr, len, prot, pgoff, flags & MAP_NONBLOCK); down_write(&mm->mmap_sem); } return addr; unmap_and_free_vma: if (correct_wcount) atomic_inc(&inode->i_writecount); vma->vm_file = NULL; fput(file); /* Undo any partial mapping done by a device driver. */ zap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start); free_vma: kmem_cache_free(vm_area_cachep, vma); unacct_error: if (charged) vm_unacct_memory(charged); return error; } /* Get an address range which is currently unmapped. * For shmat() with addr=0. * * Ugly calling convention alert: * Return value with the low bits set means error value, * ie * if (ret & ~PAGE_MASK) * error = ret; * * This function "knows" that -ENOMEM has the bits set. */ #ifndef HAVE_ARCH_UNMAPPED_AREA static inline unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; int found_hole = 0; if (len > TASK_SIZE) return -ENOMEM; if (addr) { addr = PAGE_ALIGN(addr); vma = find_vma(mm, addr); if (TASK_SIZE - len >= addr && (!vma || addr + len <= vma->vm_start)) return addr; } addr = mm->free_area_cache; for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { /* At this point: (!vma || addr < vma->vm_end). */ if (TASK_SIZE - len < addr) return -ENOMEM; /* * Record the first available hole. */ if (!found_hole && (!vma || addr < vma->vm_start)) { mm->free_area_cache = addr; found_hole = 1; } if (!vma || addr + len <= vma->vm_start) return addr; addr = vma->vm_end; } } #else extern unsigned long arch_get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); #endif unsigned long get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { if (flags & MAP_FIXED) { unsigned long ret; if (addr > TASK_SIZE - len) return -ENOMEM; if (addr & ~PAGE_MASK) return -EINVAL; if (file && is_file_hugepages(file)) /* If the request is for hugepages, then make sure that addr * and length is properly aligned. */ ret = is_aligned_hugepage_range(addr, len); else /* * Make sure that a normal request is not falling * in reserved hugepage range. For some archs like IA-64, * there is seperate region for hugepages. */ ret = is_invalid_hugepage_range(addr, len); if (ret) return ret; return addr; } if (file && file->f_op && file->f_op->get_unmapped_area) return file->f_op->get_unmapped_area(file, addr, len, pgoff, flags); return arch_get_unmapped_area(file, addr, len, pgoff, flags); } /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) { struct vm_area_struct *vma = NULL; if (mm) { /* Check the cache first. */ /* (Cache hit rate is typically around 35%.) */ vma = mm->mmap_cache; if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { struct rb_node * rb_node; rb_node = mm->mm_rb.rb_node; vma = NULL; while (rb_node) { struct vm_area_struct * vma_tmp; vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); if (vma_tmp->vm_end > addr) { vma = vma_tmp; if (vma_tmp->vm_start <= addr) break; rb_node = rb_node->rb_left; } else rb_node = rb_node->rb_right; } if (vma) mm->mmap_cache = vma; } } return vma; } /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ struct vm_area_struct * find_vma_prev(struct mm_struct *mm, unsigned long addr, struct vm_area_struct **pprev) { struct vm_area_struct *vma = NULL, *prev = NULL; struct rb_node * rb_node; if (!mm) goto out; /* Guard against addr being lower than the first VMA */ vma = mm->mmap; /* Go through the RB tree quickly. */ rb_node = mm->mm_rb.rb_node; while (rb_node) { struct vm_area_struct *vma_tmp; vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); if (addr < vma_tmp->vm_end) { rb_node = rb_node->rb_left; } else { prev = vma_tmp; if (!prev->vm_next || (addr < prev->vm_next->vm_end)) break; rb_node = rb_node->rb_right; } } out: *pprev = prev; return prev ? prev->vm_next : vma; } #ifdef CONFIG_STACK_GROWSUP /* * vma is the first one with address > vma->vm_end. Have to extend vma. */ int expand_stack(struct vm_area_struct * vma, unsigned long address) { unsigned long grow; if (!(vma->vm_flags & VM_GROWSUP)) return -EFAULT; /* * vma->vm_start/vm_end cannot change under us because the caller * is required to hold the mmap_sem in read mode. We need to get * the spinlock only before relocating the vma range ourself. */ address += 4 + PAGE_SIZE - 1; address &= PAGE_MASK; spin_lock(&vma->vm_mm->page_table_lock); grow = (address - vma->vm_end) >> PAGE_SHIFT; /* Overcommit.. */ if (!vm_enough_memory(grow)) { spin_unlock(&vma->vm_mm->page_table_lock); return -ENOMEM; } if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur || ((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur) { spin_unlock(&vma->vm_mm->page_table_lock); vm_unacct_memory(grow); return -ENOMEM; } vma->vm_end = address; vma->vm_mm->total_vm += grow; if (vma->vm_flags & VM_LOCKED) vma->vm_mm->locked_vm += grow; spin_unlock(&vma->vm_mm->page_table_lock); return 0; } struct vm_area_struct * find_extend_vma(struct mm_struct *mm, unsigned long addr) { struct vm_area_struct *vma, *prev; addr &= PAGE_MASK; vma = find_vma_prev(mm, addr, &prev); if (vma && (vma->vm_start <= addr)) return vma; if (!prev || expand_stack(prev, addr)) return NULL; if (prev->vm_flags & VM_LOCKED) { make_pages_present(addr, prev->vm_end); } return prev; } #else /* * vma is the first one with address < vma->vm_start. Have to extend vma. */ int expand_stack(struct vm_area_struct *vma, unsigned long address) { unsigned long grow; /* * vma->vm_start/vm_end cannot change under us because the caller * is required to hold the mmap_sem in read mode. We need to get * the spinlock only before relocating the vma range ourself. */ address &= PAGE_MASK; spin_lock(&vma->vm_mm->page_table_lock); grow = (vma->vm_start - address) >> PAGE_SHIFT; /* Overcommit.. */ if (!vm_enough_memory(grow)) { spin_unlock(&vma->vm_mm->page_table_lock); return -ENOMEM; } if (vma->vm_end - address > current->rlim[RLIMIT_STACK].rlim_cur || ((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur) { spin_unlock(&vma->vm_mm->page_table_lock); vm_unacct_memory(grow); return -ENOMEM; } vma->vm_start = address; vma->vm_pgoff -= grow; vma->vm_mm->total_vm += grow; if (vma->vm_flags & VM_LOCKED) vma->vm_mm->locked_vm += grow; spin_unlock(&vma->vm_mm->page_table_lock); return 0; } struct vm_area_struct * find_extend_vma(struct mm_struct * mm, unsigned long addr) { struct vm_area_struct * vma; unsigned long start; addr &= PAGE_MASK; vma = find_vma(mm,addr); if (!vma) return NULL; if (vma->vm_start <= addr) return vma; if (!(vma->vm_flags & VM_GROWSDOWN)) return NULL; start = vma->vm_start; if (expand_stack(vma, addr)) return NULL; if (vma->vm_flags & VM_LOCKED) { make_pages_present(addr, start); } return vma; } #endif /* * Try to free as many page directory entries as we can, * without having to work very hard at actually scanning * the page tables themselves. * * Right now we try to free page tables if we have a nice * PGDIR-aligned area that got free'd up. We could be more * granular if we want to, but this is fast and simple, * and covers the bad cases. * * "prev", if it exists, points to a vma before the one * we just free'd - but there's no telling how much before. */ static void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev, unsigned long start, unsigned long end) { unsigned long first = start & PGDIR_MASK; unsigned long last = end + PGDIR_SIZE - 1; unsigned long start_index, end_index; struct mm_struct *mm = tlb->mm; if (!prev) { prev = mm->mmap; if (!prev) goto no_mmaps; if (prev->vm_end > start) { if (last > prev->vm_start) last = prev->vm_start; goto no_mmaps; } } for (;;) { struct vm_area_struct *next = prev->vm_next; if (next) { if (next->vm_start < start) { prev = next; continue; } if (last > next->vm_start) last = next->vm_start; } if (prev->vm_end > first) first = prev->vm_end + PGDIR_SIZE - 1; break; } no_mmaps: if (last < first) /* for arches with discontiguous pgd indices */ return; /* * If the PGD bits are not consecutive in the virtual address, the * old method of shifting the VA >> by PGDIR_SHIFT doesn't work. */ start_index = pgd_index(first); if (start_index < FIRST_USER_PGD_NR) start_index = FIRST_USER_PGD_NR; end_index = pgd_index(last); if (end_index > start_index) { clear_page_tables(tlb, start_index, end_index - start_index); flush_tlb_pgtables(mm, first & PGDIR_MASK, last & PGDIR_MASK); } } /* Normal function to fix up a mapping * This function is the default for when an area has no specific * function. This may be used as part of a more specific routine. * * By the time this function is called, the area struct has been * removed from the process mapping list. */ static void unmap_vma(struct mm_struct *mm, struct vm_area_struct *area) { size_t len = area->vm_end - area->vm_start; area->vm_mm->total_vm -= len >> PAGE_SHIFT; if (area->vm_flags & VM_LOCKED) area->vm_mm->locked_vm -= len >> PAGE_SHIFT; /* * Is this a new hole at the lowest possible address? */ if (area->vm_start >= TASK_UNMAPPED_BASE && area->vm_start < area->vm_mm->free_area_cache) area->vm_mm->free_area_cache = area->vm_start; remove_shared_vm_struct(area); if (area->vm_ops && area->vm_ops->close) area->vm_ops->close(area); if (area->vm_file) fput(area->vm_file); kmem_cache_free(vm_area_cachep, area); } /* * Update the VMA and inode share lists. * * Ok - we have the memory areas we should free on the 'free' list, * so release them, and do the vma updates. */ static void unmap_vma_list(struct mm_struct *mm, struct vm_area_struct *mpnt) { do { struct vm_area_struct *next = mpnt->vm_next; unmap_vma(mm, mpnt); mpnt = next; } while (mpnt != NULL); validate_mm(mm); } /* * Get rid of page table information in the indicated region. * * Called with the page table lock held. */ static void unmap_region(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, unsigned long start, unsigned long end) { struct mmu_gather *tlb; unsigned long nr_accounted = 0; lru_add_drain(); tlb = tlb_gather_mmu(mm, 0); unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted); vm_unacct_memory(nr_accounted); free_pgtables(tlb, prev, start, end); tlb_finish_mmu(tlb, start, end); } /* * Create a list of vma's touched by the unmap, removing them from the mm's * vma list as we go.. * * Called with the page_table_lock held. */ static void detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, unsigned long end) { struct vm_area_struct **insertion_point; struct vm_area_struct *tail_vma = NULL; insertion_point = (prev ? &prev->vm_next : &mm->mmap); do { rb_erase(&vma->vm_rb, &mm->mm_rb); mm->map_count--; tail_vma = vma; vma = vma->vm_next; } while (vma && vma->vm_start < end); *insertion_point = vma; tail_vma->vm_next = NULL; mm->mmap_cache = NULL; /* Kill the cache. */ } /* * Split a vma into two pieces at address 'addr', a new vma is allocated * either for the first part or the the tail. */ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, unsigned long addr, int new_below) { struct vm_area_struct *new; if (mm->map_count >= MAX_MAP_COUNT) return -ENOMEM; new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); if (!new) return -ENOMEM; /* most fields are the same, copy all, and then fixup */ *new = *vma; INIT_LIST_HEAD(&new->shared); if (new_below) { new->vm_end = addr; vma->vm_start = addr; vma->vm_pgoff += ((addr - new->vm_start) >> PAGE_SHIFT); } else { vma->vm_end = addr; new->vm_start = addr; new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); } if (new->vm_file) get_file(new->vm_file); if (new->vm_ops && new->vm_ops->open) new->vm_ops->open(new); insert_vm_struct(mm, new); return 0; } /* Munmap is split into 2 main parts -- this part which finds * what needs doing, and the areas themselves, which do the * work. This now handles partial unmappings. * Jeremy Fitzhardinge <jeremy@goop.org> */ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) { unsigned long end; struct vm_area_struct *mpnt, *prev, *last; if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) return -EINVAL; if ((len = PAGE_ALIGN(len)) == 0) return -EINVAL; /* Find the first overlapping VMA */ mpnt = find_vma_prev(mm, start, &prev); if (!mpnt) return 0; /* we have start < mpnt->vm_end */ if (is_vm_hugetlb_page(mpnt)) { if ((start & ~HPAGE_MASK) || (len & ~HPAGE_MASK)) return -EINVAL; } /* if it doesn't overlap, we have nothing.. */ end = start + len; if (mpnt->vm_start >= end) return 0; /* Something will probably happen, so notify. */ if (mpnt->vm_file && (mpnt->vm_flags & VM_EXEC)) profile_exec_unmap(mm); /* * If we need to split any vma, do it now to save pain later. */ if (start > mpnt->vm_start) { if (split_vma(mm, mpnt, start, 0)) return -ENOMEM; prev = mpnt; mpnt = mpnt->vm_next; } /* Does it split the last one? */ last = find_vma(mm, end); if (last && end > last->vm_start) { if (split_vma(mm, last, end, 0)) return -ENOMEM; } /* * Remove the vma's, and unmap the actual pages */ spin_lock(&mm->page_table_lock); detach_vmas_to_be_unmapped(mm, mpnt, prev, end); unmap_region(mm, mpnt, prev, start, end); spin_unlock(&mm->page_table_lock); /* Fix up all other VM information */ unmap_vma_list(mm, mpnt); return 0; } asmlinkage long sys_munmap(unsigned long addr, size_t len) { int ret; struct mm_struct *mm = current->mm; down_write(&mm->mmap_sem); ret = do_munmap(mm, addr, len); up_write(&mm->mmap_sem); return ret; } /* * this is really a simplified "do_mmap". it only handles * anonymous maps. eventually we may be able to do some * brk-specific accounting here. */ unsigned long do_brk(unsigned long addr, unsigned long len) { struct mm_struct * mm = current->mm; struct vm_area_struct * vma, * prev; unsigned long flags; struct rb_node ** rb_link, * rb_parent; len = PAGE_ALIGN(len); if (!len) return addr; /* * mlock MCL_FUTURE? */ if (mm->def_flags & VM_LOCKED) { unsigned long locked = mm->locked_vm << PAGE_SHIFT; locked += len; if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur) return -EAGAIN; } /* * Clear old maps. this also does some error checking for us */ munmap_back: vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); if (vma && vma->vm_start < addr + len) { if (do_munmap(mm, addr, len)) return -ENOMEM; goto munmap_back; } /* Check against address space limits *after* clearing old maps... */ if ((mm->total_vm << PAGE_SHIFT) + len > current->rlim[RLIMIT_AS].rlim_cur) return -ENOMEM; if (mm->map_count > MAX_MAP_COUNT) return -ENOMEM; if (!vm_enough_memory(len >> PAGE_SHIFT)) return -ENOMEM; flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; /* Can we just expand an old anonymous mapping? */ if (rb_parent && vma_merge(mm, prev, rb_parent, addr, addr + len, flags, NULL, 0)) goto out; /* * create a vma struct for an anonymous mapping */ vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); if (!vma) { vm_unacct_memory(len >> PAGE_SHIFT); return -ENOMEM; } vma->vm_mm = mm; vma->vm_start = addr; vma->vm_end = addr + len; vma->vm_flags = flags; vma->vm_page_prot = protection_map[flags & 0x0f]; vma->vm_ops = NULL; vma->vm_pgoff = 0; vma->vm_file = NULL; vma->vm_private_data = NULL; INIT_LIST_HEAD(&vma->shared); vma_link(mm, vma, prev, rb_link, rb_parent); out: mm->total_vm += len >> PAGE_SHIFT; if (flags & VM_LOCKED) { mm->locked_vm += len >> PAGE_SHIFT; make_pages_present(addr, addr + len); } return addr; } /* Build the RB tree corresponding to the VMA list. */ void build_mmap_rb(struct mm_struct * mm) { struct vm_area_struct * vma; struct rb_node ** rb_link, * rb_parent; mm->mm_rb = RB_ROOT; rb_link = &mm->mm_rb.rb_node; rb_parent = NULL; for (vma = mm->mmap; vma; vma = vma->vm_next) { __vma_link_rb(mm, vma, rb_link, rb_parent); rb_parent = &vma->vm_rb; rb_link = &rb_parent->rb_right; } } /* Release all mmaps. */ void exit_mmap(struct mm_struct *mm) { struct mmu_gather *tlb; struct vm_area_struct *vma; unsigned long nr_accounted = 0; profile_exit_mmap(mm); lru_add_drain(); spin_lock(&mm->page_table_lock); tlb = tlb_gather_mmu(mm, 1); flush_cache_mm(mm); /* Use ~0UL here to ensure all VMAs in the mm are unmapped */ mm->map_count -= unmap_vmas(&tlb, mm, mm->mmap, 0, ~0UL, &nr_accounted); vm_unacct_memory(nr_accounted); BUG_ON(mm->map_count); /* This is just debugging */ clear_page_tables(tlb, FIRST_USER_PGD_NR, USER_PTRS_PER_PGD); tlb_finish_mmu(tlb, 0, TASK_SIZE); vma = mm->mmap; mm->mmap = mm->mmap_cache = NULL; mm->mm_rb = RB_ROOT; mm->rss = 0; mm->total_vm = 0; mm->locked_vm = 0; spin_unlock(&mm->page_table_lock); /* * Walk the list again, actually closing and freeing it * without holding any MM locks. */ while (vma) { struct vm_area_struct *next = vma->vm_next; remove_shared_vm_struct(vma); if (vma->vm_ops) { if (vma->vm_ops->close) vma->vm_ops->close(vma); } if (vma->vm_file) fput(vma->vm_file); kmem_cache_free(vm_area_cachep, vma); vma = next; } } /* Insert vm structure into process list sorted by address * and into the inode's i_mmap ring. If vm_file is non-NULL * then i_shared_sem is taken here. */ void insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) { struct vm_area_struct * __vma, * prev; struct rb_node ** rb_link, * rb_parent; __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); if (__vma && __vma->vm_start < vma->vm_end) BUG(); vma_link(mm, vma, prev, rb_link, rb_parent); validate_mm(mm); }