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-rw-r--r--mm/mmap.c3911
1 files changed, 3911 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
new file mode 100644
index 0000000000..9e018d8dd7
--- /dev/null
+++ b/mm/mmap.c
@@ -0,0 +1,3911 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mm/mmap.c
+ *
+ * Written by obz.
+ *
+ * Address space accounting code <alan@lxorguk.ukuu.org.uk>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/mm.h>
+#include <linux/mm_inline.h>
+#include <linux/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/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/ksm.h>
+
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/mmap.h>
+
+#include "internal.h"
+
+#ifndef arch_mmap_check
+#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 ma_state *mas,
+ struct vm_area_struct *vma, struct vm_area_struct *prev,
+ struct vm_area_struct *next, unsigned long start,
+ unsigned long end, unsigned long tree_end, bool mm_wr_locked);
+
+static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
+{
+ return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
+}
+
+/* Update vma->vm_page_prot to reflect vma->vm_flags. */
+void vma_set_page_prot(struct vm_area_struct *vma)
+{
+ unsigned long vm_flags = vma->vm_flags;
+ pgprot_t vm_page_prot;
+
+ vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
+ if (vma_wants_writenotify(vma, vm_page_prot)) {
+ vm_flags &= ~VM_SHARED;
+ vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
+ }
+ /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
+ WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
+}
+
+/*
+ * Requires inode->i_mapping->i_mmap_rwsem
+ */
+static void __remove_shared_vm_struct(struct vm_area_struct *vma,
+ struct file *file, struct address_space *mapping)
+{
+ if (vma->vm_flags & VM_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.
+ */
+static void remove_vma(struct vm_area_struct *vma, bool unreachable)
+{
+ 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));
+ if (unreachable)
+ __vm_area_free(vma);
+ else
+ vm_area_free(vma);
+}
+
+static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
+ unsigned long min)
+{
+ return mas_prev(&vmi->mas, min);
+}
+
+/*
+ * check_brk_limits() - Use platform specific check of range & verify mlock
+ * limits.
+ * @addr: The address to check
+ * @len: The size of increase.
+ *
+ * Return: 0 on success.
+ */
+static int check_brk_limits(unsigned long addr, unsigned long len)
+{
+ unsigned long mapped_addr;
+
+ mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
+ if (IS_ERR_VALUE(mapped_addr))
+ return mapped_addr;
+
+ return mlock_future_ok(current->mm, current->mm->def_flags, len)
+ ? 0 : -EAGAIN;
+}
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
+ unsigned long addr, unsigned long request, unsigned long flags);
+SYSCALL_DEFINE1(brk, unsigned long, brk)
+{
+ unsigned long newbrk, oldbrk, origbrk;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *brkvma, *next = NULL;
+ unsigned long min_brk;
+ bool populate = false;
+ LIST_HEAD(uf);
+ struct vma_iterator vmi;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ origbrk = mm->brk;
+
+#ifdef CONFIG_COMPAT_BRK
+ /*
+ * CONFIG_COMPAT_BRK can still be overridden by setting
+ * randomize_va_space to 2, which will still cause mm->start_brk
+ * to be arbitrarily shifted
+ */
+ if (current->brk_randomized)
+ min_brk = mm->start_brk;
+ else
+ min_brk = mm->end_data;
+#else
+ min_brk = mm->start_brk;
+#endif
+ if (brk < min_brk)
+ goto out;
+
+ /*
+ * Check against rlimit here. If this check is done later after the test
+ * of oldbrk with newbrk then it can escape the test and let the data
+ * segment grow beyond its set limit the in case where the limit is
+ * not page aligned -Ram Gupta
+ */
+ if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
+ mm->end_data, mm->start_data))
+ goto out;
+
+ newbrk = PAGE_ALIGN(brk);
+ oldbrk = PAGE_ALIGN(mm->brk);
+ if (oldbrk == newbrk) {
+ mm->brk = brk;
+ goto success;
+ }
+
+ /* Always allow shrinking brk. */
+ if (brk <= mm->brk) {
+ /* Search one past newbrk */
+ vma_iter_init(&vmi, mm, newbrk);
+ brkvma = vma_find(&vmi, oldbrk);
+ if (!brkvma || brkvma->vm_start >= oldbrk)
+ goto out; /* mapping intersects with an existing non-brk vma. */
+ /*
+ * mm->brk must be protected by write mmap_lock.
+ * do_vma_munmap() will drop the lock on success, so update it
+ * before calling do_vma_munmap().
+ */
+ mm->brk = brk;
+ if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
+ goto out;
+
+ goto success_unlocked;
+ }
+
+ if (check_brk_limits(oldbrk, newbrk - oldbrk))
+ goto out;
+
+ /*
+ * Only check if the next VMA is within the stack_guard_gap of the
+ * expansion area
+ */
+ vma_iter_init(&vmi, mm, oldbrk);
+ next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
+ goto out;
+
+ brkvma = vma_prev_limit(&vmi, mm->start_brk);
+ /* Ok, looks good - let it rip. */
+ if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
+ goto out;
+
+ mm->brk = brk;
+ if (mm->def_flags & VM_LOCKED)
+ populate = true;
+
+success:
+ mmap_write_unlock(mm);
+success_unlocked:
+ userfaultfd_unmap_complete(mm, &uf);
+ if (populate)
+ mm_populate(oldbrk, newbrk - oldbrk);
+ return brk;
+
+out:
+ mm->brk = origbrk;
+ mmap_write_unlock(mm);
+ return origbrk;
+}
+
+#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
+static void validate_mm(struct mm_struct *mm)
+{
+ int bug = 0;
+ int i = 0;
+ struct vm_area_struct *vma;
+ VMA_ITERATOR(vmi, mm, 0);
+
+ mt_validate(&mm->mm_mt);
+ for_each_vma(vmi, vma) {
+#ifdef CONFIG_DEBUG_VM_RB
+ struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc;
+#endif
+ unsigned long vmi_start, vmi_end;
+ bool warn = 0;
+
+ vmi_start = vma_iter_addr(&vmi);
+ vmi_end = vma_iter_end(&vmi);
+ if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm))
+ warn = 1;
+
+ if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm))
+ warn = 1;
+
+ if (warn) {
+ pr_emerg("issue in %s\n", current->comm);
+ dump_stack();
+ dump_vma(vma);
+ pr_emerg("tree range: %px start %lx end %lx\n", vma,
+ vmi_start, vmi_end - 1);
+ vma_iter_dump_tree(&vmi);
+ }
+
+#ifdef CONFIG_DEBUG_VM_RB
+ 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);
+ }
+#endif
+ i++;
+ }
+ if (i != mm->map_count) {
+ pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);
+ bug = 1;
+ }
+ VM_BUG_ON_MM(bug, mm);
+}
+
+#else /* !CONFIG_DEBUG_VM_MAPLE_TREE */
+#define validate_mm(mm) do { } while (0)
+#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */
+
+/*
+ * vma has some anon_vma assigned, and is already inserted on that
+ * anon_vma's interval trees.
+ *
+ * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
+ * vma must be removed from the anon_vma's interval trees using
+ * anon_vma_interval_tree_pre_update_vma().
+ *
+ * After the update, the vma will be reinserted using
+ * anon_vma_interval_tree_post_update_vma().
+ *
+ * The entire update must be protected by exclusive mmap_lock and by
+ * the root anon_vma's mutex.
+ */
+static inline void
+anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc;
+
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
+}
+
+static inline void
+anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc;
+
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
+}
+
+static unsigned long count_vma_pages_range(struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
+{
+ VMA_ITERATOR(vmi, mm, addr);
+ struct vm_area_struct *vma;
+ unsigned long nr_pages = 0;
+
+ for_each_vma_range(vmi, vma, end) {
+ unsigned long vm_start = max(addr, vma->vm_start);
+ unsigned long vm_end = min(end, vma->vm_end);
+
+ nr_pages += PHYS_PFN(vm_end - vm_start);
+ }
+
+ return nr_pages;
+}
+
+static void __vma_link_file(struct vm_area_struct *vma,
+ struct address_space *mapping)
+{
+ if (vma->vm_flags & VM_SHARED)
+ mapping_allow_writable(mapping);
+
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_insert(vma, &mapping->i_mmap);
+ flush_dcache_mmap_unlock(mapping);
+}
+
+static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+ VMA_ITERATOR(vmi, mm, 0);
+ struct address_space *mapping = NULL;
+
+ vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
+ if (vma_iter_prealloc(&vmi, vma))
+ return -ENOMEM;
+
+ vma_start_write(vma);
+
+ vma_iter_store(&vmi, vma);
+
+ if (vma->vm_file) {
+ mapping = vma->vm_file->f_mapping;
+ i_mmap_lock_write(mapping);
+ __vma_link_file(vma, mapping);
+ i_mmap_unlock_write(mapping);
+ }
+
+ mm->map_count++;
+ validate_mm(mm);
+ return 0;
+}
+
+/*
+ * init_multi_vma_prep() - Initializer for struct vma_prepare
+ * @vp: The vma_prepare struct
+ * @vma: The vma that will be altered once locked
+ * @next: The next vma if it is to be adjusted
+ * @remove: The first vma to be removed
+ * @remove2: The second vma to be removed
+ */
+static inline void init_multi_vma_prep(struct vma_prepare *vp,
+ struct vm_area_struct *vma, struct vm_area_struct *next,
+ struct vm_area_struct *remove, struct vm_area_struct *remove2)
+{
+ memset(vp, 0, sizeof(struct vma_prepare));
+ vp->vma = vma;
+ vp->anon_vma = vma->anon_vma;
+ vp->remove = remove;
+ vp->remove2 = remove2;
+ vp->adj_next = next;
+ if (!vp->anon_vma && next)
+ vp->anon_vma = next->anon_vma;
+
+ vp->file = vma->vm_file;
+ if (vp->file)
+ vp->mapping = vma->vm_file->f_mapping;
+
+}
+
+/*
+ * init_vma_prep() - Initializer wrapper for vma_prepare struct
+ * @vp: The vma_prepare struct
+ * @vma: The vma that will be altered once locked
+ */
+static inline void init_vma_prep(struct vma_prepare *vp,
+ struct vm_area_struct *vma)
+{
+ init_multi_vma_prep(vp, vma, NULL, NULL, NULL);
+}
+
+
+/*
+ * vma_prepare() - Helper function for handling locking VMAs prior to altering
+ * @vp: The initialized vma_prepare struct
+ */
+static inline void vma_prepare(struct vma_prepare *vp)
+{
+ if (vp->file) {
+ uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
+
+ if (vp->adj_next)
+ uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
+ vp->adj_next->vm_end);
+
+ i_mmap_lock_write(vp->mapping);
+ if (vp->insert && vp->insert->vm_file) {
+ /*
+ * 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(vp->insert,
+ vp->insert->vm_file->f_mapping);
+ }
+ }
+
+ if (vp->anon_vma) {
+ anon_vma_lock_write(vp->anon_vma);
+ anon_vma_interval_tree_pre_update_vma(vp->vma);
+ if (vp->adj_next)
+ anon_vma_interval_tree_pre_update_vma(vp->adj_next);
+ }
+
+ if (vp->file) {
+ flush_dcache_mmap_lock(vp->mapping);
+ vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
+ if (vp->adj_next)
+ vma_interval_tree_remove(vp->adj_next,
+ &vp->mapping->i_mmap);
+ }
+
+}
+
+/*
+ * vma_complete- Helper function for handling the unlocking after altering VMAs,
+ * or for inserting a VMA.
+ *
+ * @vp: The vma_prepare struct
+ * @vmi: The vma iterator
+ * @mm: The mm_struct
+ */
+static inline void vma_complete(struct vma_prepare *vp,
+ struct vma_iterator *vmi, struct mm_struct *mm)
+{
+ if (vp->file) {
+ if (vp->adj_next)
+ vma_interval_tree_insert(vp->adj_next,
+ &vp->mapping->i_mmap);
+ vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap);
+ flush_dcache_mmap_unlock(vp->mapping);
+ }
+
+ if (vp->remove && vp->file) {
+ __remove_shared_vm_struct(vp->remove, vp->file, vp->mapping);
+ if (vp->remove2)
+ __remove_shared_vm_struct(vp->remove2, vp->file,
+ vp->mapping);
+ } else if (vp->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).
+ */
+ vma_iter_store(vmi, vp->insert);
+ mm->map_count++;
+ }
+
+ if (vp->anon_vma) {
+ anon_vma_interval_tree_post_update_vma(vp->vma);
+ if (vp->adj_next)
+ anon_vma_interval_tree_post_update_vma(vp->adj_next);
+ anon_vma_unlock_write(vp->anon_vma);
+ }
+
+ if (vp->file) {
+ i_mmap_unlock_write(vp->mapping);
+ uprobe_mmap(vp->vma);
+
+ if (vp->adj_next)
+ uprobe_mmap(vp->adj_next);
+ }
+
+ if (vp->remove) {
+again:
+ vma_mark_detached(vp->remove, true);
+ if (vp->file) {
+ uprobe_munmap(vp->remove, vp->remove->vm_start,
+ vp->remove->vm_end);
+ fput(vp->file);
+ }
+ if (vp->remove->anon_vma)
+ anon_vma_merge(vp->vma, vp->remove);
+ mm->map_count--;
+ mpol_put(vma_policy(vp->remove));
+ if (!vp->remove2)
+ WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
+ vm_area_free(vp->remove);
+
+ /*
+ * In mprotect's case 6 (see comments on vma_merge),
+ * we are removing both mid and next vmas
+ */
+ if (vp->remove2) {
+ vp->remove = vp->remove2;
+ vp->remove2 = NULL;
+ goto again;
+ }
+ }
+ if (vp->insert && vp->file)
+ uprobe_mmap(vp->insert);
+ validate_mm(mm);
+}
+
+/*
+ * dup_anon_vma() - Helper function to duplicate anon_vma
+ * @dst: The destination VMA
+ * @src: The source VMA
+ * @dup: Pointer to the destination VMA when successful.
+ *
+ * Returns: 0 on success.
+ */
+static inline int dup_anon_vma(struct vm_area_struct *dst,
+ struct vm_area_struct *src, struct vm_area_struct **dup)
+{
+ /*
+ * 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 (src->anon_vma && !dst->anon_vma) {
+ int ret;
+
+ vma_assert_write_locked(dst);
+ dst->anon_vma = src->anon_vma;
+ ret = anon_vma_clone(dst, src);
+ if (ret)
+ return ret;
+
+ *dup = dst;
+ }
+
+ return 0;
+}
+
+/*
+ * vma_expand - Expand an existing VMA
+ *
+ * @vmi: The vma iterator
+ * @vma: The vma to expand
+ * @start: The start of the vma
+ * @end: The exclusive end of the vma
+ * @pgoff: The page offset of vma
+ * @next: The current of next vma.
+ *
+ * Expand @vma to @start and @end. Can expand off the start and end. Will
+ * expand over @next if it's different from @vma and @end == @next->vm_end.
+ * Checking if the @vma can expand and merge with @next needs to be handled by
+ * the caller.
+ *
+ * Returns: 0 on success
+ */
+int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, pgoff_t pgoff,
+ struct vm_area_struct *next)
+{
+ struct vm_area_struct *anon_dup = NULL;
+ bool remove_next = false;
+ struct vma_prepare vp;
+
+ vma_start_write(vma);
+ if (next && (vma != next) && (end == next->vm_end)) {
+ int ret;
+
+ remove_next = true;
+ vma_start_write(next);
+ ret = dup_anon_vma(vma, next, &anon_dup);
+ if (ret)
+ return ret;
+ }
+
+ init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
+ /* Not merging but overwriting any part of next is not handled. */
+ VM_WARN_ON(next && !vp.remove &&
+ next != vma && end > next->vm_start);
+ /* Only handles expanding */
+ VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
+
+ /* Note: vma iterator must be pointing to 'start' */
+ vma_iter_config(vmi, start, end);
+ if (vma_iter_prealloc(vmi, vma))
+ goto nomem;
+
+ vma_prepare(&vp);
+ vma_adjust_trans_huge(vma, start, end, 0);
+ vma->vm_start = start;
+ vma->vm_end = end;
+ vma->vm_pgoff = pgoff;
+ vma_iter_store(vmi, vma);
+
+ vma_complete(&vp, vmi, vma->vm_mm);
+ return 0;
+
+nomem:
+ if (anon_dup)
+ unlink_anon_vmas(anon_dup);
+ return -ENOMEM;
+}
+
+/*
+ * vma_shrink() - Reduce an existing VMAs memory area
+ * @vmi: The vma iterator
+ * @vma: The VMA to modify
+ * @start: The new start
+ * @end: The new end
+ *
+ * Returns: 0 on success, -ENOMEM otherwise
+ */
+int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, pgoff_t pgoff)
+{
+ struct vma_prepare vp;
+
+ WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
+
+ if (vma->vm_start < start)
+ vma_iter_config(vmi, vma->vm_start, start);
+ else
+ vma_iter_config(vmi, end, vma->vm_end);
+
+ if (vma_iter_prealloc(vmi, NULL))
+ return -ENOMEM;
+
+ vma_start_write(vma);
+
+ init_vma_prep(&vp, vma);
+ vma_prepare(&vp);
+ vma_adjust_trans_huge(vma, start, end, 0);
+
+ vma_iter_clear(vmi);
+ vma->vm_start = start;
+ vma->vm_end = end;
+ vma->vm_pgoff = pgoff;
+ vma_complete(&vp, vmi, vma->vm_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 if the caller indicates
+ * the current vma may be removed as part of the merge.
+ */
+static inline bool is_mergeable_vma(struct vm_area_struct *vma,
+ struct file *file, unsigned long vm_flags,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ struct anon_vma_name *anon_name, bool may_remove_vma)
+{
+ /*
+ * VM_SOFTDIRTY should not prevent from VMA merging, if we
+ * match the flags but dirty bit -- the caller should mark
+ * merged VMA as dirty. If dirty bit won't be excluded from
+ * comparison, we increase pressure on the memory system forcing
+ * the kernel to generate new VMAs when old one could be
+ * extended instead.
+ */
+ if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
+ return false;
+ if (vma->vm_file != file)
+ return false;
+ if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
+ return false;
+ if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
+ return false;
+ if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
+ return false;
+ return true;
+}
+
+static inline bool 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 true;
+ return anon_vma1 == anon_vma2;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * in front of (at a lower virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ *
+ * We don't check here for the merged mmap wrapping around the end of pagecache
+ * indices (16TB on ia32) because do_mmap() does not permit mmap's which
+ * wrap, nor mmaps which cover the final page at index -1UL.
+ *
+ * We assume the vma may be removed as part of the merge.
+ */
+static bool
+can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ struct anon_vma_name *anon_name)
+{
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) &&
+ is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
+ if (vma->vm_pgoff == vm_pgoff)
+ return true;
+ }
+ return false;
+}
+
+/*
+ * 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.
+ *
+ * We assume that vma is not removed as part of the merge.
+ */
+static bool
+can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ struct anon_vma_name *anon_name)
+{
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) &&
+ 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 true;
+ }
+ return false;
+}
+
+/*
+ * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
+ * figure out whether that can be merged with its predecessor or its
+ * successor. Or both (it neatly fills a hole).
+ *
+ * In most cases - when called for mmap, brk or mremap - [addr,end) is
+ * certain not to be mapped by the time vma_merge is called; but when
+ * called for mprotect, it is certain to be already mapped (either at
+ * an offset within prev, or at the start of next), and the flags of
+ * this area are about to be changed to vm_flags - and the no-change
+ * case has already been eliminated.
+ *
+ * The following mprotect cases have to be considered, where **** is
+ * the area passed down from mprotect_fixup, never extending beyond one
+ * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts
+ * at the same address as **** and is of the same or larger span, and
+ * NNNN the next vma after ****:
+ *
+ * **** **** ****
+ * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC
+ * cannot merge might become might become
+ * PPNNNNNNNNNN PPPPPPPPPPCC
+ * mmap, brk or case 4 below case 5 below
+ * mremap move:
+ * **** ****
+ * PPPP NNNN PPPPCCCCNNNN
+ * might become might become
+ * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
+ * PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or
+ * PPPPNNNNNNNN 3 PPPPNNNNNNNN 8
+ *
+ * It is important for case 8 that the vma CCCC overlapping the
+ * region **** is never going to extended over NNNN. Instead NNNN must
+ * be extended in region **** and CCCC must be removed. This way in
+ * all cases where vma_merge succeeds, the moment vma_merge 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 NNNN would be removed and
+ * CCCC would be extended over the NNNN range, remove_migration_ptes
+ * or other rmap walkers (if working on addresses beyond the "end"
+ * parameter) may establish ptes with the wrong permissions of CCCC
+ * instead of the right permissions of NNNN.
+ *
+ * In the code below:
+ * PPPP is represented by *prev
+ * CCCC is represented by *curr or not represented at all (NULL)
+ * NNNN is represented by *next or not represented at all (NULL)
+ * **** is not represented - it will be merged and the vma containing the
+ * area is returned, or the function will return NULL
+ */
+struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
+ struct vm_area_struct *prev, unsigned long addr,
+ unsigned long end, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t pgoff, struct mempolicy *policy,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ struct anon_vma_name *anon_name)
+{
+ struct vm_area_struct *curr, *next, *res;
+ struct vm_area_struct *vma, *adjust, *remove, *remove2;
+ struct vm_area_struct *anon_dup = NULL;
+ struct vma_prepare vp;
+ pgoff_t vma_pgoff;
+ int err = 0;
+ bool merge_prev = false;
+ bool merge_next = false;
+ bool vma_expanded = false;
+ unsigned long vma_start = addr;
+ unsigned long vma_end = end;
+ pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+ long adj_start = 0;
+
+ /*
+ * 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;
+
+ /* Does the input range span an existing VMA? (cases 5 - 8) */
+ curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
+
+ if (!curr || /* cases 1 - 4 */
+ end == curr->vm_end) /* cases 6 - 8, adjacent VMA */
+ next = vma_lookup(mm, end);
+ else
+ next = NULL; /* case 5 */
+
+ if (prev) {
+ vma_start = prev->vm_start;
+ vma_pgoff = prev->vm_pgoff;
+
+ /* Can we merge the predecessor? */
+ if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
+ && can_vma_merge_after(prev, vm_flags, anon_vma, file,
+ pgoff, vm_userfaultfd_ctx, anon_name)) {
+ merge_prev = true;
+ vma_prev(vmi);
+ }
+ }
+
+ /* Can we merge the successor? */
+ if (next && mpol_equal(policy, vma_policy(next)) &&
+ can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen,
+ vm_userfaultfd_ctx, anon_name)) {
+ merge_next = true;
+ }
+
+ /* Verify some invariant that must be enforced by the caller. */
+ VM_WARN_ON(prev && addr <= prev->vm_start);
+ VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
+ VM_WARN_ON(addr >= end);
+
+ if (!merge_prev && !merge_next)
+ return NULL; /* Not mergeable. */
+
+ if (merge_prev)
+ vma_start_write(prev);
+
+ res = vma = prev;
+ remove = remove2 = adjust = NULL;
+
+ /* Can we merge both the predecessor and the successor? */
+ if (merge_prev && merge_next &&
+ is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) {
+ vma_start_write(next);
+ remove = next; /* case 1 */
+ vma_end = next->vm_end;
+ err = dup_anon_vma(prev, next, &anon_dup);
+ if (curr) { /* case 6 */
+ vma_start_write(curr);
+ remove = curr;
+ remove2 = next;
+ if (!next->anon_vma)
+ err = dup_anon_vma(prev, curr, &anon_dup);
+ }
+ } else if (merge_prev) { /* case 2 */
+ if (curr) {
+ vma_start_write(curr);
+ err = dup_anon_vma(prev, curr, &anon_dup);
+ if (end == curr->vm_end) { /* case 7 */
+ remove = curr;
+ } else { /* case 5 */
+ adjust = curr;
+ adj_start = (end - curr->vm_start);
+ }
+ }
+ } else { /* merge_next */
+ vma_start_write(next);
+ res = next;
+ if (prev && addr < prev->vm_end) { /* case 4 */
+ vma_start_write(prev);
+ vma_end = addr;
+ adjust = next;
+ adj_start = -(prev->vm_end - addr);
+ err = dup_anon_vma(next, prev, &anon_dup);
+ } else {
+ /*
+ * Note that cases 3 and 8 are the ONLY ones where prev
+ * is permitted to be (but is not necessarily) NULL.
+ */
+ vma = next; /* case 3 */
+ vma_start = addr;
+ vma_end = next->vm_end;
+ vma_pgoff = next->vm_pgoff - pglen;
+ if (curr) { /* case 8 */
+ vma_pgoff = curr->vm_pgoff;
+ vma_start_write(curr);
+ remove = curr;
+ err = dup_anon_vma(next, curr, &anon_dup);
+ }
+ }
+ }
+
+ /* Error in anon_vma clone. */
+ if (err)
+ goto anon_vma_fail;
+
+ if (vma_start < vma->vm_start || vma_end > vma->vm_end)
+ vma_expanded = true;
+
+ if (vma_expanded) {
+ vma_iter_config(vmi, vma_start, vma_end);
+ } else {
+ vma_iter_config(vmi, adjust->vm_start + adj_start,
+ adjust->vm_end);
+ }
+
+ if (vma_iter_prealloc(vmi, vma))
+ goto prealloc_fail;
+
+ init_multi_vma_prep(&vp, vma, adjust, remove, remove2);
+ VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
+ vp.anon_vma != adjust->anon_vma);
+
+ vma_prepare(&vp);
+ vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start);
+
+ vma->vm_start = vma_start;
+ vma->vm_end = vma_end;
+ vma->vm_pgoff = vma_pgoff;
+
+ if (vma_expanded)
+ vma_iter_store(vmi, vma);
+
+ if (adj_start) {
+ adjust->vm_start += adj_start;
+ adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
+ if (adj_start < 0) {
+ WARN_ON(vma_expanded);
+ vma_iter_store(vmi, next);
+ }
+ }
+
+ vma_complete(&vp, vmi, mm);
+ khugepaged_enter_vma(res, vm_flags);
+ return res;
+
+prealloc_fail:
+ if (anon_dup)
+ unlink_anon_vmas(anon_dup);
+
+anon_vma_fail:
+ vma_iter_set(vmi, addr);
+ vma_iter_load(vmi);
+ return NULL;
+}
+
+/*
+ * Rough compatibility check to quickly see if it's even worth looking
+ * at sharing an anon_vma.
+ *
+ * They need to have the same vm_file, and the flags can only differ
+ * in things that mprotect may change.
+ *
+ * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
+ * we can merge the two vma's. For example, we refuse to merge a vma if
+ * there is a vm_ops->close() function, because that indicates that the
+ * driver is doing some kind of reference counting. But that doesn't
+ * really matter for the anon_vma sharing case.
+ */
+static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
+{
+ return a->vm_end == b->vm_start &&
+ mpol_equal(vma_policy(a), vma_policy(b)) &&
+ a->vm_file == b->vm_file &&
+ !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
+ b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
+}
+
+/*
+ * Do some basic sanity checking to see if we can re-use the anon_vma
+ * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
+ * the same as 'old', the other will be the new one that is trying
+ * to share the anon_vma.
+ *
+ * NOTE! This runs with mmap_lock 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 mmap_lock.
+ */
+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)
+{
+ MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end);
+ struct anon_vma *anon_vma = NULL;
+ struct vm_area_struct *prev, *next;
+
+ /* Try next first. */
+ next = mas_walk(&mas);
+ if (next) {
+ anon_vma = reusable_anon_vma(next, vma, next);
+ if (anon_vma)
+ return anon_vma;
+ }
+
+ prev = mas_prev(&mas, 0);
+ VM_BUG_ON_VMA(prev != vma, vma);
+ prev = mas_prev(&mas, 0);
+ /* Try prev next. */
+ if (prev)
+ anon_vma = reusable_anon_vma(prev, prev, vma);
+
+ /*
+ * We might reach here with anon_vma == NULL if we can't find
+ * any reusable anon_vma.
+ * There's no absolute need to look only at touching neighbours:
+ * we could search further afield for "compatible" anon_vmas.
+ * But it would probably just be a waste of time searching,
+ * or lead to too many vmas hanging off the same anon_vma.
+ * We're trying to allow mprotect remerging later on,
+ * not trying to minimize memory used for anon_vmas.
+ */
+ return anon_vma;
+}
+
+/*
+ * If a hint addr is less than mmap_min_addr change hint to be as
+ * low as possible but still greater than mmap_min_addr
+ */
+static inline unsigned long round_hint_to_min(unsigned long hint)
+{
+ hint &= PAGE_MASK;
+ if (((void *)hint != NULL) &&
+ (hint < mmap_min_addr))
+ return PAGE_ALIGN(mmap_min_addr);
+ return hint;
+}
+
+bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
+ unsigned long bytes)
+{
+ unsigned long locked_pages, limit_pages;
+
+ if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
+ return true;
+
+ locked_pages = bytes >> PAGE_SHIFT;
+ locked_pages += mm->locked_vm;
+
+ limit_pages = rlimit(RLIMIT_MEMLOCK);
+ limit_pages >>= PAGE_SHIFT;
+
+ return locked_pages <= limit_pages;
+}
+
+static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ if (S_ISBLK(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ if (S_ISSOCK(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ /* Special "we do even unsigned file positions" case */
+ if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+ return 0;
+
+ /* Yes, random drivers might want more. But I'm tired of buggy drivers */
+ return ULONG_MAX;
+}
+
+static inline bool file_mmap_ok(struct file *file, struct inode *inode,
+ unsigned long pgoff, unsigned long len)
+{
+ u64 maxsize = file_mmap_size_max(file, inode);
+
+ if (maxsize && len > maxsize)
+ return false;
+ maxsize -= len;
+ if (pgoff > maxsize >> PAGE_SHIFT)
+ return false;
+ return true;
+}
+
+/*
+ * The caller must write-lock current->mm->mmap_lock.
+ */
+unsigned long do_mmap(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot,
+ unsigned long flags, 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 (IS_ERR_VALUE(addr))
+ return addr;
+
+ if (flags & MAP_FIXED_NOREPLACE) {
+ if (find_vma_intersection(mm, addr, 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_ok(mm, vm_flags, len))
+ return -EAGAIN;
+
+ if (file) {
+ struct inode *inode = file_inode(file);
+ unsigned long flags_mask;
+
+ if (!file_mmap_ok(file, inode, pgoff, len))
+ return -EOVERFLOW;
+
+ flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
+
+ switch (flags & MAP_TYPE) {
+ case MAP_SHARED:
+ /*
+ * Force use of MAP_SHARED_VALIDATE with non-legacy
+ * flags. E.g. MAP_SYNC is dangerous to use with
+ * MAP_SHARED as you don't know which consistency model
+ * you will get. We silently ignore unsupported flags
+ * with MAP_SHARED to preserve backward compatibility.
+ */
+ flags &= LEGACY_MAP_MASK;
+ fallthrough;
+ case MAP_SHARED_VALIDATE:
+ if (flags & ~flags_mask)
+ return -EOPNOTSUPP;
+ if (prot & PROT_WRITE) {
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EACCES;
+ if (IS_SWAPFILE(file->f_mapping->host))
+ return -ETXTBSY;
+ }
+
+ /*
+ * Make sure we don't allow writing to an append-only
+ * file..
+ */
+ if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
+ return -EACCES;
+
+ vm_flags |= VM_SHARED | VM_MAYSHARE;
+ if (!(file->f_mode & FMODE_WRITE))
+ vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
+ fallthrough;
+ case MAP_PRIVATE:
+ if (!(file->f_mode & FMODE_READ))
+ return -EACCES;
+ if (path_noexec(&file->f_path)) {
+ if (vm_flags & VM_EXEC)
+ return -EPERM;
+ vm_flags &= ~VM_MAYEXEC;
+ }
+
+ if (!file->f_op->mmap)
+ return -ENODEV;
+ if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+ return -EINVAL;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ } else {
+ switch (flags & MAP_TYPE) {
+ case MAP_SHARED:
+ if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+ return -EINVAL;
+ /*
+ * Ignore pgoff.
+ */
+ pgoff = 0;
+ vm_flags |= VM_SHARED | VM_MAYSHARE;
+ break;
+ case MAP_PRIVATE:
+ /*
+ * Set pgoff according to addr for anon_vma.
+ */
+ pgoff = addr >> PAGE_SHIFT;
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * Set 'VM_NORESERVE' if we should not account for the
+ * memory use of this mapping.
+ */
+ if (flags & MAP_NORESERVE) {
+ /* We honor MAP_NORESERVE if allowed to overcommit */
+ if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+ vm_flags |= VM_NORESERVE;
+
+ /* hugetlb applies strict overcommit unless MAP_NORESERVE */
+ if (file && is_file_hugepages(file))
+ vm_flags |= VM_NORESERVE;
+ }
+
+ addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
+ if (!IS_ERR_VALUE(addr) &&
+ ((vm_flags & VM_LOCKED) ||
+ (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
+ *populate = len;
+ return addr;
+}
+
+unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flags,
+ unsigned long fd, unsigned long pgoff)
+{
+ struct file *file = NULL;
+ unsigned long retval;
+
+ if (!(flags & MAP_ANONYMOUS)) {
+ audit_mmap_fd(fd, flags);
+ file = fget(fd);
+ if (!file)
+ return -EBADF;
+ if (is_file_hugepages(file)) {
+ len = ALIGN(len, huge_page_size(hstate_file(file)));
+ } else if (unlikely(flags & MAP_HUGETLB)) {
+ retval = -EINVAL;
+ goto out_fput;
+ }
+ } else if (flags & MAP_HUGETLB) {
+ struct 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
+ */
+ file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
+ VM_NORESERVE,
+ HUGETLB_ANONHUGE_INODE,
+ (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+ }
+
+ 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 */
+
+static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops)
+{
+ return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite);
+}
+
+static bool vma_is_shared_writable(struct vm_area_struct *vma)
+{
+ return (vma->vm_flags & (VM_WRITE | VM_SHARED)) ==
+ (VM_WRITE | VM_SHARED);
+}
+
+static bool vma_fs_can_writeback(struct vm_area_struct *vma)
+{
+ /* No managed pages to writeback. */
+ if (vma->vm_flags & VM_PFNMAP)
+ return false;
+
+ return vma->vm_file && vma->vm_file->f_mapping &&
+ mapping_can_writeback(vma->vm_file->f_mapping);
+}
+
+/*
+ * Does this VMA require the underlying folios to have their dirty state
+ * tracked?
+ */
+bool vma_needs_dirty_tracking(struct vm_area_struct *vma)
+{
+ /* Only shared, writable VMAs require dirty tracking. */
+ if (!vma_is_shared_writable(vma))
+ return false;
+
+ /* Does the filesystem need to be notified? */
+ if (vm_ops_needs_writenotify(vma->vm_ops))
+ return true;
+
+ /*
+ * Even if the filesystem doesn't indicate a need for writenotify, if it
+ * can writeback, dirty tracking is still required.
+ */
+ return vma_fs_can_writeback(vma);
+}
+
+/*
+ * Some shared mappings will want the pages marked read-only
+ * to track write events. If so, we'll downgrade vm_page_prot
+ * to the private version (using protection_map[] without the
+ * VM_SHARED bit).
+ */
+int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
+{
+ /* If it was private or non-writable, the write bit is already clear */
+ if (!vma_is_shared_writable(vma))
+ return 0;
+
+ /* The backer wishes to know when pages are first written to? */
+ if (vm_ops_needs_writenotify(vma->vm_ops))
+ 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, vma->vm_flags)))
+ return 0;
+
+ /*
+ * Do we need to track softdirty? hugetlb does not support softdirty
+ * tracking yet.
+ */
+ if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma))
+ return 1;
+
+ /* Do we need write faults for uffd-wp tracking? */
+ if (userfaultfd_wp(vma))
+ return 1;
+
+ /* Can the mapping track the dirty pages? */
+ return vma_fs_can_writeback(vma);
+}
+
+/*
+ * 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;
+}
+
+/**
+ * unmapped_area() - Find an area between the low_limit and the high_limit with
+ * the correct alignment and offset, all from @info. Note: current->mm is used
+ * for the search.
+ *
+ * @info: The unmapped area information including the range [low_limit -
+ * high_limit), the alignment offset and mask.
+ *
+ * Return: A memory address or -ENOMEM.
+ */
+static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
+{
+ unsigned long length, gap;
+ unsigned long low_limit, high_limit;
+ struct vm_area_struct *tmp;
+
+ MA_STATE(mas, &current->mm->mm_mt, 0, 0);
+
+ /* Adjust search length to account for worst case alignment overhead */
+ length = info->length + info->align_mask;
+ if (length < info->length)
+ return -ENOMEM;
+
+ low_limit = info->low_limit;
+ if (low_limit < mmap_min_addr)
+ low_limit = mmap_min_addr;
+ high_limit = info->high_limit;
+retry:
+ if (mas_empty_area(&mas, low_limit, high_limit - 1, length))
+ return -ENOMEM;
+
+ gap = mas.index;
+ gap += (info->align_offset - gap) & info->align_mask;
+ tmp = mas_next(&mas, ULONG_MAX);
+ if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
+ if (vm_start_gap(tmp) < gap + length - 1) {
+ low_limit = tmp->vm_end;
+ mas_reset(&mas);
+ goto retry;
+ }
+ } else {
+ tmp = mas_prev(&mas, 0);
+ if (tmp && vm_end_gap(tmp) > gap) {
+ low_limit = vm_end_gap(tmp);
+ mas_reset(&mas);
+ goto retry;
+ }
+ }
+
+ return gap;
+}
+
+/**
+ * unmapped_area_topdown() - Find an area between the low_limit and the
+ * high_limit with the correct alignment and offset at the highest available
+ * address, all from @info. Note: current->mm is used for the search.
+ *
+ * @info: The unmapped area information including the range [low_limit -
+ * high_limit), the alignment offset and mask.
+ *
+ * Return: A memory address or -ENOMEM.
+ */
+static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
+{
+ unsigned long length, gap, gap_end;
+ unsigned long low_limit, high_limit;
+ struct vm_area_struct *tmp;
+
+ MA_STATE(mas, &current->mm->mm_mt, 0, 0);
+ /* Adjust search length to account for worst case alignment overhead */
+ length = info->length + info->align_mask;
+ if (length < info->length)
+ return -ENOMEM;
+
+ low_limit = info->low_limit;
+ if (low_limit < mmap_min_addr)
+ low_limit = mmap_min_addr;
+ high_limit = info->high_limit;
+retry:
+ if (mas_empty_area_rev(&mas, low_limit, high_limit - 1, length))
+ return -ENOMEM;
+
+ gap = mas.last + 1 - info->length;
+ gap -= (gap - info->align_offset) & info->align_mask;
+ gap_end = mas.last;
+ tmp = mas_next(&mas, ULONG_MAX);
+ if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
+ if (vm_start_gap(tmp) <= gap_end) {
+ high_limit = vm_start_gap(tmp);
+ mas_reset(&mas);
+ goto retry;
+ }
+ } else {
+ tmp = mas_prev(&mas, 0);
+ if (tmp && vm_end_gap(tmp) > gap) {
+ high_limit = tmp->vm_start;
+ mas_reset(&mas);
+ goto retry;
+ }
+ }
+
+ return gap;
+}
+
+/*
+ * Search for an unmapped address range.
+ *
+ * We are looking for a range that:
+ * - does not intersect with any VMA;
+ * - is contained within the [low_limit, high_limit) interval;
+ * - is at least the desired size.
+ * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
+ */
+unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
+{
+ unsigned long addr;
+
+ if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
+ addr = unmapped_area_topdown(info);
+ else
+ addr = unmapped_area(info);
+
+ trace_vm_unmapped_area(addr, info);
+ return addr;
+}
+
+/* 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.
+ */
+unsigned long
+generic_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma, *prev;
+ struct vm_unmapped_area_info info;
+ const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
+
+ if (len > mmap_end - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma_prev(mm, addr, &prev);
+ if (mmap_end - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = mm->mmap_base;
+ info.high_limit = mmap_end;
+ info.align_mask = 0;
+ info.align_offset = 0;
+ return vm_unmapped_area(&info);
+}
+
+#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)
+{
+ return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
+}
+#endif
+
+/*
+ * This mmap-allocator allocates new areas top-down from below the
+ * stack's low limit (the base):
+ */
+unsigned long
+generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ struct vm_area_struct *vma, *prev;
+ struct mm_struct *mm = current->mm;
+ struct vm_unmapped_area_info info;
+ const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
+
+ /* requested length too big for entire address space */
+ if (len > mmap_end - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ /* requesting a specific address */
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma_prev(mm, addr, &prev);
+ if (mmap_end - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = PAGE_SIZE;
+ info.high_limit = arch_get_mmap_base(addr, 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 = mmap_end;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+
+#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
+}
+#endif
+
+unsigned long
+get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags)
+{
+ unsigned long (*get_area)(struct file *, unsigned long,
+ unsigned long, unsigned long, unsigned long);
+
+ unsigned long error = arch_mmap_check(addr, len, flags);
+ if (error)
+ return error;
+
+ /* Careful about overflows.. */
+ if (len > TASK_SIZE)
+ return -ENOMEM;
+
+ get_area = current->mm->get_unmapped_area;
+ if (file) {
+ if (file->f_op->get_unmapped_area)
+ get_area = file->f_op->get_unmapped_area;
+ } else if (flags & MAP_SHARED) {
+ /*
+ * mmap_region() will call shmem_zero_setup() to create a file,
+ * so use shmem's get_unmapped_area in case it can be huge.
+ * do_mmap() will clear pgoff, so match alignment.
+ */
+ pgoff = 0;
+ get_area = shmem_get_unmapped_area;
+ }
+
+ addr = get_area(file, addr, len, pgoff, flags);
+ if (IS_ERR_VALUE(addr))
+ return addr;
+
+ if (addr > TASK_SIZE - len)
+ return -ENOMEM;
+ if (offset_in_page(addr))
+ return -EINVAL;
+
+ error = security_mmap_addr(addr);
+ return error ? error : addr;
+}
+
+EXPORT_SYMBOL(get_unmapped_area);
+
+/**
+ * find_vma_intersection() - Look up the first VMA which intersects the interval
+ * @mm: The process address space.
+ * @start_addr: The inclusive start user address.
+ * @end_addr: The exclusive end user address.
+ *
+ * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
+ * start_addr < end_addr.
+ */
+struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
+ unsigned long start_addr,
+ unsigned long end_addr)
+{
+ unsigned long index = start_addr;
+
+ mmap_assert_locked(mm);
+ return mt_find(&mm->mm_mt, &index, end_addr - 1);
+}
+EXPORT_SYMBOL(find_vma_intersection);
+
+/**
+ * find_vma() - Find the VMA for a given address, or the next VMA.
+ * @mm: The mm_struct to check
+ * @addr: The address
+ *
+ * Returns: The VMA associated with addr, or the next VMA.
+ * May return %NULL in the case of no VMA at addr or above.
+ */
+struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+ unsigned long index = addr;
+
+ mmap_assert_locked(mm);
+ return mt_find(&mm->mm_mt, &index, ULONG_MAX);
+}
+EXPORT_SYMBOL(find_vma);
+
+/**
+ * find_vma_prev() - Find the VMA for a given address, or the next vma and
+ * set %pprev to the previous VMA, if any.
+ * @mm: The mm_struct to check
+ * @addr: The address
+ * @pprev: The pointer to set to the previous VMA
+ *
+ * Note that RCU lock is missing here since the external mmap_lock() is used
+ * instead.
+ *
+ * Returns: The VMA associated with @addr, or the next vma.
+ * May return %NULL in the case of no vma at addr or above.
+ */
+struct vm_area_struct *
+find_vma_prev(struct mm_struct *mm, unsigned long addr,
+ struct vm_area_struct **pprev)
+{
+ struct vm_area_struct *vma;
+ MA_STATE(mas, &mm->mm_mt, addr, addr);
+
+ vma = mas_walk(&mas);
+ *pprev = mas_prev(&mas, 0);
+ if (!vma)
+ vma = mas_next(&mas, ULONG_MAX);
+ 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 (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
+ 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.
+ */
+static 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;
+ MA_STATE(mas, &mm->mm_mt, vma->vm_start, address);
+
+ 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 = find_vma_intersection(mm, vma->vm_end, gap_addr);
+ if (next && vma_is_accessible(next)) {
+ if (!(next->vm_flags & VM_GROWSUP))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
+
+ if (next)
+ mas_prev_range(&mas, address);
+
+ __mas_set_range(&mas, vma->vm_start, address - 1);
+ if (mas_preallocate(&mas, vma, GFP_KERNEL))
+ return -ENOMEM;
+
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma))) {
+ mas_destroy(&mas);
+ return -ENOMEM;
+ }
+
+ /* Lock the VMA before expanding to prevent concurrent page faults */
+ vma_start_write(vma);
+ /*
+ * vma->vm_start/vm_end cannot change under us because the caller
+ * is required to hold the mmap_lock in read mode. We need the
+ * anon_vma lock to serialize against concurrent expand_stacks.
+ */
+ anon_vma_lock_write(vma->anon_vma);
+
+ /* Somebody else might have raced and expanded it already */
+ if (address > vma->vm_end) {
+ unsigned long size, grow;
+
+ size = address - vma->vm_start;
+ grow = (address - vma->vm_end) >> PAGE_SHIFT;
+
+ error = -ENOMEM;
+ if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ /*
+ * We only hold a shared mmap_lock lock here, so
+ * we need to protect against concurrent vma
+ * expansions. anon_vma_lock_write() doesn't
+ * help here, as we don't guarantee that all
+ * growable vmas in a mm share the same root
+ * anon vma. So, we reuse mm->page_table_lock
+ * to guard against concurrent vma expansions.
+ */
+ spin_lock(&mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ mm->locked_vm += grow;
+ vm_stat_account(mm, vma->vm_flags, grow);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_end = address;
+ /* Overwrite old entry in mtree. */
+ mas_store_prealloc(&mas, vma);
+ anon_vma_interval_tree_post_update_vma(vma);
+ spin_unlock(&mm->page_table_lock);
+
+ perf_event_mmap(vma);
+ }
+ }
+ }
+ anon_vma_unlock_write(vma->anon_vma);
+ khugepaged_enter_vma(vma, vma->vm_flags);
+ mas_destroy(&mas);
+ 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.
+ * mmap_lock held for writing.
+ */
+int expand_downwards(struct vm_area_struct *vma, unsigned long address)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
+ struct vm_area_struct *prev;
+ int error = 0;
+
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ return -EFAULT;
+
+ address &= PAGE_MASK;
+ if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)
+ return -EPERM;
+
+ /* Enforce stack_guard_gap */
+ prev = mas_prev(&mas, 0);
+ /* Check that both stack segments have the same anon_vma? */
+ if (prev) {
+ if (!(prev->vm_flags & VM_GROWSDOWN) &&
+ vma_is_accessible(prev) &&
+ (address - prev->vm_end < stack_guard_gap))
+ return -ENOMEM;
+ }
+
+ if (prev)
+ mas_next_range(&mas, vma->vm_start);
+
+ __mas_set_range(&mas, address, vma->vm_end - 1);
+ if (mas_preallocate(&mas, vma, GFP_KERNEL))
+ return -ENOMEM;
+
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma))) {
+ mas_destroy(&mas);
+ return -ENOMEM;
+ }
+
+ /* Lock the VMA before expanding to prevent concurrent page faults */
+ vma_start_write(vma);
+ /*
+ * vma->vm_start/vm_end cannot change under us because the caller
+ * is required to hold the mmap_lock in read mode. We need the
+ * anon_vma lock to serialize against concurrent expand_stacks.
+ */
+ anon_vma_lock_write(vma->anon_vma);
+
+ /* Somebody else might have raced and expanded it already */
+ if (address < vma->vm_start) {
+ unsigned long size, grow;
+
+ size = vma->vm_end - address;
+ grow = (vma->vm_start - address) >> PAGE_SHIFT;
+
+ error = -ENOMEM;
+ if (grow <= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ /*
+ * We only hold a shared mmap_lock lock here, so
+ * we need to protect against concurrent vma
+ * expansions. anon_vma_lock_write() doesn't
+ * help here, as we don't guarantee that all
+ * growable vmas in a mm share the same root
+ * anon vma. So, we reuse mm->page_table_lock
+ * to guard against concurrent vma expansions.
+ */
+ spin_lock(&mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ mm->locked_vm += grow;
+ vm_stat_account(mm, vma->vm_flags, grow);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_start = address;
+ vma->vm_pgoff -= grow;
+ /* Overwrite old entry in mtree. */
+ mas_store_prealloc(&mas, vma);
+ anon_vma_interval_tree_post_update_vma(vma);
+ spin_unlock(&mm->page_table_lock);
+
+ perf_event_mmap(vma);
+ }
+ }
+ }
+ anon_vma_unlock_write(vma->anon_vma);
+ khugepaged_enter_vma(vma, vma->vm_flags);
+ mas_destroy(&mas);
+ 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_locked(struct vm_area_struct *vma, unsigned long address)
+{
+ return expand_upwards(vma, address);
+}
+
+struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma, *prev;
+
+ addr &= PAGE_MASK;
+ vma = find_vma_prev(mm, addr, &prev);
+ if (vma && (vma->vm_start <= addr))
+ return vma;
+ if (!prev)
+ return NULL;
+ if (expand_stack_locked(prev, addr))
+ return NULL;
+ if (prev->vm_flags & VM_LOCKED)
+ populate_vma_page_range(prev, addr, prev->vm_end, NULL);
+ return prev;
+}
+#else
+int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
+{
+ if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
+ return -EINVAL;
+ return expand_downwards(vma, address);
+}
+
+struct vm_area_struct *find_extend_vma_locked(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;
+ start = vma->vm_start;
+ if (expand_stack_locked(vma, addr))
+ return NULL;
+ if (vma->vm_flags & VM_LOCKED)
+ populate_vma_page_range(vma, addr, start, NULL);
+ return vma;
+}
+#endif
+
+/*
+ * IA64 has some horrid mapping rules: it can expand both up and down,
+ * but with various special rules.
+ *
+ * We'll get rid of this architecture eventually, so the ugliness is
+ * temporary.
+ */
+#ifdef CONFIG_IA64
+static inline bool vma_expand_ok(struct vm_area_struct *vma, unsigned long addr)
+{
+ return REGION_NUMBER(addr) == REGION_NUMBER(vma->vm_start) &&
+ REGION_OFFSET(addr) < RGN_MAP_LIMIT;
+}
+
+/*
+ * IA64 stacks grow down, but there's a special register backing store
+ * that can grow up. Only sequentially, though, so the new address must
+ * match vm_end.
+ */
+static inline int vma_expand_up(struct vm_area_struct *vma, unsigned long addr)
+{
+ if (!vma_expand_ok(vma, addr))
+ return -EFAULT;
+ if (vma->vm_end != (addr & PAGE_MASK))
+ return -EFAULT;
+ return expand_upwards(vma, addr);
+}
+
+static inline bool vma_expand_down(struct vm_area_struct *vma, unsigned long addr)
+{
+ if (!vma_expand_ok(vma, addr))
+ return -EFAULT;
+ return expand_downwards(vma, addr);
+}
+
+#elif defined(CONFIG_STACK_GROWSUP)
+
+#define vma_expand_up(vma,addr) expand_upwards(vma, addr)
+#define vma_expand_down(vma, addr) (-EFAULT)
+
+#else
+
+#define vma_expand_up(vma,addr) (-EFAULT)
+#define vma_expand_down(vma, addr) expand_downwards(vma, addr)
+
+#endif
+
+/*
+ * expand_stack(): legacy interface for page faulting. Don't use unless
+ * you have to.
+ *
+ * This is called with the mm locked for reading, drops the lock, takes
+ * the lock for writing, tries to look up a vma again, expands it if
+ * necessary, and downgrades the lock to reading again.
+ *
+ * If no vma is found or it can't be expanded, it returns NULL and has
+ * dropped the lock.
+ */
+struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma, *prev;
+
+ mmap_read_unlock(mm);
+ if (mmap_write_lock_killable(mm))
+ return NULL;
+
+ vma = find_vma_prev(mm, addr, &prev);
+ if (vma && vma->vm_start <= addr)
+ goto success;
+
+ if (prev && !vma_expand_up(prev, addr)) {
+ vma = prev;
+ goto success;
+ }
+
+ if (vma && !vma_expand_down(vma, addr))
+ goto success;
+
+ mmap_write_unlock(mm);
+ return NULL;
+
+success:
+ mmap_write_downgrade(mm);
+ return vma;
+}
+
+/*
+ * Ok - we have the memory areas we should free on a maple tree so release them,
+ * and do the vma updates.
+ *
+ * Called with the mm semaphore held.
+ */
+static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
+{
+ unsigned long nr_accounted = 0;
+ struct vm_area_struct *vma;
+
+ /* Update high watermark before we lower total_vm */
+ update_hiwater_vm(mm);
+ mas_for_each(mas, vma, ULONG_MAX) {
+ long nrpages = vma_pages(vma);
+
+ if (vma->vm_flags & VM_ACCOUNT)
+ nr_accounted += nrpages;
+ vm_stat_account(mm, vma->vm_flags, -nrpages);
+ remove_vma(vma, false);
+ }
+ vm_unacct_memory(nr_accounted);
+}
+
+/*
+ * 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 ma_state *mas,
+ struct vm_area_struct *vma, struct vm_area_struct *prev,
+ struct vm_area_struct *next, unsigned long start,
+ unsigned long end, unsigned long tree_end, bool mm_wr_locked)
+{
+ struct mmu_gather tlb;
+ unsigned long mt_start = mas->index;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm);
+ update_hiwater_rss(mm);
+ unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked);
+ mas_set(mas, mt_start);
+ free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
+ next ? next->vm_start : USER_PGTABLES_CEILING,
+ mm_wr_locked);
+ tlb_finish_mmu(&tlb);
+}
+
+/*
+ * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
+ * has already been checked or doesn't make sense to fail.
+ * VMA Iterator will point to the end VMA.
+ */
+int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long addr, int new_below)
+{
+ struct vma_prepare vp;
+ struct vm_area_struct *new;
+ int err;
+
+ WARN_ON(vma->vm_start >= addr);
+ WARN_ON(vma->vm_end <= addr);
+
+ if (vma->vm_ops && vma->vm_ops->may_split) {
+ err = vma->vm_ops->may_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 = -ENOMEM;
+ vma_iter_config(vmi, new->vm_start, new->vm_end);
+ if (vma_iter_prealloc(vmi, new))
+ goto out_free_vma;
+
+ err = vma_dup_policy(vma, new);
+ if (err)
+ goto out_free_vmi;
+
+ 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);
+
+ vma_start_write(vma);
+ vma_start_write(new);
+
+ init_vma_prep(&vp, vma);
+ vp.insert = new;
+ vma_prepare(&vp);
+ vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
+
+ if (new_below) {
+ vma->vm_start = addr;
+ vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
+ } else {
+ vma->vm_end = addr;
+ }
+
+ /* vma_complete stores the new vma */
+ vma_complete(&vp, vmi, vma->vm_mm);
+
+ /* Success. */
+ if (new_below)
+ vma_next(vmi);
+ return 0;
+
+out_free_mpol:
+ mpol_put(vma_policy(new));
+out_free_vmi:
+ vma_iter_free(vmi);
+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 vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long addr, int new_below)
+{
+ if (vma->vm_mm->map_count >= sysctl_max_map_count)
+ return -ENOMEM;
+
+ return __split_vma(vmi, vma, addr, new_below);
+}
+
+/*
+ * do_vmi_align_munmap() - munmap the aligned region from @start to @end.
+ * @vmi: The vma iterator
+ * @vma: The starting vm_area_struct
+ * @mm: The mm_struct
+ * @start: The aligned start address to munmap.
+ * @end: The aligned end address to munmap.
+ * @uf: The userfaultfd list_head
+ * @unlock: Set to true to drop the mmap_lock. unlocking only happens on
+ * success.
+ *
+ * Return: 0 on success and drops the lock if so directed, error and leaves the
+ * lock held otherwise.
+ */
+static int
+do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ struct mm_struct *mm, unsigned long start,
+ unsigned long end, struct list_head *uf, bool unlock)
+{
+ struct vm_area_struct *prev, *next = NULL;
+ struct maple_tree mt_detach;
+ int count = 0;
+ int error = -ENOMEM;
+ unsigned long locked_vm = 0;
+ MA_STATE(mas_detach, &mt_detach, 0, 0);
+ mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
+ mt_on_stack(mt_detach);
+
+ /*
+ * 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.
+ */
+
+ /* Does it split the first one? */
+ if (start > vma->vm_start) {
+
+ /*
+ * 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)
+ goto map_count_exceeded;
+
+ error = __split_vma(vmi, vma, start, 1);
+ if (error)
+ goto start_split_failed;
+ }
+
+ /*
+ * Detach a range of VMAs from the mm. Using next as a temp variable as
+ * it is always overwritten.
+ */
+ next = vma;
+ do {
+ /* Does it split the end? */
+ if (next->vm_end > end) {
+ error = __split_vma(vmi, next, end, 0);
+ if (error)
+ goto end_split_failed;
+ }
+ vma_start_write(next);
+ mas_set(&mas_detach, count);
+ error = mas_store_gfp(&mas_detach, next, GFP_KERNEL);
+ if (error)
+ goto munmap_gather_failed;
+ vma_mark_detached(next, true);
+ if (next->vm_flags & VM_LOCKED)
+ locked_vm += vma_pages(next);
+
+ count++;
+ if (unlikely(uf)) {
+ /*
+ * If userfaultfd_unmap_prep returns an error the vmas
+ * will remain split, 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.
+ */
+ error = userfaultfd_unmap_prep(next, start, end, uf);
+
+ if (error)
+ goto userfaultfd_error;
+ }
+#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
+ BUG_ON(next->vm_start < start);
+ BUG_ON(next->vm_start > end);
+#endif
+ } for_each_vma_range(*vmi, next, end);
+
+#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
+ /* Make sure no VMAs are about to be lost. */
+ {
+ MA_STATE(test, &mt_detach, 0, 0);
+ struct vm_area_struct *vma_mas, *vma_test;
+ int test_count = 0;
+
+ vma_iter_set(vmi, start);
+ rcu_read_lock();
+ vma_test = mas_find(&test, count - 1);
+ for_each_vma_range(*vmi, vma_mas, end) {
+ BUG_ON(vma_mas != vma_test);
+ test_count++;
+ vma_test = mas_next(&test, count - 1);
+ }
+ rcu_read_unlock();
+ BUG_ON(count != test_count);
+ }
+#endif
+
+ while (vma_iter_addr(vmi) > start)
+ vma_iter_prev_range(vmi);
+
+ error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL);
+ if (error)
+ goto clear_tree_failed;
+
+ /* Point of no return */
+ mm->locked_vm -= locked_vm;
+ mm->map_count -= count;
+ if (unlock)
+ mmap_write_downgrade(mm);
+
+ prev = vma_iter_prev_range(vmi);
+ next = vma_next(vmi);
+ if (next)
+ vma_iter_prev_range(vmi);
+
+ /*
+ * We can free page tables without write-locking mmap_lock because VMAs
+ * were isolated before we downgraded mmap_lock.
+ */
+ mas_set(&mas_detach, 1);
+ unmap_region(mm, &mas_detach, vma, prev, next, start, end, count,
+ !unlock);
+ /* Statistics and freeing VMAs */
+ mas_set(&mas_detach, 0);
+ remove_mt(mm, &mas_detach);
+ validate_mm(mm);
+ if (unlock)
+ mmap_read_unlock(mm);
+
+ __mt_destroy(&mt_detach);
+ return 0;
+
+clear_tree_failed:
+userfaultfd_error:
+munmap_gather_failed:
+end_split_failed:
+ mas_set(&mas_detach, 0);
+ mas_for_each(&mas_detach, next, end)
+ vma_mark_detached(next, false);
+
+ __mt_destroy(&mt_detach);
+start_split_failed:
+map_count_exceeded:
+ validate_mm(mm);
+ return error;
+}
+
+/*
+ * do_vmi_munmap() - munmap a given range.
+ * @vmi: The vma iterator
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length of the range to munmap
+ * @uf: The userfaultfd list_head
+ * @unlock: set to true if the user wants to drop the mmap_lock on success
+ *
+ * This function takes a @mas that is either pointing to the previous VMA or set
+ * to MA_START and sets it up to remove the mapping(s). The @len will be
+ * aligned and any arch_unmap work will be preformed.
+ *
+ * Return: 0 on success and drops the lock if so directed, error and leaves the
+ * lock held otherwise.
+ */
+int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
+ unsigned long start, size_t len, struct list_head *uf,
+ bool unlock)
+{
+ unsigned long end;
+ struct vm_area_struct *vma;
+
+ if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
+ return -EINVAL;
+
+ end = start + PAGE_ALIGN(len);
+ if (end == start)
+ return -EINVAL;
+
+ /* arch_unmap() might do unmaps itself. */
+ arch_unmap(mm, start, end);
+
+ /* Find the first overlapping VMA */
+ vma = vma_find(vmi, end);
+ if (!vma) {
+ if (unlock)
+ mmap_write_unlock(mm);
+ return 0;
+ }
+
+ return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
+}
+
+/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length to be munmapped.
+ * @uf: The userfaultfd list_head
+ *
+ * Return: 0 on success, error otherwise.
+ */
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+ struct list_head *uf)
+{
+ VMA_ITERATOR(vmi, mm, start);
+
+ return do_vmi_munmap(&vmi, mm, start, len, uf, false);
+}
+
+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 = NULL;
+ struct vm_area_struct *next, *prev, *merge;
+ pgoff_t pglen = len >> PAGE_SHIFT;
+ unsigned long charged = 0;
+ unsigned long end = addr + len;
+ unsigned long merge_start = addr, merge_end = end;
+ pgoff_t vm_pgoff;
+ int error;
+ VMA_ITERATOR(vmi, mm, addr);
+
+ /* 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, end);
+
+ if (!may_expand_vm(mm, vm_flags,
+ (len >> PAGE_SHIFT) - nr_pages))
+ return -ENOMEM;
+ }
+
+ /* Unmap any existing mapping in the area */
+ if (do_vmi_munmap(&vmi, mm, addr, len, uf, false))
+ 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;
+ }
+
+ next = vma_next(&vmi);
+ prev = vma_prev(&vmi);
+ if (vm_flags & VM_SPECIAL) {
+ if (prev)
+ vma_iter_next_range(&vmi);
+ goto cannot_expand;
+ }
+
+ /* Attempt to expand an old mapping */
+ /* Check next */
+ if (next && next->vm_start == end && !vma_policy(next) &&
+ can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen,
+ NULL_VM_UFFD_CTX, NULL)) {
+ merge_end = next->vm_end;
+ vma = next;
+ vm_pgoff = next->vm_pgoff - pglen;
+ }
+
+ /* Check prev */
+ if (prev && prev->vm_end == addr && !vma_policy(prev) &&
+ (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file,
+ pgoff, vma->vm_userfaultfd_ctx, NULL) :
+ can_vma_merge_after(prev, vm_flags, NULL, file, pgoff,
+ NULL_VM_UFFD_CTX, NULL))) {
+ merge_start = prev->vm_start;
+ vma = prev;
+ vm_pgoff = prev->vm_pgoff;
+ } else if (prev) {
+ vma_iter_next_range(&vmi);
+ }
+
+ /* Actually expand, if possible */
+ if (vma &&
+ !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
+ khugepaged_enter_vma(vma, vm_flags);
+ goto expanded;
+ }
+
+ if (vma == prev)
+ vma_iter_set(&vmi, addr);
+cannot_expand:
+
+ /*
+ * 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_iter_config(&vmi, addr, end);
+ vma->vm_start = addr;
+ vma->vm_end = end;
+ vm_flags_init(vma, vm_flags);
+ vma->vm_page_prot = vm_get_page_prot(vm_flags);
+ vma->vm_pgoff = pgoff;
+
+ if (file) {
+ if (vm_flags & VM_SHARED) {
+ error = mapping_map_writable(file->f_mapping);
+ if (error)
+ goto free_vma;
+ }
+
+ vma->vm_file = get_file(file);
+ error = call_mmap(file, vma);
+ if (error)
+ goto unmap_and_free_vma;
+
+ /*
+ * Expansion is handled above, merging is handled below.
+ * Drivers should not alter the address of the VMA.
+ */
+ error = -EINVAL;
+ if (WARN_ON((addr != vma->vm_start)))
+ goto close_and_free_vma;
+
+ vma_iter_config(&vmi, addr, end);
+ /*
+ * If vm_flags changed after call_mmap(), we should try merge
+ * vma again as we may succeed this time.
+ */
+ if (unlikely(vm_flags != vma->vm_flags && prev)) {
+ merge = vma_merge(&vmi, mm, prev, vma->vm_start,
+ vma->vm_end, vma->vm_flags, NULL,
+ vma->vm_file, vma->vm_pgoff, NULL,
+ NULL_VM_UFFD_CTX, NULL);
+ if (merge) {
+ /*
+ * ->mmap() can change vma->vm_file and fput
+ * the original file. So fput the vma->vm_file
+ * here or we would add an extra fput for file
+ * and cause general protection fault
+ * ultimately.
+ */
+ fput(vma->vm_file);
+ vm_area_free(vma);
+ vma = merge;
+ /* Update vm_flags to pick up the change. */
+ vm_flags = vma->vm_flags;
+ goto unmap_writable;
+ }
+ }
+
+ vm_flags = vma->vm_flags;
+ } else if (vm_flags & VM_SHARED) {
+ error = shmem_zero_setup(vma);
+ if (error)
+ goto free_vma;
+ } else {
+ vma_set_anonymous(vma);
+ }
+
+ if (map_deny_write_exec(vma, vma->vm_flags)) {
+ error = -EACCES;
+ goto close_and_free_vma;
+ }
+
+ /* Allow architectures to sanity-check the vm_flags */
+ error = -EINVAL;
+ if (!arch_validate_flags(vma->vm_flags))
+ goto close_and_free_vma;
+
+ error = -ENOMEM;
+ if (vma_iter_prealloc(&vmi, vma))
+ goto close_and_free_vma;
+
+ /* Lock the VMA since it is modified after insertion into VMA tree */
+ vma_start_write(vma);
+ vma_iter_store(&vmi, vma);
+ mm->map_count++;
+ if (vma->vm_file) {
+ i_mmap_lock_write(vma->vm_file->f_mapping);
+ if (vma->vm_flags & VM_SHARED)
+ mapping_allow_writable(vma->vm_file->f_mapping);
+
+ flush_dcache_mmap_lock(vma->vm_file->f_mapping);
+ vma_interval_tree_insert(vma, &vma->vm_file->f_mapping->i_mmap);
+ flush_dcache_mmap_unlock(vma->vm_file->f_mapping);
+ i_mmap_unlock_write(vma->vm_file->f_mapping);
+ }
+
+ /*
+ * vma_merge() calls khugepaged_enter_vma() either, the below
+ * call covers the non-merge case.
+ */
+ khugepaged_enter_vma(vma, vma->vm_flags);
+
+ /* Once vma denies write, undo our temporary denial count */
+unmap_writable:
+ if (file && vm_flags & VM_SHARED)
+ mapping_unmap_writable(file->f_mapping);
+ file = vma->vm_file;
+ ksm_add_vma(vma);
+expanded:
+ 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))
+ vm_flags_clear(vma, VM_LOCKED_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).
+ */
+ vm_flags_set(vma, VM_SOFTDIRTY);
+
+ vma_set_page_prot(vma);
+
+ validate_mm(mm);
+ return addr;
+
+close_and_free_vma:
+ if (file && vma->vm_ops && vma->vm_ops->close)
+ vma->vm_ops->close(vma);
+
+ if (file || vma->vm_file) {
+unmap_and_free_vma:
+ fput(vma->vm_file);
+ vma->vm_file = NULL;
+
+ vma_iter_set(&vmi, vma->vm_end);
+ /* Undo any partial mapping done by a device driver. */
+ unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start,
+ vma->vm_end, vma->vm_end, true);
+ }
+ if (file && (vm_flags & VM_SHARED))
+ mapping_unmap_writable(file->f_mapping);
+free_vma:
+ vm_area_free(vma);
+unacct_error:
+ if (charged)
+ vm_unacct_memory(charged);
+ validate_mm(mm);
+ return error;
+}
+
+static int __vm_munmap(unsigned long start, size_t len, bool unlock)
+{
+ int ret;
+ struct mm_struct *mm = current->mm;
+ LIST_HEAD(uf);
+ VMA_ITERATOR(vmi, mm, start);
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock);
+ if (ret || !unlock)
+ mmap_write_unlock(mm);
+
+ userfaultfd_unmap_complete(mm, &uf);
+ return ret;
+}
+
+int vm_munmap(unsigned long start, size_t len)
+{
+ return __vm_munmap(start, len, false);
+}
+EXPORT_SYMBOL(vm_munmap);
+
+SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+{
+ addr = untagged_addr(addr);
+ return __vm_munmap(addr, len, true);
+}
+
+
+/*
+ * Emulation of deprecated remap_file_pages() syscall.
+ */
+SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
+ unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
+{
+
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long populate = 0;
+ unsigned long ret = -EINVAL;
+ struct file *file;
+
+ pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
+ current->comm, current->pid);
+
+ if (prot)
+ return ret;
+ start = start & PAGE_MASK;
+ size = size & PAGE_MASK;
+
+ if (start + size <= start)
+ return ret;
+
+ /* Does pgoff wrap? */
+ if (pgoff + (size >> PAGE_SHIFT) < pgoff)
+ return ret;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ vma = vma_lookup(mm, start);
+
+ if (!vma || !(vma->vm_flags & VM_SHARED))
+ goto out;
+
+ if (start + size > vma->vm_end) {
+ VMA_ITERATOR(vmi, mm, vma->vm_end);
+ struct vm_area_struct *next, *prev = vma;
+
+ for_each_vma_range(vmi, next, start + size) {
+ /* hole between vmas ? */
+ if (next->vm_start != 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;
+
+ prev = next;
+ }
+
+ if (!next)
+ goto out;
+ }
+
+ prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
+ prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
+ prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
+
+ flags &= MAP_NONBLOCK;
+ flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
+ if (vma->vm_flags & VM_LOCKED)
+ flags |= MAP_LOCKED;
+
+ file = get_file(vma->vm_file);
+ ret = do_mmap(vma->vm_file, start, size,
+ prot, flags, 0, pgoff, &populate, NULL);
+ fput(file);
+out:
+ mmap_write_unlock(mm);
+ if (populate)
+ mm_populate(ret, populate);
+ if (!IS_ERR_VALUE(ret))
+ ret = 0;
+ return ret;
+}
+
+/*
+ * do_vma_munmap() - Unmap a full or partial vma.
+ * @vmi: The vma iterator pointing at the vma
+ * @vma: The first vma to be munmapped
+ * @start: the start of the address to unmap
+ * @end: The end of the address to unmap
+ * @uf: The userfaultfd list_head
+ * @unlock: Drop the lock on success
+ *
+ * unmaps a VMA mapping when the vma iterator is already in position.
+ * Does not handle alignment.
+ *
+ * Return: 0 on success drops the lock of so directed, error on failure and will
+ * still hold the lock.
+ */
+int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, struct list_head *uf,
+ bool unlock)
+{
+ struct mm_struct *mm = vma->vm_mm;
+
+ arch_unmap(mm, start, end);
+ return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
+}
+
+/*
+ * do_brk_flags() - Increase the brk vma if the flags match.
+ * @vmi: The vma iterator
+ * @addr: The start address
+ * @len: The length of the increase
+ * @vma: The vma,
+ * @flags: The VMA Flags
+ *
+ * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags
+ * do not match then create a new anonymous VMA. Eventually we may be able to
+ * do some brk-specific accounting here.
+ */
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long addr, unsigned long len, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vma_prepare vp;
+
+ /*
+ * Check against address space limits by the changed size
+ * Note: This happens *after* clearing old mappings in some code paths.
+ */
+ flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+ 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;
+
+ /*
+ * Expand the existing vma if possible; Note that singular lists do not
+ * occur after forking, so the expand will only happen on new VMAs.
+ */
+ if (vma && vma->vm_end == addr && !vma_policy(vma) &&
+ can_vma_merge_after(vma, flags, NULL, NULL,
+ addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
+ vma_iter_config(vmi, vma->vm_start, addr + len);
+ if (vma_iter_prealloc(vmi, vma))
+ goto unacct_fail;
+
+ vma_start_write(vma);
+
+ init_vma_prep(&vp, vma);
+ vma_prepare(&vp);
+ vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
+ vma->vm_end = addr + len;
+ vm_flags_set(vma, VM_SOFTDIRTY);
+ vma_iter_store(vmi, vma);
+
+ vma_complete(&vp, vmi, mm);
+ khugepaged_enter_vma(vma, flags);
+ goto out;
+ }
+
+ if (vma)
+ vma_iter_next_range(vmi);
+ /* create a vma struct for an anonymous mapping */
+ vma = vm_area_alloc(mm);
+ if (!vma)
+ goto unacct_fail;
+
+ vma_set_anonymous(vma);
+ vma->vm_start = addr;
+ vma->vm_end = addr + len;
+ vma->vm_pgoff = addr >> PAGE_SHIFT;
+ vm_flags_init(vma, flags);
+ vma->vm_page_prot = vm_get_page_prot(flags);
+ vma_start_write(vma);
+ if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
+ goto mas_store_fail;
+
+ mm->map_count++;
+ validate_mm(mm);
+ ksm_add_vma(vma);
+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);
+ vm_flags_set(vma, VM_SOFTDIRTY);
+ return 0;
+
+mas_store_fail:
+ vm_area_free(vma);
+unacct_fail:
+ vm_unacct_memory(len >> PAGE_SHIFT);
+ return -ENOMEM;
+}
+
+int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma = NULL;
+ unsigned long len;
+ int ret;
+ bool populate;
+ LIST_HEAD(uf);
+ VMA_ITERATOR(vmi, mm, addr);
+
+ len = PAGE_ALIGN(request);
+ if (len < request)
+ return -ENOMEM;
+ if (!len)
+ return 0;
+
+ /* Until we need other flags, refuse anything except VM_EXEC. */
+ if ((flags & (~VM_EXEC)) != 0)
+ return -EINVAL;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ ret = check_brk_limits(addr, len);
+ if (ret)
+ goto limits_failed;
+
+ ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0);
+ if (ret)
+ goto munmap_failed;
+
+ vma = vma_prev(&vmi);
+ ret = do_brk_flags(&vmi, vma, addr, len, flags);
+ populate = ((mm->def_flags & VM_LOCKED) != 0);
+ mmap_write_unlock(mm);
+ userfaultfd_unmap_complete(mm, &uf);
+ if (populate && !ret)
+ mm_populate(addr, len);
+ return ret;
+
+munmap_failed:
+limits_failed:
+ mmap_write_unlock(mm);
+ 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;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
+ int count = 0;
+
+ /* mm's last user has gone, and its about to be pulled down */
+ mmu_notifier_release(mm);
+
+ mmap_read_lock(mm);
+ arch_exit_mmap(mm);
+
+ vma = mas_find(&mas, ULONG_MAX);
+ if (!vma) {
+ /* Can happen if dup_mmap() received an OOM */
+ mmap_read_unlock(mm);
+ return;
+ }
+
+ lru_add_drain();
+ flush_cache_mm(mm);
+ tlb_gather_mmu_fullmm(&tlb, mm);
+ /* update_hiwater_rss(mm) here? but nobody should be looking */
+ /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
+ unmap_vmas(&tlb, &mas, vma, 0, ULONG_MAX, ULONG_MAX, false);
+ mmap_read_unlock(mm);
+
+ /*
+ * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
+ * because the memory has been already freed.
+ */
+ set_bit(MMF_OOM_SKIP, &mm->flags);
+ mmap_write_lock(mm);
+ mt_clear_in_rcu(&mm->mm_mt);
+ mas_set(&mas, vma->vm_end);
+ free_pgtables(&tlb, &mas, vma, FIRST_USER_ADDRESS,
+ USER_PGTABLES_CEILING, true);
+ tlb_finish_mmu(&tlb);
+
+ /*
+ * Walk the list again, actually closing and freeing it, with preemption
+ * enabled, without holding any MM locks besides the unreachable
+ * mmap_write_lock.
+ */
+ mas_set(&mas, vma->vm_end);
+ do {
+ if (vma->vm_flags & VM_ACCOUNT)
+ nr_accounted += vma_pages(vma);
+ remove_vma(vma, true);
+ count++;
+ cond_resched();
+ } while ((vma = mas_find(&mas, ULONG_MAX)) != NULL);
+
+ BUG_ON(count != mm->map_count);
+
+ trace_exit_mmap(mm);
+ __mt_destroy(&mm->mm_mt);
+ mmap_write_unlock(mm);
+ 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)
+{
+ unsigned long charged = vma_pages(vma);
+
+
+ if (find_vma_intersection(mm, vma->vm_start, vma->vm_end))
+ return -ENOMEM;
+
+ if ((vma->vm_flags & VM_ACCOUNT) &&
+ security_vm_enough_memory_mm(mm, charged))
+ 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 and in do_brk_flags.
+ */
+ if (vma_is_anonymous(vma)) {
+ BUG_ON(vma->anon_vma);
+ vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
+ }
+
+ if (vma_link(mm, vma)) {
+ vm_unacct_memory(charged);
+ return -ENOMEM;
+ }
+
+ 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;
+ bool faulted_in_anon_vma = true;
+ VMA_ITERATOR(vmi, mm, addr);
+
+ /*
+ * 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;
+ }
+
+ new_vma = find_vma_prev(mm, addr, &prev);
+ if (new_vma && new_vma->vm_start < addr + len)
+ return NULL; /* should never get here */
+
+ new_vma = vma_merge(&vmi, mm, prev, addr, addr + len, vma->vm_flags,
+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+ vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+ if (new_vma) {
+ /*
+ * Source vma may have been merged into new_vma
+ */
+ if (unlikely(vma_start >= new_vma->vm_start &&
+ vma_start < new_vma->vm_end)) {
+ /*
+ * The only way we can get a vma_merge with
+ * self during an mremap is if the vma hasn't
+ * been faulted in yet and we were allowed to
+ * reset the dst vma->vm_pgoff to the
+ * destination address of the mremap to allow
+ * the merge to happen. mremap must change the
+ * vm_pgoff linearity between src and dst vmas
+ * (in turn preventing a vma_merge) to be
+ * safe. It is only safe to keep the vm_pgoff
+ * linear if there are no pages mapped yet.
+ */
+ VM_BUG_ON_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);
+ if (vma_link(mm, new_vma))
+ goto out_vma_link;
+ *need_rmap_locks = false;
+ }
+ return new_vma;
+
+out_vma_link:
+ if (new_vma->vm_ops && new_vma->vm_ops->close)
+ new_vma->vm_ops->close(new_vma);
+
+ if (new_vma->vm_file)
+ fput(new_vma->vm_file);
+
+ unlink_anon_vmas(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)
+{
+ WRITE_ONCE(mm->total_vm, READ_ONCE(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 int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
+{
+ /*
+ * Forbid splitting special mappings - kernel has expectations over
+ * the number of pages in mapping. Together with VM_DONTEXPAND
+ * the size of vma should stay the same over the special mapping's
+ * lifetime.
+ */
+ return -EINVAL;
+}
+
+static const struct vm_operations_struct special_mapping_vmops = {
+ .close = special_mapping_close,
+ .fault = special_mapping_fault,
+ .mremap = special_mapping_mremap,
+ .name = special_mapping_name,
+ /* vDSO code relies that VVAR can't be accessed remotely */
+ .access = NULL,
+ .may_split = special_mapping_split,
+};
+
+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;
+
+ vm_flags_init(vma, (vm_flags | mm->def_flags |
+ VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
+ 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_lock held for writing.
+ * Insert a new vma covering the given region, with the given flags.
+ * Its pages are supplied by the given array of struct page *.
+ * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
+ * 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_lock);
+ /*
+ * 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_lock);
+ }
+}
+
+/*
+ * 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_lock in write mode before calling
+ * mm_take_all_locks(). The caller isn't allowed to release the
+ * mmap_lock until mm_drop_all_locks() returns.
+ *
+ * mmap_lock 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 vmas marked locked
+ * - 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;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
+
+ mmap_assert_write_locked(mm);
+
+ mutex_lock(&mm_all_locks_mutex);
+
+ /*
+ * vma_start_write() does not have a complement in mm_drop_all_locks()
+ * because vma_start_write() is always asymmetrical; it marks a VMA as
+ * being written to until mmap_write_unlock() or mmap_write_downgrade()
+ * is reached.
+ */
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ if (signal_pending(current))
+ goto out_unlock;
+ vma_start_write(vma);
+ }
+
+ mas_set(&mas, 0);
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ 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);
+ }
+
+ mas_set(&mas, 0);
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ 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);
+ }
+
+ mas_set(&mas, 0);
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ 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_lock 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;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
+
+ mmap_assert_write_locked(mm);
+ BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
+
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ 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 = K(global_zone_page_state(NR_FREE_PAGES));
+
+ 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 = K(global_zone_page_state(NR_FREE_PAGES));
+
+ 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 = K(global_zone_page_state(NR_FREE_PAGES));
+
+ 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 int __meminit init_reserve_notifier(void)
+{
+ if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
+ pr_err("Failed registering memory add/remove notifier for admin reserve\n");
+
+ return 0;
+}
+subsys_initcall(init_reserve_notifier);