1*20c8ccb1SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 2c1a4de99SAndrea Arcangeli /* 3c1a4de99SAndrea Arcangeli * mm/userfaultfd.c 4c1a4de99SAndrea Arcangeli * 5c1a4de99SAndrea Arcangeli * Copyright (C) 2015 Red Hat, Inc. 6c1a4de99SAndrea Arcangeli */ 7c1a4de99SAndrea Arcangeli 8c1a4de99SAndrea Arcangeli #include <linux/mm.h> 9174cd4b1SIngo Molnar #include <linux/sched/signal.h> 10c1a4de99SAndrea Arcangeli #include <linux/pagemap.h> 11c1a4de99SAndrea Arcangeli #include <linux/rmap.h> 12c1a4de99SAndrea Arcangeli #include <linux/swap.h> 13c1a4de99SAndrea Arcangeli #include <linux/swapops.h> 14c1a4de99SAndrea Arcangeli #include <linux/userfaultfd_k.h> 15c1a4de99SAndrea Arcangeli #include <linux/mmu_notifier.h> 1660d4d2d2SMike Kravetz #include <linux/hugetlb.h> 1726071cedSMike Rapoport #include <linux/shmem_fs.h> 18c1a4de99SAndrea Arcangeli #include <asm/tlbflush.h> 19c1a4de99SAndrea Arcangeli #include "internal.h" 20c1a4de99SAndrea Arcangeli 21c1a4de99SAndrea Arcangeli static int mcopy_atomic_pte(struct mm_struct *dst_mm, 22c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 23c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 24c1a4de99SAndrea Arcangeli unsigned long dst_addr, 25b6ebaedbSAndrea Arcangeli unsigned long src_addr, 26b6ebaedbSAndrea Arcangeli struct page **pagep) 27c1a4de99SAndrea Arcangeli { 28c1a4de99SAndrea Arcangeli struct mem_cgroup *memcg; 29c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 30c1a4de99SAndrea Arcangeli spinlock_t *ptl; 31c1a4de99SAndrea Arcangeli void *page_kaddr; 32c1a4de99SAndrea Arcangeli int ret; 33b6ebaedbSAndrea Arcangeli struct page *page; 34e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 35e2a50c1fSAndrea Arcangeli struct inode *inode; 36c1a4de99SAndrea Arcangeli 37b6ebaedbSAndrea Arcangeli if (!*pagep) { 38c1a4de99SAndrea Arcangeli ret = -ENOMEM; 39c1a4de99SAndrea Arcangeli page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); 40c1a4de99SAndrea Arcangeli if (!page) 41c1a4de99SAndrea Arcangeli goto out; 42c1a4de99SAndrea Arcangeli 43b6ebaedbSAndrea Arcangeli page_kaddr = kmap_atomic(page); 44b6ebaedbSAndrea Arcangeli ret = copy_from_user(page_kaddr, 45b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 46b6ebaedbSAndrea Arcangeli PAGE_SIZE); 47b6ebaedbSAndrea Arcangeli kunmap_atomic(page_kaddr); 48b6ebaedbSAndrea Arcangeli 49b6ebaedbSAndrea Arcangeli /* fallback to copy_from_user outside mmap_sem */ 50b6ebaedbSAndrea Arcangeli if (unlikely(ret)) { 519e368259SAndrea Arcangeli ret = -ENOENT; 52b6ebaedbSAndrea Arcangeli *pagep = page; 53b6ebaedbSAndrea Arcangeli /* don't free the page */ 54b6ebaedbSAndrea Arcangeli goto out; 55b6ebaedbSAndrea Arcangeli } 56b6ebaedbSAndrea Arcangeli } else { 57b6ebaedbSAndrea Arcangeli page = *pagep; 58b6ebaedbSAndrea Arcangeli *pagep = NULL; 59b6ebaedbSAndrea Arcangeli } 60c1a4de99SAndrea Arcangeli 61c1a4de99SAndrea Arcangeli /* 62c1a4de99SAndrea Arcangeli * The memory barrier inside __SetPageUptodate makes sure that 63c1a4de99SAndrea Arcangeli * preceeding stores to the page contents become visible before 64c1a4de99SAndrea Arcangeli * the set_pte_at() write. 65c1a4de99SAndrea Arcangeli */ 66c1a4de99SAndrea Arcangeli __SetPageUptodate(page); 67c1a4de99SAndrea Arcangeli 68c1a4de99SAndrea Arcangeli ret = -ENOMEM; 69f627c2f5SKirill A. Shutemov if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) 70c1a4de99SAndrea Arcangeli goto out_release; 71c1a4de99SAndrea Arcangeli 72c1a4de99SAndrea Arcangeli _dst_pte = mk_pte(page, dst_vma->vm_page_prot); 73c1a4de99SAndrea Arcangeli if (dst_vma->vm_flags & VM_WRITE) 74c1a4de99SAndrea Arcangeli _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); 75c1a4de99SAndrea Arcangeli 76c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 77e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 78e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 79e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 80e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 81e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 82e2a50c1fSAndrea Arcangeli ret = -EFAULT; 83e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 84e2a50c1fSAndrea Arcangeli goto out_release_uncharge_unlock; 85e2a50c1fSAndrea Arcangeli } 86e2a50c1fSAndrea Arcangeli ret = -EEXIST; 87c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 88c1a4de99SAndrea Arcangeli goto out_release_uncharge_unlock; 89c1a4de99SAndrea Arcangeli 90c1a4de99SAndrea Arcangeli inc_mm_counter(dst_mm, MM_ANONPAGES); 91d281ee61SKirill A. Shutemov page_add_new_anon_rmap(page, dst_vma, dst_addr, false); 92f627c2f5SKirill A. Shutemov mem_cgroup_commit_charge(page, memcg, false, false); 93c1a4de99SAndrea Arcangeli lru_cache_add_active_or_unevictable(page, dst_vma); 94c1a4de99SAndrea Arcangeli 95c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 96c1a4de99SAndrea Arcangeli 97c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 98c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 99c1a4de99SAndrea Arcangeli 100c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 101c1a4de99SAndrea Arcangeli ret = 0; 102c1a4de99SAndrea Arcangeli out: 103c1a4de99SAndrea Arcangeli return ret; 104c1a4de99SAndrea Arcangeli out_release_uncharge_unlock: 105c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 106f627c2f5SKirill A. Shutemov mem_cgroup_cancel_charge(page, memcg, false); 107c1a4de99SAndrea Arcangeli out_release: 10809cbfeafSKirill A. Shutemov put_page(page); 109c1a4de99SAndrea Arcangeli goto out; 110c1a4de99SAndrea Arcangeli } 111c1a4de99SAndrea Arcangeli 112c1a4de99SAndrea Arcangeli static int mfill_zeropage_pte(struct mm_struct *dst_mm, 113c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 114c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 115c1a4de99SAndrea Arcangeli unsigned long dst_addr) 116c1a4de99SAndrea Arcangeli { 117c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 118c1a4de99SAndrea Arcangeli spinlock_t *ptl; 119c1a4de99SAndrea Arcangeli int ret; 120e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 121e2a50c1fSAndrea Arcangeli struct inode *inode; 122c1a4de99SAndrea Arcangeli 123c1a4de99SAndrea Arcangeli _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), 124c1a4de99SAndrea Arcangeli dst_vma->vm_page_prot)); 125c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 126e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 127e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 128e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 129e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 130e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 131e2a50c1fSAndrea Arcangeli ret = -EFAULT; 132e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 133e2a50c1fSAndrea Arcangeli goto out_unlock; 134e2a50c1fSAndrea Arcangeli } 135e2a50c1fSAndrea Arcangeli ret = -EEXIST; 136c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 137c1a4de99SAndrea Arcangeli goto out_unlock; 138c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 139c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 140c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 141c1a4de99SAndrea Arcangeli ret = 0; 142c1a4de99SAndrea Arcangeli out_unlock: 143c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 144c1a4de99SAndrea Arcangeli return ret; 145c1a4de99SAndrea Arcangeli } 146c1a4de99SAndrea Arcangeli 147c1a4de99SAndrea Arcangeli static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) 148c1a4de99SAndrea Arcangeli { 149c1a4de99SAndrea Arcangeli pgd_t *pgd; 150c2febafcSKirill A. Shutemov p4d_t *p4d; 151c1a4de99SAndrea Arcangeli pud_t *pud; 152c1a4de99SAndrea Arcangeli 153c1a4de99SAndrea Arcangeli pgd = pgd_offset(mm, address); 154c2febafcSKirill A. Shutemov p4d = p4d_alloc(mm, pgd, address); 155c2febafcSKirill A. Shutemov if (!p4d) 156c2febafcSKirill A. Shutemov return NULL; 157c2febafcSKirill A. Shutemov pud = pud_alloc(mm, p4d, address); 158c2febafcSKirill A. Shutemov if (!pud) 159c2febafcSKirill A. Shutemov return NULL; 160c1a4de99SAndrea Arcangeli /* 161c1a4de99SAndrea Arcangeli * Note that we didn't run this because the pmd was 162c1a4de99SAndrea Arcangeli * missing, the *pmd may be already established and in 163c1a4de99SAndrea Arcangeli * turn it may also be a trans_huge_pmd. 164c1a4de99SAndrea Arcangeli */ 165c2febafcSKirill A. Shutemov return pmd_alloc(mm, pud, address); 166c1a4de99SAndrea Arcangeli } 167c1a4de99SAndrea Arcangeli 16860d4d2d2SMike Kravetz #ifdef CONFIG_HUGETLB_PAGE 16960d4d2d2SMike Kravetz /* 17060d4d2d2SMike Kravetz * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is 17160d4d2d2SMike Kravetz * called with mmap_sem held, it will release mmap_sem before returning. 17260d4d2d2SMike Kravetz */ 17360d4d2d2SMike Kravetz static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 17460d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 17560d4d2d2SMike Kravetz unsigned long dst_start, 17660d4d2d2SMike Kravetz unsigned long src_start, 17760d4d2d2SMike Kravetz unsigned long len, 17860d4d2d2SMike Kravetz bool zeropage) 17960d4d2d2SMike Kravetz { 1801c9e8defSMike Kravetz int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; 1811c9e8defSMike Kravetz int vm_shared = dst_vma->vm_flags & VM_SHARED; 18260d4d2d2SMike Kravetz ssize_t err; 18360d4d2d2SMike Kravetz pte_t *dst_pte; 18460d4d2d2SMike Kravetz unsigned long src_addr, dst_addr; 18560d4d2d2SMike Kravetz long copied; 18660d4d2d2SMike Kravetz struct page *page; 18760d4d2d2SMike Kravetz struct hstate *h; 18860d4d2d2SMike Kravetz unsigned long vma_hpagesize; 18960d4d2d2SMike Kravetz pgoff_t idx; 19060d4d2d2SMike Kravetz u32 hash; 19160d4d2d2SMike Kravetz struct address_space *mapping; 19260d4d2d2SMike Kravetz 19360d4d2d2SMike Kravetz /* 19460d4d2d2SMike Kravetz * There is no default zero huge page for all huge page sizes as 19560d4d2d2SMike Kravetz * supported by hugetlb. A PMD_SIZE huge pages may exist as used 19660d4d2d2SMike Kravetz * by THP. Since we can not reliably insert a zero page, this 19760d4d2d2SMike Kravetz * feature is not supported. 19860d4d2d2SMike Kravetz */ 19960d4d2d2SMike Kravetz if (zeropage) { 20060d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 20160d4d2d2SMike Kravetz return -EINVAL; 20260d4d2d2SMike Kravetz } 20360d4d2d2SMike Kravetz 20460d4d2d2SMike Kravetz src_addr = src_start; 20560d4d2d2SMike Kravetz dst_addr = dst_start; 20660d4d2d2SMike Kravetz copied = 0; 20760d4d2d2SMike Kravetz page = NULL; 20860d4d2d2SMike Kravetz vma_hpagesize = vma_kernel_pagesize(dst_vma); 20960d4d2d2SMike Kravetz 21060d4d2d2SMike Kravetz /* 21160d4d2d2SMike Kravetz * Validate alignment based on huge page size 21260d4d2d2SMike Kravetz */ 21360d4d2d2SMike Kravetz err = -EINVAL; 21460d4d2d2SMike Kravetz if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) 21560d4d2d2SMike Kravetz goto out_unlock; 21660d4d2d2SMike Kravetz 21760d4d2d2SMike Kravetz retry: 21860d4d2d2SMike Kravetz /* 21960d4d2d2SMike Kravetz * On routine entry dst_vma is set. If we had to drop mmap_sem and 22060d4d2d2SMike Kravetz * retry, dst_vma will be set to NULL and we must lookup again. 22160d4d2d2SMike Kravetz */ 22260d4d2d2SMike Kravetz if (!dst_vma) { 22327d02568SMike Rapoport err = -ENOENT; 22460d4d2d2SMike Kravetz dst_vma = find_vma(dst_mm, dst_start); 22560d4d2d2SMike Kravetz if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) 22660d4d2d2SMike Kravetz goto out_unlock; 22727d02568SMike Rapoport /* 22829ec9066SAndrea Arcangeli * Check the vma is registered in uffd, this is 22929ec9066SAndrea Arcangeli * required to enforce the VM_MAYWRITE check done at 23029ec9066SAndrea Arcangeli * uffd registration time. 23127d02568SMike Rapoport */ 23227d02568SMike Rapoport if (!dst_vma->vm_userfaultfd_ctx.ctx) 23360d4d2d2SMike Kravetz goto out_unlock; 23460d4d2d2SMike Kravetz 23560d4d2d2SMike Kravetz if (dst_start < dst_vma->vm_start || 23660d4d2d2SMike Kravetz dst_start + len > dst_vma->vm_end) 23760d4d2d2SMike Kravetz goto out_unlock; 2381c9e8defSMike Kravetz 23927d02568SMike Rapoport err = -EINVAL; 24027d02568SMike Rapoport if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) 24127d02568SMike Rapoport goto out_unlock; 24227d02568SMike Rapoport 2431c9e8defSMike Kravetz vm_shared = dst_vma->vm_flags & VM_SHARED; 24460d4d2d2SMike Kravetz } 24560d4d2d2SMike Kravetz 24660d4d2d2SMike Kravetz if (WARN_ON(dst_addr & (vma_hpagesize - 1) || 24760d4d2d2SMike Kravetz (len - copied) & (vma_hpagesize - 1))) 24860d4d2d2SMike Kravetz goto out_unlock; 24960d4d2d2SMike Kravetz 25060d4d2d2SMike Kravetz /* 2511c9e8defSMike Kravetz * If not shared, ensure the dst_vma has a anon_vma. 25260d4d2d2SMike Kravetz */ 25360d4d2d2SMike Kravetz err = -ENOMEM; 2541c9e8defSMike Kravetz if (!vm_shared) { 25560d4d2d2SMike Kravetz if (unlikely(anon_vma_prepare(dst_vma))) 25660d4d2d2SMike Kravetz goto out_unlock; 2571c9e8defSMike Kravetz } 25860d4d2d2SMike Kravetz 25960d4d2d2SMike Kravetz h = hstate_vma(dst_vma); 26060d4d2d2SMike Kravetz 26160d4d2d2SMike Kravetz while (src_addr < src_start + len) { 26260d4d2d2SMike Kravetz pte_t dst_pteval; 26360d4d2d2SMike Kravetz 26460d4d2d2SMike Kravetz BUG_ON(dst_addr >= dst_start + len); 26560d4d2d2SMike Kravetz VM_BUG_ON(dst_addr & ~huge_page_mask(h)); 26660d4d2d2SMike Kravetz 26760d4d2d2SMike Kravetz /* 268ddeaab32SMike Kravetz * Serialize via hugetlb_fault_mutex 26960d4d2d2SMike Kravetz */ 270b43a9990SMike Kravetz idx = linear_page_index(dst_vma, dst_addr); 271ddeaab32SMike Kravetz mapping = dst_vma->vm_file->f_mapping; 2721b426bacSMike Kravetz hash = hugetlb_fault_mutex_hash(h, mapping, idx, dst_addr); 27360d4d2d2SMike Kravetz mutex_lock(&hugetlb_fault_mutex_table[hash]); 27460d4d2d2SMike Kravetz 27560d4d2d2SMike Kravetz err = -ENOMEM; 27660d4d2d2SMike Kravetz dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h)); 27760d4d2d2SMike Kravetz if (!dst_pte) { 27860d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 27960d4d2d2SMike Kravetz goto out_unlock; 28060d4d2d2SMike Kravetz } 28160d4d2d2SMike Kravetz 28260d4d2d2SMike Kravetz err = -EEXIST; 28360d4d2d2SMike Kravetz dst_pteval = huge_ptep_get(dst_pte); 28460d4d2d2SMike Kravetz if (!huge_pte_none(dst_pteval)) { 28560d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 28660d4d2d2SMike Kravetz goto out_unlock; 28760d4d2d2SMike Kravetz } 28860d4d2d2SMike Kravetz 28960d4d2d2SMike Kravetz err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, 29060d4d2d2SMike Kravetz dst_addr, src_addr, &page); 29160d4d2d2SMike Kravetz 29260d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 2931c9e8defSMike Kravetz vm_alloc_shared = vm_shared; 29460d4d2d2SMike Kravetz 29560d4d2d2SMike Kravetz cond_resched(); 29660d4d2d2SMike Kravetz 2979e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 29860d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 29960d4d2d2SMike Kravetz BUG_ON(!page); 30060d4d2d2SMike Kravetz 30160d4d2d2SMike Kravetz err = copy_huge_page_from_user(page, 30260d4d2d2SMike Kravetz (const void __user *)src_addr, 303810a56b9SMike Kravetz pages_per_huge_page(h), true); 30460d4d2d2SMike Kravetz if (unlikely(err)) { 30560d4d2d2SMike Kravetz err = -EFAULT; 30660d4d2d2SMike Kravetz goto out; 30760d4d2d2SMike Kravetz } 30860d4d2d2SMike Kravetz down_read(&dst_mm->mmap_sem); 30960d4d2d2SMike Kravetz 31060d4d2d2SMike Kravetz dst_vma = NULL; 31160d4d2d2SMike Kravetz goto retry; 31260d4d2d2SMike Kravetz } else 31360d4d2d2SMike Kravetz BUG_ON(page); 31460d4d2d2SMike Kravetz 31560d4d2d2SMike Kravetz if (!err) { 31660d4d2d2SMike Kravetz dst_addr += vma_hpagesize; 31760d4d2d2SMike Kravetz src_addr += vma_hpagesize; 31860d4d2d2SMike Kravetz copied += vma_hpagesize; 31960d4d2d2SMike Kravetz 32060d4d2d2SMike Kravetz if (fatal_signal_pending(current)) 32160d4d2d2SMike Kravetz err = -EINTR; 32260d4d2d2SMike Kravetz } 32360d4d2d2SMike Kravetz if (err) 32460d4d2d2SMike Kravetz break; 32560d4d2d2SMike Kravetz } 32660d4d2d2SMike Kravetz 32760d4d2d2SMike Kravetz out_unlock: 32860d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 32960d4d2d2SMike Kravetz out: 33021205bf8SMike Kravetz if (page) { 33121205bf8SMike Kravetz /* 33221205bf8SMike Kravetz * We encountered an error and are about to free a newly 3331c9e8defSMike Kravetz * allocated huge page. 3341c9e8defSMike Kravetz * 3351c9e8defSMike Kravetz * Reservation handling is very subtle, and is different for 3361c9e8defSMike Kravetz * private and shared mappings. See the routine 3371c9e8defSMike Kravetz * restore_reserve_on_error for details. Unfortunately, we 3381c9e8defSMike Kravetz * can not call restore_reserve_on_error now as it would 3391c9e8defSMike Kravetz * require holding mmap_sem. 3401c9e8defSMike Kravetz * 3411c9e8defSMike Kravetz * If a reservation for the page existed in the reservation 3421c9e8defSMike Kravetz * map of a private mapping, the map was modified to indicate 3431c9e8defSMike Kravetz * the reservation was consumed when the page was allocated. 3441c9e8defSMike Kravetz * We clear the PagePrivate flag now so that the global 34521205bf8SMike Kravetz * reserve count will not be incremented in free_huge_page. 34621205bf8SMike Kravetz * The reservation map will still indicate the reservation 34721205bf8SMike Kravetz * was consumed and possibly prevent later page allocation. 3481c9e8defSMike Kravetz * This is better than leaking a global reservation. If no 3491c9e8defSMike Kravetz * reservation existed, it is still safe to clear PagePrivate 3501c9e8defSMike Kravetz * as no adjustments to reservation counts were made during 3511c9e8defSMike Kravetz * allocation. 3521c9e8defSMike Kravetz * 3531c9e8defSMike Kravetz * The reservation map for shared mappings indicates which 3541c9e8defSMike Kravetz * pages have reservations. When a huge page is allocated 3551c9e8defSMike Kravetz * for an address with a reservation, no change is made to 3561c9e8defSMike Kravetz * the reserve map. In this case PagePrivate will be set 3571c9e8defSMike Kravetz * to indicate that the global reservation count should be 3581c9e8defSMike Kravetz * incremented when the page is freed. This is the desired 3591c9e8defSMike Kravetz * behavior. However, when a huge page is allocated for an 3601c9e8defSMike Kravetz * address without a reservation a reservation entry is added 3611c9e8defSMike Kravetz * to the reservation map, and PagePrivate will not be set. 3621c9e8defSMike Kravetz * When the page is freed, the global reserve count will NOT 3631c9e8defSMike Kravetz * be incremented and it will appear as though we have leaked 3641c9e8defSMike Kravetz * reserved page. In this case, set PagePrivate so that the 3651c9e8defSMike Kravetz * global reserve count will be incremented to match the 3661c9e8defSMike Kravetz * reservation map entry which was created. 3671c9e8defSMike Kravetz * 3681c9e8defSMike Kravetz * Note that vm_alloc_shared is based on the flags of the vma 3691c9e8defSMike Kravetz * for which the page was originally allocated. dst_vma could 3701c9e8defSMike Kravetz * be different or NULL on error. 37121205bf8SMike Kravetz */ 3721c9e8defSMike Kravetz if (vm_alloc_shared) 3731c9e8defSMike Kravetz SetPagePrivate(page); 3741c9e8defSMike Kravetz else 37521205bf8SMike Kravetz ClearPagePrivate(page); 37660d4d2d2SMike Kravetz put_page(page); 37721205bf8SMike Kravetz } 37860d4d2d2SMike Kravetz BUG_ON(copied < 0); 37960d4d2d2SMike Kravetz BUG_ON(err > 0); 38060d4d2d2SMike Kravetz BUG_ON(!copied && !err); 38160d4d2d2SMike Kravetz return copied ? copied : err; 38260d4d2d2SMike Kravetz } 38360d4d2d2SMike Kravetz #else /* !CONFIG_HUGETLB_PAGE */ 38460d4d2d2SMike Kravetz /* fail at build time if gcc attempts to use this */ 38560d4d2d2SMike Kravetz extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 38660d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 38760d4d2d2SMike Kravetz unsigned long dst_start, 38860d4d2d2SMike Kravetz unsigned long src_start, 38960d4d2d2SMike Kravetz unsigned long len, 39060d4d2d2SMike Kravetz bool zeropage); 39160d4d2d2SMike Kravetz #endif /* CONFIG_HUGETLB_PAGE */ 39260d4d2d2SMike Kravetz 3933217d3c7SMike Rapoport static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, 3943217d3c7SMike Rapoport pmd_t *dst_pmd, 3953217d3c7SMike Rapoport struct vm_area_struct *dst_vma, 3963217d3c7SMike Rapoport unsigned long dst_addr, 3973217d3c7SMike Rapoport unsigned long src_addr, 3983217d3c7SMike Rapoport struct page **page, 3993217d3c7SMike Rapoport bool zeropage) 4003217d3c7SMike Rapoport { 4013217d3c7SMike Rapoport ssize_t err; 4023217d3c7SMike Rapoport 4035b51072eSAndrea Arcangeli /* 4045b51072eSAndrea Arcangeli * The normal page fault path for a shmem will invoke the 4055b51072eSAndrea Arcangeli * fault, fill the hole in the file and COW it right away. The 4065b51072eSAndrea Arcangeli * result generates plain anonymous memory. So when we are 4075b51072eSAndrea Arcangeli * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll 4085b51072eSAndrea Arcangeli * generate anonymous memory directly without actually filling 4095b51072eSAndrea Arcangeli * the hole. For the MAP_PRIVATE case the robustness check 4105b51072eSAndrea Arcangeli * only happens in the pagetable (to verify it's still none) 4115b51072eSAndrea Arcangeli * and not in the radix tree. 4125b51072eSAndrea Arcangeli */ 4135b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED)) { 4143217d3c7SMike Rapoport if (!zeropage) 4153217d3c7SMike Rapoport err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, 4163217d3c7SMike Rapoport dst_addr, src_addr, page); 4173217d3c7SMike Rapoport else 4183217d3c7SMike Rapoport err = mfill_zeropage_pte(dst_mm, dst_pmd, 4193217d3c7SMike Rapoport dst_vma, dst_addr); 4203217d3c7SMike Rapoport } else { 4218fb44e54SMike Rapoport if (!zeropage) 4223217d3c7SMike Rapoport err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, 4233217d3c7SMike Rapoport dst_vma, dst_addr, 4243217d3c7SMike Rapoport src_addr, page); 4258fb44e54SMike Rapoport else 4268fb44e54SMike Rapoport err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, 4278fb44e54SMike Rapoport dst_vma, dst_addr); 4283217d3c7SMike Rapoport } 4293217d3c7SMike Rapoport 4303217d3c7SMike Rapoport return err; 4313217d3c7SMike Rapoport } 4323217d3c7SMike Rapoport 433c1a4de99SAndrea Arcangeli static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, 434c1a4de99SAndrea Arcangeli unsigned long dst_start, 435c1a4de99SAndrea Arcangeli unsigned long src_start, 436c1a4de99SAndrea Arcangeli unsigned long len, 437df2cc96eSMike Rapoport bool zeropage, 438df2cc96eSMike Rapoport bool *mmap_changing) 439c1a4de99SAndrea Arcangeli { 440c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma; 441c1a4de99SAndrea Arcangeli ssize_t err; 442c1a4de99SAndrea Arcangeli pmd_t *dst_pmd; 443c1a4de99SAndrea Arcangeli unsigned long src_addr, dst_addr; 444b6ebaedbSAndrea Arcangeli long copied; 445b6ebaedbSAndrea Arcangeli struct page *page; 446c1a4de99SAndrea Arcangeli 447c1a4de99SAndrea Arcangeli /* 448c1a4de99SAndrea Arcangeli * Sanitize the command parameters: 449c1a4de99SAndrea Arcangeli */ 450c1a4de99SAndrea Arcangeli BUG_ON(dst_start & ~PAGE_MASK); 451c1a4de99SAndrea Arcangeli BUG_ON(len & ~PAGE_MASK); 452c1a4de99SAndrea Arcangeli 453c1a4de99SAndrea Arcangeli /* Does the address range wrap, or is the span zero-sized? */ 454c1a4de99SAndrea Arcangeli BUG_ON(src_start + len <= src_start); 455c1a4de99SAndrea Arcangeli BUG_ON(dst_start + len <= dst_start); 456c1a4de99SAndrea Arcangeli 457b6ebaedbSAndrea Arcangeli src_addr = src_start; 458b6ebaedbSAndrea Arcangeli dst_addr = dst_start; 459b6ebaedbSAndrea Arcangeli copied = 0; 460b6ebaedbSAndrea Arcangeli page = NULL; 461b6ebaedbSAndrea Arcangeli retry: 462c1a4de99SAndrea Arcangeli down_read(&dst_mm->mmap_sem); 463c1a4de99SAndrea Arcangeli 464c1a4de99SAndrea Arcangeli /* 465df2cc96eSMike Rapoport * If memory mappings are changing because of non-cooperative 466df2cc96eSMike Rapoport * operation (e.g. mremap) running in parallel, bail out and 467df2cc96eSMike Rapoport * request the user to retry later 468df2cc96eSMike Rapoport */ 469df2cc96eSMike Rapoport err = -EAGAIN; 470df2cc96eSMike Rapoport if (mmap_changing && READ_ONCE(*mmap_changing)) 471df2cc96eSMike Rapoport goto out_unlock; 472df2cc96eSMike Rapoport 473df2cc96eSMike Rapoport /* 474c1a4de99SAndrea Arcangeli * Make sure the vma is not shared, that the dst range is 475c1a4de99SAndrea Arcangeli * both valid and fully within a single existing vma. 476c1a4de99SAndrea Arcangeli */ 47727d02568SMike Rapoport err = -ENOENT; 478c1a4de99SAndrea Arcangeli dst_vma = find_vma(dst_mm, dst_start); 47926071cedSMike Rapoport if (!dst_vma) 48026071cedSMike Rapoport goto out_unlock; 4811c9e8defSMike Kravetz /* 48229ec9066SAndrea Arcangeli * Check the vma is registered in uffd, this is required to 48329ec9066SAndrea Arcangeli * enforce the VM_MAYWRITE check done at uffd registration 48429ec9066SAndrea Arcangeli * time. 485c1a4de99SAndrea Arcangeli */ 486c1a4de99SAndrea Arcangeli if (!dst_vma->vm_userfaultfd_ctx.ctx) 487b6ebaedbSAndrea Arcangeli goto out_unlock; 488c1a4de99SAndrea Arcangeli 48927d02568SMike Rapoport if (dst_start < dst_vma->vm_start || 49027d02568SMike Rapoport dst_start + len > dst_vma->vm_end) 49127d02568SMike Rapoport goto out_unlock; 49227d02568SMike Rapoport 49327d02568SMike Rapoport err = -EINVAL; 49427d02568SMike Rapoport /* 49527d02568SMike Rapoport * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but 49627d02568SMike Rapoport * it will overwrite vm_ops, so vma_is_anonymous must return false. 49727d02568SMike Rapoport */ 49827d02568SMike Rapoport if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && 49927d02568SMike Rapoport dst_vma->vm_flags & VM_SHARED)) 50027d02568SMike Rapoport goto out_unlock; 50127d02568SMike Rapoport 50227d02568SMike Rapoport /* 50327d02568SMike Rapoport * If this is a HUGETLB vma, pass off to appropriate routine 50427d02568SMike Rapoport */ 50527d02568SMike Rapoport if (is_vm_hugetlb_page(dst_vma)) 50627d02568SMike Rapoport return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, 50727d02568SMike Rapoport src_start, len, zeropage); 50827d02568SMike Rapoport 50926071cedSMike Rapoport if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) 510b6ebaedbSAndrea Arcangeli goto out_unlock; 511c1a4de99SAndrea Arcangeli 512c1a4de99SAndrea Arcangeli /* 513c1a4de99SAndrea Arcangeli * Ensure the dst_vma has a anon_vma or this page 514c1a4de99SAndrea Arcangeli * would get a NULL anon_vma when moved in the 515c1a4de99SAndrea Arcangeli * dst_vma. 516c1a4de99SAndrea Arcangeli */ 517c1a4de99SAndrea Arcangeli err = -ENOMEM; 5185b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED) && 5195b51072eSAndrea Arcangeli unlikely(anon_vma_prepare(dst_vma))) 520b6ebaedbSAndrea Arcangeli goto out_unlock; 521c1a4de99SAndrea Arcangeli 522b6ebaedbSAndrea Arcangeli while (src_addr < src_start + len) { 523c1a4de99SAndrea Arcangeli pmd_t dst_pmdval; 524b6ebaedbSAndrea Arcangeli 525c1a4de99SAndrea Arcangeli BUG_ON(dst_addr >= dst_start + len); 526b6ebaedbSAndrea Arcangeli 527c1a4de99SAndrea Arcangeli dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); 528c1a4de99SAndrea Arcangeli if (unlikely(!dst_pmd)) { 529c1a4de99SAndrea Arcangeli err = -ENOMEM; 530c1a4de99SAndrea Arcangeli break; 531c1a4de99SAndrea Arcangeli } 532c1a4de99SAndrea Arcangeli 533c1a4de99SAndrea Arcangeli dst_pmdval = pmd_read_atomic(dst_pmd); 534c1a4de99SAndrea Arcangeli /* 535c1a4de99SAndrea Arcangeli * If the dst_pmd is mapped as THP don't 536c1a4de99SAndrea Arcangeli * override it and just be strict. 537c1a4de99SAndrea Arcangeli */ 538c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(dst_pmdval))) { 539c1a4de99SAndrea Arcangeli err = -EEXIST; 540c1a4de99SAndrea Arcangeli break; 541c1a4de99SAndrea Arcangeli } 542c1a4de99SAndrea Arcangeli if (unlikely(pmd_none(dst_pmdval)) && 5434cf58924SJoel Fernandes (Google) unlikely(__pte_alloc(dst_mm, dst_pmd))) { 544c1a4de99SAndrea Arcangeli err = -ENOMEM; 545c1a4de99SAndrea Arcangeli break; 546c1a4de99SAndrea Arcangeli } 547c1a4de99SAndrea Arcangeli /* If an huge pmd materialized from under us fail */ 548c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(*dst_pmd))) { 549c1a4de99SAndrea Arcangeli err = -EFAULT; 550c1a4de99SAndrea Arcangeli break; 551c1a4de99SAndrea Arcangeli } 552c1a4de99SAndrea Arcangeli 553c1a4de99SAndrea Arcangeli BUG_ON(pmd_none(*dst_pmd)); 554c1a4de99SAndrea Arcangeli BUG_ON(pmd_trans_huge(*dst_pmd)); 555c1a4de99SAndrea Arcangeli 5563217d3c7SMike Rapoport err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 5573217d3c7SMike Rapoport src_addr, &page, zeropage); 558c1a4de99SAndrea Arcangeli cond_resched(); 559c1a4de99SAndrea Arcangeli 5609e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 561b6ebaedbSAndrea Arcangeli void *page_kaddr; 562b6ebaedbSAndrea Arcangeli 563b6ebaedbSAndrea Arcangeli up_read(&dst_mm->mmap_sem); 564b6ebaedbSAndrea Arcangeli BUG_ON(!page); 565b6ebaedbSAndrea Arcangeli 566b6ebaedbSAndrea Arcangeli page_kaddr = kmap(page); 567b6ebaedbSAndrea Arcangeli err = copy_from_user(page_kaddr, 568b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 569b6ebaedbSAndrea Arcangeli PAGE_SIZE); 570b6ebaedbSAndrea Arcangeli kunmap(page); 571b6ebaedbSAndrea Arcangeli if (unlikely(err)) { 572b6ebaedbSAndrea Arcangeli err = -EFAULT; 573b6ebaedbSAndrea Arcangeli goto out; 574b6ebaedbSAndrea Arcangeli } 575b6ebaedbSAndrea Arcangeli goto retry; 576b6ebaedbSAndrea Arcangeli } else 577b6ebaedbSAndrea Arcangeli BUG_ON(page); 578b6ebaedbSAndrea Arcangeli 579c1a4de99SAndrea Arcangeli if (!err) { 580c1a4de99SAndrea Arcangeli dst_addr += PAGE_SIZE; 581c1a4de99SAndrea Arcangeli src_addr += PAGE_SIZE; 582c1a4de99SAndrea Arcangeli copied += PAGE_SIZE; 583c1a4de99SAndrea Arcangeli 584c1a4de99SAndrea Arcangeli if (fatal_signal_pending(current)) 585c1a4de99SAndrea Arcangeli err = -EINTR; 586c1a4de99SAndrea Arcangeli } 587c1a4de99SAndrea Arcangeli if (err) 588c1a4de99SAndrea Arcangeli break; 589c1a4de99SAndrea Arcangeli } 590c1a4de99SAndrea Arcangeli 591b6ebaedbSAndrea Arcangeli out_unlock: 592c1a4de99SAndrea Arcangeli up_read(&dst_mm->mmap_sem); 593b6ebaedbSAndrea Arcangeli out: 594b6ebaedbSAndrea Arcangeli if (page) 59509cbfeafSKirill A. Shutemov put_page(page); 596c1a4de99SAndrea Arcangeli BUG_ON(copied < 0); 597c1a4de99SAndrea Arcangeli BUG_ON(err > 0); 598c1a4de99SAndrea Arcangeli BUG_ON(!copied && !err); 599c1a4de99SAndrea Arcangeli return copied ? copied : err; 600c1a4de99SAndrea Arcangeli } 601c1a4de99SAndrea Arcangeli 602c1a4de99SAndrea Arcangeli ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, 603df2cc96eSMike Rapoport unsigned long src_start, unsigned long len, 604df2cc96eSMike Rapoport bool *mmap_changing) 605c1a4de99SAndrea Arcangeli { 606df2cc96eSMike Rapoport return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, 607df2cc96eSMike Rapoport mmap_changing); 608c1a4de99SAndrea Arcangeli } 609c1a4de99SAndrea Arcangeli 610c1a4de99SAndrea Arcangeli ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, 611df2cc96eSMike Rapoport unsigned long len, bool *mmap_changing) 612c1a4de99SAndrea Arcangeli { 613df2cc96eSMike Rapoport return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing); 614c1a4de99SAndrea Arcangeli } 615