| /* |
| * mm/mmap.c |
| * |
| * Written by obz. |
| * |
| * Address space accounting code <alan@redhat.com> |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/backing-dev.h> |
| #include <linux/mm.h> |
| #include <linux/shm.h> |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/swap.h> |
| #include <linux/syscalls.h> |
| #include <linux/capability.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 <linux/module.h> |
| #include <linux/mount.h> |
| #include <linux/mempolicy.h> |
| #include <linux/rmap.h> |
| #include <linux/mmu_notifier.h> |
| |
| #include <asm/uaccess.h> |
| #include <asm/cacheflush.h> |
| #include <asm/tlb.h> |
| #include <asm/mmu_context.h> |
| |
| #include "internal.h" |
| |
| #ifndef arch_mmap_check |
| #define arch_mmap_check(addr, len, flags) (0) |
| #endif |
| |
| #ifndef arch_rebalance_pgtables |
| #define arch_rebalance_pgtables(addr, len) (addr) |
| #endif |
| |
| static void unmap_region(struct mm_struct *mm, |
| struct vm_area_struct *vma, struct vm_area_struct *prev, |
| unsigned long start, unsigned long end); |
| |
| /* |
| * 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 |
| }; |
| |
| pgprot_t vm_get_page_prot(unsigned long vm_flags) |
| { |
| return __pgprot(pgprot_val(protection_map[vm_flags & |
| (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | |
| pgprot_val(arch_vm_get_page_prot(vm_flags))); |
| } |
| EXPORT_SYMBOL(vm_get_page_prot); |
| |
| int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ |
| int sysctl_overcommit_ratio = 50; /* default is 50% */ |
| int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; |
| atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0); |
| |
| /* |
| * Check that a process has enough memory to allocate a new virtual |
| * mapping. 0 means there is enough memory for the allocation to |
| * succeed and -ENOMEM implies there is not. |
| * |
| * We currently support three overcommit policies, which are set via the |
| * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting |
| * |
| * Strict overcommit modes added 2002 Feb 26 by Alan Cox. |
| * Additional code 2002 Jul 20 by Robert Love. |
| * |
| * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. |
| * |
| * Note this is a helper function intended to be used by LSMs which |
| * wish to use this logic. |
| */ |
| int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) |
| { |
| unsigned long free, allowed; |
| |
| vm_acct_memory(pages); |
| |
| /* |
| * Sometimes we want to use more memory than we have |
| */ |
| if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) |
| return 0; |
| |
| if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { |
| unsigned long n; |
| |
| free = global_page_state(NR_FILE_PAGES); |
| free += nr_swap_pages; |
| |
| /* |
| * Any slabs which are created with the |
| * SLAB_RECLAIM_ACCOUNT flag claim to have contents |
| * which are reclaimable, under pressure. The dentry |
| * cache and most inode caches should fall into this |
| */ |
| free += global_page_state(NR_SLAB_RECLAIMABLE); |
| |
| /* |
| * Leave the last 3% for root |
| */ |
| if (!cap_sys_admin) |
| free -= free / 32; |
| |
| if (free > pages) |
| return 0; |
| |
| /* |
| * nr_free_pages() is very expensive on large systems, |
| * only call if we're about to fail. |
| */ |
| n = nr_free_pages(); |
| |
| /* |
| * Leave reserved pages. The pages are not for anonymous pages. |
| */ |
| if (n <= totalreserve_pages) |
| goto error; |
| else |
| n -= totalreserve_pages; |
| |
| /* |
| * Leave the last 3% for root |
| */ |
| if (!cap_sys_admin) |
| n -= n / 32; |
| free += n; |
| |
| if (free > pages) |
| return 0; |
| |
| goto error; |
| } |
| |
| allowed = (totalram_pages - hugetlb_total_pages()) |
| * sysctl_overcommit_ratio / 100; |
| /* |
| * Leave the last 3% for root |
| */ |
| if (!cap_sys_admin) |
| allowed -= allowed / 32; |
| allowed += total_swap_pages; |
| |
| /* Don't let a single process grow too big: |
| leave 3% of the size of this process for other processes */ |
| allowed -= mm->total_vm / 32; |
| |
| /* |
| * cast `allowed' as a signed long because vm_committed_space |
| * sometimes has a negative value |
| */ |
| if (atomic_long_read(&vm_committed_space) < (long)allowed) |
| return 0; |
| error: |
| vm_unacct_memory(pages); |
| |
| return -ENOMEM; |
| } |
| |
| /* |
| * Requires inode->i_mapping->i_mmap_lock |
| */ |
| static void __remove_shared_vm_struct(struct vm_area_struct *vma, |
| struct file *file, struct address_space *mapping) |
| { |
| if (vma->vm_flags & VM_DENYWRITE) |
| atomic_inc(&file->f_path.dentry->d_inode->i_writecount); |
| if (vma->vm_flags & VM_SHARED) |
| mapping->i_mmap_writable--; |
| |
| flush_dcache_mmap_lock(mapping); |
| if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
| list_del_init(&vma->shared.vm_set.list); |
| else |
| vma_prio_tree_remove(vma, &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| |
| /* |
| * Unlink a file-based vm structure from its prio_tree, to hide |
| * vma from rmap and vmtruncate before freeing its page tables. |
| */ |
| void unlink_file_vma(struct vm_area_struct *vma) |
| { |
| struct file *file = vma->vm_file; |
| |
| if (file) { |
| struct address_space *mapping = file->f_mapping; |
| spin_lock(&mapping->i_mmap_lock); |
| __remove_shared_vm_struct(vma, file, mapping); |
| spin_unlock(&mapping->i_mmap_lock); |
| } |
| } |
| |
| /* |
| * Close a vm structure and free it, returning the next. |
| */ |
| static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) |
| { |
| struct vm_area_struct *next = vma->vm_next; |
| |
| might_sleep(); |
| if (vma->vm_ops && vma->vm_ops->close) |
| vma->vm_ops->close(vma); |
| if (vma->vm_file) { |
| fput(vma->vm_file); |
| if (vma->vm_flags & VM_EXECUTABLE) |
| removed_exe_file_vma(vma->vm_mm); |
| } |
| mpol_put(vma_policy(vma)); |
| kmem_cache_free(vm_area_cachep, vma); |
| return next; |
| } |
| |
| asmlinkage unsigned long sys_brk(unsigned long brk) |
| { |
| unsigned long rlim, retval; |
| unsigned long newbrk, oldbrk; |
| struct mm_struct *mm = current->mm; |
| unsigned long min_brk; |
| |
| down_write(&mm->mmap_sem); |
| |
| #ifdef CONFIG_COMPAT_BRK |
| min_brk = mm->end_code; |
| #else |
| min_brk = mm->start_brk; |
| #endif |
| if (brk < min_brk) |
| goto out; |
| |
| /* |
| * Check against rlimit here. If this check is done later after the test |
| * of oldbrk with newbrk then it can escape the test and let the data |
| * segment grow beyond its set limit the in case where the limit is |
| * not page aligned -Ram Gupta |
| */ |
| rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; |
| if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + |
| (mm->end_data - mm->start_data) > rlim) |
| 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 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; |
| } |
| |
| #ifdef DEBUG_MM_RB |
| static int browse_rb(struct rb_root *root) |
| { |
| int i = 0, j; |
| struct rb_node *nd, *pn = NULL; |
| unsigned long prev = 0, pend = 0; |
| |
| for (nd = rb_first(root); nd; nd = rb_next(nd)) { |
| struct vm_area_struct *vma; |
| vma = rb_entry(nd, struct vm_area_struct, vm_rb); |
| if (vma->vm_start < prev) |
| printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; |
| if (vma->vm_start < pend) |
| printk("vm_start %lx pend %lx\n", vma->vm_start, pend); |
| if (vma->vm_start > vma->vm_end) |
| printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); |
| i++; |
| pn = nd; |
| prev = vma->vm_start; |
| pend = vma->vm_end; |
| } |
| j = 0; |
| for (nd = pn; nd; nd = rb_prev(nd)) { |
| j++; |
| } |
| if (i != j) |
| printk("backwards %d, forwards %d\n", j, i), i = 0; |
| return i; |
| } |
| |
| 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); |
| if (i != mm->map_count) |
| printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; |
| BUG_ON(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; |
| } |
| } |
| |
| 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 address_space *mapping = file->f_mapping; |
| |
| if (vma->vm_flags & VM_DENYWRITE) |
| atomic_dec(&file->f_path.dentry->d_inode->i_writecount); |
| if (vma->vm_flags & VM_SHARED) |
| mapping->i_mmap_writable++; |
| |
| flush_dcache_mmap_lock(mapping); |
| if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
| vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); |
| else |
| vma_prio_tree_insert(vma, &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| } |
| |
| 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); |
| __anon_vma_link(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_mapping; |
| |
| if (mapping) { |
| spin_lock(&mapping->i_mmap_lock); |
| vma->vm_truncate_count = mapping->truncate_count; |
| } |
| anon_vma_lock(vma); |
| |
| __vma_link(mm, vma, prev, rb_link, rb_parent); |
| __vma_link_file(vma); |
| |
| anon_vma_unlock(vma); |
| if (mapping) |
| spin_unlock(&mapping->i_mmap_lock); |
| |
| mm->map_count++; |
| validate_mm(mm); |
| } |
| |
| /* |
| * Helper for vma_adjust in the split_vma insert case: |
| * insert vm structure into list and rbtree and anon_vma, |
| * but it has already been inserted into prio_tree earlier. |
| */ |
| static 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); |
| BUG_ON(__vma && __vma->vm_start < vma->vm_end); |
| __vma_link(mm, vma, prev, rb_link, rb_parent); |
| mm->map_count++; |
| } |
| |
| static inline void |
| __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, |
| struct vm_area_struct *prev) |
| { |
| prev->vm_next = vma->vm_next; |
| rb_erase(&vma->vm_rb, &mm->mm_rb); |
| if (mm->mmap_cache == vma) |
| mm->mmap_cache = prev; |
| } |
| |
| /* |
| * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that |
| * is already present in an i_mmap tree without adjusting the tree. |
| * The following helper function should be used when such adjustments |
| * are necessary. The "insert" vma (if any) is to be inserted |
| * before we drop the necessary locks. |
| */ |
| void vma_adjust(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *next = vma->vm_next; |
| struct vm_area_struct *importer = NULL; |
| struct address_space *mapping = NULL; |
| struct prio_tree_root *root = NULL; |
| struct file *file = vma->vm_file; |
| struct anon_vma *anon_vma = NULL; |
| long adjust_next = 0; |
| int remove_next = 0; |
| |
| if (next && !insert) { |
| if (end >= next->vm_end) { |
| /* |
| * vma expands, overlapping all the next, and |
| * perhaps the one after too (mprotect case 6). |
| */ |
| again: remove_next = 1 + (end > next->vm_end); |
| end = next->vm_end; |
| anon_vma = next->anon_vma; |
| importer = vma; |
| } else if (end > next->vm_start) { |
| /* |
| * vma expands, overlapping part of the next: |
| * mprotect case 5 shifting the boundary up. |
| */ |
| adjust_next = (end - next->vm_start) >> PAGE_SHIFT; |
| anon_vma = next->anon_vma; |
| importer = vma; |
| } else if (end < vma->vm_end) { |
| /* |
| * vma shrinks, and !insert tells it's not |
| * split_vma inserting another: so it must be |
| * mprotect case 4 shifting the boundary down. |
| */ |
| adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); |
| anon_vma = next->anon_vma; |
| importer = next; |
| } |
| } |
| |
| if (file) { |
| mapping = file->f_mapping; |
| if (!(vma->vm_flags & VM_NONLINEAR)) |
| root = &mapping->i_mmap; |
| spin_lock(&mapping->i_mmap_lock); |
| if (importer && |
| vma->vm_truncate_count != next->vm_truncate_count) { |
| /* |
| * unmap_mapping_range might be in progress: |
| * ensure that the expanding vma is rescanned. |
| */ |
| importer->vm_truncate_count = 0; |
| } |
| if (insert) { |
| insert->vm_truncate_count = vma->vm_truncate_count; |
| /* |
| * Put into prio_tree now, so instantiated pages |
| * are visible to arm/parisc __flush_dcache_page |
| * throughout; but we cannot insert into address |
| * space until vma start or end is updated. |
| */ |
| __vma_link_file(insert); |
| } |
| } |
| |
| /* |
| * When changing only vma->vm_end, we don't really need |
| * anon_vma lock: but is that case worth optimizing out? |
| */ |
| if (vma->anon_vma) |
| anon_vma = vma->anon_vma; |
| if (anon_vma) { |
| spin_lock(&anon_vma->lock); |
| /* |
| * Easily overlooked: when mprotect shifts the boundary, |
| * make sure the expanding vma has anon_vma set if the |
| * shrinking vma had, to cover any anon pages imported. |
| */ |
| if (importer && !importer->anon_vma) { |
| importer->anon_vma = anon_vma; |
| __anon_vma_link(importer); |
| } |
| } |
| |
| if (root) { |
| flush_dcache_mmap_lock(mapping); |
| vma_prio_tree_remove(vma, root); |
| if (adjust_next) |
| vma_prio_tree_remove(next, root); |
| } |
| |
| vma->vm_start = start; |
| vma->vm_end = end; |
| vma->vm_pgoff = pgoff; |
| if (adjust_next) { |
| next->vm_start += adjust_next << PAGE_SHIFT; |
| next->vm_pgoff += adjust_next; |
| } |
| |
| if (root) { |
| if (adjust_next) |
| vma_prio_tree_insert(next, root); |
| vma_prio_tree_insert(vma, root); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| |
| if (remove_next) { |
| /* |
| * vma_merge has merged next into vma, and needs |
| * us to remove next before dropping the locks. |
| */ |
| __vma_unlink(mm, next, vma); |
| if (file) |
| __remove_shared_vm_struct(next, file, mapping); |
| if (next->anon_vma) |
| __anon_vma_merge(vma, next); |
| } else if (insert) { |
| /* |
| * split_vma has split insert from vma, and needs |
| * us to insert it before dropping the locks |
| * (it may either follow vma or precede it). |
| */ |
| __insert_vm_struct(mm, insert); |
| } |
| |
| if (anon_vma) |
| spin_unlock(&anon_vma->lock); |
| if (mapping) |
| spin_unlock(&mapping->i_mmap_lock); |
| |
| if (remove_next) { |
| if (file) { |
| fput(file); |
| if (next->vm_flags & VM_EXECUTABLE) |
| removed_exe_file_vma(mm); |
| } |
| mm->map_count--; |
| mpol_put(vma_policy(next)); |
| kmem_cache_free(vm_area_cachep, next); |
| /* |
| * In mprotect's case 6 (see comments on vma_merge), |
| * we must remove another next too. It would clutter |
| * up the code too much to do both in one go. |
| */ |
| if (remove_next == 2) { |
| next = vma->vm_next; |
| goto again; |
| } |
| } |
| |
| validate_mm(mm); |
| } |
| |
| /* |
| * If the vma has a ->close operation then the driver probably needs to release |
| * per-vma resources, so we don't attempt to merge those. |
| */ |
| #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) |
| |
| static inline int is_mergeable_vma(struct vm_area_struct *vma, |
| struct file *file, unsigned long vm_flags) |
| { |
| if (vma->vm_flags != vm_flags) |
| return 0; |
| if (vma->vm_file != file) |
| return 0; |
| if (vma->vm_ops && vma->vm_ops->close) |
| return 0; |
| return 1; |
| } |
| |
| static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, |
| struct anon_vma *anon_vma2) |
| { |
| return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); |
| } |
| |
| /* |
| * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| * in front of (at a lower virtual address and file offset than) the vma. |
| * |
| * We cannot merge two vmas if they have differently assigned (non-NULL) |
| * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| * |
| * 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 anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags) && |
| is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { |
| if (vma->vm_pgoff == vm_pgoff) |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| * beyond (at a higher virtual address and file offset than) the vma. |
| * |
| * We cannot merge two vmas if they have differently assigned (non-NULL) |
| * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| */ |
| static int |
| can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, |
| struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags) && |
| is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { |
| pgoff_t vm_pglen; |
| vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; |
| if (vma->vm_pgoff + vm_pglen == vm_pgoff) |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * Given a 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). |
| * |
| * In most cases - when called for mmap, brk or mremap - [addr,end) is |
| * certain not to be mapped by the time vma_merge is called; but when |
| * called for mprotect, it is certain to be already mapped (either at |
| * an offset within prev, or at the start of next), and the flags of |
| * this area are about to be changed to vm_flags - and the no-change |
| * case has already been eliminated. |
| * |
| * The following mprotect cases have to be considered, where AAAA is |
| * the area passed down from mprotect_fixup, never extending beyond one |
| * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: |
| * |
| * AAAA AAAA AAAA AAAA |
| * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX |
| * cannot merge might become might become might become |
| * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or |
| * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or |
| * mremap move: PPPPNNNNNNNN 8 |
| * AAAA |
| * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN |
| * might become case 1 below case 2 below case 3 below |
| * |
| * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: |
| * mprotect_fixup updates vm_flags & vm_page_prot on successful return. |
| */ |
| struct vm_area_struct *vma_merge(struct mm_struct *mm, |
| struct vm_area_struct *prev, unsigned long addr, |
| unsigned long end, unsigned long vm_flags, |
| struct anon_vma *anon_vma, struct file *file, |
| pgoff_t pgoff, struct mempolicy *policy) |
| { |
| pgoff_t pglen = (end - addr) >> PAGE_SHIFT; |
| struct vm_area_struct *area, *next; |
| |
| /* |
| * We later require that vma->vm_flags == vm_flags, |
| * so this tests vma->vm_flags & VM_SPECIAL, too. |
| */ |
| if (vm_flags & VM_SPECIAL) |
| return NULL; |
| |
| if (prev) |
| next = prev->vm_next; |
| else |
| next = mm->mmap; |
| area = next; |
| if (next && next->vm_end == end) /* cases 6, 7, 8 */ |
| next = next->vm_next; |
| |
| /* |
| * Can it merge with the predecessor? |
| */ |
| if (prev && prev->vm_end == addr && |
| mpol_equal(vma_policy(prev), policy) && |
| can_vma_merge_after(prev, vm_flags, |
| anon_vma, file, pgoff)) { |
| /* |
| * OK, it can. Can we now merge in the successor as well? |
| */ |
| if (next && end == next->vm_start && |
| mpol_equal(policy, vma_policy(next)) && |
| can_vma_merge_before(next, vm_flags, |
| anon_vma, file, pgoff+pglen) && |
| is_mergeable_anon_vma(prev->anon_vma, |
| next->anon_vma)) { |
| /* cases 1, 6 */ |
| vma_adjust(prev, prev->vm_start, |
| next->vm_end, prev->vm_pgoff, NULL); |
| } else /* cases 2, 5, 7 */ |
| vma_adjust(prev, prev->vm_start, |
| end, prev->vm_pgoff, NULL); |
| return prev; |
| } |
| |
| /* |
| * Can this new request be merged in front of next? |
| */ |
| if (next && end == next->vm_start && |
| mpol_equal(policy, vma_policy(next)) && |
| can_vma_merge_before(next, vm_flags, |
| anon_vma, file, pgoff+pglen)) { |
| if (prev && addr < prev->vm_end) /* case 4 */ |
| vma_adjust(prev, prev->vm_start, |
| addr, prev->vm_pgoff, NULL); |
| else /* cases 3, 8 */ |
| vma_adjust(area, addr, next->vm_end, |
| next->vm_pgoff - pglen, NULL); |
| return area; |
| } |
| |
| return NULL; |
| } |
| |
| /* |
| * find_mergeable_anon_vma is used by anon_vma_prepare, to check |
| * neighbouring vmas for a suitable anon_vma, before it goes off |
| * to allocate a new anon_vma. It checks because a repetitive |
| * sequence of mprotects and faults may otherwise lead to distinct |
| * anon_vmas being allocated, preventing vma merge in subsequent |
| * mprotect. |
| */ |
| struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) |
| { |
| struct vm_area_struct *near; |
| unsigned long vm_flags; |
| |
| near = vma->vm_next; |
| if (!near) |
| goto try_prev; |
| |
| /* |
| * Since only mprotect tries to remerge vmas, match flags |
| * which might be mprotected into each other later on. |
| * Neither mlock nor madvise tries to remerge at present, |
| * so leave their flags as obstructing a merge. |
| */ |
| vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); |
| vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); |
| |
| if (near->anon_vma && vma->vm_end == near->vm_start && |
| mpol_equal(vma_policy(vma), vma_policy(near)) && |
| can_vma_merge_before(near, vm_flags, |
| NULL, vma->vm_file, vma->vm_pgoff + |
| ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) |
| return near->anon_vma; |
| try_prev: |
| /* |
| * It is potentially slow to have to call find_vma_prev here. |
| * But it's only on the first write fault on the vma, not |
| * every time, and we could devise a way to avoid it later |
| * (e.g. stash info in next's anon_vma_node when assigning |
| * an anon_vma, or when trying vma_merge). Another time. |
| */ |
| BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); |
| if (!near) |
| goto none; |
| |
| vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); |
| vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); |
| |
| if (near->anon_vma && near->vm_end == vma->vm_start && |
| mpol_equal(vma_policy(near), vma_policy(vma)) && |
| can_vma_merge_after(near, vm_flags, |
| NULL, vma->vm_file, vma->vm_pgoff)) |
| return near->anon_vma; |
| none: |
| /* |
| * There's no absolute need to look only at touching neighbours: |
| * we could search further afield for "compatible" anon_vmas. |
| * But it would probably just be a waste of time searching, |
| * or lead to too many vmas hanging off the same anon_vma. |
| * We're trying to allow mprotect remerging later on, |
| * not trying to minimize memory used for anon_vmas. |
| */ |
| return NULL; |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| void vm_stat_account(struct mm_struct *mm, unsigned long flags, |
| struct file *file, long pages) |
| { |
| const unsigned long stack_flags |
| = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); |
| |
| if (file) { |
| mm->shared_vm += pages; |
| if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) |
| mm->exec_vm += pages; |
| } else if (flags & stack_flags) |
| mm->stack_vm += pages; |
| if (flags & (VM_RESERVED|VM_IO)) |
| mm->reserved_vm += pages; |
| } |
| #endif /* CONFIG_PROC_FS */ |
| |
| /* |
| * 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 inode *inode; |
| unsigned int vm_flags; |
| int error; |
| int accountable = 1; |
| unsigned long reqprot = prot; |
| |
| /* |
| * Does the application expect PROT_READ to imply PROT_EXEC? |
| * |
| * (the exception is when the underlying filesystem is noexec |
| * mounted, in which case we dont add PROT_EXEC.) |
| */ |
| if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
| if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) |
| prot |= PROT_EXEC; |
| |
| if (!len) |
| return -EINVAL; |
| |
| if (!(flags & MAP_FIXED)) |
| addr = round_hint_to_min(addr); |
| |
| error = arch_mmap_check(addr, len, flags); |
| if (error) |
| return error; |
| |
| /* Careful about overflows.. */ |
| len = PAGE_ALIGN(len); |
| if (!len || len > TASK_SIZE) |
| return -ENOMEM; |
| |
| /* offset overflow? */ |
| if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) |
| return -EOVERFLOW; |
| |
| /* Too many mappings? */ |
| if (mm->map_count > sysctl_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_prot_bits(prot) | calc_vm_flag_bits(flags) | |
| mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
| |
| if (flags & MAP_LOCKED) { |
| if (!can_do_mlock()) |
| return -EPERM; |
| vm_flags |= VM_LOCKED; |
| } |
| /* mlock MCL_FUTURE? */ |
| if (vm_flags & VM_LOCKED) { |
| unsigned long locked, lock_limit; |
| locked = len >> PAGE_SHIFT; |
| locked += mm->locked_vm; |
| lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
| lock_limit >>= PAGE_SHIFT; |
| if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
| return -EAGAIN; |
| } |
| |
| inode = file ? file->f_path.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; |
| if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { |
| if (vm_flags & VM_EXEC) |
| return -EPERM; |
| vm_flags &= ~VM_MAYEXEC; |
| } |
| if (is_file_hugepages(file)) |
| accountable = 0; |
| |
| if (!file->f_op || !file->f_op->mmap) |
| return -ENODEV; |
| break; |
| |
| default: |
| return -EINVAL; |
| } |
| } else { |
| switch (flags & MAP_TYPE) { |
| case MAP_SHARED: |
| vm_flags |= VM_SHARED | VM_MAYSHARE; |
| break; |
| case MAP_PRIVATE: |
| /* |
| * Set pgoff according to addr for anon_vma. |
| */ |
| pgoff = addr >> PAGE_SHIFT; |
| break; |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| error = security_file_mmap(file, reqprot, prot, flags, addr, 0); |
| if (error) |
| return error; |
| |
| return mmap_region(file, addr, len, flags, vm_flags, pgoff, |
| accountable); |
| } |
| EXPORT_SYMBOL(do_mmap_pgoff); |
| |
| /* |
| * Some shared mappigns will want the pages marked read-only |
| * to track write events. If so, we'll downgrade vm_page_prot |
| * to the private version (using protection_map[] without the |
| * VM_SHARED bit). |
| */ |
| int vma_wants_writenotify(struct vm_area_struct *vma) |
| { |
| unsigned int vm_flags = vma->vm_flags; |
| |
| /* If it was private or non-writable, the write bit is already clear */ |
| if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) |
| return 0; |
| |
| /* The backer wishes to know when pages are first written to? */ |
| if (vma->vm_ops && vma->vm_ops->page_mkwrite) |
| return 1; |
| |
| /* The open routine did something to the protections already? */ |
| if (pgprot_val(vma->vm_page_prot) != |
| pgprot_val(vm_get_page_prot(vm_flags))) |
| return 0; |
| |
| /* Specialty mapping? */ |
| if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) |
| return 0; |
| |
| /* Can the mapping track the dirty pages? */ |
| return vma->vm_file && vma->vm_file->f_mapping && |
| mapping_cap_account_dirty(vma->vm_file->f_mapping); |
| } |
| |
| unsigned long mmap_region(struct file *file, unsigned long addr, |
| unsigned long len, unsigned long flags, |
| unsigned int vm_flags, unsigned long pgoff, |
| int accountable) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma, *prev; |
| int correct_wcount = 0; |
| int error; |
| struct rb_node **rb_link, *rb_parent; |
| unsigned long charged = 0; |
| struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; |
| |
| /* 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 (!may_expand_vm(mm, len >> PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| if (flags & MAP_NORESERVE) |
| vm_flags |= VM_NORESERVE; |
| |
| if (accountable && (!(flags & MAP_NORESERVE) || |
| sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { |
| 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 (security_vm_enough_memory(charged)) |
| return -ENOMEM; |
| vm_flags |= VM_ACCOUNT; |
| } |
| } |
| |
| /* |
| * Can we just expand an old private anonymous mapping? |
| * The VM_SHARED test is necessary because shmem_zero_setup |
| * will create the file object for a shared anonymous map below. |
| */ |
| if (!file && !(vm_flags & VM_SHARED) && |
| vma_merge(mm, prev, addr, addr + len, vm_flags, |
| NULL, NULL, pgoff, NULL)) |
| 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_zalloc(vm_area_cachep, GFP_KERNEL); |
| if (!vma) { |
| error = -ENOMEM; |
| 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 = vm_get_page_prot(vm_flags); |
| vma->vm_pgoff = pgoff; |
| |
| 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; |
| if (vm_flags & VM_EXECUTABLE) |
| added_exe_file_vma(mm); |
| } 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; |
| pgoff = vma->vm_pgoff; |
| vm_flags = vma->vm_flags; |
| |
| if (vma_wants_writenotify(vma)) |
| vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); |
| |
| if (file && vma_merge(mm, prev, addr, vma->vm_end, |
| vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { |
| mpol_put(vma_policy(vma)); |
| kmem_cache_free(vm_area_cachep, vma); |
| fput(file); |
| if (vm_flags & VM_EXECUTABLE) |
| removed_exe_file_vma(mm); |
| } else { |
| vma_link(mm, vma, prev, rb_link, rb_parent); |
| file = vma->vm_file; |
| } |
| |
| /* Once vma denies write, undo our temporary denial count */ |
| if (correct_wcount) |
| atomic_inc(&inode->i_writecount); |
| out: |
| mm->total_vm += len >> PAGE_SHIFT; |
| vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); |
| if (vm_flags & VM_LOCKED) { |
| mm->locked_vm += len >> PAGE_SHIFT; |
| make_pages_present(addr, addr + len); |
| } |
| if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) |
| make_pages_present(addr, addr + len); |
| 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. */ |
| unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); |
| charged = 0; |
| 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 |
| 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; |
| unsigned long start_addr; |
| |
| if (len > TASK_SIZE) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma(mm, addr); |
| if (TASK_SIZE - len >= addr && |
| (!vma || addr + len <= vma->vm_start)) |
| return addr; |
| } |
| if (len > mm->cached_hole_size) { |
| start_addr = addr = mm->free_area_cache; |
| } else { |
| start_addr = addr = TASK_UNMAPPED_BASE; |
| mm->cached_hole_size = 0; |
| } |
| |
| full_search: |
| for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { |
| /* At this point: (!vma || addr < vma->vm_end). */ |
| if (TASK_SIZE - len < addr) { |
| /* |
| * Start a new search - just in case we missed |
| * some holes. |
| */ |
| if (start_addr != TASK_UNMAPPED_BASE) { |
| addr = TASK_UNMAPPED_BASE; |
| start_addr = addr; |
| mm->cached_hole_size = 0; |
| goto full_search; |
| } |
| return -ENOMEM; |
| } |
| if (!vma || addr + len <= vma->vm_start) { |
| /* |
| * Remember the place where we stopped the search: |
| */ |
| mm->free_area_cache = addr + len; |
| return addr; |
| } |
| if (addr + mm->cached_hole_size < vma->vm_start) |
| mm->cached_hole_size = vma->vm_start - addr; |
| addr = vma->vm_end; |
| } |
| } |
| #endif |
| |
| void arch_unmap_area(struct mm_struct *mm, unsigned long addr) |
| { |
| /* |
| * Is this a new hole at the lowest possible address? |
| */ |
| if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { |
| mm->free_area_cache = addr; |
| mm->cached_hole_size = ~0UL; |
| } |
| } |
| |
| /* |
| * This mmap-allocator allocates new areas top-down from below the |
| * stack's low limit (the base): |
| */ |
| #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN |
| unsigned long |
| arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, |
| const unsigned long len, const unsigned long pgoff, |
| const unsigned long flags) |
| { |
| struct vm_area_struct *vma; |
| struct mm_struct *mm = current->mm; |
| unsigned long addr = addr0; |
| |
| /* requested length too big for entire address space */ |
| if (len > TASK_SIZE) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| /* requesting a specific address */ |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma(mm, addr); |
| if (TASK_SIZE - len >= addr && |
| (!vma || addr + len <= vma->vm_start)) |
| return addr; |
| } |
| |
| /* check if free_area_cache is useful for us */ |
| if (len <= mm->cached_hole_size) { |
| mm->cached_hole_size = 0; |
| mm->free_area_cache = mm->mmap_base; |
| } |
| |
| /* either no address requested or can't fit in requested address hole */ |
| addr = mm->free_area_cache; |
| |
| /* make sure it can fit in the remaining address space */ |
| if (addr > len) { |
| vma = find_vma(mm, addr-len); |
| if (!vma || addr <= vma->vm_start) |
| /* remember the address as a hint for next time */ |
| return (mm->free_area_cache = addr-len); |
| } |
| |
| if (mm->mmap_base < len) |
| goto bottomup; |
| |
| addr = mm->mmap_base-len; |
| |
| do { |
| /* |
| * Lookup failure means no vma is above this address, |
| * else if new region fits below vma->vm_start, |
| * return with success: |
| */ |
| vma = find_vma(mm, addr); |
| if (!vma || addr+len <= vma->vm_start) |
| /* remember the address as a hint for next time */ |
| return (mm->free_area_cache = addr); |
| |
| /* remember the largest hole we saw so far */ |
| if (addr + mm->cached_hole_size < vma->vm_start) |
| mm->cached_hole_size = vma->vm_start - addr; |
| |
| /* try just below the current vma->vm_start */ |
| addr = vma->vm_start-len; |
| } while (len < vma->vm_start); |
| |
| bottomup: |
| /* |
| * A failed mmap() very likely causes application failure, |
| * so fall back to the bottom-up function here. This scenario |
| * can happen with large stack limits and large mmap() |
| * allocations. |
| */ |
| mm->cached_hole_size = ~0UL; |
| mm->free_area_cache = TASK_UNMAPPED_BASE; |
| addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); |
| /* |
| * Restore the topdown base: |
| */ |
| mm->free_area_cache = mm->mmap_base; |
| mm->cached_hole_size = ~0UL; |
| |
| return addr; |
| } |
| #endif |
| |
| void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) |
| { |
| /* |
| * Is this a new hole at the highest possible address? |
| */ |
| if (addr > mm->free_area_cache) |
| mm->free_area_cache = addr; |
| |
| /* dont allow allocations above current base */ |
| if (mm->free_area_cache > mm->mmap_base) |
| mm->free_area_cache = mm->mmap_base; |
| } |
| |
| unsigned long |
| get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, |
| unsigned long pgoff, unsigned long flags) |
| { |
| unsigned long (*get_area)(struct file *, unsigned long, |
| unsigned long, unsigned long, unsigned long); |
| |
| get_area = current->mm->get_unmapped_area; |
| if (file && file->f_op && file->f_op->get_unmapped_area) |
| get_area = file->f_op->get_unmapped_area; |
| addr = get_area(file, addr, len, pgoff, flags); |
| if (IS_ERR_VALUE(addr)) |
| return addr; |
| |
| if (addr > TASK_SIZE - len) |
| return -ENOMEM; |
| if (addr & ~PAGE_MASK) |
| return -EINVAL; |
| |
| return arch_rebalance_pgtables(addr, len); |
| } |
| |
| EXPORT_SYMBOL(get_unmapped_area); |
| |
| /* 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; |
| } |
| |
| EXPORT_SYMBOL(find_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; |
| } |
| |
| /* |
| * Verify that the stack growth is acceptable and |
| * update accounting. This is shared with both the |
| * grow-up and grow-down cases. |
| */ |
| static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct rlimit *rlim = current->signal->rlim; |
| unsigned long new_start; |
| |
| /* address space limit tests */ |
| if (!may_expand_vm(mm, grow)) |
| return -ENOMEM; |
| |
| /* Stack limit test */ |
| if (size > rlim[RLIMIT_STACK].rlim_cur) |
| return -ENOMEM; |
| |
| /* mlock limit tests */ |
| if (vma->vm_flags & VM_LOCKED) { |
| unsigned long locked; |
| unsigned long limit; |
| locked = mm->locked_vm + grow; |
| limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; |
| if (locked > limit && !capable(CAP_IPC_LOCK)) |
| return -ENOMEM; |
| } |
| |
| /* Check to ensure the stack will not grow into a hugetlb-only region */ |
| new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : |
| vma->vm_end - size; |
| if (is_hugepage_only_range(vma->vm_mm, new_start, size)) |
| return -EFAULT; |
| |
| /* |
| * Overcommit.. This must be the final test, as it will |
| * update security statistics. |
| */ |
| if (security_vm_enough_memory(grow)) |
| return -ENOMEM; |
| |
| /* Ok, everything looks good - let it rip */ |
| mm->total_vm += grow; |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm += grow; |
| vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); |
| return 0; |
| } |
| |
| #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) |
| /* |
| * PA-RISC uses this for its stack; IA64 for its Register Backing Store. |
| * vma is the last one with address > vma->vm_end. Have to extend vma. |
| */ |
| #ifndef CONFIG_IA64 |
| static inline |
| #endif |
| int expand_upwards(struct vm_area_struct *vma, unsigned long address) |
| { |
| int error; |
| |
| if (!(vma->vm_flags & VM_GROWSUP)) |
| return -EFAULT; |
| |
| /* |
| * We must make sure the anon_vma is allocated |
| * so that the anon_vma locking is not a noop. |
| */ |
| if (unlikely(anon_vma_prepare(vma))) |
| return -ENOMEM; |
| anon_vma_lock(vma); |
| |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_sem in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| * Also guard against wrapping around to address 0. |
| */ |
| if (address < PAGE_ALIGN(address+4)) |
| address = PAGE_ALIGN(address+4); |
| else { |
| anon_vma_unlock(vma); |
| return -ENOMEM; |
| } |
| error = 0; |
| |
| /* Somebody else might have raced and expanded it already */ |
| if (address > vma->vm_end) { |
| unsigned long size, grow; |
| |
| size = address - vma->vm_start; |
| grow = (address - vma->vm_end) >> PAGE_SHIFT; |
| |
| error = acct_stack_growth(vma, size, grow); |
| if (!error) |
| vma->vm_end = address; |
| } |
| anon_vma_unlock(vma); |
| return error; |
| } |
| #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ |
| |
| /* |
| * vma is the first one with address < vma->vm_start. Have to extend vma. |
| */ |
| static inline int expand_downwards(struct vm_area_struct *vma, |
| unsigned long address) |
| { |
| int error; |
| |
| /* |
| * We must make sure the anon_vma is allocated |
| * so that the anon_vma locking is not a noop. |
| */ |
| if (unlikely(anon_vma_prepare(vma))) |
| return -ENOMEM; |
| |
| address &= PAGE_MASK; |
| error = security_file_mmap(NULL, 0, 0, 0, address, 1); |
| if (error) |
| return error; |
| |
| anon_vma_lock(vma); |
| |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_sem in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| */ |
| |
| /* Somebody else might have raced and expanded it already */ |
| if (address < vma->vm_start) { |
| unsigned long size, grow; |
| |
| size = vma->vm_end - address; |
| grow = (vma->vm_start - address) >> PAGE_SHIFT; |
| |
| error = acct_stack_growth(vma, size, grow); |
| if (!error) { |
| vma->vm_start = address; |
| vma->vm_pgoff -= grow; |
| } |
| } |
| anon_vma_unlock(vma); |
| return error; |
| } |
| |
| int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) |
| { |
| return expand_downwards(vma, address); |
| } |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| { |
| return expand_upwards(vma, address); |
| } |
| |
| 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 |
| int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| { |
| return expand_downwards(vma, address); |
| } |
| |
| 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 |
| |
| /* |
| * Ok - we have the memory areas we should free on the vma list, |
| * so release them, and do the vma updates. |
| * |
| * Called with the mm semaphore held. |
| */ |
| static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) |
| { |
| /* Update high watermark before we lower total_vm */ |
| update_hiwater_vm(mm); |
| do { |
| long nrpages = vma_pages(vma); |
| |
| mm->total_vm -= nrpages; |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm -= nrpages; |
| vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); |
| vma = remove_vma(vma); |
| } while (vma); |
| validate_mm(mm); |
| } |
| |
| /* |
| * Get rid of page table information in the indicated region. |
| * |
| * Called with the mm semaphore 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 vm_area_struct *next = prev? prev->vm_next: mm->mmap; |
| struct mmu_gather *tlb; |
| unsigned long nr_accounted = 0; |
| |
| lru_add_drain(); |
| tlb = tlb_gather_mmu(mm, 0); |
| update_hiwater_rss(mm); |
| unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); |
| vm_unacct_memory(nr_accounted); |
| free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, |
| next? next->vm_start: 0); |
| 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.. |
| */ |
| 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; |
| unsigned long addr; |
| |
| 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; |
| if (mm->unmap_area == arch_unmap_area) |
| addr = prev ? prev->vm_end : mm->mmap_base; |
| else |
| addr = vma ? vma->vm_start : mm->mmap_base; |
| mm->unmap_area(mm, addr); |
| 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 tail. |
| */ |
| int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, |
| unsigned long addr, int new_below) |
| { |
| struct mempolicy *pol; |
| struct vm_area_struct *new; |
| |
| if (is_vm_hugetlb_page(vma) && (addr & |
| ~(huge_page_mask(hstate_vma(vma))))) |
| return -EINVAL; |
| |
| if (mm->map_count >= sysctl_max_map_count) |
| return -ENOMEM; |
| |
| new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| if (!new) |
| return -ENOMEM; |
| |
| /* most fields are the same, copy all, and then fixup */ |
| *new = *vma; |
| |
| if (new_below) |
| new->vm_end = addr; |
| else { |
| new->vm_start = addr; |
| new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); |
| } |
| |
| pol = mpol_dup(vma_policy(vma)); |
| if (IS_ERR(pol)) { |
| kmem_cache_free(vm_area_cachep, new); |
| return PTR_ERR(pol); |
| } |
| vma_set_policy(new, pol); |
| |
| if (new->vm_file) { |
| get_file(new->vm_file); |
| if (vma->vm_flags & VM_EXECUTABLE) |
| added_exe_file_vma(mm); |
| } |
| |
| if (new->vm_ops && new->vm_ops->open) |
| new->vm_ops->open(new); |
| |
| if (new_below) |
| vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + |
| ((addr - new->vm_start) >> PAGE_SHIFT), new); |
| else |
| vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, 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 *vma, *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 */ |
| vma = find_vma_prev(mm, start, &prev); |
| if (!vma) |
| return 0; |
| /* we have start < vma->vm_end */ |
| |
| /* if it doesn't overlap, we have nothing.. */ |
| end = start + len; |
| if (vma->vm_start >= end) |
| return 0; |
| |
| /* |
| * If we need to split any vma, do it now to save pain later. |
| * |
| * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially |
| * unmapped vm_area_struct will remain in use: so lower split_vma |
| * places tmp vma above, and higher split_vma places tmp vma below. |
| */ |
| if (start > vma->vm_start) { |
| int error = split_vma(mm, vma, start, 0); |
| if (error) |
| return error; |
| prev = vma; |
| } |
| |
| /* Does it split the last one? */ |
| last = find_vma(mm, end); |
| if (last && end > last->vm_start) { |
| int error = split_vma(mm, last, end, 1); |
| if (error) |
| return error; |
| } |
| vma = prev? prev->vm_next: mm->mmap; |
| |
| /* |
| * Remove the vma's, and unmap the actual pages |
| */ |
| detach_vmas_to_be_unmapped(mm, vma, prev, end); |
| unmap_region(mm, vma, prev, start, end); |
| |
| /* Fix up all other VM information */ |
| remove_vma_list(mm, vma); |
| |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(do_munmap); |
| |
| asmlinkage long sys_munmap(unsigned long addr, size_t len) |
| { |
| int ret; |
| struct mm_struct *mm = current->mm; |
| |
| profile_munmap(addr); |
| |
| down_write(&mm->mmap_sem); |
| ret = do_munmap(mm, addr, len); |
| up_write(&mm->mmap_sem); |
| return ret; |
| } |
| |
| static inline void verify_mm_writelocked(struct mm_struct *mm) |
| { |
| #ifdef CONFIG_DEBUG_VM |
| if (unlikely(down_read_trylock(&mm->mmap_sem))) { |
| WARN_ON(1); |
| up_read(&mm->mmap_sem); |
| } |
| #endif |
| } |
| |
| /* |
| * 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; |
| pgoff_t pgoff = addr >> PAGE_SHIFT; |
| int error; |
| |
| len = PAGE_ALIGN(len); |
| if (!len) |
| return addr; |
| |
| if ((addr + len) > TASK_SIZE || (addr + len) < addr) |
| return -EINVAL; |
| |
| if (is_hugepage_only_range(mm, addr, len)) |
| return -EINVAL; |
| |
| error = security_file_mmap(NULL, 0, 0, 0, addr, 1); |
| if (error) |
| return error; |
| |
| flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; |
| |
| error = arch_mmap_check(addr, len, flags); |
| if (error) |
| return error; |
| |
| /* |
| * mlock MCL_FUTURE? |
| */ |
| if (mm->def_flags & VM_LOCKED) { |
| unsigned long locked, lock_limit; |
| locked = len >> PAGE_SHIFT; |
| locked += mm->locked_vm; |
| lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
| lock_limit >>= PAGE_SHIFT; |
| if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
| return -EAGAIN; |
| } |
| |
| /* |
| * mm->mmap_sem is required to protect against another thread |
| * changing the mappings in case we sleep. |
| */ |
| verify_mm_writelocked(mm); |
| |
| /* |
| * 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 (!may_expand_vm(mm, len >> PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| if (mm->map_count > sysctl_max_map_count) |
| return -ENOMEM; |
| |
| if (security_vm_enough_memory(len >> PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| /* Can we just expand an old private anonymous mapping? */ |
| if (vma_merge(mm, prev, addr, addr + len, flags, |
| NULL, NULL, pgoff, NULL)) |
| goto out; |
| |
| /* |
| * create a vma struct for an anonymous mapping |
| */ |
| vma = kmem_cache_zalloc(vm_area_cachep, GFP_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_pgoff = pgoff; |
| vma->vm_flags = flags; |
| vma->vm_page_prot = vm_get_page_prot(flags); |
| 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; |
| } |
| |
| EXPORT_SYMBOL(do_brk); |
| |
| /* Release all mmaps. */ |
| void exit_mmap(struct mm_struct *mm) |
| { |
| struct mmu_gather *tlb; |
| struct vm_area_struct *vma = mm->mmap; |
| unsigned long nr_accounted = 0; |
| unsigned long end; |
| |
| /* mm's last user has gone, and its about to be pulled down */ |
| arch_exit_mmap(mm); |
| mmu_notifier_release(mm); |
| |
| lru_add_drain(); |
| flush_cache_mm(mm); |
| tlb = tlb_gather_mmu(mm, 1); |
| /* Don't update_hiwater_rss(mm) here, do_exit already did */ |
| /* Use -1 here to ensure all VMAs in the mm are unmapped */ |
| end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); |
| vm_unacct_memory(nr_accounted); |
| free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); |
| tlb_finish_mmu(tlb, 0, end); |
| |
| /* |
| * Walk the list again, actually closing and freeing it, |
| * with preemption enabled, without holding any MM locks. |
| */ |
| while (vma) |
| vma = remove_vma(vma); |
| |
| BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); |
| } |
| |
| /* Insert vm structure into process list sorted by address |
| * and into the inode's i_mmap tree. If vm_file is non-NULL |
| * then i_mmap_lock is taken here. |
| */ |
| int 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; |
| |
| /* |
| * The vm_pgoff of a purely anonymous vma should be irrelevant |
| * until its first write fault, when page's anon_vma and index |
| * are set. But now set the vm_pgoff it will almost certainly |
| * end up with (unless mremap moves it elsewhere before that |
| * first wfault), so /proc/pid/maps tells a consistent story. |
| * |
| * By setting it to reflect the virtual start address of the |
| * vma, merges and splits can happen in a seamless way, just |
| * using the existing file pgoff checks and manipulations. |
| * Similarly in do_mmap_pgoff and in do_brk. |
| */ |
| if (!vma->vm_file) { |
| BUG_ON(vma->anon_vma); |
| vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
| } |
| __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); |
| if (__vma && __vma->vm_start < vma->vm_end) |
| return -ENOMEM; |
| if ((vma->vm_flags & VM_ACCOUNT) && |
| security_vm_enough_memory_mm(mm, vma_pages(vma))) |
| return -ENOMEM; |
| vma_link(mm, vma, prev, rb_link, rb_parent); |
| return 0; |
| } |
| |
| /* |
| * Copy the vma structure to a new location in the same mm, |
| * prior to moving page table entries, to effect an mremap move. |
| */ |
| struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, |
| unsigned long addr, unsigned long len, pgoff_t pgoff) |
| { |
| struct vm_area_struct *vma = *vmap; |
| unsigned long vma_start = vma->vm_start; |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *new_vma, *prev; |
| struct rb_node **rb_link, *rb_parent; |
| struct mempolicy *pol; |
| |
| /* |
| * If anonymous vma has not yet been faulted, update new pgoff |
| * to match new location, to increase its chance of merging. |
| */ |
| if (!vma->vm_file && !vma->anon_vma) |
| pgoff = addr >> PAGE_SHIFT; |
| |
| find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); |
| new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, |
| vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); |
| if (new_vma) { |
| /* |
| * Source vma may have been merged into new_vma |
| */ |
| if (vma_start >= new_vma->vm_start && |
| vma_start < new_vma->vm_end) |
| *vmap = new_vma; |
| } else { |
| new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| if (new_vma) { |
| *new_vma = *vma; |
| pol = mpol_dup(vma_policy(vma)); |
| if (IS_ERR(pol)) { |
| kmem_cache_free(vm_area_cachep, new_vma); |
| return NULL; |
| } |
| vma_set_policy(new_vma, pol); |
| new_vma->vm_start = addr; |
| new_vma->vm_end = addr + len; |
| new_vma->vm_pgoff = pgoff; |
| if (new_vma->vm_file) { |
| get_file(new_vma->vm_file); |
| if (vma->vm_flags & VM_EXECUTABLE) |
| added_exe_file_vma(mm); |
| } |
| if (new_vma->vm_ops && new_vma->vm_ops->open) |
| new_vma->vm_ops->open(new_vma); |
| vma_link(mm, new_vma, prev, rb_link, rb_parent); |
| } |
| } |
| return new_vma; |
| } |
| |
| /* |
| * Return true if the calling process may expand its vm space by the passed |
| * number of pages |
| */ |
| int may_expand_vm(struct mm_struct *mm, unsigned long npages) |
| { |
| unsigned long cur = mm->total_vm; /* pages */ |
| unsigned long lim; |
| |
| lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; |
| |
| if (cur + npages > lim) |
| return 0; |
| return 1; |
| } |
| |
| |
| static int special_mapping_fault(struct vm_area_struct *vma, |
| struct vm_fault *vmf) |
| { |
| pgoff_t pgoff; |
| struct page **pages; |
| |
| /* |
| * special mappings have no vm_file, and in that case, the mm |
| * uses vm_pgoff internally. So we have to subtract it from here. |
| * We are allowed to do this because we are the mm; do not copy |
| * this code into drivers! |
| */ |
| pgoff = vmf->pgoff - vma->vm_pgoff; |
| |
| for (pages = vma->vm_private_data; pgoff && *pages; ++pages) |
| pgoff--; |
| |
| if (*pages) { |
| struct page *page = *pages; |
| get_page(page); |
| vmf->page = page; |
| return 0; |
| } |
| |
| return VM_FAULT_SIGBUS; |
| } |
| |
| /* |
| * Having a close hook prevents vma merging regardless of flags. |
| */ |
| static void special_mapping_close(struct vm_area_struct *vma) |
| { |
| } |
| |
| static struct vm_operations_struct special_mapping_vmops = { |
| .close = special_mapping_close, |
| .fault = special_mapping_fault, |
| }; |
| |
| /* |
| * Called with mm->mmap_sem held for writing. |
| * Insert a new vma covering the given region, with the given flags. |
| * Its pages are supplied by the given array of struct page *. |
| * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. |
| * The region past the last page supplied will always produce SIGBUS. |
| * The array pointer and the pages it points to are assumed to stay alive |
| * for as long as this mapping might exist. |
| */ |
| int install_special_mapping(struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, struct page **pages) |
| { |
| struct vm_area_struct *vma; |
| |
| vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| if (unlikely(vma == NULL)) |
| return -ENOMEM; |
| |
| vma->vm_mm = mm; |
| vma->vm_start = addr; |
| vma->vm_end = addr + len; |
| |
| vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; |
| vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| |
| vma->vm_ops = &special_mapping_vmops; |
| vma->vm_private_data = pages; |
| |
| if (unlikely(insert_vm_struct(mm, vma))) { |
| kmem_cache_free(vm_area_cachep, vma); |
| return -ENOMEM; |
| } |
| |
| mm->total_vm += len >> PAGE_SHIFT; |
| |
| return 0; |
| } |
| |
| static DEFINE_MUTEX(mm_all_locks_mutex); |
| |
| static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) |
| { |
| if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) { |
| /* |
| * The LSB of head.next can't change from under us |
| * because we hold the mm_all_locks_mutex. |
| */ |
| spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); |
| /* |
| * We can safely modify head.next after taking the |
| * anon_vma->lock. If some other vma in this mm shares |
| * the same anon_vma we won't take it again. |
| * |
| * No need of atomic instructions here, head.next |
| * can't change from under us thanks to the |
| * anon_vma->lock. |
| */ |
| if (__test_and_set_bit(0, (unsigned long *) |
| &anon_vma->head.next)) |
| BUG(); |
| } |
| } |
| |
| static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) |
| { |
| if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| /* |
| * AS_MM_ALL_LOCKS can't change from under us because |
| * we hold the mm_all_locks_mutex. |
| * |
| * Operations on ->flags have to be atomic because |
| * even if AS_MM_ALL_LOCKS is stable thanks to the |
| * mm_all_locks_mutex, there may be other cpus |
| * changing other bitflags in parallel to us. |
| */ |
| if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) |
| BUG(); |
| spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); |
| } |
| } |
| |
| /* |
| * This operation locks against the VM for all pte/vma/mm related |
| * operations that could ever happen on a certain mm. This includes |
| * vmtruncate, try_to_unmap, and all page faults. |
| * |
| * The caller must take the mmap_sem in write mode before calling |
| * mm_take_all_locks(). The caller isn't allowed to release the |
| * mmap_sem until mm_drop_all_locks() returns. |
| * |
| * mmap_sem in write mode is required in order to block all operations |
| * that could modify pagetables and free pages without need of |
| * altering the vma layout (for example populate_range() with |
| * nonlinear vmas). It's also needed in write mode to avoid new |
| * anon_vmas to be associated with existing vmas. |
| * |
| * A single task can't take more than one mm_take_all_locks() in a row |
| * or it would deadlock. |
| * |
| * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in |
| * mapping->flags avoid to take the same lock twice, if more than one |
| * vma in this mm is backed by the same anon_vma or address_space. |
| * |
| * We can take all the locks in random order because the VM code |
| * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never |
| * takes more than one of them in a row. Secondly we're protected |
| * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. |
| * |
| * mm_take_all_locks() and mm_drop_all_locks are expensive operations |
| * that may have to take thousand of locks. |
| * |
| * mm_take_all_locks() can fail if it's interrupted by signals. |
| */ |
| int mm_take_all_locks(struct mm_struct *mm) |
| { |
| struct vm_area_struct *vma; |
| int ret = -EINTR; |
| |
| BUG_ON(down_read_trylock(&mm->mmap_sem)); |
| |
| mutex_lock(&mm_all_locks_mutex); |
| |
| for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| if (vma->vm_file && vma->vm_file->f_mapping) |
| vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| } |
| |
| for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| if (vma->anon_vma) |
| vm_lock_anon_vma(mm, vma->anon_vma); |
| } |
| |
| ret = 0; |
| |
| out_unlock: |
| if (ret) |
| mm_drop_all_locks(mm); |
| |
| return ret; |
| } |
| |
| static void vm_unlock_anon_vma(struct anon_vma *anon_vma) |
| { |
| if (test_bit(0, (unsigned long *) &anon_vma->head.next)) { |
| /* |
| * The LSB of head.next can't change to 0 from under |
| * us because we hold the mm_all_locks_mutex. |
| * |
| * We must however clear the bitflag before unlocking |
| * the vma so the users using the anon_vma->head will |
| * never see our bitflag. |
| * |
| * No need of atomic instructions here, head.next |
| * can't change from under us until we release the |
| * anon_vma->lock. |
| */ |
| if (!__test_and_clear_bit(0, (unsigned long *) |
| &anon_vma->head.next)) |
| BUG(); |
| spin_unlock(&anon_vma->lock); |
| } |
| } |
| |
| static void vm_unlock_mapping(struct address_space *mapping) |
| { |
| if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| /* |
| * AS_MM_ALL_LOCKS can't change to 0 from under us |
| * because we hold the mm_all_locks_mutex. |
| */ |
| spin_unlock(&mapping->i_mmap_lock); |
| if (!test_and_clear_bit(AS_MM_ALL_LOCKS, |
| &mapping->flags)) |
| BUG(); |
| } |
| } |
| |
| /* |
| * The mmap_sem cannot be released by the caller until |
| * mm_drop_all_locks() returns. |
| */ |
| void mm_drop_all_locks(struct mm_struct *mm) |
| { |
| struct vm_area_struct *vma; |
| |
| BUG_ON(down_read_trylock(&mm->mmap_sem)); |
| BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); |
| |
| for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| if (vma->anon_vma) |
| vm_unlock_anon_vma(vma->anon_vma); |
| if (vma->vm_file && vma->vm_file->f_mapping) |
| vm_unlock_mapping(vma->vm_file->f_mapping); |
| } |
| |
| mutex_unlock(&mm_all_locks_mutex); |
| } |