diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 2721 |
1 files changed, 2721 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c new file mode 100644 index 00000000..848ef52d --- /dev/null +++ b/mm/mmap.c @@ -0,0 +1,2721 @@ +/* + * mm/mmap.c + * + * Written by obz. + * + * Address space accounting code <alan@lxorguk.ukuu.org.uk> + */ + +#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/export.h> +#include <linux/mount.h> +#include <linux/mempolicy.h> +#include <linux/rmap.h> +#include <linux/mmu_notifier.h> +#include <linux/perf_event.h> +#include <linux/audit.h> +#include <linux/khugepaged.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 __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ +int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ +int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; +/* + * Make sure vm_committed_as in one cacheline and not cacheline shared with + * other variables. It can be updated by several CPUs frequently. + */ +struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; + +/* + * 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) { + free = global_page_state(NR_FREE_PAGES); + free += global_page_state(NR_FILE_PAGES); + + /* + * shmem pages shouldn't be counted as free in this + * case, they can't be purged, only swapped out, and + * that won't affect the overall amount of available + * memory in the system. + */ + free -= global_page_state(NR_SHMEM); + + 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 reserved pages. The pages are not for anonymous pages. + */ + if (free <= totalreserve_pages) + goto error; + else + free -= totalreserve_pages; + + /* + * Leave the last 3% for root + */ + if (!cap_sys_admin) + free -= free / 32; + + 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 */ + if (mm) + allowed -= mm->total_vm / 32; + + if (percpu_counter_read_positive(&vm_committed_as) < allowed) + return 0; +error: + vm_unacct_memory(pages); + + return -ENOMEM; +} + +/* + * Requires inode->i_mapping->i_mmap_mutex + */ +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; + mutex_lock(&mapping->i_mmap_mutex); + __remove_shared_vm_struct(vma, file, mapping); + mutex_unlock(&mapping->i_mmap_mutex); + } +} + +/* + * 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; +} + +static unsigned long do_brk(unsigned long addr, unsigned long len); + +SYSCALL_DEFINE1(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 + /* + * CONFIG_COMPAT_BRK can still be overridden by setting + * randomize_va_space to 2, which will still cause mm->start_brk + * to be arbitrarily shifted + */ + if (current->brk_randomized) + min_brk = mm->start_brk; + else + min_brk = mm->end_data; +#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 = rlimit(RLIMIT_DATA); + 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) + break; + __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; +} + +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 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); +} + +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) + mutex_lock(&mapping->i_mmap_mutex); + + __vma_link(mm, vma, prev, rb_link, rb_parent); + __vma_link_file(vma); + + if (mapping) + mutex_unlock(&mapping->i_mmap_mutex); + + mm->map_count++; + validate_mm(mm); +} + +/* + * Helper for vma_adjust() in the split_vma insert case: insert a vma into the + * mm's list and rbtree. It has already been inserted into the prio_tree. + */ +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) +{ + struct vm_area_struct *next = vma->vm_next; + + prev->vm_next = next; + if (next) + next->vm_prev = prev; + 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. + */ +int 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 anon_vma *anon_vma = NULL; + struct file *file = vma->vm_file; + long adjust_next = 0; + int remove_next = 0; + + if (next && !insert) { + struct vm_area_struct *exporter = NULL; + + 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; + exporter = next; + 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; + exporter = next; + 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); + exporter = vma; + importer = next; + } + + /* + * 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 (exporter && exporter->anon_vma && !importer->anon_vma) { + if (anon_vma_clone(importer, exporter)) + return -ENOMEM; + importer->anon_vma = exporter->anon_vma; + } + } + + if (file) { + mapping = file->f_mapping; + if (!(vma->vm_flags & VM_NONLINEAR)) + root = &mapping->i_mmap; + mutex_lock(&mapping->i_mmap_mutex); + if (insert) { + /* + * 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); + } + } + + vma_adjust_trans_huge(vma, start, end, adjust_next); + + /* + * When changing only vma->vm_end, we don't really need anon_vma + * lock. This is a fairly rare case by itself, but the anon_vma + * lock may be shared between many sibling processes. Skipping + * the lock for brk adjustments makes a difference sometimes. + */ + if (vma->anon_vma && (importer || start != vma->vm_start)) { + anon_vma = vma->anon_vma; + anon_vma_lock(anon_vma); + } + + 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); + } 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) + anon_vma_unlock(anon_vma); + if (mapping) + mutex_unlock(&mapping->i_mmap_mutex); + + if (remove_next) { + if (file) { + fput(file); + if (next->vm_flags & VM_EXECUTABLE) + removed_exe_file_vma(mm); + } + if (next->anon_vma) + anon_vma_merge(vma, next); + 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); + + return 0; +} + +/* + * 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. + */ +static inline int is_mergeable_vma(struct vm_area_struct *vma, + struct file *file, unsigned long vm_flags) +{ + /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */ + if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR) + 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, + struct vm_area_struct *vma) +{ + /* + * The list_is_singular() test is to avoid merging VMA cloned from + * parents. This can improve scalability caused by anon_vma lock. + */ + if ((!anon_vma1 || !anon_vma2) && (!vma || + list_is_singular(&vma->anon_vma_chain))) + return 1; + return 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, 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, 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; + int err; + + /* + * 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, NULL)) { + /* cases 1, 6 */ + err = vma_adjust(prev, prev->vm_start, + next->vm_end, prev->vm_pgoff, NULL); + } else /* cases 2, 5, 7 */ + err = vma_adjust(prev, prev->vm_start, + end, prev->vm_pgoff, NULL); + if (err) + return NULL; + khugepaged_enter_vma_merge(prev); + 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 */ + err = vma_adjust(prev, prev->vm_start, + addr, prev->vm_pgoff, NULL); + else /* cases 3, 8 */ + err = vma_adjust(area, addr, next->vm_end, + next->vm_pgoff - pglen, NULL); + if (err) + return NULL; + khugepaged_enter_vma_merge(area); + return area; + } + + return NULL; +} + +/* + * Rough compatbility check to quickly see if it's even worth looking + * at sharing an anon_vma. + * + * They need to have the same vm_file, and the flags can only differ + * in things that mprotect may change. + * + * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that + * we can merge the two vma's. For example, we refuse to merge a vma if + * there is a vm_ops->close() function, because that indicates that the + * driver is doing some kind of reference counting. But that doesn't + * really matter for the anon_vma sharing case. + */ +static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) +{ + return a->vm_end == b->vm_start && + mpol_equal(vma_policy(a), vma_policy(b)) && + a->vm_file == b->vm_file && + !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) && + b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); +} + +/* + * Do some basic sanity checking to see if we can re-use the anon_vma + * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be + * the same as 'old', the other will be the new one that is trying + * to share the anon_vma. + * + * NOTE! This runs with mm_sem held for reading, so it is possible that + * the anon_vma of 'old' is concurrently in the process of being set up + * by another page fault trying to merge _that_. But that's ok: if it + * is being set up, that automatically means that it will be a singleton + * acceptable for merging, so we can do all of this optimistically. But + * we do that ACCESS_ONCE() to make sure that we never re-load the pointer. + * + * IOW: that the "list_is_singular()" test on the anon_vma_chain only + * matters for the 'stable anon_vma' case (ie the thing we want to avoid + * is to return an anon_vma that is "complex" due to having gone through + * a fork). + * + * We also make sure that the two vma's are compatible (adjacent, + * and with the same memory policies). That's all stable, even with just + * a read lock on the mm_sem. + */ +static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) +{ + if (anon_vma_compatible(a, b)) { + struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma); + + if (anon_vma && list_is_singular(&old->anon_vma_chain)) + return anon_vma; + } + 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 anon_vma *anon_vma; + struct vm_area_struct *near; + + near = vma->vm_next; + if (!near) + goto try_prev; + + anon_vma = reusable_anon_vma(near, vma, near); + if (anon_vma) + return anon_vma; +try_prev: + near = vma->vm_prev; + if (!near) + goto none; + + anon_vma = reusable_anon_vma(near, near, vma); + if (anon_vma) + return 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 */ + +/* + * If a hint addr is less than mmap_min_addr change hint to be as + * low as possible but still greater than mmap_min_addr + */ +static inline unsigned long round_hint_to_min(unsigned long hint) +{ + hint &= PAGE_MASK; + if (((void *)hint != NULL) && + (hint < mmap_min_addr)) + return PAGE_ALIGN(mmap_min_addr); + return hint; +} + +/* + * The caller must hold down_write(¤t->mm->mmap_sem). + */ + +static 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; + vm_flags_t vm_flags; + int error; + 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); + + /* Careful about overflows.. */ + len = PAGE_ALIGN(len); + if (!len) + 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; + + /* mlock MCL_FUTURE? */ + if (vm_flags & VM_LOCKED) { + unsigned long locked, lock_limit; + locked = len >> PAGE_SHIFT; + locked += mm->locked_vm; + lock_limit = rlimit(RLIMIT_MEMLOCK); + 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 (!file->f_op || !file->f_op->mmap) + return -ENODEV; + break; + + default: + return -EINVAL; + } + } else { + switch (flags & MAP_TYPE) { + case MAP_SHARED: + /* + * Ignore pgoff. + */ + pgoff = 0; + 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); +} + +unsigned long do_mmap(struct file *file, unsigned long addr, + unsigned long len, unsigned long prot, + unsigned long flag, unsigned long offset) +{ + if (unlikely(offset + PAGE_ALIGN(len) < offset)) + return -EINVAL; + if (unlikely(offset & ~PAGE_MASK)) + return -EINVAL; + return do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT); +} +EXPORT_SYMBOL(do_mmap); + +unsigned long vm_mmap(struct file *file, unsigned long addr, + unsigned long len, unsigned long prot, + unsigned long flag, unsigned long offset) +{ + unsigned long ret; + struct mm_struct *mm = current->mm; + + down_write(&mm->mmap_sem); + ret = do_mmap(file, addr, len, prot, flag, offset); + up_write(&mm->mmap_sem); + return ret; +} +EXPORT_SYMBOL(vm_mmap); + +SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, + unsigned long, prot, unsigned long, flags, + unsigned long, fd, unsigned long, pgoff) +{ + struct file *file = NULL; + unsigned long retval = -EBADF; + + if (!(flags & MAP_ANONYMOUS)) { + audit_mmap_fd(fd, flags); + if (unlikely(flags & MAP_HUGETLB)) + return -EINVAL; + file = fget(fd); + if (!file) + goto out; + } else if (flags & MAP_HUGETLB) { + struct user_struct *user = NULL; + /* + * VM_NORESERVE is used because the reservations will be + * taken when vm_ops->mmap() is called + * A dummy user value is used because we are not locking + * memory so no accounting is necessary + */ + file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len, + VM_NORESERVE, &user, + HUGETLB_ANONHUGE_INODE); + if (IS_ERR(file)) + return PTR_ERR(file); + } + + flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); + + down_write(¤t->mm->mmap_sem); + retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff); + up_write(¤t->mm->mmap_sem); + + if (file) + fput(file); +out: + return retval; +} + +#ifdef __ARCH_WANT_SYS_OLD_MMAP +struct mmap_arg_struct { + unsigned long addr; + unsigned long len; + unsigned long prot; + unsigned long flags; + unsigned long fd; + unsigned long offset; +}; + +SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) +{ + struct mmap_arg_struct a; + + if (copy_from_user(&a, arg, sizeof(a))) + return -EFAULT; + if (a.offset & ~PAGE_MASK) + return -EINVAL; + + return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, + a.offset >> PAGE_SHIFT); +} +#endif /* __ARCH_WANT_SYS_OLD_MMAP */ + +/* + * 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) +{ + vm_flags_t 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); +} + +/* + * We account for memory if it's a private writeable mapping, + * not hugepages and VM_NORESERVE wasn't set. + */ +static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) +{ + /* + * hugetlb has its own accounting separate from the core VM + * VM_HUGETLB may not be set yet so we cannot check for that flag. + */ + if (file && is_file_hugepages(file)) + return 0; + + return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; +} + +unsigned long mmap_region(struct file *file, unsigned long addr, + unsigned long len, unsigned long flags, + vm_flags_t vm_flags, unsigned long pgoff) +{ + 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; + + /* + * Set 'VM_NORESERVE' if we should not account for the + * memory use of this mapping. + */ + if ((flags & MAP_NORESERVE)) { + /* We honor MAP_NORESERVE if allowed to overcommit */ + if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) + vm_flags |= VM_NORESERVE; + + /* hugetlb applies strict overcommit unless MAP_NORESERVE */ + if (file && is_file_hugepages(file)) + vm_flags |= VM_NORESERVE; + } + + /* + * Private writable mapping: check memory availability + */ + if (accountable_mapping(file, vm_flags)) { + charged = len >> PAGE_SHIFT; + if (security_vm_enough_memory_mm(mm, charged)) + return -ENOMEM; + vm_flags |= VM_ACCOUNT; + } + + /* + * Can we just expand an old mapping? + */ + vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); + if (vma) + 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; + INIT_LIST_HEAD(&vma->anon_vma_chain); + + error = -EINVAL; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */ + + if (file) { + 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); + + /* 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; + } else if (vm_flags & VM_SHARED) { + if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP))) + goto free_vma; + error = shmem_zero_setup(vma); + if (error) + goto free_vma; + } + + if (vma_wants_writenotify(vma)) { + pgprot_t pprot = vma->vm_page_prot; + + /* Can vma->vm_page_prot have changed?? + * + * Answer: Yes, drivers may have changed it in their + * f_op->mmap method. + * + * Ensures that vmas marked as uncached stay that way. + */ + vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); + if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot))) + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); + } + + 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: + perf_event_mmap(vma); + + mm->total_vm += len >> PAGE_SHIFT; + vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); + if (vm_flags & VM_LOCKED) { + if (!mlock_vma_pages_range(vma, addr, addr + len)) + mm->locked_vm += (len >> PAGE_SHIFT); + } else 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; +} + +/* + * 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, start_addr; + + /* 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; + } + +try_again: + /* either no address requested or can't fit in requested address hole */ + start_addr = addr = mm->free_area_cache; + + if (addr < len) + goto fail; + + addr -= 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); + +fail: + /* + * if hint left us with no space for the requested + * mapping then try again: + * + * Note: this is different with the case of bottomup + * which does the fully line-search, but we use find_vma + * here that causes some holes skipped. + */ + if (start_addr != mm->mmap_base) { + mm->free_area_cache = mm->mmap_base; + mm->cached_hole_size = 0; + goto try_again; + } + + /* + * 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); + + unsigned long error = arch_mmap_check(addr, len, flags); + if (error) + return error; + + /* Careful about overflows.. */ + if (len > TASK_SIZE) + return -ENOMEM; + + 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; + + vma = find_vma(mm, addr); + if (vma) { + *pprev = vma->vm_prev; + } else { + struct rb_node *rb_node = mm->mm_rb.rb_node; + *pprev = NULL; + while (rb_node) { + *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); + rb_node = rb_node->rb_right; + } + } + return 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 > ACCESS_ONCE(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 = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); + limit >>= 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_mm(mm, 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. + */ +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; + vma_lock_anon_vma(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 { + vma_unlock_anon_vma(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 = -ENOMEM; + if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) { + vma->vm_end = address; + perf_event_mmap(vma); + } + } + } + vma_unlock_anon_vma(vma); + khugepaged_enter_vma_merge(vma); + return error; +} +#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ + +/* + * vma is the first one with address < vma->vm_start. Have to extend vma. + */ +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; + + vma_lock_anon_vma(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 = -ENOMEM; + if (grow <= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) { + vma->vm_start = address; + vma->vm_pgoff -= grow; + perf_event_mmap(vma); + } + } + } + vma_unlock_anon_vma(vma); + khugepaged_enter_vma_merge(vma); + return error; +} + +#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) { + mlock_vma_pages_range(prev, 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) { + mlock_vma_pages_range(vma, 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; + 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_gather_mmu(&tlb, 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); + vma->vm_prev = NULL; + 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; + if (vma) + vma->vm_prev = prev; + 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_vma() bypasses sysctl_max_map_count checking. We use this on the + * munmap path where it doesn't make sense to fail. + */ +static 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; + int err = -ENOMEM; + + if (is_vm_hugetlb_page(vma) && (addr & + ~(huge_page_mask(hstate_vma(vma))))) + return -EINVAL; + + new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + if (!new) + goto out_err; + + /* most fields are the same, copy all, and then fixup */ + *new = *vma; + + INIT_LIST_HEAD(&new->anon_vma_chain); + + 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)) { + err = PTR_ERR(pol); + goto out_free_vma; + } + vma_set_policy(new, pol); + + if (anon_vma_clone(new, vma)) + goto out_free_mpol; + + 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) + err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + + ((addr - new->vm_start) >> PAGE_SHIFT), new); + else + err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); + + /* Success. */ + if (!err) + return 0; + + /* Clean everything up if vma_adjust failed. */ + if (new->vm_ops && new->vm_ops->close) + new->vm_ops->close(new); + if (new->vm_file) { + if (vma->vm_flags & VM_EXECUTABLE) + removed_exe_file_vma(mm); + fput(new->vm_file); + } + unlink_anon_vmas(new); + out_free_mpol: + mpol_put(pol); + out_free_vma: + kmem_cache_free(vm_area_cachep, new); + out_err: + return err; +} + +/* + * 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) +{ + if (mm->map_count >= sysctl_max_map_count) + return -ENOMEM; + + return __split_vma(mm, vma, addr, new_below); +} + +/* 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(mm, start); + if (!vma) + return 0; + prev = vma->vm_prev; + /* 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; + + /* + * Make sure that map_count on return from munmap() will + * not exceed its limit; but let map_count go just above + * its limit temporarily, to help free resources as expected. + */ + if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) + return -ENOMEM; + + 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; + + /* + * unlock any mlock()ed ranges before detaching vmas + */ + if (mm->locked_vm) { + struct vm_area_struct *tmp = vma; + while (tmp && tmp->vm_start < end) { + if (tmp->vm_flags & VM_LOCKED) { + mm->locked_vm -= vma_pages(tmp); + munlock_vma_pages_all(tmp); + } + tmp = tmp->vm_next; + } + } + + /* + * 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); + +int vm_munmap(unsigned long start, size_t len) +{ + int ret; + struct mm_struct *mm = current->mm; + + down_write(&mm->mmap_sem); + ret = do_munmap(mm, start, len); + up_write(&mm->mmap_sem); + return ret; +} +EXPORT_SYMBOL(vm_munmap); + +SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) +{ + profile_munmap(addr); + return vm_munmap(addr, len); +} + +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. + */ +static 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; + + 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 = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); + if (error & ~PAGE_MASK) + 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 = rlimit(RLIMIT_MEMLOCK); + 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_mm(mm, len >> PAGE_SHIFT)) + return -ENOMEM; + + /* Can we just expand an old private anonymous mapping? */ + vma = vma_merge(mm, prev, addr, addr + len, flags, + NULL, NULL, pgoff, NULL); + if (vma) + 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; + } + + INIT_LIST_HEAD(&vma->anon_vma_chain); + 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: + perf_event_mmap(vma); + mm->total_vm += len >> PAGE_SHIFT; + if (flags & VM_LOCKED) { + if (!mlock_vma_pages_range(vma, addr, addr + len)) + mm->locked_vm += (len >> PAGE_SHIFT); + } + return addr; +} + +unsigned long vm_brk(unsigned long addr, unsigned long len) +{ + struct mm_struct *mm = current->mm; + unsigned long ret; + + down_write(&mm->mmap_sem); + ret = do_brk(addr, len); + up_write(&mm->mmap_sem); + return ret; +} +EXPORT_SYMBOL(vm_brk); + +/* Release all mmaps. */ +void exit_mmap(struct mm_struct *mm) +{ + struct mmu_gather tlb; + struct vm_area_struct *vma; + unsigned long nr_accounted = 0; + + /* mm's last user has gone, and its about to be pulled down */ + mmu_notifier_release(mm); + + if (mm->locked_vm) { + vma = mm->mmap; + while (vma) { + if (vma->vm_flags & VM_LOCKED) + munlock_vma_pages_all(vma); + vma = vma->vm_next; + } + } + + arch_exit_mmap(mm); + + vma = mm->mmap; + if (!vma) /* Can happen if dup_mmap() received an OOM */ + return; + + lru_add_drain(); + flush_cache_mm(mm); + tlb_gather_mmu(&tlb, mm, 1); + /* update_hiwater_rss(mm) here? but nobody should be looking */ + /* Use -1 here to ensure all VMAs in the mm are unmapped */ + 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, -1); + + /* + * 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_mutex 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; + bool faulted_in_anon_vma = true; + + /* + * If anonymous vma has not yet been faulted, update new pgoff + * to match new location, to increase its chance of merging. + */ + if (unlikely(!vma->vm_file && !vma->anon_vma)) { + pgoff = addr >> PAGE_SHIFT; + faulted_in_anon_vma = false; + } + + 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 (unlikely(vma_start >= new_vma->vm_start && + vma_start < new_vma->vm_end)) { + /* + * The only way we can get a vma_merge with + * self during an mremap is if the vma hasn't + * been faulted in yet and we were allowed to + * reset the dst vma->vm_pgoff to the + * destination address of the mremap to allow + * the merge to happen. mremap must change the + * vm_pgoff linearity between src and dst vmas + * (in turn preventing a vma_merge) to be + * safe. It is only safe to keep the vm_pgoff + * linear if there are no pages mapped yet. + */ + VM_BUG_ON(faulted_in_anon_vma); + *vmap = new_vma; + } else + anon_vma_moveto_tail(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)) + goto out_free_vma; + INIT_LIST_HEAD(&new_vma->anon_vma_chain); + if (anon_vma_clone(new_vma, vma)) + goto out_free_mempol; + 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; + + out_free_mempol: + mpol_put(pol); + out_free_vma: + kmem_cache_free(vm_area_cachep, new_vma); + return NULL; +} + +/* + * 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 = rlimit(RLIMIT_AS) >> 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 const 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) +{ + int ret; + struct vm_area_struct *vma; + + vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); + if (unlikely(vma == NULL)) + return -ENOMEM; + + INIT_LIST_HEAD(&vma->anon_vma_chain); + 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; + + ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); + if (ret) + goto out; + + ret = insert_vm_struct(mm, vma); + if (ret) + goto out; + + mm->total_vm += len >> PAGE_SHIFT; + + perf_event_mmap(vma); + + return 0; + +out: + kmem_cache_free(vm_area_cachep, vma); + return ret; +} + +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->root->head.next)) { + /* + * The LSB of head.next can't change from under us + * because we hold the mm_all_locks_mutex. + */ + mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem); + /* + * We can safely modify head.next after taking the + * anon_vma->root->mutex. 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->root->mutex. + */ + if (__test_and_set_bit(0, (unsigned long *) + &anon_vma->root->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(); + mutex_lock_nest_lock(&mapping->i_mmap_mutex, &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_mutex or anon_vma->mutex 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; + struct anon_vma_chain *avc; + + 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) + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + vm_lock_anon_vma(mm, avc->anon_vma); + } + + return 0; + +out_unlock: + mm_drop_all_locks(mm); + return -EINTR; +} + +static void vm_unlock_anon_vma(struct anon_vma *anon_vma) +{ + if (test_bit(0, (unsigned long *) &anon_vma->root->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->root->mutex. + */ + if (!__test_and_clear_bit(0, (unsigned long *) + &anon_vma->root->head.next)) + BUG(); + anon_vma_unlock(anon_vma); + } +} + +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. + */ + mutex_unlock(&mapping->i_mmap_mutex); + 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; + struct anon_vma_chain *avc; + + 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) + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + vm_unlock_anon_vma(avc->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); +} + +/* + * initialise the VMA slab + */ +void __init mmap_init(void) +{ + int ret; + + ret = percpu_counter_init(&vm_committed_as, 0); + VM_BUG_ON(ret); +} |