| /* |
| * mm/mmap.c |
| * |
| * Written by obz. |
| * |
| * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/backing-dev.h> |
| #include <linux/mm.h> |
| #include <linux/vmacache.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/mmdebug.h> |
| #include <linux/perf_event.h> |
| #include <linux/audit.h> |
| #include <linux/khugepaged.h> |
| #include <linux/uprobes.h> |
| #include <linux/rbtree_augmented.h> |
| #include <linux/sched/sysctl.h> |
| #include <linux/notifier.h> |
| #include <linux/memory.h> |
| #include <linux/printk.h> |
| #include <linux/userfaultfd_k.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); |
| |
| /* 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); |
| |
| static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) |
| { |
| return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); |
| } |
| |
| /* Update vma->vm_page_prot to reflect vma->vm_flags. */ |
| void vma_set_page_prot(struct vm_area_struct *vma) |
| { |
| unsigned long vm_flags = vma->vm_flags; |
| |
| vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); |
| if (vma_wants_writenotify(vma)) { |
| vm_flags &= ~VM_SHARED; |
| vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, |
| vm_flags); |
| } |
| } |
| |
| |
| int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ |
| int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ |
| unsigned long sysctl_overcommit_kbytes __read_mostly; |
| int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; |
| unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ |
| unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ |
| /* |
| * 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; |
| |
| /* |
| * The global memory commitment made in the system can be a metric |
| * that can be used to drive ballooning decisions when Linux is hosted |
| * as a guest. On Hyper-V, the host implements a policy engine for dynamically |
| * balancing memory across competing virtual machines that are hosted. |
| * Several metrics drive this policy engine including the guest reported |
| * memory commitment. |
| */ |
| unsigned long vm_memory_committed(void) |
| { |
| return percpu_counter_read_positive(&vm_committed_as); |
| } |
| EXPORT_SYMBOL_GPL(vm_memory_committed); |
| |
| /* |
| * 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) |
| { |
| long free, allowed, reserve; |
| |
| VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < |
| -(s64)vm_committed_as_batch * num_online_cpus(), |
| "memory commitment underflow"); |
| |
| 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 += get_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; |
| |
| /* |
| * Reserve some for root |
| */ |
| if (!cap_sys_admin) |
| free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
| |
| if (free > pages) |
| return 0; |
| |
| goto error; |
| } |
| |
| allowed = vm_commit_limit(); |
| /* |
| * Reserve some for root |
| */ |
| if (!cap_sys_admin) |
| allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
| |
| /* |
| * Don't let a single process grow so big a user can't recover |
| */ |
| if (mm) { |
| reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); |
| allowed -= min_t(long, mm->total_vm / 32, reserve); |
| } |
| |
| if (percpu_counter_read_positive(&vm_committed_as) < allowed) |
| return 0; |
| error: |
| vm_unacct_memory(pages); |
| |
| return -ENOMEM; |
| } |
| |
| /* |
| * Requires inode->i_mapping->i_mmap_rwsem |
| */ |
| 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_inode(file)->i_writecount); |
| if (vma->vm_flags & VM_SHARED) |
| mapping_unmap_writable(mapping); |
| |
| flush_dcache_mmap_lock(mapping); |
| vma_interval_tree_remove(vma, &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| |
| /* |
| * Unlink a file-based vm structure from its interval 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; |
| i_mmap_lock_write(mapping); |
| __remove_shared_vm_struct(vma, file, mapping); |
| i_mmap_unlock_write(mapping); |
| } |
| } |
| |
| /* |
| * 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); |
| 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 retval; |
| unsigned long newbrk, oldbrk; |
| struct mm_struct *mm = current->mm; |
| unsigned long min_brk; |
| bool populate; |
| |
| 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 |
| */ |
| if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, |
| mm->end_data, mm->start_data)) |
| 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; |
| populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; |
| up_write(&mm->mmap_sem); |
| if (populate) |
| mm_populate(oldbrk, newbrk - oldbrk); |
| return brk; |
| |
| out: |
| retval = mm->brk; |
| up_write(&mm->mmap_sem); |
| return retval; |
| } |
| |
| static long vma_compute_subtree_gap(struct vm_area_struct *vma) |
| { |
| unsigned long max, subtree_gap; |
| max = vma->vm_start; |
| if (vma->vm_prev) |
| max -= vma->vm_prev->vm_end; |
| if (vma->vm_rb.rb_left) { |
| subtree_gap = rb_entry(vma->vm_rb.rb_left, |
| struct vm_area_struct, vm_rb)->rb_subtree_gap; |
| if (subtree_gap > max) |
| max = subtree_gap; |
| } |
| if (vma->vm_rb.rb_right) { |
| subtree_gap = rb_entry(vma->vm_rb.rb_right, |
| struct vm_area_struct, vm_rb)->rb_subtree_gap; |
| if (subtree_gap > max) |
| max = subtree_gap; |
| } |
| return max; |
| } |
| |
| #ifdef CONFIG_DEBUG_VM_RB |
| static int browse_rb(struct rb_root *root) |
| { |
| int i = 0, j, bug = 0; |
| 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) { |
| pr_emerg("vm_start %lx < prev %lx\n", |
| vma->vm_start, prev); |
| bug = 1; |
| } |
| if (vma->vm_start < pend) { |
| pr_emerg("vm_start %lx < pend %lx\n", |
| vma->vm_start, pend); |
| bug = 1; |
| } |
| if (vma->vm_start > vma->vm_end) { |
| pr_emerg("vm_start %lx > vm_end %lx\n", |
| vma->vm_start, vma->vm_end); |
| bug = 1; |
| } |
| if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { |
| pr_emerg("free gap %lx, correct %lx\n", |
| vma->rb_subtree_gap, |
| vma_compute_subtree_gap(vma)); |
| bug = 1; |
| } |
| 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) { |
| pr_emerg("backwards %d, forwards %d\n", j, i); |
| bug = 1; |
| } |
| return bug ? -1 : i; |
| } |
| |
| static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) |
| { |
| struct rb_node *nd; |
| |
| 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); |
| VM_BUG_ON_VMA(vma != ignore && |
| vma->rb_subtree_gap != vma_compute_subtree_gap(vma), |
| vma); |
| } |
| } |
| |
| static void validate_mm(struct mm_struct *mm) |
| { |
| int bug = 0; |
| int i = 0; |
| unsigned long highest_address = 0; |
| struct vm_area_struct *vma = mm->mmap; |
| |
| while (vma) { |
| struct anon_vma_chain *avc; |
| |
| vma_lock_anon_vma(vma); |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_verify(avc); |
| vma_unlock_anon_vma(vma); |
| highest_address = vma->vm_end; |
| vma = vma->vm_next; |
| i++; |
| } |
| if (i != mm->map_count) { |
| pr_emerg("map_count %d vm_next %d\n", mm->map_count, i); |
| bug = 1; |
| } |
| if (highest_address != mm->highest_vm_end) { |
| pr_emerg("mm->highest_vm_end %lx, found %lx\n", |
| mm->highest_vm_end, highest_address); |
| bug = 1; |
| } |
| i = browse_rb(&mm->mm_rb); |
| if (i != mm->map_count) { |
| if (i != -1) |
| pr_emerg("map_count %d rb %d\n", mm->map_count, i); |
| bug = 1; |
| } |
| VM_BUG_ON_MM(bug, mm); |
| } |
| #else |
| #define validate_mm_rb(root, ignore) do { } while (0) |
| #define validate_mm(mm) do { } while (0) |
| #endif |
| |
| RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, |
| unsigned long, rb_subtree_gap, vma_compute_subtree_gap) |
| |
| /* |
| * Update augmented rbtree rb_subtree_gap values after vma->vm_start or |
| * vma->vm_prev->vm_end values changed, without modifying the vma's position |
| * in the rbtree. |
| */ |
| static void vma_gap_update(struct vm_area_struct *vma) |
| { |
| /* |
| * As it turns out, RB_DECLARE_CALLBACKS() already created a callback |
| * function that does exacltly what we want. |
| */ |
| vma_gap_callbacks_propagate(&vma->vm_rb, NULL); |
| } |
| |
| static inline void vma_rb_insert(struct vm_area_struct *vma, |
| struct rb_root *root) |
| { |
| /* All rb_subtree_gap values must be consistent prior to insertion */ |
| validate_mm_rb(root, NULL); |
| |
| rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); |
| } |
| |
| static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) |
| { |
| /* |
| * All rb_subtree_gap values must be consistent prior to erase, |
| * with the possible exception of the vma being erased. |
| */ |
| validate_mm_rb(root, vma); |
| |
| /* |
| * Note rb_erase_augmented is a fairly large inline function, |
| * so make sure we instantiate it only once with our desired |
| * augmented rbtree callbacks. |
| */ |
| rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); |
| } |
| |
| /* |
| * vma has some anon_vma assigned, and is already inserted on that |
| * anon_vma's interval trees. |
| * |
| * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the |
| * vma must be removed from the anon_vma's interval trees using |
| * anon_vma_interval_tree_pre_update_vma(). |
| * |
| * After the update, the vma will be reinserted using |
| * anon_vma_interval_tree_post_update_vma(). |
| * |
| * The entire update must be protected by exclusive mmap_sem and by |
| * the root anon_vma's mutex. |
| */ |
| static inline void |
| anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) |
| { |
| struct anon_vma_chain *avc; |
| |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); |
| } |
| |
| static inline void |
| anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) |
| { |
| struct anon_vma_chain *avc; |
| |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); |
| } |
| |
| static int find_vma_links(struct mm_struct *mm, unsigned long addr, |
| unsigned long end, struct vm_area_struct **pprev, |
| struct rb_node ***rb_link, struct rb_node **rb_parent) |
| { |
| struct rb_node **__rb_link, *__rb_parent, *rb_prev; |
| |
| __rb_link = &mm->mm_rb.rb_node; |
| rb_prev = __rb_parent = 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) { |
| /* Fail if an existing vma overlaps the area */ |
| if (vma_tmp->vm_start < end) |
| return -ENOMEM; |
| __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 0; |
| } |
| |
| static unsigned long count_vma_pages_range(struct mm_struct *mm, |
| unsigned long addr, unsigned long end) |
| { |
| unsigned long nr_pages = 0; |
| struct vm_area_struct *vma; |
| |
| /* Find first overlaping mapping */ |
| vma = find_vma_intersection(mm, addr, end); |
| if (!vma) |
| return 0; |
| |
| nr_pages = (min(end, vma->vm_end) - |
| max(addr, vma->vm_start)) >> PAGE_SHIFT; |
| |
| /* Iterate over the rest of the overlaps */ |
| for (vma = vma->vm_next; vma; vma = vma->vm_next) { |
| unsigned long overlap_len; |
| |
| if (vma->vm_start > end) |
| break; |
| |
| overlap_len = min(end, vma->vm_end) - vma->vm_start; |
| nr_pages += overlap_len >> PAGE_SHIFT; |
| } |
| |
| return nr_pages; |
| } |
| |
| void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, |
| struct rb_node **rb_link, struct rb_node *rb_parent) |
| { |
| /* Update tracking information for the gap following the new vma. */ |
| if (vma->vm_next) |
| vma_gap_update(vma->vm_next); |
| else |
| mm->highest_vm_end = vma->vm_end; |
| |
| /* |
| * vma->vm_prev wasn't known when we followed the rbtree to find the |
| * correct insertion point for that vma. As a result, we could not |
| * update the vma vm_rb parents rb_subtree_gap values on the way down. |
| * So, we first insert the vma with a zero rb_subtree_gap value |
| * (to be consistent with what we did on the way down), and then |
| * immediately update the gap to the correct value. Finally we |
| * rebalance the rbtree after all augmented values have been set. |
| */ |
| rb_link_node(&vma->vm_rb, rb_parent, rb_link); |
| vma->rb_subtree_gap = 0; |
| vma_gap_update(vma); |
| vma_rb_insert(vma, &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_inode(file)->i_writecount); |
| if (vma->vm_flags & VM_SHARED) |
| atomic_inc(&mapping->i_mmap_writable); |
| |
| flush_dcache_mmap_lock(mapping); |
| vma_interval_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; |
| i_mmap_lock_write(mapping); |
| } |
| |
| __vma_link(mm, vma, prev, rb_link, rb_parent); |
| __vma_link_file(vma); |
| |
| if (mapping) |
| i_mmap_unlock_write(mapping); |
| |
| 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 interval tree. |
| */ |
| static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| { |
| struct vm_area_struct *prev; |
| struct rb_node **rb_link, *rb_parent; |
| |
| if (find_vma_links(mm, vma->vm_start, vma->vm_end, |
| &prev, &rb_link, &rb_parent)) |
| BUG(); |
| __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_rb_erase(vma, &mm->mm_rb); |
| prev->vm_next = next = vma->vm_next; |
| if (next) |
| next->vm_prev = prev; |
| |
| /* Kill the cache */ |
| vmacache_invalidate(mm); |
| } |
| |
| /* |
| * 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 rb_root *root = NULL; |
| struct anon_vma *anon_vma = NULL; |
| struct file *file = vma->vm_file; |
| bool start_changed = false, end_changed = false; |
| 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) { |
| int error; |
| |
| importer->anon_vma = exporter->anon_vma; |
| error = anon_vma_clone(importer, exporter); |
| if (error) |
| return error; |
| } |
| } |
| |
| if (file) { |
| mapping = file->f_mapping; |
| root = &mapping->i_mmap; |
| uprobe_munmap(vma, vma->vm_start, vma->vm_end); |
| |
| if (adjust_next) |
| uprobe_munmap(next, next->vm_start, next->vm_end); |
| |
| i_mmap_lock_write(mapping); |
| if (insert) { |
| /* |
| * Put into interval 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); |
| |
| anon_vma = vma->anon_vma; |
| if (!anon_vma && adjust_next) |
| anon_vma = next->anon_vma; |
| if (anon_vma) { |
| VM_BUG_ON_VMA(adjust_next && next->anon_vma && |
| anon_vma != next->anon_vma, next); |
| anon_vma_lock_write(anon_vma); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| if (adjust_next) |
| anon_vma_interval_tree_pre_update_vma(next); |
| } |
| |
| if (root) { |
| flush_dcache_mmap_lock(mapping); |
| vma_interval_tree_remove(vma, root); |
| if (adjust_next) |
| vma_interval_tree_remove(next, root); |
| } |
| |
| if (start != vma->vm_start) { |
| vma->vm_start = start; |
| start_changed = true; |
| } |
| if (end != vma->vm_end) { |
| vma->vm_end = end; |
| end_changed = true; |
| } |
| 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_interval_tree_insert(next, root); |
| vma_interval_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); |
| } else { |
| if (start_changed) |
| vma_gap_update(vma); |
| if (end_changed) { |
| if (!next) |
| mm->highest_vm_end = end; |
| else if (!adjust_next) |
| vma_gap_update(next); |
| } |
| } |
| |
| if (anon_vma) { |
| anon_vma_interval_tree_post_update_vma(vma); |
| if (adjust_next) |
| anon_vma_interval_tree_post_update_vma(next); |
| anon_vma_unlock_write(anon_vma); |
| } |
| if (mapping) |
| i_mmap_unlock_write(mapping); |
| |
| if (root) { |
| uprobe_mmap(vma); |
| |
| if (adjust_next) |
| uprobe_mmap(next); |
| } |
| |
| if (remove_next) { |
| if (file) { |
| uprobe_munmap(next, next->vm_start, next->vm_end); |
| fput(file); |
| } |
| 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. |
| */ |
| next = vma->vm_next; |
| if (remove_next == 2) |
| goto again; |
| else if (next) |
| vma_gap_update(next); |
| else |
| mm->highest_vm_end = end; |
| } |
| if (insert && file) |
| uprobe_mmap(insert); |
| |
| 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, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx) |
| { |
| /* |
| * VM_SOFTDIRTY should not prevent from VMA merging, if we |
| * match the flags but dirty bit -- the caller should mark |
| * merged VMA as dirty. If dirty bit won't be excluded from |
| * comparison, we increase pressue on the memory system forcing |
| * the kernel to generate new VMAs when old one could be |
| * extended instead. |
| */ |
| if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) |
| return 0; |
| if (vma->vm_file != file) |
| return 0; |
| if (vma->vm_ops && vma->vm_ops->close) |
| return 0; |
| if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) |
| 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, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && |
| 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, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && |
| is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| pgoff_t vm_pglen; |
| vm_pglen = vma_pages(vma); |
| 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, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx) |
| { |
| 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, |
| vm_userfaultfd_ctx)) { |
| /* |
| * 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, |
| vm_userfaultfd_ctx) && |
| 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, vm_flags); |
| 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, |
| vm_userfaultfd_ctx)) { |
| 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, vm_flags); |
| 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|VM_SOFTDIRTY)) && |
| 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 READ_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 = READ_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); |
| |
| mm->total_vm += pages; |
| |
| 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; |
| } |
| #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; |
| } |
| |
| static inline int mlock_future_check(struct mm_struct *mm, |
| unsigned long flags, |
| unsigned long len) |
| { |
| unsigned long locked, lock_limit; |
| |
| /* mlock MCL_FUTURE? */ |
| if (flags & VM_LOCKED) { |
| 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; |
| } |
| return 0; |
| } |
| |
| /* |
| * The caller must hold down_write(¤t->mm->mmap_sem). |
| */ |
| unsigned long do_mmap(struct file *file, unsigned long addr, |
| unsigned long len, unsigned long prot, |
| unsigned long flags, vm_flags_t vm_flags, |
| unsigned long pgoff, unsigned long *populate) |
| { |
| struct mm_struct *mm = current->mm; |
| |
| *populate = 0; |
| |
| if (!len) |
| return -EINVAL; |
| |
| /* |
| * 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 && path_noexec(&file->f_path))) |
| prot |= PROT_EXEC; |
| |
| 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; |
| |
| if (mlock_future_check(mm, vm_flags, len)) |
| return -EAGAIN; |
| |
| if (file) { |
| struct inode *inode = file_inode(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(file)) |
| 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 (path_noexec(&file->f_path)) { |
| if (vm_flags & VM_EXEC) |
| return -EPERM; |
| vm_flags &= ~VM_MAYEXEC; |
| } |
| |
| if (!file->f_op->mmap) |
| return -ENODEV; |
| if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| return -EINVAL; |
| break; |
| |
| default: |
| return -EINVAL; |
| } |
| } else { |
| switch (flags & MAP_TYPE) { |
| case MAP_SHARED: |
| if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| return -EINVAL; |
| /* |
| * 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; |
| } |
| } |
| |
| /* |
| * 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; |
| } |
| |
| addr = mmap_region(file, addr, len, vm_flags, pgoff); |
| if (!IS_ERR_VALUE(addr) && |
| ((vm_flags & VM_LOCKED) || |
| (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) |
| *populate = len; |
| return addr; |
| } |
| |
| 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); |
| file = fget(fd); |
| if (!file) |
| goto out; |
| if (is_file_hugepages(file)) |
| len = ALIGN(len, huge_page_size(hstate_file(file))); |
| retval = -EINVAL; |
| if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) |
| goto out_fput; |
| } else if (flags & MAP_HUGETLB) { |
| struct user_struct *user = NULL; |
| struct hstate *hs; |
| |
| hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK); |
| if (!hs) |
| return -EINVAL; |
| |
| len = ALIGN(len, huge_page_size(hs)); |
| /* |
| * 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, len, |
| VM_NORESERVE, |
| &user, HUGETLB_ANONHUGE_INODE, |
| (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| if (IS_ERR(file)) |
| return PTR_ERR(file); |
| } |
| |
| flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
| |
| retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
| out_fput: |
| 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; |
| const struct vm_operations_struct *vm_ops = vma->vm_ops; |
| |
| /* 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 (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) |
| return 1; |
| |
| /* The open routine did something to the protections that pgprot_modify |
| * won't preserve? */ |
| if (pgprot_val(vma->vm_page_prot) != |
| pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags))) |
| return 0; |
| |
| /* Do we need to track softdirty? */ |
| if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) |
| return 1; |
| |
| /* Specialty mapping? */ |
| if (vm_flags & VM_PFNMAP) |
| 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, vm_flags_t vm_flags, unsigned long pgoff) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma, *prev; |
| int error; |
| struct rb_node **rb_link, *rb_parent; |
| unsigned long charged = 0; |
| |
| /* Check against address space limit. */ |
| if (!may_expand_vm(mm, len >> PAGE_SHIFT)) { |
| unsigned long nr_pages; |
| |
| /* |
| * MAP_FIXED may remove pages of mappings that intersects with |
| * requested mapping. Account for the pages it would unmap. |
| */ |
| if (!(vm_flags & MAP_FIXED)) |
| return -ENOMEM; |
| |
| nr_pages = count_vma_pages_range(mm, addr, addr + len); |
| |
| if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) |
| return -ENOMEM; |
| } |
| |
| /* Clear old maps */ |
| error = -ENOMEM; |
| while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, |
| &rb_parent)) { |
| if (do_munmap(mm, addr, len)) |
| return -ENOMEM; |
| } |
| |
| /* |
| * 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, NULL_VM_UFFD_CTX); |
| 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); |
| |
| if (file) { |
| if (vm_flags & VM_DENYWRITE) { |
| error = deny_write_access(file); |
| if (error) |
| goto free_vma; |
| } |
| if (vm_flags & VM_SHARED) { |
| error = mapping_map_writable(file->f_mapping); |
| if (error) |
| goto allow_write_and_free_vma; |
| } |
| |
| /* ->mmap() can change vma->vm_file, but must guarantee that |
| * vma_link() below can deny write-access if VM_DENYWRITE is set |
| * and map writably if VM_SHARED is set. This usually means the |
| * new file must not have been exposed to user-space, yet. |
| */ |
| vma->vm_file = get_file(file); |
| error = file->f_op->mmap(file, vma); |
| if (error) |
| goto unmap_and_free_vma; |
| |
| /* Can addr have changed?? |
| * |
| * Answer: Yes, several device drivers can do it in their |
| * f_op->mmap method. -DaveM |
| * Bug: If addr is changed, prev, rb_link, rb_parent should |
| * be updated for vma_link() |
| */ |
| WARN_ON_ONCE(addr != vma->vm_start); |
| |
| addr = vma->vm_start; |
| vm_flags = vma->vm_flags; |
| } else if (vm_flags & VM_SHARED) { |
| error = shmem_zero_setup(vma); |
| if (error) |
| goto free_vma; |
| } |
| |
| vma_link(mm, vma, prev, rb_link, rb_parent); |
| /* Once vma denies write, undo our temporary denial count */ |
| if (file) { |
| if (vm_flags & VM_SHARED) |
| mapping_unmap_writable(file->f_mapping); |
| if (vm_flags & VM_DENYWRITE) |
| allow_write_access(file); |
| } |
| file = vma->vm_file; |
| out: |
| perf_event_mmap(vma); |
| |
| vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); |
| if (vm_flags & VM_LOCKED) { |
| if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || |
| vma == get_gate_vma(current->mm))) |
| mm->locked_vm += (len >> PAGE_SHIFT); |
| else |
| vma->vm_flags &= ~VM_LOCKED; |
| } |
| |
| if (file) |
| uprobe_mmap(vma); |
| |
| /* |
| * New (or expanded) vma always get soft dirty status. |
| * Otherwise user-space soft-dirty page tracker won't |
| * be able to distinguish situation when vma area unmapped, |
| * then new mapped in-place (which must be aimed as |
| * a completely new data area). |
| */ |
| vma->vm_flags |= VM_SOFTDIRTY; |
| |
| vma_set_page_prot(vma); |
| |
| return addr; |
| |
| unmap_and_free_vma: |
| 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; |
| if (vm_flags & VM_SHARED) |
| mapping_unmap_writable(file->f_mapping); |
| allow_write_and_free_vma: |
| if (vm_flags & VM_DENYWRITE) |
| allow_write_access(file); |
| free_vma: |
| kmem_cache_free(vm_area_cachep, vma); |
| unacct_error: |
| if (charged) |
| vm_unacct_memory(charged); |
| return error; |
| } |
| |
| unsigned long unmapped_area(struct vm_unmapped_area_info *info) |
| { |
| /* |
| * We implement the search by looking for an rbtree node that |
| * immediately follows a suitable gap. That is, |
| * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; |
| * - gap_end = vma->vm_start >= info->low_limit + length; |
| * - gap_end - gap_start >= length |
| */ |
| |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long length, low_limit, high_limit, gap_start, gap_end; |
| |
| /* Adjust search length to account for worst case alignment overhead */ |
| length = info->length + info->align_mask; |
| if (length < info->length) |
| return -ENOMEM; |
| |
| /* Adjust search limits by the desired length */ |
| if (info->high_limit < length) |
| return -ENOMEM; |
| high_limit = info->high_limit - length; |
| |
| if (info->low_limit > high_limit) |
| return -ENOMEM; |
| low_limit = info->low_limit + length; |
| |
| /* Check if rbtree root looks promising */ |
| if (RB_EMPTY_ROOT(&mm->mm_rb)) |
| goto check_highest; |
| vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); |
| if (vma->rb_subtree_gap < length) |
| goto check_highest; |
| |
| while (true) { |
| /* Visit left subtree if it looks promising */ |
| gap_end = vma->vm_start; |
| if (gap_end >= low_limit && vma->vm_rb.rb_left) { |
| struct vm_area_struct *left = |
| rb_entry(vma->vm_rb.rb_left, |
| struct vm_area_struct, vm_rb); |
| if (left->rb_subtree_gap >= length) { |
| vma = left; |
| continue; |
| } |
| } |
| |
| gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; |
| check_current: |
| /* Check if current node has a suitable gap */ |
| if (gap_start > high_limit) |
| return -ENOMEM; |
| if (gap_end >= low_limit && gap_end - gap_start >= length) |
| goto found; |
| |
| /* Visit right subtree if it looks promising */ |
| if (vma->vm_rb.rb_right) { |
| struct vm_area_struct *right = |
| rb_entry(vma->vm_rb.rb_right, |
| struct vm_area_struct, vm_rb); |
| if (right->rb_subtree_gap >= length) { |
| vma = right; |
| continue; |
| } |
| } |
| |
| /* Go back up the rbtree to find next candidate node */ |
| while (true) { |
| struct rb_node *prev = &vma->vm_rb; |
| if (!rb_parent(prev)) |
| goto check_highest; |
| vma = rb_entry(rb_parent(prev), |
| struct vm_area_struct, vm_rb); |
| if (prev == vma->vm_rb.rb_left) { |
| gap_start = vma->vm_prev->vm_end; |
| gap_end = vma->vm_start; |
| goto check_current; |
| } |
| } |
| } |
| |
| check_highest: |
| /* Check highest gap, which does not precede any rbtree node */ |
| gap_start = mm->highest_vm_end; |
| gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ |
| if (gap_start > high_limit) |
| return -ENOMEM; |
| |
| found: |
| /* We found a suitable gap. Clip it with the original low_limit. */ |
| if (gap_start < info->low_limit) |
| gap_start = info->low_limit; |
| |
| /* Adjust gap address to the desired alignment */ |
| gap_start += (info->align_offset - gap_start) & info->align_mask; |
| |
| VM_BUG_ON(gap_start + info->length > info->high_limit); |
| VM_BUG_ON(gap_start + info->length > gap_end); |
| return gap_start; |
| } |
| |
| unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long length, low_limit, high_limit, gap_start, gap_end; |
| |
| /* Adjust search length to account for worst case alignment overhead */ |
| length = info->length + info->align_mask; |
| if (length < info->length) |
| return -ENOMEM; |
| |
| /* |
| * Adjust search limits by the desired length. |
| * See implementation comment at top of unmapped_area(). |
| */ |
| gap_end = info->high_limit; |
| if (gap_end < length) |
| return -ENOMEM; |
| high_limit = gap_end - length; |
| |
| if (info->low_limit > high_limit) |
| return -ENOMEM; |
| low_limit = info->low_limit + length; |
| |
| /* Check highest gap, which does not precede any rbtree node */ |
| gap_start = mm->highest_vm_end; |
| if (gap_start <= high_limit) |
| goto found_highest; |
| |
| /* Check if rbtree root looks promising */ |
| if (RB_EMPTY_ROOT(&mm->mm_rb)) |
| return -ENOMEM; |
| vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); |
| if (vma->rb_subtree_gap < length) |
| return -ENOMEM; |
| |
| while (true) { |
| /* Visit right subtree if it looks promising */ |
| gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; |
| if (gap_start <= high_limit && vma->vm_rb.rb_right) { |
| struct vm_area_struct *right = |
| rb_entry(vma->vm_rb.rb_right, |
| struct vm_area_struct, vm_rb); |
| if (right->rb_subtree_gap >= length) { |
| vma = right; |
| continue; |
| } |
| } |
| |
| check_current: |
| /* Check if current node has a suitable gap */ |
| gap_end = vma->vm_start; |
| if (gap_end < low_limit) |
| return -ENOMEM; |
| if (gap_start <= high_limit && gap_end - gap_start >= length) |
| goto found; |
| |
| /* Visit left subtree if it looks promising */ |
| if (vma->vm_rb.rb_left) { |
| struct vm_area_struct *left = |
| rb_entry(vma->vm_rb.rb_left, |
| struct vm_area_struct, vm_rb); |
| if (left->rb_subtree_gap >= length) { |
| vma = left; |
| continue; |
| } |
| } |
| |
| /* Go back up the rbtree to find next candidate node */ |
| while (true) { |
| struct rb_node *prev = &vma->vm_rb; |
| if (!rb_parent(prev)) |
| return -ENOMEM; |
| vma = rb_entry(rb_parent(prev), |
| struct vm_area_struct, vm_rb); |
| if (prev == vma->vm_rb.rb_right) { |
| gap_start = vma->vm_prev ? |
| vma->vm_prev->vm_end : 0; |
| goto check_current; |
| } |
| } |
| } |
| |
| found: |
| /* We found a suitable gap. Clip it with the original high_limit. */ |
| if (gap_end > info->high_limit) |
| gap_end = info->high_limit; |
| |
| found_highest: |
| /* Compute highest gap address at the desired alignment */ |
| gap_end -= info->length; |
| gap_end -= (gap_end - info->align_offset) & info->align_mask; |
| |
| VM_BUG_ON(gap_end < info->low_limit); |
| VM_BUG_ON(gap_end < gap_start); |
| return gap_end; |
| } |
| |
| /* 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; |
| struct vm_unmapped_area_info info; |
| |
| if (len > TASK_SIZE - mmap_min_addr) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma(mm, addr); |
| if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && |
| (!vma || addr + len <= vma->vm_start)) |
| return addr; |
| } |
| |
| info.flags = 0; |
| info.length = len; |
| info.low_limit = mm->mmap_base; |
| info.high_limit = TASK_SIZE; |
| info.align_mask = 0; |
| return vm_unmapped_area(&info); |
| } |
| #endif |
| |
| /* |
| * 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; |
| struct vm_unmapped_area_info info; |
| |
| /* requested length too big for entire address space */ |
| if (len > TASK_SIZE - mmap_min_addr) |
| 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 && addr >= mmap_min_addr && |
| (!vma || addr + len <= vma->vm_start)) |
| return addr; |
| } |
| |
| info.flags = VM_UNMAPPED_AREA_TOPDOWN; |
| info.length = len; |
| info.low_limit = max(PAGE_SIZE, mmap_min_addr); |
| info.high_limit = mm->mmap_base; |
| info.align_mask = 0; |
| addr = vm_unmapped_area(&info); |
| |
| /* |
| * 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. |
| */ |
| if (addr & ~PAGE_MASK) { |
| VM_BUG_ON(addr != -ENOMEM); |
| info.flags = 0; |
| info.low_limit = TASK_UNMAPPED_BASE; |
| info.high_limit = TASK_SIZE; |
| addr = vm_unmapped_area(&info); |
| } |
| |
| return addr; |
| } |
| #endif |
| |
| 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->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; |
| |
| addr = arch_rebalance_pgtables(addr, len); |
| error = security_mmap_addr(addr); |
| return error ? error : addr; |
| } |
| |
| 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 rb_node *rb_node; |
| struct vm_area_struct *vma; |
| |
| /* Check the cache first. */ |
| vma = vmacache_find(mm, addr); |
| if (likely(vma)) |
| return vma; |
| |
| rb_node = mm->mm_rb.rb_node; |
| |
| while (rb_node) { |
| struct vm_area_struct *tmp; |
| |
| tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); |
| |
| if (tmp->vm_end > addr) { |
| vma = tmp; |
| if (tmp->vm_start <= addr) |
| break; |
| rb_node = rb_node->rb_left; |
| } else |
| rb_node = rb_node->rb_right; |
| } |
| |
| if (vma) |
| vmacache_update(addr, 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, actual_size; |
| |
| /* address space limit tests */ |
| if (!may_expand_vm(mm, grow)) |
| return -ENOMEM; |
| |
| /* Stack limit test */ |
| actual_size = size; |
| if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN))) |
| actual_size -= PAGE_SIZE; |
| if (actual_size > READ_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 = READ_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 */ |
| 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_gap_update() doesn't support concurrent |
| * updates, but we only hold a shared mmap_sem |
| * lock here, so we need to protect against |
| * concurrent vma expansions. |
| * vma_lock_anon_vma() doesn't help here, as |
| * we don't guarantee that all growable vmas |
| * in a mm share the same root anon vma. |
| * So, we reuse mm->page_table_lock to guard |
| * against concurrent vma expansions. |
| */ |
| spin_lock(&vma->vm_mm->page_table_lock); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| vma->vm_end = address; |
| anon_vma_interval_tree_post_update_vma(vma); |
| if (vma->vm_next) |
| vma_gap_update(vma->vm_next); |
| else |
| vma->vm_mm->highest_vm_end = address; |
| spin_unlock(&vma->vm_mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| vma_unlock_anon_vma(vma); |
| khugepaged_enter_vma_merge(vma, vma->vm_flags); |
| validate_mm(vma->vm_mm); |
| 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_mmap_addr(address); |
| 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_gap_update() doesn't support concurrent |
| * updates, but we only hold a shared mmap_sem |
| * lock here, so we need to protect against |
| * concurrent vma expansions. |
| * vma_lock_anon_vma() doesn't help here, as |
| * we don't guarantee that all growable vmas |
| * in a mm share the same root anon vma. |
| * So, we reuse mm->page_table_lock to guard |
| * against concurrent vma expansions. |
| */ |
| spin_lock(&vma->vm_mm->page_table_lock); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| vma->vm_start = address; |
| vma->vm_pgoff -= grow; |
| anon_vma_interval_tree_post_update_vma(vma); |
| vma_gap_update(vma); |
| spin_unlock(&vma->vm_mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| vma_unlock_anon_vma(vma); |
| khugepaged_enter_vma_merge(vma, vma->vm_flags); |
| validate_mm(vma->vm_mm); |
| return error; |
| } |
| |
| /* |
| * Note how expand_stack() refuses to expand the stack all the way to |
| * abut the next virtual mapping, *unless* that mapping itself is also |
| * a stack mapping. We want to leave room for a guard page, after all |
| * (the guard page itself is not added here, that is done by the |
| * actual page faulting logic) |
| * |
| * This matches the behavior of the guard page logic (see mm/memory.c: |
| * check_stack_guard_page()), which only allows the guard page to be |
| * removed under these circumstances. |
| */ |
| #ifdef CONFIG_STACK_GROWSUP |
| int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| { |
| struct vm_area_struct *next; |
| |
| address &= PAGE_MASK; |
| next = vma->vm_next; |
| if (next && next->vm_start == address + PAGE_SIZE) { |
| if (!(next->vm_flags & VM_GROWSUP)) |
| return -ENOMEM; |
| } |
| 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) |
| populate_vma_page_range(prev, addr, prev->vm_end, NULL); |
| return prev; |
| } |
| #else |
| int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| { |
| struct vm_area_struct *prev; |
| |
| address &= PAGE_MASK; |
| prev = vma->vm_prev; |
| if (prev && prev->vm_end == address) { |
| if (!(prev->vm_flags & VM_GROWSDOWN)) |
| return -ENOMEM; |
| } |
| 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) |
| populate_vma_page_range(vma, addr, start, NULL); |
| return vma; |
| } |
| #endif |
| |
| EXPORT_SYMBOL_GPL(find_extend_vma); |
| |
| /* |
| * 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) |
| { |
| unsigned long nr_accounted = 0; |
| |
| /* Update high watermark before we lower total_vm */ |
| update_hiwater_vm(mm); |
| do { |
| long nrpages = vma_pages(vma); |
| |
| if (vma->vm_flags & VM_ACCOUNT) |
| nr_accounted += nrpages; |
| vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); |
| vma = remove_vma(vma); |
| } while (vma); |
| vm_unacct_memory(nr_accounted); |
| 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; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm, start, end); |
| update_hiwater_rss(mm); |
| unmap_vmas(&tlb, vma, start, end); |
| free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, |
| next ? next->vm_start : USER_PGTABLES_CEILING); |
| 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; |
| |
| insertion_point = (prev ? &prev->vm_next : &mm->mmap); |
| vma->vm_prev = NULL; |
| do { |
| vma_rb_erase(vma, &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; |
| vma_gap_update(vma); |
| } else |
| mm->highest_vm_end = prev ? prev->vm_end : 0; |
| tail_vma->vm_next = NULL; |
| |
| /* Kill the cache */ |
| vmacache_invalidate(mm); |
| } |
| |
| /* |
| * __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 vm_area_struct *new; |
| int err; |
| |
| 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) |
| return -ENOMEM; |
| |
| /* 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); |
| } |
| |
| err = vma_dup_policy(vma, new); |
| if (err) |
| goto out_free_vma; |
| |
| err = anon_vma_clone(new, vma); |
| if (err) |
| goto out_free_mpol; |
| |
| if (new->vm_file) |
| get_file(new->vm_file); |
| |
| 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) |
| fput(new->vm_file); |
| unlink_anon_vmas(new); |
| out_free_mpol: |
| mpol_put(vma_policy(new)); |
| out_free_vma: |
| kmem_cache_free(vm_area_cachep, new); |
| 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; |
| |
| len = PAGE_ALIGN(len); |
| if (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); |
| |
| arch_unmap(mm, vma, start, end); |
| |
| /* Fix up all other VM information */ |
| remove_vma_list(mm, vma); |
| |
| return 0; |
| } |
| |
| 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); |
| } |
| |
| |
| /* |
| * Emulation of deprecated remap_file_pages() syscall. |
| */ |
| SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, |
| unsigned long, prot, unsigned long, pgoff, unsigned long, flags) |
| { |
| |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long populate = 0; |
| unsigned long ret = -EINVAL; |
| struct file *file; |
| |
| pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. " |
| "See Documentation/vm/remap_file_pages.txt.\n", |
| current->comm, current->pid); |
| |
| if (prot) |
| return ret; |
| start = start & PAGE_MASK; |
| size = size & PAGE_MASK; |
| |
| if (start + size <= start) |
| return ret; |
| |
| /* Does pgoff wrap? */ |
| if (pgoff + (size >> PAGE_SHIFT) < pgoff) |
| return ret; |
| |
| down_write(&mm->mmap_sem); |
| vma = find_vma(mm, start); |
| |
| if (!vma || !(vma->vm_flags & VM_SHARED)) |
| goto out; |
| |
| if (start < vma->vm_start || start + size > vma->vm_end) |
| goto out; |
| |
| if (pgoff == linear_page_index(vma, start)) { |
| ret = 0; |
| goto out; |
| } |
| |
| prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; |
| prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; |
| prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; |
| |
| flags &= MAP_NONBLOCK; |
| flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; |
| if (vma->vm_flags & VM_LOCKED) { |
| flags |= MAP_LOCKED; |
| /* drop PG_Mlocked flag for over-mapped range */ |
| munlock_vma_pages_range(vma, start, start + size); |
| } |
| |
| file = get_file(vma->vm_file); |
| ret = do_mmap_pgoff(vma->vm_file, start, size, |
| prot, flags, pgoff, &populate); |
| fput(file); |
| out: |
| up_write(&mm->mmap_sem); |
| if (populate) |
| mm_populate(ret, populate); |
| if (!IS_ERR_VALUE(ret)) |
| ret = 0; |
| 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. |
| */ |
| 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; |
| |
| 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; |
| |
| error = mlock_future_check(mm, mm->def_flags, len); |
| if (error) |
| return error; |
| |
| /* |
| * 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 |
| */ |
| while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, |
| &rb_parent)) { |
| if (do_munmap(mm, addr, len)) |
| return -ENOMEM; |
| } |
| |
| /* 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, NULL_VM_UFFD_CTX); |
| 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) |
| mm->locked_vm += (len >> PAGE_SHIFT); |
| vma->vm_flags |= VM_SOFTDIRTY; |
| return addr; |
| } |
| |
| unsigned long vm_brk(unsigned long addr, unsigned long len) |
| { |
| struct mm_struct *mm = current->mm; |
| unsigned long ret; |
| bool populate; |
| |
| down_write(&mm->mmap_sem); |
| ret = do_brk(addr, len); |
| populate = ((mm->def_flags & VM_LOCKED) != 0); |
| up_write(&mm->mmap_sem); |
| if (populate) |
| mm_populate(addr, len); |
| 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, 0, -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); |
| |
| free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); |
| 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) { |
| if (vma->vm_flags & VM_ACCOUNT) |
| nr_accounted += vma_pages(vma); |
| vma = remove_vma(vma); |
| } |
| vm_unacct_memory(nr_accounted); |
| } |
| |
| /* 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_rwsem is taken here. |
| */ |
| int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| { |
| struct vm_area_struct *prev; |
| struct rb_node **rb_link, *rb_parent; |
| |
| if (find_vma_links(mm, vma->vm_start, vma->vm_end, |
| &prev, &rb_link, &rb_parent)) |
| return -ENOMEM; |
| if ((vma->vm_flags & VM_ACCOUNT) && |
| security_vm_enough_memory_mm(mm, vma_pages(vma))) |
| return -ENOMEM; |
| |
| /* |
| * 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_is_anonymous(vma)) { |
| BUG_ON(vma->anon_vma); |
| vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
| } |
| |
| 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, |
| bool *need_rmap_locks) |
| { |
| 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; |
| 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_is_anonymous(vma) && !vma->anon_vma)) { |
| pgoff = addr >> PAGE_SHIFT; |
| faulted_in_anon_vma = false; |
| } |
| |
| if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) |
| return NULL; /* should never get here */ |
| new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, |
| vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), |
| vma->vm_userfaultfd_ctx); |
| 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_VMA(faulted_in_anon_vma, new_vma); |
| *vmap = vma = new_vma; |
| } |
| *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); |
| } else { |
| new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| if (!new_vma) |
| goto out; |
| *new_vma = *vma; |
| new_vma->vm_start = addr; |
| new_vma->vm_end = addr + len; |
| new_vma->vm_pgoff = pgoff; |
| if (vma_dup_policy(vma, new_vma)) |
| goto out_free_vma; |
| INIT_LIST_HEAD(&new_vma->anon_vma_chain); |
| if (anon_vma_clone(new_vma, vma)) |
| goto out_free_mempol; |
| if (new_vma->vm_file) |
| get_file(new_vma->vm_file); |
| 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); |
| *need_rmap_locks = false; |
| } |
| return new_vma; |
| |
| out_free_mempol: |
| mpol_put(vma_policy(new_vma)); |
| out_free_vma: |
| kmem_cache_free(vm_area_cachep, new_vma); |
| out: |
| 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); |
| |
| /* |
| * Having a close hook prevents vma merging regardless of flags. |
| */ |
| static void special_mapping_close(struct vm_area_struct *vma) |
| { |
| } |
| |
| static const char *special_mapping_name(struct vm_area_struct *vma) |
| { |
| return ((struct vm_special_mapping *)vma->vm_private_data)->name; |
| } |
| |
| static const struct vm_operations_struct special_mapping_vmops = { |
| .close = special_mapping_close, |
| .fault = special_mapping_fault, |
| .name = special_mapping_name, |
| }; |
| |
| static const struct vm_operations_struct legacy_special_mapping_vmops = { |
| .close = special_mapping_close, |
| .fault = special_mapping_fault, |
| }; |
| |
| static int special_mapping_fault(struct vm_area_struct *vma, |
| struct vm_fault *vmf) |
| { |
| pgoff_t pgoff; |
| struct page **pages; |
| |
| if (vma->vm_ops == &legacy_special_mapping_vmops) |
| pages = vma->vm_private_data; |
| else |
| pages = ((struct vm_special_mapping *)vma->vm_private_data)-> |
| pages; |
| |
| for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) |
| pgoff--; |
| |
| if (*pages) { |
| struct page *page = *pages; |
| get_page(page); |
| vmf->page = page; |
| return 0; |
| } |
| |
| return VM_FAULT_SIGBUS; |
| } |
| |
| static struct vm_area_struct *__install_special_mapping( |
| struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, const struct vm_operations_struct *ops, |
| void *priv) |
| { |
| int ret; |
| struct vm_area_struct *vma; |
| |
| vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| if (unlikely(vma == NULL)) |
| return ERR_PTR(-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 | VM_SOFTDIRTY; |
| vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| |
| vma->vm_ops = ops; |
| vma->vm_private_data = priv; |
| |
| ret = insert_vm_struct(mm, vma); |
| if (ret) |
| goto out; |
| |
| mm->total_vm += len >> PAGE_SHIFT; |
| |
| perf_event_mmap(vma); |
| |
| return vma; |
| |
| out: |
| kmem_cache_free(vm_area_cachep, vma); |
| return ERR_PTR(ret); |
| } |
| |
| /* |
| * 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. |
| */ |
| struct vm_area_struct *_install_special_mapping( |
| struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, const struct vm_special_mapping *spec) |
| { |
| return __install_special_mapping(mm, addr, len, vm_flags, |
| &special_mapping_vmops, (void *)spec); |
| } |
| |
| 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 = __install_special_mapping( |
| mm, addr, len, vm_flags, &legacy_special_mapping_vmops, |
| (void *)pages); |
| |
| return PTR_ERR_OR_ZERO(vma); |
| } |
| |
| 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->rb_root.rb_node)) { |
| /* |
| * The LSB of head.next can't change from under us |
| * because we hold the mm_all_locks_mutex. |
| */ |
| down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); |
| /* |
| * We can safely modify head.next after taking the |
| * anon_vma->root->rwsem. 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->rwsem. |
| */ |
| if (__test_and_set_bit(0, (unsigned long *) |
| &anon_vma->root->rb_root.rb_node)) |
| 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(); |
| down_write_nest_lock(&mapping->i_mmap_rwsem, &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. 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->rb_root.rb_node 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_rwsem or anon_vma->rwsem 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->rb_root.rb_node)) { |
| /* |
| * 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->rb_root 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->rwsem. |
| */ |
| if (!__test_and_clear_bit(0, (unsigned long *) |
| &anon_vma->root->rb_root.rb_node)) |
| BUG(); |
| anon_vma_unlock_write(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. |
| */ |
| i_mmap_unlock_write(mapping); |
| 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, GFP_KERNEL); |
| VM_BUG_ON(ret); |
| } |
| |
| /* |
| * Initialise sysctl_user_reserve_kbytes. |
| * |
| * This is intended to prevent a user from starting a single memory hogging |
| * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
| * mode. |
| * |
| * The default value is min(3% of free memory, 128MB) |
| * 128MB is enough to recover with sshd/login, bash, and top/kill. |
| */ |
| static int init_user_reserve(void) |
| { |
| unsigned long free_kbytes; |
| |
| free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| |
| sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
| return 0; |
| } |
| subsys_initcall(init_user_reserve); |
| |
| /* |
| * Initialise sysctl_admin_reserve_kbytes. |
| * |
| * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
| * to log in and kill a memory hogging process. |
| * |
| * Systems with more than 256MB will reserve 8MB, enough to recover |
| * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
| * only reserve 3% of free pages by default. |
| */ |
| static int init_admin_reserve(void) |
| { |
| unsigned long free_kbytes; |
| |
| free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| |
| sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
| return 0; |
| } |
| subsys_initcall(init_admin_reserve); |
| |
| /* |
| * Reinititalise user and admin reserves if memory is added or removed. |
| * |
| * The default user reserve max is 128MB, and the default max for the |
| * admin reserve is 8MB. These are usually, but not always, enough to |
| * enable recovery from a memory hogging process using login/sshd, a shell, |
| * and tools like top. It may make sense to increase or even disable the |
| * reserve depending on the existence of swap or variations in the recovery |
| * tools. So, the admin may have changed them. |
| * |
| * If memory is added and the reserves have been eliminated or increased above |
| * the default max, then we'll trust the admin. |
| * |
| * If memory is removed and there isn't enough free memory, then we |
| * need to reset the reserves. |
| * |
| * Otherwise keep the reserve set by the admin. |
| */ |
| static int reserve_mem_notifier(struct notifier_block *nb, |
| unsigned long action, void *data) |
| { |
| unsigned long tmp, free_kbytes; |
| |
| switch (action) { |
| case MEM_ONLINE: |
| /* Default max is 128MB. Leave alone if modified by operator. */ |
| tmp = sysctl_user_reserve_kbytes; |
| if (0 < tmp && tmp < (1UL << 17)) |
| init_user_reserve(); |
| |
| /* Default max is 8MB. Leave alone if modified by operator. */ |
| tmp = sysctl_admin_reserve_kbytes; |
| if (0 < tmp && tmp < (1UL << 13)) |
| init_admin_reserve(); |
| |
| break; |
| case MEM_OFFLINE: |
| free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| |
| if (sysctl_user_reserve_kbytes > free_kbytes) { |
| init_user_reserve(); |
| pr_info("vm.user_reserve_kbytes reset to %lu\n", |
| sysctl_user_reserve_kbytes); |
| } |
| |
| if (sysctl_admin_reserve_kbytes > free_kbytes) { |
| init_admin_reserve(); |
| pr_info("vm.admin_reserve_kbytes reset to %lu\n", |
| sysctl_admin_reserve_kbytes); |
| } |
| break; |
| default: |
| break; |
| } |
| return NOTIFY_OK; |
| } |
| |
| static struct notifier_block reserve_mem_nb = { |
| .notifier_call = reserve_mem_notifier, |
| }; |
| |
| static int __meminit init_reserve_notifier(void) |
| { |
| if (register_hotmemory_notifier(&reserve_mem_nb)) |
| pr_err("Failed registering memory add/remove notifier for admin reserve\n"); |
| |
| return 0; |
| } |
| subsys_initcall(init_reserve_notifier); |