diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 48 |
1 files changed, 31 insertions, 17 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index d91ecb00d38c..10598e5d4757 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1808,6 +1808,17 @@ unsigned long mmap_region(struct file *file, unsigned long addr, if (error) goto unmap_and_free_vma; + /* Can addr have changed?? + * + * Answer: Yes, several device drivers can do it in their + * f_op->mmap method. -DaveM + * Bug: If addr is changed, prev, rb_link, rb_parent should + * be updated for vma_link() + */ + WARN_ON_ONCE(addr != vma->vm_start); + + addr = vma->vm_start; + /* If vm_flags changed after call_mmap(), we should try merge vma again * as we may succeed this time. */ @@ -1822,25 +1833,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr, fput(vma->vm_file); vm_area_free(vma); vma = merge; - /* Update vm_flags and possible addr to pick up the change. We don't - * warn here if addr changed as the vma is not linked by vma_link(). - */ - addr = vma->vm_start; + /* Update vm_flags to pick up the change. */ vm_flags = vma->vm_flags; goto unmap_writable; } } - /* Can addr have changed?? - * - * Answer: Yes, several device drivers can do it in their - * f_op->mmap method. -DaveM - * Bug: If addr is changed, prev, rb_link, rb_parent should - * be updated for vma_link() - */ - WARN_ON_ONCE(addr != vma->vm_start); - - addr = vma->vm_start; vm_flags = vma->vm_flags; } else if (vm_flags & VM_SHARED) { error = shmem_zero_setup(vma); @@ -2733,8 +2731,8 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *new; int err; - if (vma->vm_ops && vma->vm_ops->split) { - err = vma->vm_ops->split(vma, addr); + if (vma->vm_ops && vma->vm_ops->may_split) { + err = vma->vm_ops->may_split(vma, addr); if (err) return err; } @@ -3407,10 +3405,14 @@ 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) +static int special_mapping_mremap(struct vm_area_struct *new_vma, + unsigned long flags) { struct vm_special_mapping *sm = new_vma->vm_private_data; + if (flags & MREMAP_DONTUNMAP) + return -EINVAL; + if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) return -EFAULT; @@ -3420,6 +3422,17 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma) return 0; } +static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) +{ + /* + * Forbid splitting special mappings - kernel has expectations over + * the number of pages in mapping. Together with VM_DONTEXPAND + * the size of vma should stay the same over the special mapping's + * lifetime. + */ + return -EINVAL; +} + static const struct vm_operations_struct special_mapping_vmops = { .close = special_mapping_close, .fault = special_mapping_fault, @@ -3427,6 +3440,7 @@ static const struct vm_operations_struct special_mapping_vmops = { .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 = { |