diff options
Diffstat (limited to '')
| -rw-r--r-- | mm/mmap.c | 3710 |
1 files changed, 3710 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c new file mode 100644 index 000000000..bb8ba3258 --- /dev/null +++ b/mm/mmap.c @@ -0,0 +1,3710 @@ +/* + * mm/mmap.c + * + * Written by obz. + * + * Address space accounting code <alan@lxorguk.ukuu.org.uk> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/backing-dev.h> +#include <linux/mm.h> +#include <linux/vmacache.h> +#include <linux/shm.h> +#include <linux/mman.h> +#include <linux/pagemap.h> +#include <linux/swap.h> +#include <linux/syscalls.h> +#include <linux/capability.h> +#include <linux/init.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/personality.h> +#include <linux/security.h> +#include <linux/hugetlb.h> +#include <linux/shmem_fs.h> +#include <linux/profile.h> +#include <linux/export.h> +#include <linux/mount.h> +#include <linux/mempolicy.h> +#include <linux/rmap.h> +#include <linux/mmu_notifier.h> +#include <linux/mmdebug.h> +#include <linux/perf_event.h> +#include <linux/audit.h> +#include <linux/khugepaged.h> +#include <linux/uprobes.h> +#include <linux/rbtree_augmented.h> +#include <linux/notifier.h> +#include <linux/memory.h> +#include <linux/printk.h> +#include <linux/userfaultfd_k.h> +#include <linux/moduleparam.h> +#include <linux/pkeys.h> +#include <linux/oom.h> +#include <linux/sched/mm.h> + +#include <linux/uaccess.h> +#include <asm/cacheflush.h> +#include <asm/tlb.h> +#include <asm/mmu_context.h> + +#include "internal.h" + +#ifndef arch_mmap_check +#define arch_mmap_check(addr, len, flags) (0) +#endif + +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS +const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; +const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; +int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS +const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; +const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; +int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; +#endif + +static bool ignore_rlimit_data; +core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); + +static void unmap_region(struct mm_struct *mm, + struct vm_area_struct *vma, struct vm_area_struct *prev, + unsigned long start, unsigned long end); + +/* description of effects of mapping type and prot in current implementation. + * this is due to the limited x86 page protection hardware. The expected + * behavior is in parens: + * + * map_type prot + * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC + * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes + * w: (no) no w: (no) no w: (yes) yes w: (no) no + * x: (no) no x: (no) yes x: (no) yes x: (yes) yes + * + * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes + * w: (no) no w: (no) no w: (copy) copy w: (no) no + * x: (no) no x: (no) yes x: (no) yes x: (yes) yes + */ +pgprot_t protection_map[16] __ro_after_init = { + __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, + __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 +}; + +#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT +static inline pgprot_t arch_filter_pgprot(pgprot_t prot) +{ + return prot; +} +#endif + +pgprot_t vm_get_page_prot(unsigned long vm_flags) +{ + pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags & + (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | + pgprot_val(arch_vm_get_page_prot(vm_flags))); + + return arch_filter_pgprot(ret); +} +EXPORT_SYMBOL(vm_get_page_prot); + +static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) +{ + return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); +} + +/* Update vma->vm_page_prot to reflect vma->vm_flags. */ +void vma_set_page_prot(struct vm_area_struct *vma) +{ + unsigned long vm_flags = vma->vm_flags; + pgprot_t vm_page_prot; + + vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); + if (vma_wants_writenotify(vma, vm_page_prot)) { + vm_flags &= ~VM_SHARED; + vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); + } + /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */ + WRITE_ONCE(vma->vm_page_prot, vm_page_prot); +} + +/* + * Requires inode->i_mapping->i_mmap_rwsem + */ +static void __remove_shared_vm_struct(struct vm_area_struct *vma, + struct file *file, struct address_space *mapping) +{ + if (vma->vm_flags & VM_DENYWRITE) + atomic_inc(&file_inode(file)->i_writecount); + if (vma->vm_flags & VM_SHARED) + mapping_unmap_writable(mapping); + + flush_dcache_mmap_lock(mapping); + vma_interval_tree_remove(vma, &mapping->i_mmap); + flush_dcache_mmap_unlock(mapping); +} + +/* + * Unlink a file-based vm structure from its interval tree, to hide + * vma from rmap and vmtruncate before freeing its page tables. + */ +void unlink_file_vma(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + + if (file) { + struct address_space *mapping = file->f_mapping; + i_mmap_lock_write(mapping); + __remove_shared_vm_struct(vma, file, mapping); + i_mmap_unlock_write(mapping); + } +} + +/* + * Close a vm structure and free it, returning the next. + */ +static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) +{ + struct vm_area_struct *next = vma->vm_next; + + might_sleep(); + if (vma->vm_ops && vma->vm_ops->close) + vma->vm_ops->close(vma); + if (vma->vm_file) + fput(vma->vm_file); + mpol_put(vma_policy(vma)); + vm_area_free(vma); + return next; +} + +static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, + struct list_head *uf); +SYSCALL_DEFINE1(brk, unsigned long, brk) +{ + unsigned long retval; + unsigned long newbrk, oldbrk; + struct mm_struct *mm = current->mm; + struct vm_area_struct *next; + unsigned long min_brk; + bool populate; + LIST_HEAD(uf); + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + +#ifdef CONFIG_COMPAT_BRK + /* + * CONFIG_COMPAT_BRK can still be overridden by setting + * randomize_va_space to 2, which will still cause mm->start_brk + * to be arbitrarily shifted + */ + if (current->brk_randomized) + min_brk = mm->start_brk; + else + min_brk = mm->end_data; +#else + min_brk = mm->start_brk; +#endif + if (brk < min_brk) + goto out; + + /* + * Check against rlimit here. If this check is done later after the test + * of oldbrk with newbrk then it can escape the test and let the data + * segment grow beyond its set limit the in case where the limit is + * not page aligned -Ram Gupta + */ + if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, + mm->end_data, mm->start_data)) + goto out; + + newbrk = PAGE_ALIGN(brk); + oldbrk = PAGE_ALIGN(mm->brk); + if (oldbrk == newbrk) + goto set_brk; + + /* Always allow shrinking brk. */ + if (brk <= mm->brk) { + if (!do_munmap(mm, newbrk, oldbrk-newbrk, &uf)) + goto set_brk; + goto out; + } + + /* Check against existing mmap mappings. */ + next = find_vma(mm, oldbrk); + if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) + goto out; + + /* Ok, looks good - let it rip. */ + if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0) + goto out; + +set_brk: + mm->brk = brk; + populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; + up_write(&mm->mmap_sem); + userfaultfd_unmap_complete(mm, &uf); + if (populate) + mm_populate(oldbrk, newbrk - oldbrk); + return brk; + +out: + retval = mm->brk; + up_write(&mm->mmap_sem); + return retval; +} + +static long vma_compute_subtree_gap(struct vm_area_struct *vma) +{ + unsigned long max, 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; +} + +/* + * If a hint addr is less than mmap_min_addr change hint to be as + * low as possible but still greater than mmap_min_addr + */ +static inline unsigned long round_hint_to_min(unsigned long hint) +{ + hint &= PAGE_MASK; + if (((void *)hint != NULL) && + (hint < mmap_min_addr)) + return PAGE_ALIGN(mmap_min_addr); + return hint; +} + +static inline int mlock_future_check(struct mm_struct *mm, + unsigned long flags, + unsigned long len) +{ + unsigned long locked, lock_limit; + + /* mlock MCL_FUTURE? */ + if (flags & VM_LOCKED) { + locked = len >> PAGE_SHIFT; + locked += mm->locked_vm; + lock_limit = rlimit(RLIMIT_MEMLOCK); + lock_limit >>= PAGE_SHIFT; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) + return -EAGAIN; + } + return 0; +} + +static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) +{ + if (S_ISREG(inode->i_mode)) + return MAX_LFS_FILESIZE; + + if (S_ISBLK(inode->i_mode)) + return MAX_LFS_FILESIZE; + + /* Special "we do even unsigned file positions" case */ + if (file->f_mode & FMODE_UNSIGNED_OFFSET) + return 0; + + /* Yes, random drivers might want more. But I'm tired of buggy drivers */ + return ULONG_MAX; +} + +static inline bool file_mmap_ok(struct file *file, struct inode *inode, + unsigned long pgoff, unsigned long len) +{ + u64 maxsize = file_mmap_size_max(file, inode); + + if (maxsize && len > maxsize) + return false; + maxsize -= len; + if (pgoff > maxsize >> PAGE_SHIFT) + return false; + return true; +} + +/* + * The caller must hold down_write(¤t->mm->mmap_sem). + */ +unsigned long do_mmap(struct file *file, unsigned long addr, + unsigned long len, unsigned long prot, + unsigned long flags, vm_flags_t vm_flags, + unsigned long pgoff, unsigned long *populate, + struct list_head *uf) +{ + struct mm_struct *mm = current->mm; + int pkey = 0; + + *populate = 0; + + if (!len) + return -EINVAL; + + /* + * Does the application expect PROT_READ to imply PROT_EXEC? + * + * (the exception is when the underlying filesystem is noexec + * mounted, in which case we dont add PROT_EXEC.) + */ + if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) + if (!(file && path_noexec(&file->f_path))) + prot |= PROT_EXEC; + + /* force arch specific MAP_FIXED handling in get_unmapped_area */ + if (flags & MAP_FIXED_NOREPLACE) + flags |= MAP_FIXED; + + if (!(flags & MAP_FIXED)) + addr = round_hint_to_min(addr); + + /* Careful about overflows.. */ + len = PAGE_ALIGN(len); + if (!len) + return -ENOMEM; + + /* offset overflow? */ + if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) + return -EOVERFLOW; + + /* Too many mappings? */ + if (mm->map_count > sysctl_max_map_count) + return -ENOMEM; + + /* Obtain the address to map to. we verify (or select) it and ensure + * that it represents a valid section of the address space. + */ + addr = get_unmapped_area(file, addr, len, pgoff, flags); + if (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); + if (pkey < 0) + pkey = 0; + } + + /* Do simple checking here so the lower-level routines won't have + * to. we assume access permissions have been handled by the open + * of the memory object, so we don't do any here. + */ + vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | + mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; + + if (flags & MAP_LOCKED) + if (!can_do_mlock()) + return -EPERM; + + if (mlock_future_check(mm, vm_flags, len)) + return -EAGAIN; + + if (file) { + struct inode *inode = file_inode(file); + unsigned long flags_mask; + + if (!file_mmap_ok(file, inode, pgoff, len)) + return -EOVERFLOW; + + flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; + + switch (flags & MAP_TYPE) { + case MAP_SHARED: + /* + * Force use of MAP_SHARED_VALIDATE with non-legacy + * flags. E.g. MAP_SYNC is dangerous to use with + * MAP_SHARED as you don't know which consistency model + * you will get. We silently ignore unsupported flags + * with MAP_SHARED to preserve backward compatibility. + */ + flags &= LEGACY_MAP_MASK; + /* fall through */ + case MAP_SHARED_VALIDATE: + if (flags & ~flags_mask) + return -EOPNOTSUPP; + if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) + return -EACCES; + + /* + * Make sure we don't allow writing to an append-only + * file.. + */ + if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) + return -EACCES; + + /* + * Make sure there are no mandatory locks on the file. + */ + if (locks_verify_locked(file)) + return -EAGAIN; + + vm_flags |= VM_SHARED | VM_MAYSHARE; + if (!(file->f_mode & FMODE_WRITE)) + vm_flags &= ~(VM_MAYWRITE | VM_SHARED); + + /* fall through */ + case MAP_PRIVATE: + if (!(file->f_mode & FMODE_READ)) + return -EACCES; + if (path_noexec(&file->f_path)) { + if (vm_flags & VM_EXEC) + return -EPERM; + vm_flags &= ~VM_MAYEXEC; + } + + if (!file->f_op->mmap) + return -ENODEV; + if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) + return -EINVAL; + break; + + default: + return -EINVAL; + } + } else { + switch (flags & MAP_TYPE) { + case MAP_SHARED: + if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) + return -EINVAL; + /* + * Ignore pgoff. + */ + pgoff = 0; + vm_flags |= VM_SHARED | VM_MAYSHARE; + break; + case MAP_PRIVATE: + /* + * Set pgoff according to addr for anon_vma. + */ + pgoff = addr >> PAGE_SHIFT; + break; + default: + return -EINVAL; + } + } + + /* + * Set 'VM_NORESERVE' if we should not account for the + * memory use of this mapping. + */ + if (flags & MAP_NORESERVE) { + /* We honor MAP_NORESERVE if allowed to overcommit */ + if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) + vm_flags |= VM_NORESERVE; + + /* hugetlb applies strict overcommit unless MAP_NORESERVE */ + if (file && is_file_hugepages(file)) + vm_flags |= VM_NORESERVE; + } + + addr = mmap_region(file, addr, len, vm_flags, pgoff, uf); + if (!IS_ERR_VALUE(addr) && + ((vm_flags & VM_LOCKED) || + (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) + *populate = len; + return addr; +} + +unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, + unsigned long prot, unsigned long flags, + unsigned long fd, unsigned long pgoff) +{ + struct file *file = NULL; + unsigned long retval; + + if (!(flags & MAP_ANONYMOUS)) { + audit_mmap_fd(fd, flags); + file = fget(fd); + if (!file) + return -EBADF; + if (is_file_hugepages(file)) + len = ALIGN(len, huge_page_size(hstate_file(file))); + retval = -EINVAL; + if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) + goto out_fput; + } else if (flags & MAP_HUGETLB) { + struct user_struct *user = NULL; + struct hstate *hs; + + hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); + if (!hs) + return -EINVAL; + + len = ALIGN(len, huge_page_size(hs)); + /* + * VM_NORESERVE is used because the reservations will be + * taken when vm_ops->mmap() is called + * A dummy user value is used because we are not locking + * memory so no accounting is necessary + */ + file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, + VM_NORESERVE, + &user, HUGETLB_ANONHUGE_INODE, + (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); + if (IS_ERR(file)) + return PTR_ERR(file); + } + + flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); + + retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); +out_fput: + if (file) + fput(file); + return retval; +} + +SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, + unsigned long, prot, unsigned long, flags, + unsigned long, fd, unsigned long, pgoff) +{ + return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); +} + +#ifdef __ARCH_WANT_SYS_OLD_MMAP +struct mmap_arg_struct { + unsigned long addr; + unsigned long len; + unsigned long prot; + unsigned long flags; + unsigned long fd; + unsigned long offset; +}; + +SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) +{ + struct mmap_arg_struct a; + + if (copy_from_user(&a, arg, sizeof(a))) + return -EFAULT; + if (offset_in_page(a.offset)) + return -EINVAL; + + return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, + a.offset >> PAGE_SHIFT); +} +#endif /* __ARCH_WANT_SYS_OLD_MMAP */ + +/* + * Some shared mappigns will want the pages marked read-only + * to track write events. If so, we'll downgrade vm_page_prot + * to the private version (using protection_map[] without the + * VM_SHARED bit). + */ +int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) +{ + vm_flags_t vm_flags = vma->vm_flags; + const struct vm_operations_struct *vm_ops = vma->vm_ops; + + /* If it was private or non-writable, the write bit is already clear */ + if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) + return 0; + + /* The backer wishes to know when pages are first written to? */ + if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) + return 1; + + /* The open routine did something to the protections that pgprot_modify + * won't preserve? */ + if (pgprot_val(vm_page_prot) != + pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags))) + return 0; + + /* Do we need to track softdirty? */ + if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) + return 1; + + /* Specialty mapping? */ + if (vm_flags & VM_PFNMAP) + return 0; + + /* Can the mapping track the dirty pages? */ + return vma->vm_file && vma->vm_file->f_mapping && + mapping_cap_account_dirty(vma->vm_file->f_mapping); +} + +/* + * We account for memory if it's a private writeable mapping, + * not hugepages and VM_NORESERVE wasn't set. + */ +static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) +{ + /* + * hugetlb has its own accounting separate from the core VM + * VM_HUGETLB may not be set yet so we cannot check for that flag. + */ + if (file && is_file_hugepages(file)) + return 0; + + return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; +} + +unsigned long mmap_region(struct file *file, unsigned long addr, + unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, + struct list_head *uf) +{ + 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; + + vma_set_page_prot(vma); + + return addr; + +unmap_and_free_vma: + vma->vm_file = NULL; + fput(file); + + /* Undo any partial mapping done by a device driver. */ + unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); + charged = 0; + if (vm_flags & VM_SHARED) + mapping_unmap_writable(file->f_mapping); +allow_write_and_free_vma: + if (vm_flags & VM_DENYWRITE) + allow_write_access(file); +free_vma: + 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; +} + +/* Get an address range which is currently unmapped. + * For shmat() with addr=0. + * + * Ugly calling convention alert: + * Return value with the low bits set means error value, + * ie + * if (ret & ~PAGE_MASK) + * error = ret; + * + * This function "knows" that -ENOMEM has the bits set. + */ +#ifndef HAVE_ARCH_UNMAPPED_AREA +unsigned long +arch_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma, *prev; + struct vm_unmapped_area_info info; + + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma_prev(mm, addr, &prev); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vm_start_gap(vma)) && + (!prev || addr >= vm_end_gap(prev))) + return addr; + } + + info.flags = 0; + info.length = len; + info.low_limit = mm->mmap_base; + info.high_limit = TASK_SIZE; + info.align_mask = 0; + info.align_offset = 0; + return vm_unmapped_area(&info); +} +#endif + +/* + * This mmap-allocator allocates new areas top-down from below the + * stack's low limit (the base): + */ +#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN +unsigned long +arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + const unsigned long len, const unsigned long pgoff, + const unsigned long flags) +{ + struct vm_area_struct *vma, *prev; + struct mm_struct *mm = current->mm; + unsigned long addr = addr0; + struct vm_unmapped_area_info info; + + /* requested length too big for entire address space */ + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + /* requesting a specific address */ + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma_prev(mm, addr, &prev); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vm_start_gap(vma)) && + (!prev || addr >= vm_end_gap(prev))) + return addr; + } + + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.length = len; + info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.high_limit = mm->mmap_base; + info.align_mask = 0; + info.align_offset = 0; + addr = vm_unmapped_area(&info); + + /* + * A failed mmap() very likely causes application failure, + * so fall back to the bottom-up function here. This scenario + * can happen with large stack limits and large mmap() + * allocations. + */ + if (offset_in_page(addr)) { + VM_BUG_ON(addr != -ENOMEM); + info.flags = 0; + info.low_limit = TASK_UNMAPPED_BASE; + info.high_limit = TASK_SIZE; + addr = vm_unmapped_area(&info); + } + + return addr; +} +#endif + +unsigned long +get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + unsigned long (*get_area)(struct file *, unsigned long, + unsigned long, unsigned long, unsigned long); + + unsigned long error = arch_mmap_check(addr, len, flags); + if (error) + return error; + + /* Careful about overflows.. */ + if (len > TASK_SIZE) + return -ENOMEM; + + get_area = current->mm->get_unmapped_area; + if (file) { + if (file->f_op->get_unmapped_area) + get_area = file->f_op->get_unmapped_area; + } else if (flags & MAP_SHARED) { + /* + * mmap_region() will call shmem_zero_setup() to create a file, + * so use shmem's get_unmapped_area in case it can be huge. + * do_mmap_pgoff() will clear pgoff, so match alignment. + */ + pgoff = 0; + get_area = shmem_get_unmapped_area; + } + + addr = get_area(file, addr, len, pgoff, flags); + if (IS_ERR_VALUE(addr)) + return addr; + + if (addr > TASK_SIZE - len) + return -ENOMEM; + if (offset_in_page(addr)) + return -EINVAL; + + error = security_mmap_addr(addr); + return error ? error : addr; +} + +EXPORT_SYMBOL(get_unmapped_area); + +/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ +struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) +{ + struct rb_node *rb_node; + struct vm_area_struct *vma; + + /* Check the cache first. */ + vma = vmacache_find(mm, addr); + if (likely(vma)) + return vma; + + rb_node = mm->mm_rb.rb_node; + + while (rb_node) { + struct vm_area_struct *tmp; + + tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); + + if (tmp->vm_end > addr) { + vma = tmp; + if (tmp->vm_start <= addr) + break; + rb_node = rb_node->rb_left; + } else + rb_node = rb_node->rb_right; + } + + if (vma) + vmacache_update(addr, vma); + return vma; +} + +EXPORT_SYMBOL(find_vma); + +/* + * Same as find_vma, but also return a pointer to the previous VMA in *pprev. + */ +struct vm_area_struct * +find_vma_prev(struct mm_struct *mm, unsigned long addr, + struct vm_area_struct **pprev) +{ + struct vm_area_struct *vma; + + vma = find_vma(mm, addr); + if (vma) { + *pprev = vma->vm_prev; + } else { + struct rb_node *rb_node = mm->mm_rb.rb_node; + *pprev = NULL; + while (rb_node) { + *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); + rb_node = rb_node->rb_right; + } + } + return vma; +} + +/* + * Verify that the stack growth is acceptable and + * update accounting. This is shared with both the + * grow-up and grow-down cases. + */ +static int acct_stack_growth(struct vm_area_struct *vma, + unsigned long size, unsigned long grow) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long new_start; + + /* address space limit tests */ + if (!may_expand_vm(mm, vma->vm_flags, grow)) + return -ENOMEM; + + /* Stack limit test */ + if (size > rlimit(RLIMIT_STACK)) + return -ENOMEM; + + /* mlock limit tests */ + if (vma->vm_flags & VM_LOCKED) { + unsigned long locked; + unsigned long limit; + locked = mm->locked_vm + grow; + limit = rlimit(RLIMIT_MEMLOCK); + limit >>= PAGE_SHIFT; + if (locked > limit && !capable(CAP_IPC_LOCK)) + return -ENOMEM; + } + + /* Check to ensure the stack will not grow into a hugetlb-only region */ + new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : + vma->vm_end - size; + if (is_hugepage_only_range(vma->vm_mm, new_start, size)) + return -EFAULT; + + /* + * Overcommit.. This must be the final test, as it will + * update security statistics. + */ + if (security_vm_enough_memory_mm(mm, grow)) + return -ENOMEM; + + return 0; +} + +#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) +/* + * PA-RISC uses this for its stack; IA64 for its Register Backing Store. + * vma is the last one with address > vma->vm_end. Have to extend vma. + */ +int expand_upwards(struct vm_area_struct *vma, unsigned long address) +{ + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *next; + unsigned long gap_addr; + int error = 0; + + if (!(vma->vm_flags & VM_GROWSUP)) + return -EFAULT; + + /* Guard against exceeding limits of the address space. */ + address &= PAGE_MASK; + if (address >= (TASK_SIZE & PAGE_MASK)) + return -ENOMEM; + address += PAGE_SIZE; + + /* Enforce stack_guard_gap */ + gap_addr = address + stack_guard_gap; + + /* Guard against overflow */ + if (gap_addr < address || gap_addr > TASK_SIZE) + gap_addr = TASK_SIZE; + + next = vma->vm_next; + if (next && next->vm_start < gap_addr && + (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; +} +#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ + +/* + * vma is the first one with address < vma->vm_start. Have to extend vma. + */ +int expand_downwards(struct vm_area_struct *vma, + unsigned long address) +{ + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *prev; + int error = 0; + + address &= PAGE_MASK; + if (address < mmap_min_addr) + return -EPERM; + + /* Enforce stack_guard_gap */ + prev = vma->vm_prev; + /* Check that both stack segments have the same anon_vma? */ + if (prev && !(prev->vm_flags & VM_GROWSDOWN) && + (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; + + /* + * 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; +} + +/* enforced gap between the expanding stack and other mappings. */ +unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; + +static int __init cmdline_parse_stack_guard_gap(char *p) +{ + unsigned long val; + char *endptr; + + val = simple_strtoul(p, &endptr, 10); + if (!*endptr) + stack_guard_gap = val << PAGE_SHIFT; + + return 1; +} +__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); + +#ifdef CONFIG_STACK_GROWSUP +int expand_stack(struct vm_area_struct *vma, unsigned long address) +{ + return expand_upwards(vma, address); +} + +struct vm_area_struct * +find_extend_vma(struct mm_struct *mm, unsigned long addr) +{ + struct vm_area_struct *vma, *prev; + + addr &= PAGE_MASK; + vma = find_vma_prev(mm, addr, &prev); + if (vma && (vma->vm_start <= addr)) + return vma; + /* don't alter vm_end if the coredump is running */ + if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr)) + return NULL; + if (prev->vm_flags & VM_LOCKED) + populate_vma_page_range(prev, addr, prev->vm_end, NULL); + return prev; +} +#else +int expand_stack(struct vm_area_struct *vma, unsigned long address) +{ + return expand_downwards(vma, address); +} + +struct vm_area_struct * +find_extend_vma(struct mm_struct *mm, unsigned long addr) +{ + struct vm_area_struct *vma; + unsigned long start; + + addr &= PAGE_MASK; + vma = find_vma(mm, addr); + if (!vma) + return NULL; + if (vma->vm_start <= addr) + return vma; + if (!(vma->vm_flags & VM_GROWSDOWN)) + return NULL; + /* don't alter vm_start if the coredump is running */ + if (!mmget_still_valid(mm)) + return NULL; + start = vma->vm_start; + if (expand_stack(vma, addr)) + return NULL; + if (vma->vm_flags & VM_LOCKED) + populate_vma_page_range(vma, addr, start, NULL); + return vma; +} +#endif + +EXPORT_SYMBOL_GPL(find_extend_vma); + +/* + * Ok - we have the memory areas we should free on the vma list, + * so release them, and do the vma updates. + * + * Called with the mm semaphore held. + */ +static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) +{ + unsigned long nr_accounted = 0; + + /* Update high watermark before we lower total_vm */ + update_hiwater_vm(mm); + do { + long nrpages = vma_pages(vma); + + if (vma->vm_flags & VM_ACCOUNT) + nr_accounted += nrpages; + vm_stat_account(mm, vma->vm_flags, -nrpages); + vma = remove_vma(vma); + } while (vma); + vm_unacct_memory(nr_accounted); + validate_mm(mm); +} + +/* + * Get rid of page table information in the indicated region. + * + * Called with the mm semaphore held. + */ +static void unmap_region(struct mm_struct *mm, + struct vm_area_struct *vma, struct vm_area_struct *prev, + unsigned long start, unsigned long end) +{ + struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; + struct mmu_gather tlb; + + lru_add_drain(); + tlb_gather_mmu(&tlb, mm, start, end); + update_hiwater_rss(mm); + unmap_vmas(&tlb, vma, start, end); + free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, + next ? next->vm_start : USER_PGTABLES_CEILING); + tlb_finish_mmu(&tlb, start, end); +} + +/* + * Create a list of vma's touched by the unmap, removing them from the mm's + * vma list as we go.. + */ +static void +detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, + struct vm_area_struct *prev, unsigned long end) +{ + struct vm_area_struct **insertion_point; + struct vm_area_struct *tail_vma = NULL; + + insertion_point = (prev ? &prev->vm_next : &mm->mmap); + vma->vm_prev = NULL; + do { + vma_rb_erase(vma, &mm->mm_rb); + mm->map_count--; + tail_vma = vma; + vma = vma->vm_next; + } while (vma && vma->vm_start < end); + *insertion_point = vma; + if (vma) { + vma->vm_prev = prev; + vma_gap_update(vma); + } else + mm->highest_vm_end = prev ? vm_end_gap(prev) : 0; + tail_vma->vm_next = NULL; + + /* Kill the cache */ + vmacache_invalidate(mm); +} + +/* + * __split_vma() bypasses sysctl_max_map_count checking. We use this where it + * has already been checked or doesn't make sense to fail. + */ +int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, int new_below) +{ + struct vm_area_struct *new; + int err; + + if (vma->vm_ops && vma->vm_ops->split) { + err = vma->vm_ops->split(vma, addr); + if (err) + return err; + } + + new = vm_area_dup(vma); + if (!new) + return -ENOMEM; + + if (new_below) + new->vm_end = addr; + else { + new->vm_start = addr; + new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); + } + + err = vma_dup_policy(vma, new); + if (err) + goto out_free_vma; + + err = anon_vma_clone(new, vma); + if (err) + goto out_free_mpol; + + if (new->vm_file) + get_file(new->vm_file); + + if (new->vm_ops && new->vm_ops->open) + new->vm_ops->open(new); + + if (new_below) + err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + + ((addr - new->vm_start) >> PAGE_SHIFT), new); + else + err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); + + /* Success. */ + if (!err) + return 0; + + /* Clean everything up if vma_adjust failed. */ + if (new->vm_ops && new->vm_ops->close) + new->vm_ops->close(new); + if (new->vm_file) + fput(new->vm_file); + unlink_anon_vmas(new); + out_free_mpol: + mpol_put(vma_policy(new)); + out_free_vma: + vm_area_free(new); + return err; +} + +/* + * Split a vma into two pieces at address 'addr', a new vma is allocated + * either for the first part or the tail. + */ +int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, int new_below) +{ + if (mm->map_count >= sysctl_max_map_count) + return -ENOMEM; + + return __split_vma(mm, vma, addr, new_below); +} + +/* Munmap is split into 2 main parts -- this part which finds + * what needs doing, and the areas themselves, which do the + * work. This now handles partial unmappings. + * Jeremy Fitzhardinge <jeremy@goop.org> + */ +int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, + struct list_head *uf) +{ + 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; + } + } + + /* + * Remove the vma's, and unmap the actual pages + */ + detach_vmas_to_be_unmapped(mm, vma, prev, end); + unmap_region(mm, vma, prev, start, end); + + arch_unmap(mm, vma, start, end); + + /* Fix up all other VM information */ + remove_vma_list(mm, vma); + + return 0; +} + +int vm_munmap(unsigned long start, size_t len) +{ + int ret; + struct mm_struct *mm = current->mm; + LIST_HEAD(uf); + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + ret = do_munmap(mm, start, len, &uf); + up_write(&mm->mmap_sem); + userfaultfd_unmap_complete(mm, &uf); + return ret; +} +EXPORT_SYMBOL(vm_munmap); + +SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) +{ + profile_munmap(addr); + return vm_munmap(addr, len); +} + + +/* + * Emulation of deprecated remap_file_pages() syscall. + */ +SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, + unsigned long, prot, unsigned long, pgoff, unsigned long, flags) +{ + + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long populate = 0; + unsigned long ret = -EINVAL; + struct file *file; + + pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n", + current->comm, current->pid); + + if (prot) + return ret; + start = start & PAGE_MASK; + size = size & PAGE_MASK; + + if (start + size <= start) + return ret; + + /* Does pgoff wrap? */ + if (pgoff + (size >> PAGE_SHIFT) < pgoff) + return ret; + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + vma = find_vma(mm, start); + + if (!vma || !(vma->vm_flags & VM_SHARED)) + goto out; + + if (start < vma->vm_start) + goto out; + + if (start + size > vma->vm_end) { + struct vm_area_struct *next; + + for (next = vma->vm_next; next; next = next->vm_next) { + /* hole between vmas ? */ + if (next->vm_start != next->vm_prev->vm_end) + goto out; + + if (next->vm_file != vma->vm_file) + goto out; + + if (next->vm_flags != vma->vm_flags) + goto out; + + if (start + size <= next->vm_end) + break; + } + + if (!next) + goto out; + } + + prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; + 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); +out: + up_write(&mm->mmap_sem); + if (populate) + mm_populate(ret, populate); + if (!IS_ERR_VALUE(ret)) + ret = 0; + return ret; +} + +static inline void verify_mm_writelocked(struct mm_struct *mm) +{ +#ifdef CONFIG_DEBUG_VM + if (unlikely(down_read_trylock(&mm->mmap_sem))) { + WARN_ON(1); + up_read(&mm->mmap_sem); + } +#endif +} + +/* + * this is really a simplified "do_mmap". it only handles + * anonymous maps. eventually we may be able to do some + * brk-specific accounting here. + */ +static 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; + + /* + * mm->mmap_sem is required to protect against another thread + * changing the mappings in case we sleep. + */ + verify_mm_writelocked(mm); + + /* + * Clear old maps. this also does some error checking for us + */ + while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, + &rb_parent)) { + if (do_munmap(mm, addr, len, 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) +{ + struct mm_struct *mm = current->mm; + unsigned long len; + int ret; + bool populate; + LIST_HEAD(uf); + + len = PAGE_ALIGN(request); + if (len < request) + return -ENOMEM; + if (!len) + return 0; + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + ret = do_brk_flags(addr, len, flags, &uf); + populate = ((mm->def_flags & VM_LOCKED) != 0); + up_write(&mm->mmap_sem); + 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); +} +EXPORT_SYMBOL(vm_brk); + +/* Release all mmaps. */ +void exit_mmap(struct mm_struct *mm) +{ + struct mmu_gather tlb; + struct vm_area_struct *vma; + unsigned long nr_accounted = 0; + + /* mm's last user has gone, and its about to be pulled down */ + mmu_notifier_release(mm); + + if (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; + } + } + + arch_exit_mmap(mm); + + vma = mm->mmap; + if (!vma) /* Can happen if dup_mmap() received an OOM */ + return; + + lru_add_drain(); + flush_cache_mm(mm); + tlb_gather_mmu(&tlb, mm, 0, -1); + /* update_hiwater_rss(mm) here? but nobody should be looking */ + /* Use -1 here to ensure all VMAs in the mm are unmapped */ + unmap_vmas(&tlb, vma, 0, -1); + free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); + tlb_finish_mmu(&tlb, 0, -1); + + /* + * Walk the list again, actually closing and freeing it, + * with preemption enabled, without holding any MM locks. + */ + while (vma) { + if (vma->vm_flags & VM_ACCOUNT) + nr_accounted += vma_pages(vma); + vma = remove_vma(vma); + cond_resched(); + } + vm_unacct_memory(nr_accounted); +} + +/* Insert vm structure into process list sorted by address + * and into the inode's i_mmap tree. If vm_file is non-NULL + * then i_mmap_rwsem is taken here. + */ +int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) +{ + struct vm_area_struct *prev; + struct rb_node **rb_link, *rb_parent; + + if (find_vma_links(mm, vma->vm_start, vma->vm_end, + &prev, &rb_link, &rb_parent)) + return -ENOMEM; + if ((vma->vm_flags & VM_ACCOUNT) && + security_vm_enough_memory_mm(mm, vma_pages(vma))) + return -ENOMEM; + + /* + * The vm_pgoff of a purely anonymous vma should be irrelevant + * until its first write fault, when page's anon_vma and index + * are set. But now set the vm_pgoff it will almost certainly + * end up with (unless mremap moves it elsewhere before that + * first wfault), so /proc/pid/maps tells a consistent story. + * + * By setting it to reflect the virtual start address of the + * vma, merges and splits can happen in a seamless way, just + * using the existing file pgoff checks and manipulations. + * Similarly in do_mmap_pgoff and in do_brk. + */ + if (vma_is_anonymous(vma)) { + BUG_ON(vma->anon_vma); + vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; + } + + vma_link(mm, vma, prev, rb_link, rb_parent); + return 0; +} + +/* + * Copy the vma structure to a new location in the same mm, + * prior to moving page table entries, to effect an mremap move. + */ +struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, + unsigned long addr, unsigned long len, pgoff_t pgoff, + bool *need_rmap_locks) +{ + struct vm_area_struct *vma = *vmap; + unsigned long vma_start = vma->vm_start; + struct mm_struct *mm = vma->vm_mm; + struct vm_area_struct *new_vma, *prev; + struct rb_node **rb_link, *rb_parent; + bool faulted_in_anon_vma = true; + + /* + * If anonymous vma has not yet been faulted, update new pgoff + * to match new location, to increase its chance of merging. + */ + if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { + pgoff = addr >> PAGE_SHIFT; + faulted_in_anon_vma = false; + } + + if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) + return NULL; /* should never get here */ + new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, + vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), + vma->vm_userfaultfd_ctx); + if (new_vma) { + /* + * Source vma may have been merged into new_vma + */ + if (unlikely(vma_start >= new_vma->vm_start && + vma_start < new_vma->vm_end)) { + /* + * The only way we can get a vma_merge with + * self during an mremap is if the vma hasn't + * been faulted in yet and we were allowed to + * reset the dst vma->vm_pgoff to the + * destination address of the mremap to allow + * the merge to happen. mremap must change the + * vm_pgoff linearity between src and dst vmas + * (in turn preventing a vma_merge) to be + * safe. It is only safe to keep the vm_pgoff + * linear if there are no pages mapped yet. + */ + VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); + *vmap = vma = new_vma; + } + *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); + } else { + new_vma = 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; +} + +/* + * Return true if the calling process may expand its vm space by the passed + * number of pages + */ +bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) +{ + if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) + return false; + + if (is_data_mapping(flags) && + mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { + /* Workaround for Valgrind */ + if (rlimit(RLIMIT_DATA) == 0 && + mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT) + return true; + + pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n", + current->comm, current->pid, + (mm->data_vm + npages) << PAGE_SHIFT, + rlimit(RLIMIT_DATA), + ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data"); + + if (!ignore_rlimit_data) + return false; + } + + return true; +} + +void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) +{ + mm->total_vm += npages; + + if (is_exec_mapping(flags)) + mm->exec_vm += npages; + else if (is_stack_mapping(flags)) + mm->stack_vm += npages; + else if (is_data_mapping(flags)) + mm->data_vm += npages; +} + +static vm_fault_t special_mapping_fault(struct vm_fault *vmf); + +/* + * Having a close hook prevents vma merging regardless of flags. + */ +static void special_mapping_close(struct vm_area_struct *vma) +{ +} + +static const char *special_mapping_name(struct vm_area_struct *vma) +{ + return ((struct vm_special_mapping *)vma->vm_private_data)->name; +} + +static int special_mapping_mremap(struct vm_area_struct *new_vma) +{ + struct vm_special_mapping *sm = new_vma->vm_private_data; + + if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) + return -EFAULT; + + if (sm->mremap) + return sm->mremap(sm, new_vma); + + return 0; +} + +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, +}; + +static vm_fault_t special_mapping_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + pgoff_t pgoff; + struct page **pages; + + 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); + + pages = sm->pages; + } + + for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) + pgoff--; + + if (*pages) { + struct page *page = *pages; + get_page(page); + vmf->page = page; + return 0; + } + + return VM_FAULT_SIGBUS; +} + +static struct vm_area_struct *__install_special_mapping( + struct mm_struct *mm, + unsigned long addr, unsigned long len, + unsigned long vm_flags, void *priv, + const struct vm_operations_struct *ops) +{ + int ret; + struct vm_area_struct *vma; + + vma = vm_area_alloc(mm); + 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->vm_page_prot = vm_get_page_prot(vma->vm_flags); + + vma->vm_ops = ops; + vma->vm_private_data = priv; + + ret = insert_vm_struct(mm, vma); + if (ret) + goto out; + + vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); + + perf_event_mmap(vma); + + return vma; + +out: + vm_area_free(vma); + return ERR_PTR(ret); +} + +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); +} + +/* + * Called with mm->mmap_sem held for writing. + * Insert a new vma covering the given region, with the given flags. + * Its pages are supplied by the given array of struct page *. + * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. + * The region past the last page supplied will always produce SIGBUS. + * The array pointer and the pages it points to are assumed to stay alive + * for as long as this mapping might exist. + */ +struct vm_area_struct *_install_special_mapping( + struct mm_struct *mm, + unsigned long addr, unsigned long len, + unsigned long vm_flags, const struct vm_special_mapping *spec) +{ + return __install_special_mapping(mm, addr, len, vm_flags, (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); + } + + mutex_unlock(&mm_all_locks_mutex); +} + +/* + * initialise the percpu counter for VM + */ +void __init mmap_init(void) +{ + int ret; + + ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); + VM_BUG_ON(ret); +} + +/* + * Initialise sysctl_user_reserve_kbytes. + * + * This is intended to prevent a user from starting a single memory hogging + * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER + * mode. + * + * The default value is min(3% of free memory, 128MB) + * 128MB is enough to recover with sshd/login, bash, and top/kill. + */ +static int init_user_reserve(void) +{ + unsigned long free_kbytes; + + free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + + sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); + return 0; +} +subsys_initcall(init_user_reserve); + +/* + * Initialise sysctl_admin_reserve_kbytes. + * + * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin + * to log in and kill a memory hogging process. + * + * Systems with more than 256MB will reserve 8MB, enough to recover + * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will + * only reserve 3% of free pages by default. + */ +static int init_admin_reserve(void) +{ + unsigned long free_kbytes; + + free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + + sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); + return 0; +} +subsys_initcall(init_admin_reserve); + +/* + * Reinititalise user and admin reserves if memory is added or removed. + * + * The default user reserve max is 128MB, and the default max for the + * admin reserve is 8MB. These are usually, but not always, enough to + * enable recovery from a memory hogging process using login/sshd, a shell, + * and tools like top. It may make sense to increase or even disable the + * reserve depending on the existence of swap or variations in the recovery + * tools. So, the admin may have changed them. + * + * If memory is added and the reserves have been eliminated or increased above + * the default max, then we'll trust the admin. + * + * If memory is removed and there isn't enough free memory, then we + * need to reset the reserves. + * + * Otherwise keep the reserve set by the admin. + */ +static int reserve_mem_notifier(struct notifier_block *nb, + unsigned long action, void *data) +{ + unsigned long tmp, free_kbytes; + + switch (action) { + case MEM_ONLINE: + /* Default max is 128MB. Leave alone if modified by operator. */ + tmp = sysctl_user_reserve_kbytes; + if (0 < tmp && tmp < (1UL << 17)) + init_user_reserve(); + + /* Default max is 8MB. Leave alone if modified by operator. */ + tmp = sysctl_admin_reserve_kbytes; + if (0 < tmp && tmp < (1UL << 13)) + init_admin_reserve(); + + break; + case MEM_OFFLINE: + free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); + + if (sysctl_user_reserve_kbytes > free_kbytes) { + init_user_reserve(); + pr_info("vm.user_reserve_kbytes reset to %lu\n", + sysctl_user_reserve_kbytes); + } + + if (sysctl_admin_reserve_kbytes > free_kbytes) { + init_admin_reserve(); + pr_info("vm.admin_reserve_kbytes reset to %lu\n", + sysctl_admin_reserve_kbytes); + } + break; + default: + break; + } + return NOTIFY_OK; +} + +static struct notifier_block reserve_mem_nb = { + .notifier_call = reserve_mem_notifier, +}; + +static int __meminit init_reserve_notifier(void) +{ + if (register_hotmemory_notifier(&reserve_mem_nb)) + pr_err("Failed registering memory add/remove notifier for admin reserve\n"); + + return 0; +} +subsys_initcall(init_reserve_notifier); |