diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 3566 |
1 files changed, 846 insertions, 2720 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index f901065c4c64..4bdb9ffa9e25 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * mm/mmap.c * @@ -12,7 +13,7 @@ #include <linux/slab.h> #include <linux/backing-dev.h> #include <linux/mm.h> -#include <linux/vmacache.h> +#include <linux/mm_inline.h> #include <linux/shm.h> #include <linux/mman.h> #include <linux/pagemap.h> @@ -37,7 +38,6 @@ #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> @@ -45,12 +45,18 @@ #include <linux/moduleparam.h> #include <linux/pkeys.h> #include <linux/oom.h> +#include <linux/sched/mm.h> +#include <linux/ksm.h> +#include <linux/memfd.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> + #include "internal.h" #ifndef arch_mmap_check @@ -59,7 +65,7 @@ #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_max __ro_after_init = 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 @@ -71,61 +77,10 @@ int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; 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 - * - * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and - * MAP_PRIVATE: - * r: (no) no - * w: (no) no - * 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; + vm_flags_t vm_flags = vma->vm_flags; pgprot_t vm_page_prot; vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); @@ -133,89 +88,54 @@ void vma_set_page_prot(struct vm_area_struct *vma) 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_sem */ + /* 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 + * check_brk_limits() - Use platform specific check of range & verify mlock + * limits. + * @addr: The address to check + * @len: The size of increase. + * + * Return: 0 on success. */ -static void __remove_shared_vm_struct(struct vm_area_struct *vma, - struct file *file, struct address_space *mapping) +static int check_brk_limits(unsigned long addr, unsigned long len) { - if (vma->vm_flags & VM_DENYWRITE) - atomic_inc(&file_inode(file)->i_writecount); - if (vma->vm_flags & VM_SHARED) - mapping_unmap_writable(mapping); - - flush_dcache_mmap_lock(mapping); - vma_interval_tree_remove(vma, &mapping->i_mmap); - flush_dcache_mmap_unlock(mapping); -} + unsigned long mapped_addr; -/* - * 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; + mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); + if (IS_ERR_VALUE(mapped_addr)) + return mapped_addr; - if (file) { - struct address_space *mapping = file->f_mapping; - i_mmap_lock_write(mapping); - __remove_shared_vm_struct(vma, file, mapping); - i_mmap_unlock_write(mapping); - } -} - -/* - * Close a vm structure and free it, returning the next. - */ -static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) -{ - struct vm_area_struct *next = vma->vm_next; - - might_sleep(); - if (vma->vm_ops && vma->vm_ops->close) - vma->vm_ops->close(vma); - if (vma->vm_file) - fput(vma->vm_file); - mpol_put(vma_policy(vma)); - vm_area_free(vma); - return next; + return mlock_future_ok(current->mm, current->mm->def_flags, len) + ? 0 : -EAGAIN; } -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; + struct vm_area_struct *brkvma, *next = NULL; unsigned long min_brk; - bool populate; - bool downgraded = false; + bool populate = false; LIST_HEAD(uf); + struct vma_iterator vmi; - if (down_write_killable(&mm->mmap_sem)) + if (mmap_write_lock_killable(mm)) return -EINTR; origbrk = mm->brk; + min_brk = mm->start_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 + if (!current->brk_randomized) min_brk = mm->end_data; -#else - min_brk = mm->start_brk; #endif if (brk < min_brk) goto out; @@ -237,1084 +157,59 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) goto success; } - /* - * Always allow shrinking brk. - * __do_munmap() may downgrade mmap_sem to read. - */ + /* Always allow shrinking brk. */ if (brk <= mm->brk) { - int ret; - + /* Search one past newbrk */ + vma_iter_init(&vmi, mm, newbrk); + brkvma = vma_find(&vmi, oldbrk); + if (!brkvma || brkvma->vm_start >= oldbrk) + goto out; /* mapping intersects with an existing non-brk vma. */ /* - * mm->brk must to be protected by write mmap_sem so update it - * before downgrading mmap_sem. When __do_munmap() fails, - * mm->brk will be restored from origbrk. + * mm->brk must be protected by write mmap_lock. + * do_vmi_align_munmap() will drop the lock on success, so + * update it before calling do_vma_munmap(). */ mm->brk = brk; - ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); - if (ret < 0) { - mm->brk = origbrk; + if (do_vmi_align_munmap(&vmi, brkvma, mm, newbrk, oldbrk, &uf, + /* unlock = */ true)) goto out; - } else if (ret == 1) { - downgraded = true; - } - goto success; + + goto success_unlocked; } - /* Check against existing mmap mappings. */ - next = find_vma(mm, oldbrk); + if (check_brk_limits(oldbrk, newbrk - oldbrk)) + goto out; + + /* + * Only check if the next VMA is within the stack_guard_gap of the + * expansion area + */ + vma_iter_init(&vmi, mm, oldbrk); + next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap); if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) goto out; + brkvma = vma_prev_limit(&vmi, mm->start_brk); /* Ok, looks good - let it rip. */ - if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0) + if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0) goto out; + mm->brk = brk; + if (mm->def_flags & VM_LOCKED) + populate = true; success: - populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; - if (downgraded) - up_read(&mm->mmap_sem); - else - up_write(&mm->mmap_sem); + mmap_write_unlock(mm); +success_unlocked: userfaultfd_unmap_complete(mm, &uf); if (populate) mm_populate(oldbrk, newbrk - oldbrk); return brk; out: - retval = origbrk; - up_write(&mm->mmap_sem); - return retval; -} - -static long vma_compute_subtree_gap(struct vm_area_struct *vma) -{ - unsigned long max, prev_end, subtree_gap; - - /* - * 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. - */ - max = vm_start_gap(vma); - if (vma->vm_prev) { - prev_end = vm_end_gap(vma->vm_prev); - if (max > prev_end) - max -= prev_end; - else - max = 0; - } - if (vma->vm_rb.rb_left) { - subtree_gap = rb_entry(vma->vm_rb.rb_left, - struct vm_area_struct, vm_rb)->rb_subtree_gap; - if (subtree_gap > max) - max = subtree_gap; - } - if (vma->vm_rb.rb_right) { - subtree_gap = rb_entry(vma->vm_rb.rb_right, - struct vm_area_struct, vm_rb)->rb_subtree_gap; - if (subtree_gap > max) - max = subtree_gap; - } - return max; -} - -#ifdef CONFIG_DEBUG_VM_RB -static int browse_rb(struct 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(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, - unsigned long, rb_subtree_gap, vma_compute_subtree_gap) - -/* - * Update augmented rbtree rb_subtree_gap values after vma->vm_start or - * vma->vm_prev->vm_end values changed, without modifying the vma's position - * in the rbtree. - */ -static void vma_gap_update(struct vm_area_struct *vma) -{ - /* - * As it turns out, RB_DECLARE_CALLBACKS() already created a callback - * function that does exacltly what we want. - */ - vma_gap_callbacks_propagate(&vma->vm_rb, NULL); -} - -static inline void vma_rb_insert(struct vm_area_struct *vma, - struct rb_root *root) -{ - /* All rb_subtree_gap values must be consistent prior to insertion */ - validate_mm_rb(root, NULL); - - rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); -} - -static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) -{ - /* - * Note rb_erase_augmented is a fairly large inline function, - * so make sure we instantiate it only once with our desired - * augmented rbtree callbacks. - */ - rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); -} - -static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma, - struct rb_root *root, - struct vm_area_struct *ignore) -{ - /* - * All rb_subtree_gap values must be consistent prior to erase, - * with the possible exception of the "next" vma being erased if - * next->vm_start was reduced. - */ - validate_mm_rb(root, ignore); - - __vma_rb_erase(vma, root); -} - -static __always_inline void vma_rb_erase(struct vm_area_struct *vma, - struct rb_root *root) -{ - /* - * All rb_subtree_gap values must be consistent prior to erase, - * with the possible exception of the vma being erased. - */ - validate_mm_rb(root, vma); - - __vma_rb_erase(vma, root); -} - -/* - * vma has some anon_vma assigned, and is already inserted on that - * anon_vma's interval trees. - * - * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the - * vma must be removed from the anon_vma's interval trees using - * anon_vma_interval_tree_pre_update_vma(). - * - * After the update, the vma will be reinserted using - * anon_vma_interval_tree_post_update_vma(). - * - * The entire update must be protected by exclusive mmap_sem and by - * the root anon_vma's mutex. - */ -static inline void -anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) -{ - struct anon_vma_chain *avc; - - list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) - anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); -} - -static inline void -anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) -{ - struct anon_vma_chain *avc; - - list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) - anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); -} - -static int find_vma_links(struct mm_struct *mm, unsigned long addr, - unsigned long end, struct vm_area_struct **pprev, - struct rb_node ***rb_link, struct rb_node **rb_parent) -{ - struct rb_node **__rb_link, *__rb_parent, *rb_prev; - - __rb_link = &mm->mm_rb.rb_node; - rb_prev = __rb_parent = NULL; - - while (*__rb_link) { - struct vm_area_struct *vma_tmp; - - __rb_parent = *__rb_link; - vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); - - if (vma_tmp->vm_end > addr) { - /* Fail if an existing vma overlaps the area */ - if (vma_tmp->vm_start < end) - return -ENOMEM; - __rb_link = &__rb_parent->rb_left; - } else { - rb_prev = __rb_parent; - __rb_link = &__rb_parent->rb_right; - } - } - - *pprev = NULL; - if (rb_prev) - *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); - *rb_link = __rb_link; - *rb_parent = __rb_parent; - return 0; -} - -static unsigned long count_vma_pages_range(struct mm_struct *mm, - unsigned long addr, unsigned long end) -{ - unsigned long nr_pages = 0; - struct vm_area_struct *vma; - - /* Find first overlaping mapping */ - vma = find_vma_intersection(mm, addr, end); - if (!vma) - return 0; - - nr_pages = (min(end, vma->vm_end) - - max(addr, vma->vm_start)) >> PAGE_SHIFT; - - /* Iterate over the rest of the overlaps */ - for (vma = vma->vm_next; vma; vma = vma->vm_next) { - unsigned long overlap_len; - - if (vma->vm_start > end) - break; - - overlap_len = min(end, vma->vm_end) - vma->vm_start; - nr_pages += overlap_len >> PAGE_SHIFT; - } - - return nr_pages; -} - -void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, - struct rb_node **rb_link, struct rb_node *rb_parent) -{ - /* Update tracking information for the gap following the new vma. */ - if (vma->vm_next) - vma_gap_update(vma->vm_next); - else - mm->highest_vm_end = 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. - */ - rb_link_node(&vma->vm_rb, rb_parent, rb_link); - vma->rb_subtree_gap = 0; - vma_gap_update(vma); - vma_rb_insert(vma, &mm->mm_rb); -} - -static void __vma_link_file(struct vm_area_struct *vma) -{ - struct file *file; - - file = vma->vm_file; - if (file) { - struct address_space *mapping = file->f_mapping; - - if (vma->vm_flags & VM_DENYWRITE) - atomic_dec(&file_inode(file)->i_writecount); - if (vma->vm_flags & VM_SHARED) - atomic_inc(&mapping->i_mmap_writable); - - flush_dcache_mmap_lock(mapping); - vma_interval_tree_insert(vma, &mapping->i_mmap); - flush_dcache_mmap_unlock(mapping); - } -} - -static void -__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, - struct vm_area_struct *prev, struct rb_node **rb_link, - struct rb_node *rb_parent) -{ - __vma_link_list(mm, vma, prev, rb_parent); - __vma_link_rb(mm, vma, rb_link, rb_parent); -} - -static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, - struct vm_area_struct *prev, struct rb_node **rb_link, - struct rb_node *rb_parent) -{ - struct address_space *mapping = NULL; - - if (vma->vm_file) { - mapping = vma->vm_file->f_mapping; - i_mmap_lock_write(mapping); - } - - __vma_link(mm, vma, prev, rb_link, rb_parent); - __vma_link_file(vma); - - if (mapping) - i_mmap_unlock_write(mapping); - - mm->map_count++; - validate_mm(mm); -} - -/* - * Helper for vma_adjust() in the split_vma insert case: insert a vma into the - * mm's list and rbtree. It has already been inserted into the interval tree. - */ -static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) -{ - struct vm_area_struct *prev; - struct rb_node **rb_link, *rb_parent; - - if (find_vma_links(mm, vma->vm_start, vma->vm_end, - &prev, &rb_link, &rb_parent)) - BUG(); - __vma_link(mm, vma, prev, rb_link, rb_parent); - mm->map_count++; -} - -static __always_inline void __vma_unlink_common(struct mm_struct *mm, - struct vm_area_struct *vma, - struct vm_area_struct *prev, - bool has_prev, - struct vm_area_struct *ignore) -{ - struct vm_area_struct *next; - - vma_rb_erase_ignore(vma, &mm->mm_rb, ignore); - next = vma->vm_next; - if (has_prev) - prev->vm_next = next; - else { - prev = vma->vm_prev; - if (prev) - prev->vm_next = next; - else - mm->mmap = next; - } - if (next) - next->vm_prev = prev; - - /* Kill the cache */ - vmacache_invalidate(mm); -} - -static inline void __vma_unlink_prev(struct mm_struct *mm, - struct vm_area_struct *vma, - struct vm_area_struct *prev) -{ - __vma_unlink_common(mm, vma, prev, true, vma); -} - -/* - * 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) -{ - 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; - - 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); - VM_WARN_ON(remove_next == 1 && - end != 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) >> PAGE_SHIFT; - 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) >> PAGE_SHIFT); - 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) - 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 (root) { - flush_dcache_mmap_lock(mapping); - vma_interval_tree_remove(vma, root); - if (adjust_next) - vma_interval_tree_remove(next, root); - } - - if (start != vma->vm_start) { - vma->vm_start = start; - start_changed = true; - } - if (end != vma->vm_end) { - vma->vm_end = end; - end_changed = true; - } - vma->vm_pgoff = pgoff; - if (adjust_next) { - next->vm_start += adjust_next << PAGE_SHIFT; - next->vm_pgoff += adjust_next; - } - - if (root) { - if (adjust_next) - vma_interval_tree_insert(next, root); - vma_interval_tree_insert(vma, root); - flush_dcache_mmap_unlock(mapping); - } - - if (remove_next) { - /* - * vma_merge has merged next into vma, and needs - * us to remove next before dropping the locks. - */ - if (remove_next != 3) - __vma_unlink_prev(mm, next, vma); - 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_common(mm, next, NULL, false, 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 (mapping) - i_mmap_unlock_write(mapping); - - if (root) { - uprobe_mmap(vma); - - if (adjust_next) - uprobe_mmap(next); - } - - if (remove_next) { - if (file) { - uprobe_munmap(next, next->vm_start, next->vm_end); - fput(file); - } - if (next->anon_vma) - anon_vma_merge(vma, next); - mm->map_count--; - mpol_put(vma_policy(next)); - vm_area_free(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; - } 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); - - validate_mm(mm); - - return 0; -} - -/* - * If the vma has a ->close operation then the driver probably needs to release - * per-vma resources, so we don't attempt to merge those. - */ -static inline int is_mergeable_vma(struct vm_area_struct *vma, - struct file *file, unsigned long vm_flags, - struct vm_userfaultfd_ctx vm_userfaultfd_ctx) -{ - /* - * VM_SOFTDIRTY should not prevent from VMA merging, if we - * match the flags but dirty bit -- the caller should mark - * merged VMA as dirty. If dirty bit won't be excluded from - * comparison, we increase pressue on the memory system forcing - * the kernel to generate new VMAs when old one could be - * extended instead. - */ - if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) - return 0; - if (vma->vm_file != file) - return 0; - if (vma->vm_ops && vma->vm_ops->close) - return 0; - if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) - return 0; - return 1; -} - -static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, - struct anon_vma *anon_vma2, - struct vm_area_struct *vma) -{ - /* - * The list_is_singular() test is to avoid merging VMA cloned from - * parents. This can improve scalability caused by anon_vma lock. - */ - if ((!anon_vma1 || !anon_vma2) && (!vma || - list_is_singular(&vma->anon_vma_chain))) - return 1; - return anon_vma1 == anon_vma2; -} - -/* - * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) - * in front of (at a lower virtual address and file offset than) the vma. - * - * We cannot merge two vmas if they have differently assigned (non-NULL) - * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. - * - * We don't check here for the merged mmap wrapping around the end of pagecache - * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which - * wrap, nor mmaps which cover the final page at index -1UL. - */ -static int -can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, - struct anon_vma *anon_vma, struct file *file, - pgoff_t vm_pgoff, - struct vm_userfaultfd_ctx vm_userfaultfd_ctx) -{ - if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && - is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { - if (vma->vm_pgoff == vm_pgoff) - return 1; - } - return 0; -} - -/* - * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) - * beyond (at a higher virtual address and file offset than) the vma. - * - * We cannot merge two vmas if they have differently assigned (non-NULL) - * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. - */ -static int -can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, - struct anon_vma *anon_vma, struct file *file, - pgoff_t vm_pgoff, - struct vm_userfaultfd_ctx vm_userfaultfd_ctx) -{ - if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && - is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { - pgoff_t vm_pglen; - vm_pglen = vma_pages(vma); - if (vma->vm_pgoff + vm_pglen == vm_pgoff) - return 1; - } - return 0; -} - -/* - * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out - * whether that can be merged with its predecessor or its successor. - * Or both (it neatly fills a hole). - * - * In most cases - when called for mmap, brk or mremap - [addr,end) is - * certain not to be mapped by the time vma_merge is called; but when - * called for mprotect, it is certain to be already mapped (either at - * an offset within prev, or at the start of next), and the flags of - * this area are about to be changed to vm_flags - and the no-change - * case has already been eliminated. - * - * The following mprotect cases have to be considered, where AAAA is - * the area passed down from mprotect_fixup, never extending beyond one - * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: - * - * AAAA AAAA AAAA AAAA - * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX - * cannot merge might become might become might become - * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or - * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or - * mremap move: PPPPXXXXXXXX 8 - * AAAA - * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN - * might become case 1 below case 2 below case 3 below - * - * It is important for case 8 that the 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) -{ - pgoff_t pglen = (end - addr) >> PAGE_SHIFT; - struct vm_area_struct *area, *next; - int err; - - /* - * We later require that vma->vm_flags == vm_flags, - * so this tests vma->vm_flags & VM_SPECIAL, too. - */ - if (vm_flags & VM_SPECIAL) - return NULL; - - if (prev) - next = prev->vm_next; - else - next = mm->mmap; - area = next; - if (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)) { - /* - * OK, it can. Can we now merge in the successor as well? - */ - if (next && end == next->vm_start && - mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, - pgoff+pglen, - vm_userfaultfd_ctx) && - is_mergeable_anon_vma(prev->anon_vma, - next->anon_vma, NULL)) { - /* cases 1, 6 */ - err = __vma_adjust(prev, prev->vm_start, - next->vm_end, prev->vm_pgoff, NULL, - prev); - } else /* cases 2, 5, 7 */ - err = __vma_adjust(prev, prev->vm_start, - end, prev->vm_pgoff, NULL, prev); - if (err) - return NULL; - khugepaged_enter_vma_merge(prev, vm_flags); - return prev; - } - - /* - * Can this new request be merged in front of next? - */ - if (next && end == next->vm_start && - mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, pgoff+pglen, - vm_userfaultfd_ctx)) { - if (prev && addr < prev->vm_end) /* case 4 */ - err = __vma_adjust(prev, prev->vm_start, - addr, prev->vm_pgoff, NULL, next); - else { /* cases 3, 8 */ - err = __vma_adjust(area, addr, next->vm_end, - next->vm_pgoff - pglen, NULL, next); - /* - * 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 compatbility check to quickly see if it's even worth looking - * at sharing an anon_vma. - * - * They need to have the same vm_file, and the flags can only differ - * in things that mprotect may change. - * - * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that - * we can merge the two vma's. For example, we refuse to merge a vma if - * there is a vm_ops->close() function, because that indicates that the - * driver is doing some kind of reference counting. But that doesn't - * really matter for the anon_vma sharing case. - */ -static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) -{ - return a->vm_end == b->vm_start && - mpol_equal(vma_policy(a), vma_policy(b)) && - a->vm_file == b->vm_file && - !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) && - b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); -} - -/* - * Do some basic sanity checking to see if we can re-use the anon_vma - * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be - * the same as 'old', the other will be the new one that is trying - * to share the anon_vma. - * - * NOTE! This runs with mm_sem held for reading, so it is possible that - * the anon_vma of 'old' is concurrently in the process of being set up - * by another page fault trying to merge _that_. But that's ok: if it - * is being set up, that automatically means that it will be a singleton - * acceptable for merging, so we can do all of this optimistically. But - * we do that READ_ONCE() to make sure that we never re-load the pointer. - * - * IOW: that the "list_is_singular()" test on the anon_vma_chain only - * matters for the 'stable anon_vma' case (ie the thing we want to avoid - * is to return an anon_vma that is "complex" due to having gone through - * a fork). - * - * We also make sure that the two vma's are compatible (adjacent, - * and with the same memory policies). That's all stable, even with just - * a read lock on the mm_sem. - */ -static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) -{ - if (anon_vma_compatible(a, b)) { - struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); - - if (anon_vma && list_is_singular(&old->anon_vma_chain)) - return anon_vma; - } - return NULL; -} - -/* - * find_mergeable_anon_vma is used by anon_vma_prepare, to check - * neighbouring vmas for a suitable anon_vma, before it goes off - * to allocate a new anon_vma. It checks because a repetitive - * sequence of mprotects and faults may otherwise lead to distinct - * anon_vmas being allocated, preventing vma merge in subsequent - * mprotect. - */ -struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) -{ - struct anon_vma *anon_vma; - struct vm_area_struct *near; - - near = vma->vm_next; - if (!near) - goto try_prev; - - anon_vma = reusable_anon_vma(near, vma, near); - if (anon_vma) - return anon_vma; -try_prev: - near = vma->vm_prev; - if (!near) - goto none; - - anon_vma = reusable_anon_vma(near, near, vma); - if (anon_vma) - return anon_vma; -none: - /* - * There's no absolute need to look only at touching neighbours: - * we could search further afield for "compatible" anon_vmas. - * But it would probably just be a waste of time searching, - * or lead to too many vmas hanging off the same anon_vma. - * We're trying to allow mprotect remerging later on, - * not trying to minimize memory used for anon_vmas. - */ - return NULL; + mm->brk = origbrk; + mmap_write_unlock(mm); + return origbrk; } /* @@ -1330,22 +225,21 @@ static inline unsigned long round_hint_to_min(unsigned long hint) return hint; } -static inline int mlock_future_check(struct mm_struct *mm, - unsigned long flags, - unsigned long len) +bool mlock_future_ok(const struct mm_struct *mm, vm_flags_t vm_flags, + unsigned long bytes) { - 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; + unsigned long locked_pages, limit_pages; + + if (!(vm_flags & VM_LOCKED) || capable(CAP_IPC_LOCK)) + return true; + + locked_pages = bytes >> PAGE_SHIFT; + locked_pages += mm->locked_vm; + + limit_pages = rlimit(RLIMIT_MEMLOCK); + limit_pages >>= PAGE_SHIFT; + + return locked_pages <= limit_pages; } static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) @@ -1356,8 +250,11 @@ static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) 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) + if (file->f_op->fop_flags & FOP_UNSIGNED_OFFSET) return 0; /* Yes, random drivers might want more. But I'm tired of buggy drivers */ @@ -1377,8 +274,62 @@ static inline bool file_mmap_ok(struct file *file, struct inode *inode, return true; } -/* - * The caller must hold down_write(¤t->mm->mmap_sem). +/** + * do_mmap() - Perform a userland memory mapping into the current process + * address space of length @len with protection bits @prot, mmap flags @flags + * (from which VMA flags will be inferred), and any additional VMA flags to + * apply @vm_flags. If this is a file-backed mapping then the file is specified + * in @file and page offset into the file via @pgoff. + * + * This function does not perform security checks on the file and assumes, if + * @uf is non-NULL, the caller has provided a list head to track unmap events + * for userfaultfd @uf. + * + * It also simply indicates whether memory population is required by setting + * @populate, which must be non-NULL, expecting the caller to actually perform + * this task itself if appropriate. + * + * This function will invoke architecture-specific (and if provided and + * relevant, file system-specific) logic to determine the most appropriate + * unmapped area in which to place the mapping if not MAP_FIXED. + * + * Callers which require userland mmap() behaviour should invoke vm_mmap(), + * which is also exported for module use. + * + * Those which require this behaviour less security checks, userfaultfd and + * populate behaviour, and who handle the mmap write lock themselves, should + * call this function. + * + * Note that the returned address may reside within a merged VMA if an + * appropriate merge were to take place, so it doesn't necessarily specify the + * start of a VMA, rather only the start of a valid mapped range of length + * @len bytes, rounded down to the nearest page size. + * + * The caller must write-lock current->mm->mmap_lock. + * + * @file: An optional struct file pointer describing the file which is to be + * mapped, if a file-backed mapping. + * @addr: If non-zero, hints at (or if @flags has MAP_FIXED set, specifies) the + * address at which to perform this mapping. See mmap (2) for details. Must be + * page-aligned. + * @len: The length of the mapping. Will be page-aligned and must be at least 1 + * page in size. + * @prot: Protection bits describing access required to the mapping. See mmap + * (2) for details. + * @flags: Flags specifying how the mapping should be performed, see mmap (2) + * for details. + * @vm_flags: VMA flags which should be set by default, or 0 otherwise. + * @pgoff: Page offset into the @file if file-backed, should be 0 otherwise. + * @populate: A pointer to a value which will be set to 0 if no population of + * the range is required, or the number of bytes to populate if it is. Must be + * non-NULL. See mmap (2) for details as to under what circumstances population + * of the range occurs. + * @uf: An optional pointer to a list head to track userfaultfd unmap events + * should unmapping events arise. If provided, it is up to the caller to manage + * this. + * + * Returns: Either an error, or the address at which the requested mapping has + * been performed. */ unsigned long do_mmap(struct file *file, unsigned long addr, unsigned long len, unsigned long prot, @@ -1391,6 +342,8 @@ unsigned long do_mmap(struct file *file, unsigned long addr, *populate = 0; + mmap_assert_write_locked(mm); + if (!len) return -EINVAL; @@ -1398,7 +351,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, * 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.) + * mounted, in which case we don't add PROT_EXEC.) */ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) if (!(file && path_noexec(&file->f_path))) @@ -1424,19 +377,15 @@ unsigned long do_mmap(struct file *file, unsigned long addr, 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 is returned from get_unmapped_area, + * There are two cases: + * 1> MAP_FIXED == false + * unallocated memory, no need to check sealing. + * 1> MAP_FIXED == true + * sealing is checked inside mmap_region when + * do_vmi_munmap is called. */ - addr = get_unmapped_area(file, addr, len, pgoff, flags); - if (offset_in_page(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); @@ -1448,24 +397,39 @@ unsigned long do_mmap(struct file *file, unsigned long addr, * 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) | + vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(file, flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; + /* 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, vm_flags); + if (IS_ERR_VALUE(addr)) + return addr; + + if (flags & MAP_FIXED_NOREPLACE) { + if (find_vma_intersection(mm, addr, addr + len)) + return -EEXIST; + } + if (flags & MAP_LOCKED) if (!can_do_mlock()) return -EPERM; - if (mlock_future_check(mm, vm_flags, len)) + if (!mlock_future_ok(mm, vm_flags, len)) return -EAGAIN; if (file) { struct inode *inode = file_inode(file); unsigned long flags_mask; + int err; if (!file_mmap_ok(file, inode, pgoff, len)) return -EOVERFLOW; - flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; + flags_mask = LEGACY_MAP_MASK; + if (file->f_op->fop_flags & FOP_MMAP_SYNC) + flags_mask |= MAP_SYNC; switch (flags & MAP_TYPE) { case MAP_SHARED: @@ -1477,12 +441,16 @@ unsigned long do_mmap(struct file *file, unsigned long addr, * with MAP_SHARED to preserve backward compatibility. */ flags &= LEGACY_MAP_MASK; - /* fall through */ + fallthrough; case MAP_SHARED_VALIDATE: if (flags & ~flags_mask) return -EOPNOTSUPP; - if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) - return -EACCES; + 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 @@ -1491,17 +459,10 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) return -EACCES; - /* - * Make sure there are no mandatory locks on the file. - */ - if (locks_verify_locked(file)) - return -EAGAIN; - vm_flags |= VM_SHARED | VM_MAYSHARE; if (!(file->f_mode & FMODE_WRITE)) vm_flags &= ~(VM_MAYWRITE | VM_SHARED); - - /* fall through */ + fallthrough; case MAP_PRIVATE: if (!(file->f_mode & FMODE_READ)) return -EACCES; @@ -1511,7 +472,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, vm_flags &= ~VM_MAYEXEC; } - if (!file->f_op->mmap) + if (!can_mmap_file(file)) return -ENODEV; if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) return -EINVAL; @@ -1520,6 +481,14 @@ unsigned long do_mmap(struct file *file, unsigned long addr, default: return -EINVAL; } + + /* + * Check to see if we are violating any seals and update VMA + * flags if necessary to avoid future seal violations. + */ + err = memfd_check_seals_mmap(file, &vm_flags); + if (err) + return (unsigned long)err; } else { switch (flags & MAP_TYPE) { case MAP_SHARED: @@ -1531,6 +500,36 @@ unsigned long do_mmap(struct file *file, unsigned long addr, pgoff = 0; vm_flags |= VM_SHARED | VM_MAYSHARE; break; + case MAP_DROPPABLE: + if (VM_DROPPABLE == VM_NONE) + return -ENOTSUPP; + /* + * A locked or stack area makes no sense to be droppable. + * + * Also, since droppable pages can just go away at any time + * it makes no sense to copy them on fork or dump them. + * + * And don't attempt to combine with hugetlb for now. + */ + if (flags & (MAP_LOCKED | MAP_HUGETLB)) + return -EINVAL; + if (vm_flags & (VM_GROWSDOWN | VM_GROWSUP)) + return -EINVAL; + + vm_flags |= VM_DROPPABLE; + + /* + * If the pages can be dropped, then it doesn't make + * sense to reserve them. + */ + vm_flags |= VM_NORESERVE; + + /* + * Likewise, they're volatile enough that they + * shouldn't survive forks or coredumps. + */ + vm_flags |= VM_WIPEONFORK | VM_DONTDUMP; + fallthrough; case MAP_PRIVATE: /* * Set pgoff according to addr for anon_vma. @@ -1576,13 +575,13 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, file = fget(fd); if (!file) return -EBADF; - if (is_file_hugepages(file)) + if (is_file_hugepages(file)) { len = ALIGN(len, huge_page_size(hstate_file(file))); - retval = -EINVAL; - if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) + } 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); @@ -1593,19 +592,15 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, /* * 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, + 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) @@ -1645,436 +640,39 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) #endif /* __ARCH_WANT_SYS_OLD_MMAP */ /* - * Some shared mappigns will want the pages marked read-only - * to track write events. If so, we'll downgrade vm_page_prot - * to the private version (using protection_map[] without the - * VM_SHARED bit). + * Determine if the allocation needs to ensure that there is no + * existing mapping within it's guard gaps, for use as start_gap. */ -int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) +static inline unsigned long stack_guard_placement(vm_flags_t vm_flags) { - vm_flags_t vm_flags = vma->vm_flags; - const struct vm_operations_struct *vm_ops = vma->vm_ops; + if (vm_flags & VM_SHADOW_STACK) + return PAGE_SIZE; - /* 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? */ - if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) - return 1; - - /* Specialty mapping? */ - if (vm_flags & VM_PFNMAP) - return 0; - - /* Can the mapping track the dirty pages? */ - return vma->vm_file && vma->vm_file->f_mapping && - mapping_cap_account_dirty(vma->vm_file->f_mapping); + return 0; } /* - * We account for memory if it's a private writeable mapping, - * not hugepages and VM_NORESERVE wasn't set. + * 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) */ -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) +unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) { - struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev; - int error; - struct rb_node **rb_link, *rb_parent; - unsigned long charged = 0; - - /* Check against address space limit. */ - if (!may_expand_vm(mm, 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 */ - while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, - &rb_parent)) { - if (do_munmap(mm, addr, len, 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); - 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; - 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); - } - - vma_link(mm, vma, prev, rb_link, rb_parent); - /* Once vma denies write, undo our temporary denial count */ - if (file) { - if (vm_flags & VM_SHARED) - mapping_unmap_writable(file->f_mapping); - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); - } - file = vma->vm_file; -out: - perf_event_mmap(vma); - - vm_stat_account(mm, vm_flags, 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)) - 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). - */ - vma->vm_flags |= VM_SOFTDIRTY; + unsigned long addr; - vma_set_page_prot(vma); + 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; - -unmap_and_free_vma: - vma->vm_file = NULL; - fput(file); - - /* Undo any partial mapping done by a device driver. */ - unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); - charged = 0; - if (vm_flags & VM_SHARED) - mapping_unmap_writable(file->f_mapping); -allow_write_and_free_vma: - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); -free_vma: - vm_area_free(vma); -unacct_error: - if (charged) - vm_unacct_memory(charged); - return error; -} - -unsigned long unmapped_area(struct vm_unmapped_area_info *info) -{ - /* - * We implement the search by looking for an rbtree node that - * immediately follows a suitable gap. That is, - * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; - * - gap_end = vma->vm_start >= info->low_limit + length; - * - gap_end - gap_start >= length - */ - - struct mm_struct *mm = current->mm; - struct vm_area_struct *vma; - unsigned long length, low_limit, high_limit, gap_start, gap_end; - - /* Adjust search length to account for worst case alignment overhead */ - length = info->length + info->align_mask; - if (length < info->length) - return -ENOMEM; - - /* Adjust search limits by the desired length */ - if (info->high_limit < length) - return -ENOMEM; - high_limit = info->high_limit - length; - - if (info->low_limit > high_limit) - return -ENOMEM; - low_limit = info->low_limit + length; - - /* Check if rbtree root looks promising */ - if (RB_EMPTY_ROOT(&mm->mm_rb)) - goto check_highest; - vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); - if (vma->rb_subtree_gap < length) - goto check_highest; - - while (true) { - /* Visit left subtree if it looks promising */ - gap_end = 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; -} - -unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) -{ - struct mm_struct *mm = current->mm; - struct vm_area_struct *vma; - unsigned long length, low_limit, high_limit, gap_start, gap_end; - - /* Adjust search length to account for worst case alignment overhead */ - length = info->length + info->align_mask; - if (length < info->length) - return -ENOMEM; - - /* - * Adjust search limits by the desired length. - * See implementation comment at top of unmapped_area(). - */ - gap_end = info->high_limit; - if (gap_end < length) - return -ENOMEM; - high_limit = gap_end - length; - - if (info->low_limit > high_limit) - return -ENOMEM; - low_limit = info->low_limit + length; - - /* Check highest gap, which does not precede any rbtree node */ - gap_start = mm->highest_vm_end; - if (gap_start <= high_limit) - goto found_highest; - - /* Check if rbtree root looks promising */ - if (RB_EMPTY_ROOT(&mm->mm_rb)) - return -ENOMEM; - vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); - if (vma->rb_subtree_gap < length) - return -ENOMEM; - - while (true) { - /* Visit right subtree if it looks promising */ - gap_start = vma->vm_prev ? 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; } - -#ifndef arch_get_mmap_end -#define arch_get_mmap_end(addr) (TASK_SIZE) -#endif - -#ifndef arch_get_mmap_base -#define arch_get_mmap_base(addr, base) (base) -#endif - /* Get an address range which is currently unmapped. * For shmat() with addr=0. * @@ -2086,15 +684,15 @@ found_highest: * * 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) +generic_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t vm_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); + struct vm_unmapped_area_info info = {}; + const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); if (len > mmap_end - mmap_min_addr) return -ENOMEM; @@ -2111,30 +709,39 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, return addr; } - info.flags = 0; info.length = len; info.low_limit = mm->mmap_base; info.high_limit = mmap_end; - info.align_mask = 0; + info.start_gap = stack_guard_placement(vm_flags); + if (filp && is_file_hugepages(filp)) + info.align_mask = huge_page_mask_align(filp); return vm_unmapped_area(&info); } + +#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, vm_flags_t vm_flags) +{ + return generic_get_unmapped_area(filp, addr, len, pgoff, flags, + vm_flags); +} #endif /* * This mmap-allocator allocates new areas top-down from below the * stack's low limit (the base): */ -#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN unsigned long -arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, - const unsigned long len, const unsigned long pgoff, - const unsigned long flags) +generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t vm_flags) { struct vm_area_struct *vma, *prev; struct mm_struct *mm = current->mm; - unsigned long addr = addr0; - struct vm_unmapped_area_info info; - const unsigned long mmap_end = arch_get_mmap_end(addr); + struct vm_unmapped_area_info info = {}; + const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); /* requested length too big for entire address space */ if (len > mmap_end - mmap_min_addr) @@ -2155,9 +762,11 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, info.flags = VM_UNMAPPED_AREA_TOPDOWN; info.length = len; - info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.low_limit = PAGE_SIZE; info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); - info.align_mask = 0; + info.start_gap = stack_guard_placement(vm_flags); + if (filp && is_file_hugepages(filp)) + info.align_mask = huge_page_mask_align(filp); addr = vm_unmapped_area(&info); /* @@ -2176,14 +785,35 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } + +#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, vm_flags_t vm_flags) +{ + return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags, + vm_flags); +} #endif +unsigned long mm_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t vm_flags) +{ + if (mm_flags_test(MMF_TOPDOWN, current->mm)) + return arch_get_unmapped_area_topdown(filp, addr, len, pgoff, + flags, vm_flags); + return arch_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags); +} + unsigned long -get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, - unsigned long pgoff, unsigned long flags) +__get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) { unsigned long (*get_area)(struct file *, unsigned long, - unsigned long, unsigned long, unsigned long); + unsigned long, unsigned long, unsigned long) + = NULL; unsigned long error = arch_mmap_check(addr, len, flags); if (error) @@ -2193,7 +823,6 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 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; @@ -2201,13 +830,26 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, /* * 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_pgoff() will clear pgoff, so match alignment. */ - pgoff = 0; get_area = shmem_get_unmapped_area; } - addr = get_area(file, addr, len, pgoff, flags); + /* Always treat pgoff as zero for anonymous memory. */ + if (!file) + pgoff = 0; + + if (get_area) { + addr = get_area(file, addr, len, pgoff, flags); + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && !file + && !addr /* no hint */ + && IS_ALIGNED(len, PMD_SIZE)) { + /* Ensures that larger anonymous mappings are THP aligned. */ + addr = thp_get_unmapped_area_vmflags(file, addr, len, + pgoff, flags, vm_flags); + } else { + addr = mm_get_unmapped_area_vmflags(file, addr, len, + pgoff, flags, vm_flags); + } if (IS_ERR_VALUE(addr)) return addr; @@ -2220,280 +862,76 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, return error ? error : addr; } -EXPORT_SYMBOL(get_unmapped_area); - -/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ -struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) -{ - struct rb_node *rb_node; - struct vm_area_struct *vma; - - /* Check the cache first. */ - vma = vmacache_find(mm, addr); - if (likely(vma)) - return vma; - - rb_node = mm->mm_rb.rb_node; - - while (rb_node) { - struct vm_area_struct *tmp; - - tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); - - if (tmp->vm_end > addr) { - vma = tmp; - if (tmp->vm_start <= addr) - break; - rb_node = rb_node->rb_left; - } else - rb_node = rb_node->rb_right; - } - - if (vma) - vmacache_update(addr, vma); - return vma; -} - -EXPORT_SYMBOL(find_vma); - -/* - * Same as find_vma, but also return a pointer to the previous VMA in *pprev. - */ -struct vm_area_struct * -find_vma_prev(struct mm_struct *mm, unsigned long addr, - struct vm_area_struct **pprev) +unsigned long +mm_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags) { - struct vm_area_struct *vma; - - vma = find_vma(mm, addr); - if (vma) { - *pprev = vma->vm_prev; - } else { - struct rb_node *rb_node = mm->mm_rb.rb_node; - *pprev = NULL; - while (rb_node) { - *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); - rb_node = rb_node->rb_right; - } - } - return vma; + return mm_get_unmapped_area_vmflags(file, addr, len, pgoff, flags, 0); } +EXPORT_SYMBOL(mm_get_unmapped_area); -/* - * Verify that the stack growth is acceptable and - * update accounting. This is shared with both the - * grow-up and grow-down cases. +/** + * find_vma_intersection() - Look up the first VMA which intersects the interval + * @mm: The process address space. + * @start_addr: The inclusive start user address. + * @end_addr: The exclusive end user address. + * + * Returns: The first VMA within the provided range, %NULL otherwise. Assumes + * start_addr < end_addr. */ -static int acct_stack_growth(struct vm_area_struct *vma, - unsigned long size, unsigned long grow) +struct vm_area_struct *find_vma_intersection(struct mm_struct *mm, + unsigned long start_addr, + unsigned long end_addr) { - 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; + unsigned long index = start_addr; - return 0; + mmap_assert_locked(mm); + return mt_find(&mm->mm_mt, &index, end_addr - 1); } +EXPORT_SYMBOL(find_vma_intersection); -#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. +/** + * find_vma() - Find the VMA for a given address, or the next VMA. + * @mm: The mm_struct to check + * @addr: The address + * + * Returns: The VMA associated with addr, or the next VMA. + * May return %NULL in the case of no VMA at addr or above. */ -int expand_upwards(struct vm_area_struct *vma, unsigned long address) +struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) { - 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; + unsigned long index = addr; - /* 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 && - (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) { - 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_sem 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_sem - * 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; + mmap_assert_locked(mm); + return mt_find(&mm->mm_mt, &index, ULONG_MAX); } -#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ +EXPORT_SYMBOL(find_vma); -/* - * vma is the first one with address < vma->vm_start. Have to extend vma. +/** + * find_vma_prev() - Find the VMA for a given address, or the next vma and + * set %pprev to the previous VMA, if any. + * @mm: The mm_struct to check + * @addr: The address + * @pprev: The pointer to set to the previous VMA + * + * Note that RCU lock is missing here since the external mmap_lock() is used + * instead. + * + * Returns: The VMA associated with @addr, or the next vma. + * May return %NULL in the case of no vma at addr or above. */ -int expand_downwards(struct vm_area_struct *vma, - unsigned long address) +struct vm_area_struct * +find_vma_prev(struct mm_struct *mm, unsigned long addr, + struct vm_area_struct **pprev) { - struct mm_struct *mm = vma->vm_mm; - struct vm_area_struct *prev; - int error; - - address &= PAGE_MASK; - error = security_mmap_addr(address); - if (error) - return error; - - /* 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) && - (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) { - 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; + struct vm_area_struct *vma; + VMA_ITERATOR(vmi, mm, addr); - /* - * vma->vm_start/vm_end cannot change under us because the caller - * is required to hold the mmap_sem in read mode. We need the - * anon_vma lock to serialize against concurrent expand_stacks. - */ - 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_sem - * 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_start = address; - 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; + vma = vma_iter_load(&vmi); + *pprev = vma_prev(&vmi); + if (!vma) + vma = vma_next(&vmi); + return vma; } /* enforced gap between the expanding stack and other mappings. */ @@ -2508,18 +946,17 @@ static int __init cmdline_parse_stack_guard_gap(char *p) if (!*endptr) stack_guard_gap = val << PAGE_SHIFT; - return 0; + 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) +int expand_stack_locked(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 *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) { struct vm_area_struct *vma, *prev; @@ -2527,20 +964,21 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) vma = find_vma_prev(mm, addr, &prev); if (vma && (vma->vm_start <= addr)) return vma; - if (!prev || expand_stack(prev, addr)) + if (!prev) + return NULL; + if (expand_stack_locked(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) +int expand_stack_locked(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 *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) { struct vm_area_struct *vma; unsigned long start; @@ -2551,10 +989,8 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) 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)) + if (expand_stack_locked(vma, addr)) return NULL; if (vma->vm_flags & VM_LOCKED) populate_vma_page_range(vma, addr, start, NULL); @@ -2562,303 +998,71 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) } #endif -EXPORT_SYMBOL_GPL(find_extend_vma); +#if defined(CONFIG_STACK_GROWSUP) -/* - * 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); +#define vma_expand_up(vma,addr) expand_upwards(vma, addr) +#define vma_expand_down(vma, addr) (-EFAULT) - 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 = prev ? prev->vm_next : mm->mmap; - struct mmu_gather tlb; - - lru_add_drain(); - tlb_gather_mmu(&tlb, mm, start, end); - update_hiwater_rss(mm); - unmap_vmas(&tlb, vma, start, end); - free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, - next ? next->vm_start : USER_PGTABLES_CEILING); - tlb_finish_mmu(&tlb, start, end); -} +#else -/* - * Create a list of vma's touched by the unmap, removing them from the mm's - * vma list as we go.. - */ -static void -detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, - struct vm_area_struct *prev, unsigned long end) -{ - struct vm_area_struct **insertion_point; - struct vm_area_struct *tail_vma = NULL; +#define vma_expand_up(vma,addr) (-EFAULT) +#define vma_expand_down(vma, addr) expand_downwards(vma, addr) - insertion_point = (prev ? &prev->vm_next : &mm->mmap); - vma->vm_prev = NULL; - do { - vma_rb_erase(vma, &mm->mm_rb); - mm->map_count--; - tail_vma = vma; - vma = vma->vm_next; - } while (vma && vma->vm_start < end); - *insertion_point = vma; - if (vma) { - vma->vm_prev = prev; - vma_gap_update(vma); - } else - mm->highest_vm_end = prev ? vm_end_gap(prev) : 0; - tail_vma->vm_next = NULL; - - /* Kill the cache */ - vmacache_invalidate(mm); -} +#endif /* - * __split_vma() bypasses sysctl_max_map_count checking. We use this where it - * has already been checked or doesn't make sense to fail. + * expand_stack(): legacy interface for page faulting. Don't use unless + * you have to. + * + * This is called with the mm locked for reading, drops the lock, takes + * the lock for writing, tries to look up a vma again, expands it if + * necessary, and downgrades the lock to reading again. + * + * If no vma is found or it can't be expanded, it returns NULL and has + * dropped the lock. */ -int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long addr, int new_below) +struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr) { - struct vm_area_struct *new; - int err; + struct vm_area_struct *vma, *prev; - if (vma->vm_ops && vma->vm_ops->split) { - err = vma->vm_ops->split(vma, addr); - if (err) - return err; - } + mmap_read_unlock(mm); + if (mmap_write_lock_killable(mm)) + return NULL; - new = vm_area_dup(vma); - if (!new) - return -ENOMEM; + vma = find_vma_prev(mm, addr, &prev); + if (vma && vma->vm_start <= addr) + goto success; - if (new_below) - new->vm_end = addr; - else { - new->vm_start = addr; - new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); + if (prev && !vma_expand_up(prev, addr)) { + vma = prev; + goto success; } - err = vma_dup_policy(vma, new); - if (err) - goto out_free_vma; - - err = anon_vma_clone(new, vma); - if (err) - goto out_free_mpol; - - if (new->vm_file) - get_file(new->vm_file); - - if (new->vm_ops && new->vm_ops->open) - new->vm_ops->open(new); - - if (new_below) - err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + - ((addr - new->vm_start) >> PAGE_SHIFT), new); - else - err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); - - /* Success. */ - if (!err) - return 0; - - /* Clean everything up if vma_adjust failed. */ - if (new->vm_ops && new->vm_ops->close) - new->vm_ops->close(new); - if (new->vm_file) - fput(new->vm_file); - unlink_anon_vmas(new); - out_free_mpol: - mpol_put(vma_policy(new)); - out_free_vma: - vm_area_free(new); - return err; -} + if (vma && !vma_expand_down(vma, addr)) + goto success; -/* - * 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; + mmap_write_unlock(mm); + return NULL; - return __split_vma(mm, vma, addr, new_below); +success: + mmap_write_downgrade(mm); + return vma; } -/* 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> +/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls. + * @mm: The mm_struct + * @start: The start address to munmap + * @len: The length to be munmapped. + * @uf: The userfaultfd list_head + * + * Return: 0 on success, error otherwise. */ -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); - if (len == 0) - return -EINVAL; - - /* Find the first overlapping VMA */ - vma = find_vma(mm, start); - if (!vma) - return 0; - prev = vma->vm_prev; - /* we have start < vma->vm_end */ - - /* if it doesn't overlap, we have nothing.. */ - end = start + len; - if (vma->vm_start >= end) - return 0; - - /* - * If we need to split any vma, do it now to save pain later. - * - * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially - * unmapped vm_area_struct will remain in use: so lower split_vma - * places tmp vma above, and higher split_vma places tmp vma below. - */ - if (start > vma->vm_start) { - int error; - - /* - * Make sure that map_count on return from munmap() will - * not exceed its limit; but let map_count go just above - * its limit temporarily, to help free resources as expected. - */ - if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) - return -ENOMEM; - - error = __split_vma(mm, vma, start, 0); - if (error) - return error; - prev = vma; - } - - /* Does it split the last one? */ - last = find_vma(mm, end); - if (last && end > last->vm_start) { - int error = __split_vma(mm, last, end, 1); - if (error) - return error; - } - vma = prev ? prev->vm_next : mm->mmap; - - 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 */ - detach_vmas_to_be_unmapped(mm, vma, prev, end); - - /* - * mpx unmap needs to be called with mmap_sem held for write. - * It is safe to call it before unmap_region(). - */ - arch_unmap(mm, vma, start, end); - - if (downgrade) - downgrade_write(&mm->mmap_sem); - - 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); -} + VMA_ITERATOR(vmi, mm, start); -static int __vm_munmap(unsigned long start, size_t len, bool downgrade) -{ - int ret; - struct mm_struct *mm = current->mm; - LIST_HEAD(uf); - - if (down_write_killable(&mm->mmap_sem)) - return -EINTR; - - ret = __do_munmap(mm, start, len, &uf, downgrade); - /* - * Returning 1 indicates mmap_sem is downgraded. - * But 1 is not legal return value of vm_munmap() and munmap(), reset - * it to 0 before return. - */ - if (ret == 1) { - up_read(&mm->mmap_sem); - ret = 0; - } else - up_write(&mm->mmap_sem); - - userfaultfd_unmap_complete(mm, &uf); - return ret; + return do_vmi_munmap(&vmi, mm, start, len, uf, false); } int vm_munmap(unsigned long start, size_t len) @@ -2869,7 +1073,7 @@ EXPORT_SYMBOL(vm_munmap); SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) { - profile_munmap(addr); + addr = untagged_addr(addr); return __vm_munmap(addr, len, true); } @@ -2886,8 +1090,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, unsigned long populate = 0; unsigned long ret = -EINVAL; struct file *file; + vm_flags_t vm_flags; - pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n", + pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n", current->comm, current->pid); if (prot) @@ -2902,23 +1107,69 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, if (pgoff + (size >> PAGE_SHIFT) < pgoff) return ret; - if (down_write_killable(&mm->mmap_sem)) + if (mmap_read_lock_killable(mm)) return -EINTR; - vma = find_vma(mm, start); + /* + * Look up VMA under read lock first so we can perform the security + * without holding locks (which can be problematic). We reacquire a + * write lock later and check nothing changed underneath us. + */ + vma = vma_lookup(mm, start); + + if (!vma || !(vma->vm_flags & VM_SHARED)) { + mmap_read_unlock(mm); + return -EINVAL; + } - if (!vma || !(vma->vm_flags & VM_SHARED)) + prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; + prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; + prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; + + flags &= MAP_NONBLOCK; + flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; + if (vma->vm_flags & VM_LOCKED) + flags |= MAP_LOCKED; + + /* Save vm_flags used to calculate prot and flags, and recheck later. */ + vm_flags = vma->vm_flags; + file = get_file(vma->vm_file); + + mmap_read_unlock(mm); + + /* Call outside mmap_lock to be consistent with other callers. */ + ret = security_mmap_file(file, prot, flags); + if (ret) { + fput(file); + return ret; + } + + ret = -EINVAL; + + /* OK security check passed, take write lock + let it rip. */ + if (mmap_write_lock_killable(mm)) { + fput(file); + return -EINTR; + } + + vma = vma_lookup(mm, start); + + if (!vma) goto out; - if (start < vma->vm_start) + /* Make sure things didn't change under us. */ + if (vma->vm_flags != vm_flags) + goto out; + if (vma->vm_file != file) goto out; if (start + size > vma->vm_end) { - struct vm_area_struct *next; + VMA_ITERATOR(vmi, mm, vma->vm_end); + struct vm_area_struct *next, *prev = vma; - for (next = vma->vm_next; next; next = next->vm_next) { + for_each_vma_range(vmi, next, start + size) { /* hole between vmas ? */ - if (next->vm_start != next->vm_prev->vm_end) + if (next->vm_start != prev->vm_end) goto out; if (next->vm_file != vma->vm_file) @@ -2929,43 +1180,19 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, if (start + size <= next->vm_end) break; + + prev = next; } if (!next) goto out; } - prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; - prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; - prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; - - flags &= MAP_NONBLOCK; - flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; - if (vma->vm_flags & VM_LOCKED) { - struct vm_area_struct *tmp; - flags |= MAP_LOCKED; - - /* drop PG_Mlocked flag for over-mapped range */ - for (tmp = vma; tmp->vm_start >= start + size; - tmp = tmp->vm_next) { - /* - * Split pmd and munlock page on the border - * of the range. - */ - vma_adjust_trans_huge(tmp, start, start + size, 0); - - munlock_vma_pages_range(tmp, - max(tmp->vm_start, start), - min(tmp->vm_end, start + size)); - } - } - - file = get_file(vma->vm_file); - ret = do_mmap_pgoff(vma->vm_file, start, size, - prot, flags, pgoff, &populate, NULL); - fput(file); + ret = do_mmap(vma->vm_file, start, size, + prot, flags, 0, pgoff, &populate, NULL); out: - up_write(&mm->mmap_sem); + mmap_write_unlock(mm); + fput(file); if (populate) mm_populate(ret, populate); if (!IS_ERR_VALUE(ret)) @@ -2973,90 +1200,15 @@ out: return ret; } -/* - * this is really a simplified "do_mmap". it only handles - * anonymous maps. eventually we may be able to do some - * brk-specific accounting here. - */ -static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf) -{ - struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev; - struct rb_node **rb_link, *rb_parent; - pgoff_t pgoff = addr >> PAGE_SHIFT; - int error; - - /* Until we need other flags, refuse anything except VM_EXEC. */ - if ((flags & (~VM_EXEC)) != 0) - return -EINVAL; - flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; - - error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); - if (offset_in_page(error)) - return error; - - error = mlock_future_check(mm, mm->def_flags, len); - if (error) - return error; - - /* - * Clear old maps. this also does some error checking for us - */ - while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, - &rb_parent)) { - if (do_munmap(mm, addr, len, uf)) - return -ENOMEM; - } - - /* Check against address space limits *after* clearing old maps... */ - if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) - return -ENOMEM; - - if (mm->map_count > sysctl_max_map_count) - return -ENOMEM; - - if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) - return -ENOMEM; - - /* Can we just expand an old private anonymous mapping? */ - vma = vma_merge(mm, prev, addr, addr + len, flags, - NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX); - if (vma) - goto out; - - /* - * create a vma struct for an anonymous mapping - */ - vma = vm_area_alloc(mm); - if (!vma) { - vm_unacct_memory(len >> PAGE_SHIFT); - return -ENOMEM; - } - - vma_set_anonymous(vma); - vma->vm_start = addr; - vma->vm_end = addr + len; - vma->vm_pgoff = pgoff; - vma->vm_flags = flags; - vma->vm_page_prot = vm_get_page_prot(flags); - vma_link(mm, vma, prev, rb_link, rb_parent); -out: - perf_event_mmap(vma); - mm->total_vm += len >> PAGE_SHIFT; - mm->data_vm += len >> PAGE_SHIFT; - if (flags & VM_LOCKED) - mm->locked_vm += (len >> PAGE_SHIFT); - vma->vm_flags |= VM_SOFTDIRTY; - return 0; -} - -int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) +int vm_brk_flags(unsigned long addr, unsigned long request, vm_flags_t vm_flags) { struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = NULL; unsigned long len; int ret; bool populate; LIST_HEAD(uf); + VMA_ITERATOR(vmi, mm, addr); len = PAGE_ALIGN(request); if (len < request) @@ -3064,24 +1216,36 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) if (!len) return 0; - if (down_write_killable(&mm->mmap_sem)) + /* Until we need other flags, refuse anything except VM_EXEC. */ + if ((vm_flags & (~VM_EXEC)) != 0) + return -EINVAL; + + if (mmap_write_lock_killable(mm)) return -EINTR; - ret = do_brk_flags(addr, len, flags, &uf); + ret = check_brk_limits(addr, len); + if (ret) + goto limits_failed; + + ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0); + if (ret) + goto munmap_failed; + + vma = vma_prev(&vmi); + ret = do_brk_flags(&vmi, vma, addr, len, vm_flags); populate = ((mm->def_flags & VM_LOCKED) != 0); - up_write(&mm->mmap_sem); + mmap_write_unlock(mm); userfaultfd_unmap_complete(mm, &uf); if (populate && !ret) mm_populate(addr, len); return ret; -} -EXPORT_SYMBOL(vm_brk_flags); -int vm_brk(unsigned long addr, unsigned long len) -{ - return vm_brk_flags(addr, len, 0); +munmap_failed: +limits_failed: + mmap_write_unlock(mm); + return ret; } -EXPORT_SYMBOL(vm_brk); +EXPORT_SYMBOL(vm_brk_flags); /* Release all mmaps. */ void exit_mmap(struct mm_struct *mm) @@ -3089,184 +1253,65 @@ void exit_mmap(struct mm_struct *mm) struct mmu_gather tlb; struct vm_area_struct *vma; unsigned long nr_accounted = 0; + VMA_ITERATOR(vmi, mm, 0); + int count = 0; /* mm's last user has gone, and its about to be pulled down */ mmu_notifier_release(mm); - if (unlikely(mm_is_oom_victim(mm))) { - /* - * Manually reap the mm to free as much memory as possible. - * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard - * this mm from further consideration. Taking mm->mmap_sem for - * write after setting MMF_OOM_SKIP will guarantee that the oom - * reaper will not run on this mm again after mmap_sem is - * dropped. - * - * Nothing can be holding mm->mmap_sem here and the above call - * to mmu_notifier_release(mm) ensures mmu notifier callbacks in - * __oom_reap_task_mm() will not block. - * - * This needs to be done before calling munlock_vma_pages_all(), - * which clears VM_LOCKED, otherwise the oom reaper cannot - * reliably test it. - */ - (void)__oom_reap_task_mm(mm); - - set_bit(MMF_OOM_SKIP, &mm->flags); - down_write(&mm->mmap_sem); - up_write(&mm->mmap_sem); - } - - if (mm->locked_vm) { - vma = mm->mmap; - while (vma) { - if (vma->vm_flags & VM_LOCKED) - munlock_vma_pages_all(vma); - vma = vma->vm_next; - } - } - + mmap_read_lock(mm); arch_exit_mmap(mm); - vma = mm->mmap; - if (!vma) /* Can happen if dup_mmap() received an OOM */ - return; + vma = vma_next(&vmi); + if (!vma || unlikely(xa_is_zero(vma))) { + /* Can happen if dup_mmap() received an OOM */ + mmap_read_unlock(mm); + mmap_write_lock(mm); + goto destroy; + } - lru_add_drain(); flush_cache_mm(mm); - tlb_gather_mmu(&tlb, mm, 0, -1); + tlb_gather_mmu_fullmm(&tlb, mm); /* update_hiwater_rss(mm) here? but nobody should be looking */ - /* Use -1 here to ensure all VMAs in the mm are unmapped */ - unmap_vmas(&tlb, vma, 0, -1); - free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); - tlb_finish_mmu(&tlb, 0, -1); - - /* - * Walk the list again, actually closing and freeing it, - * with preemption enabled, without holding any MM locks. - */ - while (vma) { - if (vma->vm_flags & VM_ACCOUNT) - nr_accounted += vma_pages(vma); - vma = remove_vma(vma); - } - vm_unacct_memory(nr_accounted); -} - -/* Insert vm structure into process list sorted by address - * and into the inode's i_mmap tree. If vm_file is non-NULL - * then i_mmap_rwsem is taken here. - */ -int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) -{ - struct vm_area_struct *prev; - struct rb_node **rb_link, *rb_parent; - - if (find_vma_links(mm, vma->vm_start, vma->vm_end, - &prev, &rb_link, &rb_parent)) - return -ENOMEM; - if ((vma->vm_flags & VM_ACCOUNT) && - security_vm_enough_memory_mm(mm, vma_pages(vma))) - return -ENOMEM; + /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ + unmap_vmas(&tlb, &vmi.mas, vma, 0, ULONG_MAX, ULONG_MAX); + mmap_read_unlock(mm); /* - * The vm_pgoff of a purely anonymous vma should be irrelevant - * until its first write fault, when page's anon_vma and index - * are set. But now set the vm_pgoff it will almost certainly - * end up with (unless mremap moves it elsewhere before that - * first wfault), so /proc/pid/maps tells a consistent story. - * - * By setting it to reflect the virtual start address of the - * vma, merges and splits can happen in a seamless way, just - * using the existing file pgoff checks and manipulations. - * Similarly in do_mmap_pgoff and in do_brk. + * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper + * because the memory has been already freed. */ - if (vma_is_anonymous(vma)) { - BUG_ON(vma->anon_vma); - vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; - } - - vma_link(mm, vma, prev, rb_link, rb_parent); - return 0; -} - -/* - * Copy the vma structure to a new location in the same mm, - * prior to moving page table entries, to effect an mremap move. - */ -struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, - unsigned long addr, unsigned long len, pgoff_t pgoff, - bool *need_rmap_locks) -{ - struct vm_area_struct *vma = *vmap; - unsigned long vma_start = vma->vm_start; - struct mm_struct *mm = vma->vm_mm; - struct vm_area_struct *new_vma, *prev; - struct rb_node **rb_link, *rb_parent; - bool faulted_in_anon_vma = true; + mm_flags_set(MMF_OOM_SKIP, mm); + mmap_write_lock(mm); + mt_clear_in_rcu(&mm->mm_mt); + vma_iter_set(&vmi, vma->vm_end); + free_pgtables(&tlb, &vmi.mas, vma, FIRST_USER_ADDRESS, + USER_PGTABLES_CEILING, true); + tlb_finish_mmu(&tlb); /* - * If anonymous vma has not yet been faulted, update new pgoff - * to match new location, to increase its chance of merging. + * Walk the list again, actually closing and freeing it, with preemption + * enabled, without holding any MM locks besides the unreachable + * mmap_write_lock. */ - if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { - pgoff = addr >> PAGE_SHIFT; - faulted_in_anon_vma = false; - } - - if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) - return NULL; /* should never get here */ - new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, - vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), - vma->vm_userfaultfd_ctx); - if (new_vma) { - /* - * Source vma may have been merged into new_vma - */ - if (unlikely(vma_start >= new_vma->vm_start && - vma_start < new_vma->vm_end)) { - /* - * The only way we can get a vma_merge with - * self during an mremap is if the vma hasn't - * been faulted in yet and we were allowed to - * reset the dst vma->vm_pgoff to the - * destination address of the mremap to allow - * the merge to happen. mremap must change the - * vm_pgoff linearity between src and dst vmas - * (in turn preventing a vma_merge) to be - * safe. It is only safe to keep the vm_pgoff - * linear if there are no pages mapped yet. - */ - VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); - *vmap = vma = new_vma; - } - *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); - } else { - new_vma = vm_area_dup(vma); - if (!new_vma) - goto out; - new_vma->vm_start = addr; - new_vma->vm_end = addr + len; - new_vma->vm_pgoff = pgoff; - if (vma_dup_policy(vma, new_vma)) - goto out_free_vma; - if (anon_vma_clone(new_vma, vma)) - goto out_free_mempol; - if (new_vma->vm_file) - get_file(new_vma->vm_file); - if (new_vma->vm_ops && new_vma->vm_ops->open) - new_vma->vm_ops->open(new_vma); - vma_link(mm, new_vma, prev, rb_link, rb_parent); - *need_rmap_locks = false; - } - return new_vma; - -out_free_mempol: - mpol_put(vma_policy(new_vma)); -out_free_vma: - vm_area_free(new_vma); -out: - return NULL; + vma_iter_set(&vmi, vma->vm_end); + do { + if (vma->vm_flags & VM_ACCOUNT) + nr_accounted += vma_pages(vma); + vma_mark_detached(vma); + remove_vma(vma); + count++; + cond_resched(); + vma = vma_next(&vmi); + } while (vma && likely(!xa_is_zero(vma))); + + BUG_ON(count != mm->map_count); + + trace_exit_mmap(mm); +destroy: + __mt_destroy(&mm->mm_mt); + mmap_write_unlock(mm); + vm_unacct_memory(nr_accounted); } /* @@ -3300,7 +1345,7 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) { - mm->total_vm += npages; + WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages); if (is_exec_mapping(flags)) mm->exec_vm += npages; @@ -3313,10 +1358,16 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) static vm_fault_t special_mapping_fault(struct vm_fault *vmf); /* + * Close hook, called for unmap() and on the old vma for mremap(). + * * Having a close hook prevents vma merging regardless of flags. */ static void special_mapping_close(struct vm_area_struct *vma) { + const struct vm_special_mapping *sm = vma->vm_private_data; + + if (sm->close) + sm->close(sm, vma); } static const char *special_mapping_name(struct vm_area_struct *vma) @@ -3337,16 +1388,25 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma) return 0; } +static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) +{ + /* + * Forbid splitting special mappings - kernel has expectations over + * the number of pages in mapping. Together with VM_DONTEXPAND + * the size of vma should stay the same over the special mapping's + * lifetime. + */ + return -EINVAL; +} + static const struct vm_operations_struct special_mapping_vmops = { .close = special_mapping_close, .fault = special_mapping_fault, .mremap = special_mapping_mremap, .name = special_mapping_name, -}; - -static const struct vm_operations_struct legacy_special_mapping_vmops = { - .close = special_mapping_close, - .fault = special_mapping_fault, + /* vDSO code relies that VVAR can't be accessed remotely */ + .access = NULL, + .may_split = special_mapping_split, }; static vm_fault_t special_mapping_fault(struct vm_fault *vmf) @@ -3354,17 +1414,12 @@ static vm_fault_t special_mapping_fault(struct vm_fault *vmf) struct vm_area_struct *vma = vmf->vma; pgoff_t pgoff; struct page **pages; + struct vm_special_mapping *sm = vma->vm_private_data; - if (vma->vm_ops == &legacy_special_mapping_vmops) { - pages = vma->vm_private_data; - } else { - struct vm_special_mapping *sm = vma->vm_private_data; - - if (sm->fault) - return sm->fault(sm, vmf->vma, vmf); + if (sm->fault) + return sm->fault(sm, vmf->vma, vmf); - pages = sm->pages; - } + pages = sm->pages; for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) pgoff--; @@ -3382,7 +1437,7 @@ static vm_fault_t special_mapping_fault(struct vm_fault *vmf) static struct vm_area_struct *__install_special_mapping( struct mm_struct *mm, unsigned long addr, unsigned long len, - unsigned long vm_flags, void *priv, + vm_flags_t vm_flags, void *priv, const struct vm_operations_struct *ops) { int ret; @@ -3392,10 +1447,11 @@ static struct vm_area_struct *__install_special_mapping( if (unlikely(vma == NULL)) return ERR_PTR(-ENOMEM); - vma->vm_start = addr; - vma->vm_end = addr + len; - - vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; + vma_set_range(vma, addr, addr + len, 0); + vm_flags |= mm->def_flags | VM_DONTEXPAND; + if (pgtable_supports_soft_dirty()) + vm_flags |= VM_SOFTDIRTY; + vm_flags_init(vma, vm_flags & ~VM_LOCKED_MASK); vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); vma->vm_ops = ops; @@ -3420,12 +1476,11 @@ bool vma_is_special_mapping(const struct vm_area_struct *vma, const struct vm_special_mapping *sm) { return vma->vm_private_data == sm && - (vma->vm_ops == &special_mapping_vmops || - vma->vm_ops == &legacy_special_mapping_vmops); + vma->vm_ops == &special_mapping_vmops; } /* - * Called with mm->mmap_sem held for writing. + * Called with mm->mmap_lock held for writing. * Insert a new vma covering the given region, with the given flags. * Its pages are supplied by the given array of struct page *. * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. @@ -3436,204 +1491,65 @@ bool vma_is_special_mapping(const struct vm_area_struct *vma, struct vm_area_struct *_install_special_mapping( struct mm_struct *mm, unsigned long addr, unsigned long len, - unsigned long vm_flags, const struct vm_special_mapping *spec) + vm_flags_t vm_flags, const struct vm_special_mapping *spec) { return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, &special_mapping_vmops); } -int install_special_mapping(struct mm_struct *mm, - unsigned long addr, unsigned long len, - unsigned long vm_flags, struct page **pages) -{ - struct vm_area_struct *vma = __install_special_mapping( - mm, addr, len, vm_flags, (void *)pages, - &legacy_special_mapping_vmops); - - return PTR_ERR_OR_ZERO(vma); -} - -static DEFINE_MUTEX(mm_all_locks_mutex); - -static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) -{ - if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { - /* - * The LSB of head.next can't change from under us - * because we hold the mm_all_locks_mutex. - */ - down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); - /* - * We can safely modify head.next after taking the - * anon_vma->root->rwsem. If some other vma in this mm shares - * the same anon_vma we won't take it again. - * - * No need of atomic instructions here, head.next - * can't change from under us thanks to the - * anon_vma->root->rwsem. - */ - if (__test_and_set_bit(0, (unsigned long *) - &anon_vma->root->rb_root.rb_root.rb_node)) - BUG(); - } -} - -static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) -{ - if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { - /* - * AS_MM_ALL_LOCKS can't change from under us because - * we hold the mm_all_locks_mutex. - * - * Operations on ->flags have to be atomic because - * even if AS_MM_ALL_LOCKS is stable thanks to the - * mm_all_locks_mutex, there may be other cpus - * changing other bitflags in parallel to us. - */ - if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) - BUG(); - down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); - } -} - -/* - * This operation locks against the VM for all pte/vma/mm related - * operations that could ever happen on a certain mm. This includes - * vmtruncate, try_to_unmap, and all page faults. - * - * The caller must take the mmap_sem in write mode before calling - * mm_take_all_locks(). The caller isn't allowed to release the - * mmap_sem until mm_drop_all_locks() returns. - * - * mmap_sem in write mode is required in order to block all operations - * that could modify pagetables and free pages without need of - * altering the vma layout. It's also needed in write mode to avoid new - * anon_vmas to be associated with existing vmas. - * - * A single task can't take more than one mm_take_all_locks() in a row - * or it would deadlock. - * - * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in - * mapping->flags avoid to take the same lock twice, if more than one - * vma in this mm is backed by the same anon_vma or address_space. - * - * We take locks in following order, accordingly to comment at beginning - * of mm/rmap.c: - * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for - * hugetlb mapping); - * - all i_mmap_rwsem locks; - * - all anon_vma->rwseml - * - * We can take all locks within these types randomly because the VM code - * doesn't nest them and we protected from parallel mm_take_all_locks() by - * mm_all_locks_mutex. - * - * mm_take_all_locks() and mm_drop_all_locks are expensive operations - * that may have to take thousand of locks. - * - * mm_take_all_locks() can fail if it's interrupted by signals. - */ -int mm_take_all_locks(struct mm_struct *mm) -{ - struct vm_area_struct *vma; - struct anon_vma_chain *avc; - - BUG_ON(down_read_trylock(&mm->mmap_sem)); - - mutex_lock(&mm_all_locks_mutex); - - for (vma = mm->mmap; vma; vma = vma->vm_next) { - if (signal_pending(current)) - goto out_unlock; - if (vma->vm_file && vma->vm_file->f_mapping && - is_vm_hugetlb_page(vma)) - vm_lock_mapping(mm, vma->vm_file->f_mapping); - } - - for (vma = mm->mmap; vma; vma = vma->vm_next) { - if (signal_pending(current)) - goto out_unlock; - if (vma->vm_file && vma->vm_file->f_mapping && - !is_vm_hugetlb_page(vma)) - vm_lock_mapping(mm, vma->vm_file->f_mapping); - } - - for (vma = mm->mmap; vma; vma = vma->vm_next) { - if (signal_pending(current)) - goto out_unlock; - if (vma->anon_vma) - list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) - vm_lock_anon_vma(mm, avc->anon_vma); - } - - return 0; - -out_unlock: - mm_drop_all_locks(mm); - return -EINTR; -} - -static void vm_unlock_anon_vma(struct anon_vma *anon_vma) -{ - if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { - /* - * The LSB of head.next can't change to 0 from under - * us because we hold the mm_all_locks_mutex. - * - * We must however clear the bitflag before unlocking - * the vma so the users using the anon_vma->rb_root will - * never see our bitflag. - * - * No need of atomic instructions here, head.next - * can't change from under us until we release the - * anon_vma->root->rwsem. - */ - if (!__test_and_clear_bit(0, (unsigned long *) - &anon_vma->root->rb_root.rb_root.rb_node)) - BUG(); - anon_vma_unlock_write(anon_vma); - } -} - -static void vm_unlock_mapping(struct address_space *mapping) -{ - if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { - /* - * AS_MM_ALL_LOCKS can't change to 0 from under us - * because we hold the mm_all_locks_mutex. - */ - i_mmap_unlock_write(mapping); - if (!test_and_clear_bit(AS_MM_ALL_LOCKS, - &mapping->flags)) - BUG(); - } -} - -/* - * The mmap_sem cannot be released by the caller until - * mm_drop_all_locks() returns. - */ -void mm_drop_all_locks(struct mm_struct *mm) -{ - struct vm_area_struct *vma; - struct anon_vma_chain *avc; - - BUG_ON(down_read_trylock(&mm->mmap_sem)); - BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); - - for (vma = mm->mmap; vma; vma = vma->vm_next) { - if (vma->anon_vma) - list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) - vm_unlock_anon_vma(avc->anon_vma); - if (vma->vm_file && vma->vm_file->f_mapping) - vm_unlock_mapping(vma->vm_file->f_mapping); - } +#ifdef CONFIG_SYSCTL +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \ + defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT) +int sysctl_legacy_va_layout; +#endif - mutex_unlock(&mm_all_locks_mutex); -} +static const struct ctl_table mmap_table[] = { + { + .procname = "max_map_count", + .data = &sysctl_max_map_count, + .maxlen = sizeof(sysctl_max_map_count), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + }, +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \ + defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT) + { + .procname = "legacy_va_layout", + .data = &sysctl_legacy_va_layout, + .maxlen = sizeof(sysctl_legacy_va_layout), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + }, +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS + { + .procname = "mmap_rnd_bits", + .data = &mmap_rnd_bits, + .maxlen = sizeof(mmap_rnd_bits), + .mode = 0600, + .proc_handler = proc_dointvec_minmax, + .extra1 = (void *)&mmap_rnd_bits_min, + .extra2 = (void *)&mmap_rnd_bits_max, + }, +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS + { + .procname = "mmap_rnd_compat_bits", + .data = &mmap_rnd_compat_bits, + .maxlen = sizeof(mmap_rnd_compat_bits), + .mode = 0600, + .proc_handler = proc_dointvec_minmax, + .extra1 = (void *)&mmap_rnd_compat_bits_min, + .extra2 = (void *)&mmap_rnd_compat_bits_max, + }, +#endif +}; +#endif /* CONFIG_SYSCTL */ /* - * initialise the percpu counter for VM + * initialise the percpu counter for VM, initialise VMA state. */ void __init mmap_init(void) { @@ -3641,6 +1557,10 @@ void __init mmap_init(void) ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); VM_BUG_ON(ret); +#ifdef CONFIG_SYSCTL + register_sysctl_init("vm", mmap_table); +#endif + vma_state_init(); } /* @@ -3657,9 +1577,9 @@ static int init_user_reserve(void) { unsigned long free_kbytes; - free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); - sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); + sysctl_user_reserve_kbytes = min(free_kbytes / 32, SZ_128K); return 0; } subsys_initcall(init_user_reserve); @@ -3678,9 +1598,9 @@ static int init_admin_reserve(void) { unsigned long free_kbytes; - free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); - sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); + sysctl_admin_reserve_kbytes = min(free_kbytes / 32, SZ_8K); return 0; } subsys_initcall(init_admin_reserve); @@ -3712,17 +1632,17 @@ static int reserve_mem_notifier(struct notifier_block *nb, case MEM_ONLINE: /* Default max is 128MB. Leave alone if modified by operator. */ tmp = sysctl_user_reserve_kbytes; - if (0 < tmp && tmp < (1UL << 17)) + if (tmp > 0 && tmp < SZ_128K) init_user_reserve(); /* Default max is 8MB. Leave alone if modified by operator. */ tmp = sysctl_admin_reserve_kbytes; - if (0 < tmp && tmp < (1UL << 13)) + if (tmp > 0 && tmp < SZ_8K) init_admin_reserve(); break; case MEM_OFFLINE: - free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); if (sysctl_user_reserve_kbytes > free_kbytes) { init_user_reserve(); @@ -3742,15 +1662,221 @@ static int reserve_mem_notifier(struct notifier_block *nb, return NOTIFY_OK; } -static struct notifier_block reserve_mem_nb = { - .notifier_call = reserve_mem_notifier, -}; - static int __meminit init_reserve_notifier(void) { - if (register_hotmemory_notifier(&reserve_mem_nb)) + if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI)) pr_err("Failed registering memory add/remove notifier for admin reserve\n"); return 0; } subsys_initcall(init_reserve_notifier); + +/* + * Obtain a read lock on mm->mmap_lock, if the specified address is below the + * start of the VMA, the intent is to perform a write, and it is a + * downward-growing stack, then attempt to expand the stack to contain it. + * + * This function is intended only for obtaining an argument page from an ELF + * image, and is almost certainly NOT what you want to use for any other + * purpose. + * + * IMPORTANT - VMA fields are accessed without an mmap lock being held, so the + * VMA referenced must not be linked in any user-visible tree, i.e. it must be a + * new VMA being mapped. + * + * The function assumes that addr is either contained within the VMA or below + * it, and makes no attempt to validate this value beyond that. + * + * Returns true if the read lock was obtained and a stack was perhaps expanded, + * false if the stack expansion failed. + * + * On stack expansion the function temporarily acquires an mmap write lock + * before downgrading it. + */ +bool mmap_read_lock_maybe_expand(struct mm_struct *mm, + struct vm_area_struct *new_vma, + unsigned long addr, bool write) +{ + if (!write || addr >= new_vma->vm_start) { + mmap_read_lock(mm); + return true; + } + + if (!(new_vma->vm_flags & VM_GROWSDOWN)) + return false; + + mmap_write_lock(mm); + if (expand_downwards(new_vma, addr)) { + mmap_write_unlock(mm); + return false; + } + + mmap_write_downgrade(mm); + return true; +} + +__latent_entropy int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) +{ + struct vm_area_struct *mpnt, *tmp; + int retval; + unsigned long charge = 0; + LIST_HEAD(uf); + VMA_ITERATOR(vmi, mm, 0); + + if (mmap_write_lock_killable(oldmm)) + return -EINTR; + flush_cache_dup_mm(oldmm); + uprobe_dup_mmap(oldmm, mm); + /* + * Not linked in yet - no deadlock potential: + */ + mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); + + /* No ordering required: file already has been exposed. */ + dup_mm_exe_file(mm, oldmm); + + mm->total_vm = oldmm->total_vm; + mm->data_vm = oldmm->data_vm; + mm->exec_vm = oldmm->exec_vm; + mm->stack_vm = oldmm->stack_vm; + + /* Use __mt_dup() to efficiently build an identical maple tree. */ + retval = __mt_dup(&oldmm->mm_mt, &mm->mm_mt, GFP_KERNEL); + if (unlikely(retval)) + goto out; + + mt_clear_in_rcu(vmi.mas.tree); + for_each_vma(vmi, mpnt) { + struct file *file; + + retval = vma_start_write_killable(mpnt); + if (retval < 0) + goto loop_out; + if (mpnt->vm_flags & VM_DONTCOPY) { + retval = vma_iter_clear_gfp(&vmi, mpnt->vm_start, + mpnt->vm_end, GFP_KERNEL); + if (retval) + goto loop_out; + + vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); + continue; + } + charge = 0; + if (mpnt->vm_flags & VM_ACCOUNT) { + unsigned long len = vma_pages(mpnt); + + if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ + goto fail_nomem; + charge = len; + } + + tmp = vm_area_dup(mpnt); + if (!tmp) + goto fail_nomem; + retval = vma_dup_policy(mpnt, tmp); + if (retval) + goto fail_nomem_policy; + tmp->vm_mm = mm; + retval = dup_userfaultfd(tmp, &uf); + if (retval) + goto fail_nomem_anon_vma_fork; + if (tmp->vm_flags & VM_WIPEONFORK) { + /* + * VM_WIPEONFORK gets a clean slate in the child. + * Don't prepare anon_vma until fault since we don't + * copy page for current vma. + */ + tmp->anon_vma = NULL; + } else if (anon_vma_fork(tmp, mpnt)) + goto fail_nomem_anon_vma_fork; + vm_flags_clear(tmp, VM_LOCKED_MASK); + /* + * Copy/update hugetlb private vma information. + */ + if (is_vm_hugetlb_page(tmp)) + hugetlb_dup_vma_private(tmp); + + /* + * Link the vma into the MT. After using __mt_dup(), memory + * allocation is not necessary here, so it cannot fail. + */ + vma_iter_bulk_store(&vmi, tmp); + + mm->map_count++; + + if (tmp->vm_ops && tmp->vm_ops->open) + tmp->vm_ops->open(tmp); + + file = tmp->vm_file; + if (file) { + struct address_space *mapping = file->f_mapping; + + get_file(file); + i_mmap_lock_write(mapping); + if (vma_is_shared_maywrite(tmp)) + mapping_allow_writable(mapping); + flush_dcache_mmap_lock(mapping); + /* insert tmp into the share list, just after mpnt */ + vma_interval_tree_insert_after(tmp, mpnt, + &mapping->i_mmap); + flush_dcache_mmap_unlock(mapping); + i_mmap_unlock_write(mapping); + } + + if (!(tmp->vm_flags & VM_WIPEONFORK)) + retval = copy_page_range(tmp, mpnt); + + if (retval) { + mpnt = vma_next(&vmi); + goto loop_out; + } + } + /* a new mm has just been created */ + retval = arch_dup_mmap(oldmm, mm); +loop_out: + vma_iter_free(&vmi); + if (!retval) { + mt_set_in_rcu(vmi.mas.tree); + ksm_fork(mm, oldmm); + khugepaged_fork(mm, oldmm); + } else { + + /* + * The entire maple tree has already been duplicated. If the + * mmap duplication fails, mark the failure point with + * XA_ZERO_ENTRY. In exit_mmap(), if this marker is encountered, + * stop releasing VMAs that have not been duplicated after this + * point. + */ + if (mpnt) { + mas_set_range(&vmi.mas, mpnt->vm_start, mpnt->vm_end - 1); + mas_store(&vmi.mas, XA_ZERO_ENTRY); + /* Avoid OOM iterating a broken tree */ + mm_flags_set(MMF_OOM_SKIP, mm); + } + /* + * The mm_struct is going to exit, but the locks will be dropped + * first. Set the mm_struct as unstable is advisable as it is + * not fully initialised. + */ + mm_flags_set(MMF_UNSTABLE, mm); + } +out: + mmap_write_unlock(mm); + flush_tlb_mm(oldmm); + mmap_write_unlock(oldmm); + if (!retval) + dup_userfaultfd_complete(&uf); + else + dup_userfaultfd_fail(&uf); + return retval; + +fail_nomem_anon_vma_fork: + mpol_put(vma_policy(tmp)); +fail_nomem_policy: + vm_area_free(tmp); +fail_nomem: + retval = -ENOMEM; + vm_unacct_memory(charge); + goto loop_out; +} |