| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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/mm_inline.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/pgsize_migration.h> |
| #include <linux/personality.h> |
| #include <linux/security.h> |
| #include <linux/hugetlb.h> |
| #include <linux/shmem_fs.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/notifier.h> |
| #include <linux/memory.h> |
| #include <linux/printk.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/moduleparam.h> |
| #include <linux/pkeys.h> |
| #include <linux/oom.h> |
| #include <linux/sched/mm.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/cacheflush.h> |
| #include <asm/tlb.h> |
| #include <asm/mmu_context.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/mmap.h> |
| #undef CREATE_TRACE_POINTS |
| #include <trace/hooks/mm.h> |
| #include "internal.h" |
| |
| #ifndef arch_mmap_check |
| #define arch_mmap_check(addr, len, flags) (0) |
| #endif |
| |
| #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS |
| const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; |
| const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; |
| int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; |
| #endif |
| #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; |
| const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; |
| int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; |
| #endif |
| |
| static bool ignore_rlimit_data; |
| core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); |
| |
| 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] __ro_after_init = { |
| __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, |
| __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 |
| }; |
| |
| #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT |
| static inline pgprot_t arch_filter_pgprot(pgprot_t prot) |
| { |
| return prot; |
| } |
| #endif |
| |
| pgprot_t vm_get_page_prot(unsigned long vm_flags) |
| { |
| pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags & |
| (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | |
| pgprot_val(arch_vm_get_page_prot(vm_flags))); |
| |
| return arch_filter_pgprot(ret); |
| } |
| 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; |
| pgprot_t vm_page_prot; |
| |
| vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); |
| if (vma_wants_writenotify(vma, vm_page_prot)) { |
| vm_flags &= ~VM_SHARED; |
| vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); |
| } |
| /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */ |
| WRITE_ONCE(vma->vm_page_prot, vm_page_prot); |
| } |
| |
| /* |
| * 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) |
| allow_write_access(file); |
| 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); |
| } |
| } |
| |
| static void __free_vma(struct vm_area_struct *vma) |
| { |
| if (vma->vm_file) |
| fput(vma->vm_file); |
| mpol_put(vma_policy(vma)); |
| vm_area_free(vma); |
| } |
| |
| #ifdef CONFIG_SPECULATIVE_PAGE_FAULT |
| void put_vma(struct vm_area_struct *vma) |
| { |
| if (atomic_dec_and_test(&vma->vm_ref_count)) |
| __free_vma(vma); |
| } |
| #else |
| static inline void put_vma(struct vm_area_struct *vma) |
| { |
| __free_vma(vma); |
| } |
| #endif |
| |
| /* |
| * 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); |
| put_vma(vma); |
| return next; |
| } |
| |
| static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, |
| struct list_head *uf); |
| SYSCALL_DEFINE1(brk, unsigned long, brk) |
| { |
| unsigned long retval; |
| unsigned long newbrk, oldbrk, origbrk; |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *next; |
| unsigned long min_brk; |
| bool populate; |
| bool downgraded = false; |
| LIST_HEAD(uf); |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| origbrk = mm->brk; |
| |
| #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) { |
| mm->brk = brk; |
| goto success; |
| } |
| |
| /* |
| * Always allow shrinking brk. |
| * __do_munmap() may downgrade mmap_lock to read. |
| */ |
| if (brk <= mm->brk) { |
| int ret; |
| |
| /* |
| * mm->brk must to be protected by write mmap_lock so update it |
| * before downgrading mmap_lock. When __do_munmap() fails, |
| * mm->brk will be restored from origbrk. |
| */ |
| mm->brk = brk; |
| ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); |
| if (ret < 0) { |
| mm->brk = origbrk; |
| goto out; |
| } else if (ret == 1) { |
| downgraded = true; |
| } |
| goto success; |
| } |
| |
| /* Check against existing mmap mappings. */ |
| next = find_vma(mm, oldbrk); |
| if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) |
| goto out; |
| |
| /* Ok, looks good - let it rip. */ |
| if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0) |
| goto out; |
| mm->brk = brk; |
| |
| success: |
| populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; |
| if (downgraded) |
| mmap_read_unlock(mm); |
| else |
| mmap_write_unlock(mm); |
| userfaultfd_unmap_complete(mm, &uf); |
| if (populate) |
| mm_populate(oldbrk, newbrk - oldbrk); |
| return brk; |
| |
| out: |
| retval = origbrk; |
| mmap_write_unlock(mm); |
| return retval; |
| } |
| |
| static inline unsigned long vma_compute_gap(struct vm_area_struct *vma) |
| { |
| unsigned long gap, prev_end; |
| |
| /* |
| * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we |
| * allow two stack_guard_gaps between them here, and when choosing |
| * an unmapped area; whereas when expanding we only require one. |
| * That's a little inconsistent, but keeps the code here simpler. |
| */ |
| gap = vm_start_gap(vma); |
| if (vma->vm_prev) { |
| prev_end = vm_end_gap(vma->vm_prev); |
| if (gap > prev_end) |
| gap -= prev_end; |
| else |
| gap = 0; |
| } |
| return gap; |
| } |
| |
| #ifdef CONFIG_DEBUG_VM_RB |
| static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma) |
| { |
| unsigned long max = vma_compute_gap(vma), subtree_gap; |
| 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; |
| } |
| |
| static int browse_rb(struct mm_struct *mm) |
| { |
| struct rb_root *root = &mm->mm_rb; |
| 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; |
| } |
| spin_lock(&mm->page_table_lock); |
| 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; |
| } |
| spin_unlock(&mm->page_table_lock); |
| 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 *anon_vma = vma->anon_vma; |
| struct anon_vma_chain *avc; |
| |
| if (anon_vma) { |
| anon_vma_lock_read(anon_vma); |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_verify(avc); |
| anon_vma_unlock_read(anon_vma); |
| } |
| |
| highest_address = vm_end_gap(vma); |
| 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); |
| 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_MAX(static, vma_gap_callbacks, |
| struct vm_area_struct, vm_rb, |
| unsigned long, rb_subtree_gap, vma_compute_gap) |
| #ifdef CONFIG_SPECULATIVE_PAGE_FAULT |
| #define mm_rb_write_lock(mm) write_lock(&(mm)->mm_rb_lock) |
| #define mm_rb_write_unlock(mm) write_unlock(&(mm)->mm_rb_lock) |
| #else |
| #define mm_rb_write_lock(mm) do { } while (0) |
| #define mm_rb_write_unlock(mm) do { } while (0) |
| #endif /* CONFIG_SPECULATIVE_PAGE_FAULT */ |
| |
| /* |
| * 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_MAX() already created |
| * a callback function that does exactly what we want. |
| */ |
| vma_gap_callbacks_propagate(&vma->vm_rb, NULL); |
| } |
| |
| static inline void vma_rb_insert(struct vm_area_struct *vma, |
| struct mm_struct *mm) |
| { |
| struct rb_root *root = &mm->mm_rb; |
| |
| /* 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 mm_struct *mm) |
| { |
| struct rb_root *root = &mm->mm_rb; |
| /* |
| * Note rb_erase_augmented is a fairly large inline function, |
| * so make sure we instantiate it only once with our desired |
| * augmented rbtree callbacks. |
| */ |
| mm_rb_write_lock(mm); |
| rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); |
| mm_rb_write_unlock(mm); /* wmb */ |
| |
| /* |
| * Ensure the removal is complete before clearing the node. |
| * Matched by vma_has_changed()/handle_speculative_fault(). |
| */ |
| RB_CLEAR_NODE(&vma->vm_rb); |
| } |
| |
| static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma, |
| struct mm_struct *mm, |
| struct vm_area_struct *ignore) |
| { |
| /* |
| * All rb_subtree_gap values must be consistent prior to erase, |
| * with the possible exception of |
| * |
| * a. the "next" vma being erased if next->vm_start was reduced in |
| * __vma_adjust() -> __vma_unlink() |
| * b. the vma being erased in detach_vmas_to_be_unmapped() -> |
| * vma_rb_erase() |
| */ |
| validate_mm_rb(&mm->mm_rb, ignore); |
| |
| __vma_rb_erase(vma, mm); |
| } |
| |
| static __always_inline void vma_rb_erase(struct vm_area_struct *vma, |
| struct mm_struct *mm) |
| { |
| vma_rb_erase_ignore(vma, mm, vma); |
| } |
| |
| /* |
| * 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_lock 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; |
| } |
| |
| /* |
| * vma_next() - Get the next VMA. |
| * @mm: The mm_struct. |
| * @vma: The current vma. |
| * |
| * If @vma is NULL, return the first vma in the mm. |
| * |
| * Returns: The next VMA after @vma. |
| */ |
| static inline struct vm_area_struct *vma_next(struct mm_struct *mm, |
| struct vm_area_struct *vma) |
| { |
| if (!vma) |
| return mm->mmap; |
| |
| return vma->vm_next; |
| } |
| |
| /* |
| * munmap_vma_range() - munmap VMAs that overlap a range. |
| * @mm: The mm struct |
| * @start: The start of the range. |
| * @len: The length of the range. |
| * @pprev: pointer to the pointer that will be set to previous vm_area_struct |
| * @rb_link: the rb_node |
| * @rb_parent: the parent rb_node |
| * |
| * Find all the vm_area_struct that overlap from @start to |
| * @end and munmap them. Set @pprev to the previous vm_area_struct. |
| * |
| * Returns: -ENOMEM on munmap failure or 0 on success. |
| */ |
| static inline int |
| munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len, |
| struct vm_area_struct **pprev, struct rb_node ***link, |
| struct rb_node **parent, struct list_head *uf) |
| { |
| |
| while (find_vma_links(mm, start, start + len, pprev, link, parent)) |
| if (do_munmap(mm, start, len, uf)) |
| return -ENOMEM; |
| |
| 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 = vm_end_gap(vma); |
| |
| /* |
| * 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. |
| */ |
| mm_rb_write_lock(mm); |
| 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_write_unlock(mm); |
| } |
| |
| 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) |
| put_write_access(file_inode(file)); |
| if (vma->vm_flags & VM_SHARED) |
| mapping_allow_writable(mapping); |
| |
| 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); |
| __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 __always_inline void __vma_unlink(struct mm_struct *mm, |
| struct vm_area_struct *vma, |
| struct vm_area_struct *ignore) |
| { |
| vma_rb_erase_ignore(vma, mm, ignore); |
| __vma_unlink_list(mm, vma); |
| /* 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 vm_area_struct *expand, bool keep_locked) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *next = vma->vm_next, *orig_vma = vma; |
| struct address_space *mapping = NULL; |
| struct rb_root_cached *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; |
| |
| vm_write_begin(vma); |
| if (next) |
| vm_write_begin(next); |
| |
| if (next && !insert) { |
| struct vm_area_struct *exporter = NULL, *importer = NULL; |
| |
| if (end >= next->vm_end) { |
| /* |
| * vma expands, overlapping all the next, and |
| * perhaps the one after too (mprotect case 6). |
| * The only other cases that gets here are |
| * case 1, case 7 and case 8. |
| */ |
| if (next == expand) { |
| /* |
| * The only case where we don't expand "vma" |
| * and we expand "next" instead is case 8. |
| */ |
| VM_WARN_ON(end != next->vm_end); |
| /* |
| * remove_next == 3 means we're |
| * removing "vma" and that to do so we |
| * swapped "vma" and "next". |
| */ |
| remove_next = 3; |
| VM_WARN_ON(file != next->vm_file); |
| swap(vma, next); |
| } else { |
| VM_WARN_ON(expand != vma); |
| /* |
| * case 1, 6, 7, remove_next == 2 is case 6, |
| * remove_next == 1 is case 1 or 7. |
| */ |
| remove_next = 1 + (end > next->vm_end); |
| VM_WARN_ON(remove_next == 2 && |
| end != next->vm_next->vm_end); |
| /* trim end to next, for case 6 first pass */ |
| end = next->vm_end; |
| } |
| |
| exporter = next; |
| importer = vma; |
| |
| /* |
| * If next doesn't have anon_vma, import from vma after |
| * next, if the vma overlaps with it. |
| */ |
| if (remove_next == 2 && !next->anon_vma) |
| exporter = next->vm_next; |
| |
| } 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); |
| exporter = next; |
| importer = vma; |
| VM_WARN_ON(expand != importer); |
| } 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); |
| exporter = vma; |
| importer = next; |
| VM_WARN_ON(expand != importer); |
| } |
| |
| /* |
| * 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) { |
| if (next && next != vma) |
| vm_write_end(next); |
| vm_write_end(vma); |
| return error; |
| } |
| } |
| } |
| again: |
| vma_adjust_trans_huge(orig_vma, start, end, adjust_next); |
| |
| 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); |
| } |
| } |
| |
| anon_vma = vma->anon_vma; |
| if (!anon_vma && adjust_next) |
| anon_vma = next->anon_vma; |
| if (anon_vma) { |
| VM_WARN_ON(adjust_next && next->anon_vma && |
| anon_vma != next->anon_vma); |
| 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 (file) { |
| 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) { |
| WRITE_ONCE(vma->vm_start, start); |
| start_changed = true; |
| } |
| if (end != vma->vm_end) { |
| WRITE_ONCE(vma->vm_end, end); |
| end_changed = true; |
| } |
| WRITE_ONCE(vma->vm_pgoff, pgoff); |
| if (adjust_next) { |
| WRITE_ONCE(next->vm_start, |
| next->vm_start + adjust_next); |
| WRITE_ONCE(next->vm_pgoff, |
| next->vm_pgoff + (adjust_next >> PAGE_SHIFT)); |
| } |
| |
| if (file) { |
| 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. |
| */ |
| if (remove_next != 3) |
| __vma_unlink(mm, next, next); |
| else |
| /* |
| * vma is not before next if they've been |
| * swapped. |
| * |
| * pre-swap() next->vm_start was reduced so |
| * tell validate_mm_rb to ignore pre-swap() |
| * "next" (which is stored in post-swap() |
| * "vma"). |
| */ |
| __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 = vm_end_gap(vma); |
| 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 (file) { |
| i_mmap_unlock_write(mapping); |
| uprobe_mmap(vma); |
| |
| if (adjust_next) |
| uprobe_mmap(next); |
| } |
| |
| if (remove_next) { |
| if (file) |
| uprobe_munmap(next, next->vm_start, next->vm_end); |
| if (next->anon_vma) |
| anon_vma_merge(vma, next); |
| mm->map_count--; |
| vm_write_end(next); |
| put_vma(next); |
| /* |
| * In mprotect's case 6 (see comments on vma_merge), |
| * we must remove another next too. It would clutter |
| * up the code too much to do both in one go. |
| */ |
| if (remove_next != 3) { |
| /* |
| * If "next" was removed and vma->vm_end was |
| * expanded (up) over it, in turn |
| * "next->vm_prev->vm_end" changed and the |
| * "vma->vm_next" gap must be updated. |
| */ |
| next = vma->vm_next; |
| if (next) |
| vm_write_begin(next); |
| } else { |
| /* |
| * For the scope of the comment "next" and |
| * "vma" considered pre-swap(): if "vma" was |
| * removed, next->vm_start was expanded (down) |
| * over it and the "next" gap must be updated. |
| * Because of the swap() the post-swap() "vma" |
| * actually points to pre-swap() "next" |
| * (post-swap() "next" as opposed is now a |
| * dangling pointer). |
| */ |
| next = vma; |
| } |
| if (remove_next == 2) { |
| remove_next = 1; |
| end = next->vm_end; |
| goto again; |
| } |
| else if (next) |
| vma_gap_update(next); |
| else { |
| /* |
| * If remove_next == 2 we obviously can't |
| * reach this path. |
| * |
| * If remove_next == 3 we can't reach this |
| * path because pre-swap() next is always not |
| * NULL. pre-swap() "next" is not being |
| * removed and its next->vm_end is not altered |
| * (and furthermore "end" already matches |
| * next->vm_end in remove_next == 3). |
| * |
| * We reach this only in the remove_next == 1 |
| * case if the "next" vma that was removed was |
| * the highest vma of the mm. However in such |
| * case next->vm_end == "end" and the extended |
| * "vma" has vma->vm_end == next->vm_end so |
| * mm->highest_vm_end doesn't need any update |
| * in remove_next == 1 case. |
| */ |
| VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); |
| } |
| } |
| if (insert && file) |
| uprobe_mmap(insert); |
| |
| if (next && next != vma) |
| vm_write_end(next); |
| if (!keep_locked) |
| vm_write_end(vma); |
| |
| 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, |
| struct anon_vma_name *anon_name) |
| { |
| /* |
| * 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 pressure 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; |
| if (!anon_vma_name_eq(anon_vma_name(vma), anon_name)) |
| return 0; |
| if (!is_mergable_pad_vma(vma, vm_flags)) |
| 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() 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, |
| struct anon_vma_name *anon_name) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) && |
| 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, |
| struct anon_vma_name *anon_name) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) && |
| 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,anon_name), |
| * 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 |
| * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN |
| * cannot merge might become might become |
| * PPNNNNNNNNNN PPPPPPPPPPNN |
| * mmap, brk or case 4 below case 5 below |
| * mremap move: |
| * AAAA AAAA |
| * PPPP NNNN PPPPNNNNXXXX |
| * might become might become |
| * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or |
| * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or |
| * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8 |
| * |
| * It is important for case 8 that the vma NNNN overlapping the |
| * region AAAA is never going to extended over XXXX. Instead XXXX must |
| * be extended in region AAAA and NNNN must be removed. This way in |
| * all cases where vma_merge succeeds, the moment vma_adjust drops the |
| * rmap_locks, the properties of the merged vma will be already |
| * correct for the whole merged range. Some of those properties like |
| * vm_page_prot/vm_flags may be accessed by rmap_walks and they must |
| * be correct for the whole merged range immediately after the |
| * rmap_locks are released. Otherwise if XXXX would be removed and |
| * NNNN would be extended over the XXXX range, remove_migration_ptes |
| * or other rmap walkers (if working on addresses beyond the "end" |
| * parameter) may establish ptes with the wrong permissions of NNNN |
| * instead of the right permissions of XXXX. |
| */ |
| 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, |
| struct anon_vma_name *anon_name, bool keep_locked) |
| { |
| 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; |
| |
| next = vma_next(mm, prev); |
| area = next; |
| if (area && area->vm_end == end) /* cases 6, 7, 8 */ |
| next = next->vm_next; |
| |
| /* verify some invariant that must be enforced by the caller */ |
| VM_WARN_ON(prev && addr <= prev->vm_start); |
| VM_WARN_ON(area && end > area->vm_end); |
| VM_WARN_ON(addr >= end); |
| |
| /* |
| * 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, anon_name)) { |
| /* |
| * 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, anon_name) && |
| 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, |
| prev, keep_locked); |
| } else /* cases 2, 5, 7 */ |
| err = __vma_adjust(prev, prev->vm_start, |
| end, prev->vm_pgoff, NULL, prev, |
| keep_locked); |
| 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, anon_name)) { |
| if (prev && addr < prev->vm_end) /* case 4 */ |
| err = __vma_adjust(prev, prev->vm_start, |
| addr, prev->vm_pgoff, NULL, next, |
| keep_locked); |
| else { /* cases 3, 8 */ |
| err = __vma_adjust(area, addr, next->vm_end, |
| next->vm_pgoff - pglen, NULL, next, |
| keep_locked); |
| /* |
| * In case 3 area is already equal to next and |
| * this is a noop, but in case 8 "area" has |
| * been removed and next was expanded over it. |
| */ |
| area = next; |
| } |
| if (err) |
| return NULL; |
| khugepaged_enter_vma_merge(area, vm_flags); |
| return area; |
| } |
| |
| return NULL; |
| } |
| |
| /* |
| * Rough compatibility 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_ACCESS_FLAGS | 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 = NULL; |
| |
| /* Try next first. */ |
| if (vma->vm_next) { |
| anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next); |
| if (anon_vma) |
| return anon_vma; |
| } |
| |
| /* Try prev next. */ |
| if (vma->vm_prev) |
| anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma); |
| |
| /* |
| * We might reach here with anon_vma == NULL if we can't find |
| * any reusable anon_vma. |
| * 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 anon_vma; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) |
| { |
| if (S_ISREG(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| if (S_ISBLK(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| if (S_ISSOCK(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| /* Special "we do even unsigned file positions" case */ |
| if (file->f_mode & FMODE_UNSIGNED_OFFSET) |
| return 0; |
| |
| /* Yes, random drivers might want more. But I'm tired of buggy drivers */ |
| return ULONG_MAX; |
| } |
| |
| static inline bool file_mmap_ok(struct file *file, struct inode *inode, |
| unsigned long pgoff, unsigned long len) |
| { |
| u64 maxsize = file_mmap_size_max(file, inode); |
| |
| if (maxsize && len > maxsize) |
| return false; |
| maxsize -= len; |
| if (pgoff > maxsize >> PAGE_SHIFT) |
| return false; |
| return true; |
| } |
| |
| /* |
| * The caller must write-lock current->mm->mmap_lock. |
| */ |
| unsigned long do_mmap(struct file *file, unsigned long addr, |
| unsigned long len, unsigned long prot, |
| unsigned long flags, unsigned long pgoff, |
| unsigned long *populate, struct list_head *uf) |
| { |
| struct mm_struct *mm = current->mm; |
| vm_flags_t vm_flags; |
| int pkey = 0; |
| |
| *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; |
| |
| /* force arch specific MAP_FIXED handling in get_unmapped_area */ |
| if (flags & MAP_FIXED_NOREPLACE) |
| flags |= MAP_FIXED; |
| |
| 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 (IS_ERR_VALUE(addr)) |
| return addr; |
| |
| if (flags & MAP_FIXED_NOREPLACE) { |
| struct vm_area_struct *vma = find_vma(mm, addr); |
| |
| if (vma && vma->vm_start < addr + len) |
| return -EEXIST; |
| } |
| |
| if (prot == PROT_EXEC) { |
| pkey = execute_only_pkey(mm); |
| if (pkey < 0) |
| pkey = 0; |
| } |
| |
| /* 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, pkey) | 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); |
| unsigned long flags_mask; |
| |
| if (!file_mmap_ok(file, inode, pgoff, len)) |
| return -EOVERFLOW; |
| |
| flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; |
| |
| switch (flags & MAP_TYPE) { |
| case MAP_SHARED: |
| /* |
| * Force use of MAP_SHARED_VALIDATE with non-legacy |
| * flags. E.g. MAP_SYNC is dangerous to use with |
| * MAP_SHARED as you don't know which consistency model |
| * you will get. We silently ignore unsupported flags |
| * with MAP_SHARED to preserve backward compatibility. |
| */ |
| flags &= LEGACY_MAP_MASK; |
| fallthrough; |
| case MAP_SHARED_VALIDATE: |
| if (flags & ~flags_mask) |
| return -EOPNOTSUPP; |
| if (prot & PROT_WRITE) { |
| if (!(file->f_mode & FMODE_WRITE)) |
| return -EACCES; |
| if (IS_SWAPFILE(file->f_mapping->host)) |
| return -ETXTBSY; |
| } |
| |
| /* |
| * 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); |
| fallthrough; |
| 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, uf); |
| if (!IS_ERR_VALUE(addr) && |
| ((vm_flags & VM_LOCKED) || |
| (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) |
| *populate = len; |
| return addr; |
| } |
| |
| unsigned long ksys_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; |
| |
| if (!(flags & MAP_ANONYMOUS)) { |
| audit_mmap_fd(fd, flags); |
| file = fget(fd); |
| if (!file) |
| return -EBADF; |
| if (is_file_hugepages(file)) { |
| len = ALIGN(len, huge_page_size(hstate_file(file))); |
| } else if (unlikely(flags & MAP_HUGETLB)) { |
| retval = -EINVAL; |
| goto out_fput; |
| } |
| } else if (flags & MAP_HUGETLB) { |
| struct user_struct *user = NULL; |
| struct hstate *hs; |
| |
| hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_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); |
| return retval; |
| } |
| |
| SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
| unsigned long, prot, unsigned long, flags, |
| unsigned long, fd, unsigned long, pgoff) |
| { |
| return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); |
| } |
| |
| #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 (offset_in_page(a.offset)) |
| return -EINVAL; |
| |
| return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
| a.offset >> PAGE_SHIFT); |
| } |
| #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
| |
| /* |
| * Some shared mappings 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, pgprot_t vm_page_prot) |
| { |
| 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(vm_page_prot) != |
| pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags))) |
| return 0; |
| |
| /* |
| * Do we need to track softdirty? hugetlb does not support softdirty |
| * tracking yet. |
| */ |
| if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY) && |
| !is_vm_hugetlb_page(vma)) |
| 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_can_writeback(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 list_head *uf) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma, *prev, *merge; |
| int error; |
| struct rb_node **rb_link, *rb_parent; |
| unsigned long charged = 0; |
| |
| /* Check against address space limit. */ |
| if (!may_expand_vm(mm, vm_flags, 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. |
| */ |
| nr_pages = count_vma_pages_range(mm, addr, addr + len); |
| |
| if (!may_expand_vm(mm, vm_flags, |
| (len >> PAGE_SHIFT) - nr_pages)) |
| return -ENOMEM; |
| } |
| |
| /* Clear old maps, set up prev, rb_link, rb_parent, and uf */ |
| if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf)) |
| 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, NULL); |
| if (vma) |
| goto out; |
| |
| /* |
| * Determine the object being mapped and call the appropriate |
| * specific mapper. the address has already been validated, but |
| * not unmapped, but the maps are removed from the list. |
| */ |
| vma = vm_area_alloc(mm); |
| if (!vma) { |
| error = -ENOMEM; |
| goto unacct_error; |
| } |
| |
| vma->vm_start = addr; |
| vma->vm_end = addr + len; |
| vma->vm_flags = vm_flags; |
| vma->vm_page_prot = vm_get_page_prot(vm_flags); |
| vma->vm_pgoff = pgoff; |
| |
| if (file) { |
| 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 = call_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; |
| |
| /* If vm_flags changed after call_mmap(), we should try merge vma again |
| * as we may succeed this time. |
| */ |
| if (unlikely(vm_flags != vma->vm_flags && prev)) { |
| merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags, |
| NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX, NULL); |
| if (merge) { |
| /* ->mmap() can change vma->vm_file and fput the original file. So |
| * fput the vma->vm_file here or we would add an extra fput for file |
| * and cause general protection fault ultimately. |
| */ |
| fput(vma->vm_file); |
| vm_area_free(vma); |
| vma = merge; |
| /* Update vm_flags to pick up the change. */ |
| vm_flags = vma->vm_flags; |
| goto unmap_writable; |
| } |
| } |
| |
| vm_flags = vma->vm_flags; |
| } else if (vm_flags & VM_SHARED) { |
| error = shmem_zero_setup(vma); |
| if (error) |
| goto free_vma; |
| } else { |
| vma_set_anonymous(vma); |
| } |
| |
| /* Allow architectures to sanity-check the vm_flags */ |
| if (!arch_validate_flags(vma->vm_flags)) { |
| error = -EINVAL; |
| if (file) |
| goto close_and_free_vma; |
| else |
| goto free_vma; |
| } |
| |
| vma_link(mm, vma, prev, rb_link, rb_parent); |
| /* Once vma denies write, undo our temporary denial count */ |
| if (file) { |
| unmap_writable: |
| 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_write_begin(vma); |
| vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); |
| if (vm_flags & VM_LOCKED) { |
| if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || |
| is_vm_hugetlb_page(vma) || |
| vma == get_gate_vma(current->mm)) |
| WRITE_ONCE(vma->vm_flags, |
| vma->vm_flags & VM_LOCKED_CLEAR_MASK); |
| else |
| mm->locked_vm += (len >> PAGE_SHIFT); |
| } |
| |
| 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). |
| */ |
| WRITE_ONCE(vma->vm_flags, vma->vm_flags | VM_SOFTDIRTY); |
| |
| vma_set_page_prot(vma); |
| vm_write_end(vma); |
| |
| return addr; |
| |
| close_and_free_vma: |
| if (vma->vm_ops && vma->vm_ops->close) |
| vma->vm_ops->close(vma); |
| 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); |
| 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: |
| vm_area_free(vma); |
| unacct_error: |
| if (charged) |
| vm_unacct_memory(charged); |
| return error; |
| } |
| |
| static 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 = vm_start_gap(vma); |
| 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 ? vm_end_gap(vma->vm_prev) : 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 && 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 = vm_end_gap(vma->vm_prev); |
| gap_end = vm_start_gap(vma); |
| 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; |
| } |
| |
| static 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; |
| unsigned long addr = 0; |
| |
| /* Adjust search length to account for worst case alignment overhead */ |
| length = info->length + info->align_mask; |
| if (length < info->length) |
| return -ENOMEM; |
| |
| trace_android_vh_get_from_fragment_pool(mm, info, &addr); |
| if (addr) |
| return addr; |
| |
| /* |
| * 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 ? vm_end_gap(vma->vm_prev) : 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 = vm_start_gap(vma); |
| if (gap_end < low_limit) |
| return -ENOMEM; |
| if (gap_start <= high_limit && |
| gap_end > gap_start && 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 ? |
| vm_end_gap(vma->vm_prev) : 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; |
| } |
| |
| /* |
| * Search for an unmapped address range. |
| * |
| * We are looking for a range that: |
| * - does not intersect with any VMA; |
| * - is contained within the [low_limit, high_limit) interval; |
| * - is at least the desired size. |
| * - satisfies (begin_addr & align_mask) == (align_offset & align_mask) |
| */ |
| unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) |
| { |
| unsigned long addr; |
| |
| if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) |
| addr = unmapped_area_topdown(info); |
| else |
| addr = unmapped_area(info); |
| |
| trace_vm_unmapped_area(addr, info); |
| return addr; |
| } |
| EXPORT_SYMBOL_GPL(vm_unmapped_area); |
| |
| /* 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, *prev; |
| struct vm_unmapped_area_info info; |
| const unsigned long mmap_end = arch_get_mmap_end(addr); |
| |
| if (len > mmap_end - mmap_min_addr) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma_prev(mm, addr, &prev); |
| if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| (!vma || addr + len <= vm_start_gap(vma)) && |
| (!prev || addr >= vm_end_gap(prev))) |
| return addr; |
| } |
| |
| info.flags = 0; |
| info.length = len; |
| info.low_limit = mm->mmap_base; |
| info.high_limit = mmap_end; |
| info.align_mask = 0; |
| info.align_offset = 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, unsigned long addr, |
| unsigned long len, unsigned long pgoff, |
| unsigned long flags) |
| { |
| struct vm_area_struct *vma, *prev; |
| struct mm_struct *mm = current->mm; |
| struct vm_unmapped_area_info info; |
| const unsigned long mmap_end = arch_get_mmap_end(addr); |
| |
| /* requested length too big for entire address space */ |
| if (len > mmap_end - mmap_min_addr) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| /* requesting a specific address */ |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma_prev(mm, addr, &prev); |
| if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| (!vma || addr + len <= vm_start_gap(vma)) && |
| (!prev || addr >= vm_end_gap(prev))) |
| return addr; |
| } |
| |
| info.flags = VM_UNMAPPED_AREA_TOPDOWN; |
| info.length = len; |
| info.low_limit = max(PAGE_SIZE, mmap_min_addr); |
| info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); |
| info.align_mask = 0; |
| info.align_offset = 0; |
| trace_android_vh_exclude_reserved_zone(mm, &info); |
| 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 (offset_in_page(addr)) { |
| VM_BUG_ON(addr != -ENOMEM); |
| info.flags = 0; |
| info.low_limit = TASK_UNMAPPED_BASE; |
| info.high_limit = mmap_end; |
| addr = vm_unmapped_area(&info); |
| } |
| |
| trace_android_vh_include_reserved_zone(mm, &info, &addr); |
| |
| 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) { |
| if (file->f_op->get_unmapped_area) |
| get_area = file->f_op->get_unmapped_area; |
| } else if (flags & MAP_SHARED) { |
| /* |
| * mmap_region() will call shmem_zero_setup() to create a file, |
| * so use shmem's get_unmapped_area in case it can be huge. |
| * do_mmap() will clear pgoff, so match alignment. |
| */ |
| pgoff = 0; |
| get_area = shmem_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 (offset_in_page(addr)) |
| return -EINVAL; |
| |
| 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. */ |
| static struct vm_area_struct *__find_vma(struct mm_struct *mm, |
| unsigned long addr) |
| { |
| struct rb_node *rb_node; |
| struct vm_area_struct *vma = NULL; |
| |
| 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; |
| } |
| |
| return vma; |
| } |
| |
| struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma; |
| |
| /* Check the cache first. */ |
| vma = vmacache_find(mm, addr); |
| if (likely(vma)) |
| return vma; |
| |
| vma = __find_vma(mm, addr); |
| if (vma) |
| vmacache_update(addr, vma); |
| return vma; |
| } |
| EXPORT_SYMBOL(find_vma); |
| |
| #ifdef CONFIG_SPECULATIVE_PAGE_FAULT |
| struct vm_area_struct *get_vma(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma = NULL; |
| |
| read_lock(&mm->mm_rb_lock); |
| vma = __find_vma(mm, addr); |
| |
| /* |
| * If there is a concurrent fast mremap, bail out since the entire |
| * PMD/PUD subtree may have been remapped. |
| * |
| * This is usually safe for conventional mremap since it takes the |
| * PTE locks as does SPF. However fast mremap only takes the lock |
| * at the PMD/PUD level which is ok as it is done with the mmap |
| * write lock held. But since SPF, as the term implies forgoes, |
| * taking the mmap read lock and also cannot take PTL lock at the |
| * larger PMD/PUD granualrity, since it would introduce huge |
| * contention in the page fault path; fall back to regular fault |
| * handling. |
| */ |
| if (vma && !atomic_inc_unless_negative(&vma->vm_ref_count)) |
| vma = NULL; |
| read_unlock(&mm->mm_rb_lock); |
| |
| return vma; |
| } |
| #endif |
| |
| /* |
| * 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 = rb_last(&mm->mm_rb); |
| |
| *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL; |
| } |
| 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; |
| unsigned long new_start; |
| |
| /* address space limit tests */ |
| if (!may_expand_vm(mm, vma->vm_flags, grow)) |
| return -ENOMEM; |
| |
| /* Stack limit test */ |
| if (size > rlimit(RLIMIT_STACK)) |
| return -ENOMEM; |
| |
| /* mlock limit tests */ |
| if (vma->vm_flags & VM_LOCKED) { |
| unsigned long locked; |
| unsigned long limit; |
| locked = mm->locked_vm + grow; |
| limit = rlimit(RLIMIT_MEMLOCK); |
| 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; |
| |
| 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) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *next; |
| unsigned long gap_addr; |
| int error = 0; |
| |
| if (!(vma->vm_flags & VM_GROWSUP)) |
| return -EFAULT; |
| |
| /* Guard against exceeding limits of the address space. */ |
| address &= PAGE_MASK; |
| if (address >= (TASK_SIZE & PAGE_MASK)) |
| return -ENOMEM; |
| address += PAGE_SIZE; |
| |
| /* Enforce stack_guard_gap */ |
| gap_addr = address + stack_guard_gap; |
| |
| /* Guard against overflow */ |
| if (gap_addr < address || gap_addr > TASK_SIZE) |
| gap_addr = TASK_SIZE; |
| |
| next = vma->vm_next; |
| if (next && next->vm_start < gap_addr && vma_is_accessible(next)) { |
| if (!(next->vm_flags & VM_GROWSUP)) |
| return -ENOMEM; |
| /* Check that both stack segments have the same anon_vma? */ |
| } |
| |
| /* We must make sure the anon_vma is allocated. */ |
| if (unlikely(anon_vma_prepare(vma))) |
| return -ENOMEM; |
| |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_lock in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| */ |
| anon_vma_lock_write(vma->anon_vma); |
| |
| /* 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_lock |
| * lock here, so we need to protect against |
| * concurrent vma expansions. |
| * anon_vma_lock_write() 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(&mm->page_table_lock); |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm += grow; |
| vm_stat_account(mm, vma->vm_flags, grow); |
| 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 |
| mm->highest_vm_end = vm_end_gap(vma); |
| spin_unlock(&mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| anon_vma_unlock_write(vma->anon_vma); |
| khugepaged_enter_vma_merge(vma, vma->vm_flags); |
| validate_mm(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) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *prev; |
| int error = 0; |
| |
| address &= PAGE_MASK; |
| if (address < mmap_min_addr) |
| return -EPERM; |
| |
| /* Enforce stack_guard_gap */ |
| prev = vma->vm_prev; |
| /* Check that both stack segments have the same anon_vma? */ |
| if (prev && !(prev->vm_flags & VM_GROWSDOWN) && |
| vma_is_accessible(prev)) { |
| if (address - prev->vm_end < stack_guard_gap) |
| return -ENOMEM; |
| } |
| |
| /* We must make sure the anon_vma is allocated. */ |
| if (unlikely(anon_vma_prepare(vma))) |
| return -ENOMEM; |
| |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_lock in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| */ |
| anon_vma_lock_write(vma->anon_vma); |
| |
| /* 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_lock |
| * lock here, so we need to protect against |
| * concurrent vma expansions. |
| * anon_vma_lock_write() 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(&mm->page_table_lock); |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm += grow; |
| vm_stat_account(mm, vma->vm_flags, grow); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| WRITE_ONCE(vma->vm_start, address); |
| WRITE_ONCE(vma->vm_pgoff, vma->vm_pgoff - grow); |
| anon_vma_interval_tree_post_update_vma(vma); |
| vma_gap_update(vma); |
| spin_unlock(&mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| anon_vma_unlock_write(vma->anon_vma); |
| khugepaged_enter_vma_merge(vma, vma->vm_flags); |
| validate_mm(mm); |
| return error; |
| } |
| |
| /* enforced gap between the expanding stack and other mappings. */ |
| unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; |
| |
| static int __init cmdline_parse_stack_guard_gap(char *p) |
| { |
| unsigned long val; |
| char *endptr; |
| |
| val = simple_strtoul(p, &endptr, 10); |
| if (!*endptr) |
| stack_guard_gap = val << PAGE_SHIFT; |
| |
| return 1; |
| } |
| __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| { |
| return expand_upwards(vma, address); |
| } |
| |
| struct vm_area_struct * |
| find_extend_vma(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma, *prev; |
| |
| addr &= PAGE_MASK; |
| vma = find_vma_prev(mm, addr, &prev); |
| if (vma && (vma->vm_start <= addr)) |
| return vma; |
| /* don't alter vm_end if the coredump is running */ |
| 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) |
| { |
| 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, -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 = vma_next(mm, prev); |
| struct mmu_gather tlb; |
| struct vm_area_struct *cur_vma; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm, start, end); |
| update_hiwater_rss(mm); |
| unmap_vmas(&tlb, vma, start, end); |
| |
| /* |
| * Ensure we have no stale TLB entries by the time this mapping is |
| * removed from the rmap. |
| * Note that we don't have to worry about nested flushes here because |
| * we're holding the mm semaphore for removing the mapping - so any |
| * concurrent flush in this region has to be coming through the rmap, |
| * and we synchronize against that using the rmap lock. |
| */ |
| for (cur_vma = vma; cur_vma; cur_vma = cur_vma->vm_next) { |
| if ((cur_vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0) { |
| tlb_flush_mmu(&tlb); |
| break; |
| } |
| } |
| |
| 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 bool |
| 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->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 ? vm_end_gap(prev) : 0; |
| tail_vma->vm_next = NULL; |
| |
| /* Kill the cache */ |
| vmacache_invalidate(mm); |
| |
| /* |
| * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or |
| * VM_GROWSUP VMA. Such VMAs can change their size under |
| * down_read(mmap_lock) and collide with the VMA we are about to unmap. |
| */ |
| if (vma && (vma->vm_flags & VM_GROWSDOWN)) |
| return false; |
| if (prev && (prev->vm_flags & VM_GROWSUP)) |
| return false; |
| return true; |
| } |
| |
| /* |
| * __split_vma() bypasses sysctl_max_map_count checking. We use this where it |
| * has already been checked or doesn't make sense to fail. |
| */ |
| 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 (vma->vm_ops && vma->vm_ops->split) { |
| err = vma->vm_ops->split(vma, addr); |
| if (err) |
| return err; |
| } |
| |
| new = vm_area_dup(vma); |
| if (!new) |
| return -ENOMEM; |
| |
| 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) { |
| split_pad_vma(vma, new, addr, new_below); |
| 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: |
| vm_area_free(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, |
| struct list_head *uf, bool downgrade) |
| { |
| unsigned long end; |
| struct vm_area_struct *vma, *prev, *last; |
| |
| if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) |
| return -EINVAL; |
| |
| len = PAGE_ALIGN(len); |
| end = start + len; |
| if (len == 0) |
| return -EINVAL; |
| |
| /* |
| * arch_unmap() might do unmaps itself. It must be called |
| * and finish any rbtree manipulation before this code |
| * runs and also starts to manipulate the rbtree. |
| */ |
| arch_unmap(mm, start, end); |
| |
| /* 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.. */ |
| 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 = vma_next(mm, prev); |
| |
| if (unlikely(uf)) { |
| /* |
| * If userfaultfd_unmap_prep returns an error the vmas |
| * will remain splitted, but userland will get a |
| * highly unexpected error anyway. This is no |
| * different than the case where the first of the two |
| * __split_vma fails, but we don't undo the first |
| * split, despite we could. This is unlikely enough |
| * failure that it's not worth optimizing it for. |
| */ |
| int error = userfaultfd_unmap_prep(vma, start, end, uf); |
| if (error) |
| return error; |
| } |
| |
| /* |
| * 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; |
| } |
| } |
| |
| /* Detach vmas from rbtree */ |
| if (!detach_vmas_to_be_unmapped(mm, vma, prev, end)) |
| downgrade = false; |
| |
| if (downgrade) |
| mmap_write_downgrade(mm); |
| |
| unmap_region(mm, vma, prev, start, end); |
| |
| /* Fix up all other VM information */ |
| remove_vma_list(mm, vma); |
| |
| return downgrade ? 1 : 0; |
| } |
| |
| int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, |
| struct list_head *uf) |
| { |
| return __do_munmap(mm, start, len, uf, false); |
| } |
| |
| static int __vm_munmap(unsigned long start, size_t len, bool downgrade) |
| { |
| int ret; |
| struct mm_struct *mm = current->mm; |
| LIST_HEAD(uf); |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| ret = __do_munmap(mm, start, len, &uf, downgrade); |
| /* |
| * Returning 1 indicates mmap_lock is downgraded. |
| * But 1 is not legal return value of vm_munmap() and munmap(), reset |
| * it to 0 before return. |
| */ |
| if (ret == 1) { |
| mmap_read_unlock(mm); |
| ret = 0; |
| } else |
| mmap_write_unlock(mm); |
| |
| userfaultfd_unmap_complete(mm, &uf); |
| return ret; |
| } |
| |
| int vm_munmap(unsigned long start, size_t len) |
| { |
| return __vm_munmap(start, len, false); |
| } |
| EXPORT_SYMBOL(vm_munmap); |
| |
| SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
| { |
| addr = untagged_addr(addr); |
| profile_munmap(addr); |
| return __vm_munmap(addr, len, true); |
| } |
| |
| |
| /* |
| * 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.rst.\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; |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| vma = find_vma(mm, start); |
| |
| if (!vma || !(vma->vm_flags & VM_SHARED)) |
| goto out; |
| |
| if (start < vma->vm_start) |
| goto out; |
| |
| if (start + size > vma->vm_end) { |
| struct vm_area_struct *next; |
| |
| for (next = vma->vm_next; next; next = next->vm_next) { |
| /* hole between vmas ? */ |
| if (next->vm_start != next->vm_prev->vm_end) |
| goto out; |
| |
| if (next->vm_file != vma->vm_file) |
| goto out; |
| |
| if (next->vm_flags != vma->vm_flags) |
| goto out; |
| |
| if (start + size <= next->vm_end) |
| break; |
| } |
| |
| if (!next) |
| goto out; |
| } |
| |
| prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; |
|