120c8ccb1SThomas 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> 194a18419fSNadav Amit #include <asm/tlb.h> 20c1a4de99SAndrea Arcangeli #include "internal.h" 21c1a4de99SAndrea Arcangeli 22643aa36eSWei Yang static __always_inline 23643aa36eSWei Yang struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, 24643aa36eSWei Yang unsigned long dst_start, 25643aa36eSWei Yang unsigned long len) 26643aa36eSWei Yang { 27643aa36eSWei Yang /* 28643aa36eSWei Yang * Make sure that the dst range is both valid and fully within a 29643aa36eSWei Yang * single existing vma. 30643aa36eSWei Yang */ 31643aa36eSWei Yang struct vm_area_struct *dst_vma; 32643aa36eSWei Yang 33643aa36eSWei Yang dst_vma = find_vma(dst_mm, dst_start); 34643aa36eSWei Yang if (!dst_vma) 35643aa36eSWei Yang return NULL; 36643aa36eSWei Yang 37643aa36eSWei Yang if (dst_start < dst_vma->vm_start || 38643aa36eSWei Yang dst_start + len > dst_vma->vm_end) 39643aa36eSWei Yang return NULL; 40643aa36eSWei Yang 41643aa36eSWei Yang /* 42643aa36eSWei Yang * Check the vma is registered in uffd, this is required to 43643aa36eSWei Yang * enforce the VM_MAYWRITE check done at uffd registration 44643aa36eSWei Yang * time. 45643aa36eSWei Yang */ 46643aa36eSWei Yang if (!dst_vma->vm_userfaultfd_ctx.ctx) 47643aa36eSWei Yang return NULL; 48643aa36eSWei Yang 49643aa36eSWei Yang return dst_vma; 50643aa36eSWei Yang } 51643aa36eSWei Yang 5215313257SAxel Rasmussen /* 5315313257SAxel Rasmussen * Install PTEs, to map dst_addr (within dst_vma) to page. 5415313257SAxel Rasmussen * 557d64ae3aSAxel Rasmussen * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem 567d64ae3aSAxel Rasmussen * and anon, and for both shared and private VMAs. 5715313257SAxel Rasmussen */ 587d64ae3aSAxel Rasmussen int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, 5915313257SAxel Rasmussen struct vm_area_struct *dst_vma, 6015313257SAxel Rasmussen unsigned long dst_addr, struct page *page, 6115313257SAxel Rasmussen bool newly_allocated, bool wp_copy) 6215313257SAxel Rasmussen { 6315313257SAxel Rasmussen int ret; 6415313257SAxel Rasmussen pte_t _dst_pte, *dst_pte; 6515313257SAxel Rasmussen bool writable = dst_vma->vm_flags & VM_WRITE; 6615313257SAxel Rasmussen bool vm_shared = dst_vma->vm_flags & VM_SHARED; 6793b0d917SPeter Xu bool page_in_cache = page_mapping(page); 6815313257SAxel Rasmussen spinlock_t *ptl; 69*28965f0fSVishal Moola (Oracle) struct folio *folio; 7015313257SAxel Rasmussen struct inode *inode; 7115313257SAxel Rasmussen pgoff_t offset, max_off; 7215313257SAxel Rasmussen 7315313257SAxel Rasmussen _dst_pte = mk_pte(page, dst_vma->vm_page_prot); 749ae0f87dSPeter Xu _dst_pte = pte_mkdirty(_dst_pte); 7515313257SAxel Rasmussen if (page_in_cache && !vm_shared) 7615313257SAxel Rasmussen writable = false; 770e88904cSNadav Amit 780e88904cSNadav Amit /* 790e88904cSNadav Amit * Always mark a PTE as write-protected when needed, regardless of 800e88904cSNadav Amit * VM_WRITE, which the user might change. 810e88904cSNadav Amit */ 828ee79edfSPeter Xu if (wp_copy) { 8315313257SAxel Rasmussen _dst_pte = pte_mkuffd_wp(_dst_pte); 848ee79edfSPeter Xu writable = false; 858ee79edfSPeter Xu } 868ee79edfSPeter Xu 878ee79edfSPeter Xu if (writable) 8815313257SAxel Rasmussen _dst_pte = pte_mkwrite(_dst_pte); 898ee79edfSPeter Xu else 908ee79edfSPeter Xu /* 918ee79edfSPeter Xu * We need this to make sure write bit removed; as mk_pte() 928ee79edfSPeter Xu * could return a pte with write bit set. 938ee79edfSPeter Xu */ 948ee79edfSPeter Xu _dst_pte = pte_wrprotect(_dst_pte); 9515313257SAxel Rasmussen 9615313257SAxel Rasmussen dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 9715313257SAxel Rasmussen 9815313257SAxel Rasmussen if (vma_is_shmem(dst_vma)) { 9915313257SAxel Rasmussen /* serialize against truncate with the page table lock */ 10015313257SAxel Rasmussen inode = dst_vma->vm_file->f_inode; 10115313257SAxel Rasmussen offset = linear_page_index(dst_vma, dst_addr); 10215313257SAxel Rasmussen max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 10315313257SAxel Rasmussen ret = -EFAULT; 10415313257SAxel Rasmussen if (unlikely(offset >= max_off)) 10515313257SAxel Rasmussen goto out_unlock; 10615313257SAxel Rasmussen } 10715313257SAxel Rasmussen 10815313257SAxel Rasmussen ret = -EEXIST; 1098ee79edfSPeter Xu /* 1108ee79edfSPeter Xu * We allow to overwrite a pte marker: consider when both MISSING|WP 1118ee79edfSPeter Xu * registered, we firstly wr-protect a none pte which has no page cache 1128ee79edfSPeter Xu * page backing it, then access the page. 1138ee79edfSPeter Xu */ 1148ee79edfSPeter Xu if (!pte_none_mostly(*dst_pte)) 11515313257SAxel Rasmussen goto out_unlock; 11615313257SAxel Rasmussen 117*28965f0fSVishal Moola (Oracle) folio = page_folio(page); 118cea86fe2SHugh Dickins if (page_in_cache) { 119cea86fe2SHugh Dickins /* Usually, cache pages are already added to LRU */ 120cea86fe2SHugh Dickins if (newly_allocated) 121*28965f0fSVishal Moola (Oracle) folio_add_lru(folio); 122cea86fe2SHugh Dickins page_add_file_rmap(page, dst_vma, false); 123cea86fe2SHugh Dickins } else { 12440f2bbf7SDavid Hildenbrand page_add_new_anon_rmap(page, dst_vma, dst_addr); 125*28965f0fSVishal Moola (Oracle) folio_add_lru_vma(folio, dst_vma); 126cea86fe2SHugh Dickins } 12715313257SAxel Rasmussen 12815313257SAxel Rasmussen /* 12915313257SAxel Rasmussen * Must happen after rmap, as mm_counter() checks mapping (via 13015313257SAxel Rasmussen * PageAnon()), which is set by __page_set_anon_rmap(). 13115313257SAxel Rasmussen */ 13215313257SAxel Rasmussen inc_mm_counter(dst_mm, mm_counter(page)); 13315313257SAxel Rasmussen 13415313257SAxel Rasmussen set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 13515313257SAxel Rasmussen 13615313257SAxel Rasmussen /* No need to invalidate - it was non-present before */ 13715313257SAxel Rasmussen update_mmu_cache(dst_vma, dst_addr, dst_pte); 13815313257SAxel Rasmussen ret = 0; 13915313257SAxel Rasmussen out_unlock: 14015313257SAxel Rasmussen pte_unmap_unlock(dst_pte, ptl); 14115313257SAxel Rasmussen return ret; 14215313257SAxel Rasmussen } 14315313257SAxel Rasmussen 144c1a4de99SAndrea Arcangeli static int mcopy_atomic_pte(struct mm_struct *dst_mm, 145c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 146c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 147c1a4de99SAndrea Arcangeli unsigned long dst_addr, 148b6ebaedbSAndrea Arcangeli unsigned long src_addr, 14972981e0eSAndrea Arcangeli struct page **pagep, 15072981e0eSAndrea Arcangeli bool wp_copy) 151c1a4de99SAndrea Arcangeli { 152c1a4de99SAndrea Arcangeli void *page_kaddr; 153c1a4de99SAndrea Arcangeli int ret; 154b6ebaedbSAndrea Arcangeli struct page *page; 155c1a4de99SAndrea Arcangeli 156b6ebaedbSAndrea Arcangeli if (!*pagep) { 157c1a4de99SAndrea Arcangeli ret = -ENOMEM; 158c1a4de99SAndrea Arcangeli page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); 159c1a4de99SAndrea Arcangeli if (!page) 160c1a4de99SAndrea Arcangeli goto out; 161c1a4de99SAndrea Arcangeli 1625521de7dSIra Weiny page_kaddr = kmap_local_page(page); 1635521de7dSIra Weiny /* 1645521de7dSIra Weiny * The read mmap_lock is held here. Despite the 1655521de7dSIra Weiny * mmap_lock being read recursive a deadlock is still 1665521de7dSIra Weiny * possible if a writer has taken a lock. For example: 1675521de7dSIra Weiny * 1685521de7dSIra Weiny * process A thread 1 takes read lock on own mmap_lock 1695521de7dSIra Weiny * process A thread 2 calls mmap, blocks taking write lock 1705521de7dSIra Weiny * process B thread 1 takes page fault, read lock on own mmap lock 1715521de7dSIra Weiny * process B thread 2 calls mmap, blocks taking write lock 1725521de7dSIra Weiny * process A thread 1 blocks taking read lock on process B 1735521de7dSIra Weiny * process B thread 1 blocks taking read lock on process A 1745521de7dSIra Weiny * 1755521de7dSIra Weiny * Disable page faults to prevent potential deadlock 1765521de7dSIra Weiny * and retry the copy outside the mmap_lock. 1775521de7dSIra Weiny */ 1785521de7dSIra Weiny pagefault_disable(); 179b6ebaedbSAndrea Arcangeli ret = copy_from_user(page_kaddr, 180b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 181b6ebaedbSAndrea Arcangeli PAGE_SIZE); 1825521de7dSIra Weiny pagefault_enable(); 1835521de7dSIra Weiny kunmap_local(page_kaddr); 184b6ebaedbSAndrea Arcangeli 185c1e8d7c6SMichel Lespinasse /* fallback to copy_from_user outside mmap_lock */ 186b6ebaedbSAndrea Arcangeli if (unlikely(ret)) { 1879e368259SAndrea Arcangeli ret = -ENOENT; 188b6ebaedbSAndrea Arcangeli *pagep = page; 189b6ebaedbSAndrea Arcangeli /* don't free the page */ 190b6ebaedbSAndrea Arcangeli goto out; 191b6ebaedbSAndrea Arcangeli } 1927c25a0b8SMuchun Song 1937c25a0b8SMuchun Song flush_dcache_page(page); 194b6ebaedbSAndrea Arcangeli } else { 195b6ebaedbSAndrea Arcangeli page = *pagep; 196b6ebaedbSAndrea Arcangeli *pagep = NULL; 197b6ebaedbSAndrea Arcangeli } 198c1a4de99SAndrea Arcangeli 199c1a4de99SAndrea Arcangeli /* 200c1a4de99SAndrea Arcangeli * The memory barrier inside __SetPageUptodate makes sure that 201f4f5329dSWei Yang * preceding stores to the page contents become visible before 202c1a4de99SAndrea Arcangeli * the set_pte_at() write. 203c1a4de99SAndrea Arcangeli */ 204c1a4de99SAndrea Arcangeli __SetPageUptodate(page); 205c1a4de99SAndrea Arcangeli 206c1a4de99SAndrea Arcangeli ret = -ENOMEM; 2078f425e4eSMatthew Wilcox (Oracle) if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL)) 208c1a4de99SAndrea Arcangeli goto out_release; 209c1a4de99SAndrea Arcangeli 21015313257SAxel Rasmussen ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 21115313257SAxel Rasmussen page, true, wp_copy); 21215313257SAxel Rasmussen if (ret) 21315313257SAxel Rasmussen goto out_release; 214c1a4de99SAndrea Arcangeli out: 215c1a4de99SAndrea Arcangeli return ret; 216c1a4de99SAndrea Arcangeli out_release: 21709cbfeafSKirill A. Shutemov put_page(page); 218c1a4de99SAndrea Arcangeli goto out; 219c1a4de99SAndrea Arcangeli } 220c1a4de99SAndrea Arcangeli 221c1a4de99SAndrea Arcangeli static int mfill_zeropage_pte(struct mm_struct *dst_mm, 222c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 223c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 224c1a4de99SAndrea Arcangeli unsigned long dst_addr) 225c1a4de99SAndrea Arcangeli { 226c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 227c1a4de99SAndrea Arcangeli spinlock_t *ptl; 228c1a4de99SAndrea Arcangeli int ret; 229e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 230e2a50c1fSAndrea Arcangeli struct inode *inode; 231c1a4de99SAndrea Arcangeli 232c1a4de99SAndrea Arcangeli _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), 233c1a4de99SAndrea Arcangeli dst_vma->vm_page_prot)); 234c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 235e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 236e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 237e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 238e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 239e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 240e2a50c1fSAndrea Arcangeli ret = -EFAULT; 241e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 242e2a50c1fSAndrea Arcangeli goto out_unlock; 243e2a50c1fSAndrea Arcangeli } 244e2a50c1fSAndrea Arcangeli ret = -EEXIST; 245c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 246c1a4de99SAndrea Arcangeli goto out_unlock; 247c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 248c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 249c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 250c1a4de99SAndrea Arcangeli ret = 0; 251c1a4de99SAndrea Arcangeli out_unlock: 252c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 253c1a4de99SAndrea Arcangeli return ret; 254c1a4de99SAndrea Arcangeli } 255c1a4de99SAndrea Arcangeli 25615313257SAxel Rasmussen /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */ 25715313257SAxel Rasmussen static int mcontinue_atomic_pte(struct mm_struct *dst_mm, 25815313257SAxel Rasmussen pmd_t *dst_pmd, 25915313257SAxel Rasmussen struct vm_area_struct *dst_vma, 26015313257SAxel Rasmussen unsigned long dst_addr, 26115313257SAxel Rasmussen bool wp_copy) 26215313257SAxel Rasmussen { 26315313257SAxel Rasmussen struct inode *inode = file_inode(dst_vma->vm_file); 26415313257SAxel Rasmussen pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); 26512acf4fbSMatthew Wilcox (Oracle) struct folio *folio; 26615313257SAxel Rasmussen struct page *page; 26715313257SAxel Rasmussen int ret; 26815313257SAxel Rasmussen 26912acf4fbSMatthew Wilcox (Oracle) ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); 27012acf4fbSMatthew Wilcox (Oracle) /* Our caller expects us to return -EFAULT if we failed to find folio */ 27173f37dbcSAxel Rasmussen if (ret == -ENOENT) 27273f37dbcSAxel Rasmussen ret = -EFAULT; 27315313257SAxel Rasmussen if (ret) 27415313257SAxel Rasmussen goto out; 27512acf4fbSMatthew Wilcox (Oracle) if (!folio) { 27615313257SAxel Rasmussen ret = -EFAULT; 27715313257SAxel Rasmussen goto out; 27815313257SAxel Rasmussen } 27915313257SAxel Rasmussen 28012acf4fbSMatthew Wilcox (Oracle) page = folio_file_page(folio, pgoff); 281a7605426SYang Shi if (PageHWPoison(page)) { 282a7605426SYang Shi ret = -EIO; 283a7605426SYang Shi goto out_release; 284a7605426SYang Shi } 285a7605426SYang Shi 28615313257SAxel Rasmussen ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 28715313257SAxel Rasmussen page, false, wp_copy); 28815313257SAxel Rasmussen if (ret) 28915313257SAxel Rasmussen goto out_release; 29015313257SAxel Rasmussen 29112acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 29215313257SAxel Rasmussen ret = 0; 29315313257SAxel Rasmussen out: 29415313257SAxel Rasmussen return ret; 29515313257SAxel Rasmussen out_release: 29612acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 29712acf4fbSMatthew Wilcox (Oracle) folio_put(folio); 29815313257SAxel Rasmussen goto out; 29915313257SAxel Rasmussen } 30015313257SAxel Rasmussen 301c1a4de99SAndrea Arcangeli static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) 302c1a4de99SAndrea Arcangeli { 303c1a4de99SAndrea Arcangeli pgd_t *pgd; 304c2febafcSKirill A. Shutemov p4d_t *p4d; 305c1a4de99SAndrea Arcangeli pud_t *pud; 306c1a4de99SAndrea Arcangeli 307c1a4de99SAndrea Arcangeli pgd = pgd_offset(mm, address); 308c2febafcSKirill A. Shutemov p4d = p4d_alloc(mm, pgd, address); 309c2febafcSKirill A. Shutemov if (!p4d) 310c2febafcSKirill A. Shutemov return NULL; 311c2febafcSKirill A. Shutemov pud = pud_alloc(mm, p4d, address); 312c2febafcSKirill A. Shutemov if (!pud) 313c2febafcSKirill A. Shutemov return NULL; 314c1a4de99SAndrea Arcangeli /* 315c1a4de99SAndrea Arcangeli * Note that we didn't run this because the pmd was 316c1a4de99SAndrea Arcangeli * missing, the *pmd may be already established and in 317c1a4de99SAndrea Arcangeli * turn it may also be a trans_huge_pmd. 318c1a4de99SAndrea Arcangeli */ 319c2febafcSKirill A. Shutemov return pmd_alloc(mm, pud, address); 320c1a4de99SAndrea Arcangeli } 321c1a4de99SAndrea Arcangeli 32260d4d2d2SMike Kravetz #ifdef CONFIG_HUGETLB_PAGE 32360d4d2d2SMike Kravetz /* 32460d4d2d2SMike Kravetz * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is 325c1e8d7c6SMichel Lespinasse * called with mmap_lock held, it will release mmap_lock before returning. 32660d4d2d2SMike Kravetz */ 32760d4d2d2SMike Kravetz static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 32860d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 32960d4d2d2SMike Kravetz unsigned long dst_start, 33060d4d2d2SMike Kravetz unsigned long src_start, 33160d4d2d2SMike Kravetz unsigned long len, 3326041c691SPeter Xu enum mcopy_atomic_mode mode, 3336041c691SPeter Xu bool wp_copy) 33460d4d2d2SMike Kravetz { 3351c9e8defSMike Kravetz int vm_shared = dst_vma->vm_flags & VM_SHARED; 33660d4d2d2SMike Kravetz ssize_t err; 33760d4d2d2SMike Kravetz pte_t *dst_pte; 33860d4d2d2SMike Kravetz unsigned long src_addr, dst_addr; 33960d4d2d2SMike Kravetz long copied; 34060d4d2d2SMike Kravetz struct page *page; 34160d4d2d2SMike Kravetz unsigned long vma_hpagesize; 34260d4d2d2SMike Kravetz pgoff_t idx; 34360d4d2d2SMike Kravetz u32 hash; 34460d4d2d2SMike Kravetz struct address_space *mapping; 34560d4d2d2SMike Kravetz 34660d4d2d2SMike Kravetz /* 34760d4d2d2SMike Kravetz * There is no default zero huge page for all huge page sizes as 34860d4d2d2SMike Kravetz * supported by hugetlb. A PMD_SIZE huge pages may exist as used 34960d4d2d2SMike Kravetz * by THP. Since we can not reliably insert a zero page, this 35060d4d2d2SMike Kravetz * feature is not supported. 35160d4d2d2SMike Kravetz */ 352f6191471SAxel Rasmussen if (mode == MCOPY_ATOMIC_ZEROPAGE) { 353d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 35460d4d2d2SMike Kravetz return -EINVAL; 35560d4d2d2SMike Kravetz } 35660d4d2d2SMike Kravetz 35760d4d2d2SMike Kravetz src_addr = src_start; 35860d4d2d2SMike Kravetz dst_addr = dst_start; 35960d4d2d2SMike Kravetz copied = 0; 36060d4d2d2SMike Kravetz page = NULL; 36160d4d2d2SMike Kravetz vma_hpagesize = vma_kernel_pagesize(dst_vma); 36260d4d2d2SMike Kravetz 36360d4d2d2SMike Kravetz /* 36460d4d2d2SMike Kravetz * Validate alignment based on huge page size 36560d4d2d2SMike Kravetz */ 36660d4d2d2SMike Kravetz err = -EINVAL; 36760d4d2d2SMike Kravetz if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) 36860d4d2d2SMike Kravetz goto out_unlock; 36960d4d2d2SMike Kravetz 37060d4d2d2SMike Kravetz retry: 37160d4d2d2SMike Kravetz /* 372c1e8d7c6SMichel Lespinasse * On routine entry dst_vma is set. If we had to drop mmap_lock and 37360d4d2d2SMike Kravetz * retry, dst_vma will be set to NULL and we must lookup again. 37460d4d2d2SMike Kravetz */ 37560d4d2d2SMike Kravetz if (!dst_vma) { 37627d02568SMike Rapoport err = -ENOENT; 377643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 37860d4d2d2SMike Kravetz if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) 37960d4d2d2SMike Kravetz goto out_unlock; 3801c9e8defSMike Kravetz 38127d02568SMike Rapoport err = -EINVAL; 38227d02568SMike Rapoport if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) 38327d02568SMike Rapoport goto out_unlock; 38427d02568SMike Rapoport 3851c9e8defSMike Kravetz vm_shared = dst_vma->vm_flags & VM_SHARED; 38660d4d2d2SMike Kravetz } 38760d4d2d2SMike Kravetz 38860d4d2d2SMike Kravetz /* 3891c9e8defSMike Kravetz * If not shared, ensure the dst_vma has a anon_vma. 39060d4d2d2SMike Kravetz */ 39160d4d2d2SMike Kravetz err = -ENOMEM; 3921c9e8defSMike Kravetz if (!vm_shared) { 39360d4d2d2SMike Kravetz if (unlikely(anon_vma_prepare(dst_vma))) 39460d4d2d2SMike Kravetz goto out_unlock; 3951c9e8defSMike Kravetz } 39660d4d2d2SMike Kravetz 39760d4d2d2SMike Kravetz while (src_addr < src_start + len) { 39860d4d2d2SMike Kravetz BUG_ON(dst_addr >= dst_start + len); 39960d4d2d2SMike Kravetz 40060d4d2d2SMike Kravetz /* 40140549ba8SMike Kravetz * Serialize via vma_lock and hugetlb_fault_mutex. 40240549ba8SMike Kravetz * vma_lock ensures the dst_pte remains valid even 40340549ba8SMike Kravetz * in the case of shared pmds. fault mutex prevents 40440549ba8SMike Kravetz * races with other faulting threads. 40560d4d2d2SMike Kravetz */ 406c0d0381aSMike Kravetz idx = linear_page_index(dst_vma, dst_addr); 4073a47c54fSMike Kravetz mapping = dst_vma->vm_file->f_mapping; 408188b04a7SWei Yang hash = hugetlb_fault_mutex_hash(mapping, idx); 40960d4d2d2SMike Kravetz mutex_lock(&hugetlb_fault_mutex_table[hash]); 41040549ba8SMike Kravetz hugetlb_vma_lock_read(dst_vma); 41160d4d2d2SMike Kravetz 41260d4d2d2SMike Kravetz err = -ENOMEM; 413aec44e0fSPeter Xu dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); 41460d4d2d2SMike Kravetz if (!dst_pte) { 41540549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 41660d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 41760d4d2d2SMike Kravetz goto out_unlock; 41860d4d2d2SMike Kravetz } 41960d4d2d2SMike Kravetz 420f6191471SAxel Rasmussen if (mode != MCOPY_ATOMIC_CONTINUE && 4216041c691SPeter Xu !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { 42260d4d2d2SMike Kravetz err = -EEXIST; 42340549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 42460d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 42560d4d2d2SMike Kravetz goto out_unlock; 42660d4d2d2SMike Kravetz } 42760d4d2d2SMike Kravetz 42860d4d2d2SMike Kravetz err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, 4296041c691SPeter Xu dst_addr, src_addr, mode, &page, 4306041c691SPeter Xu wp_copy); 43160d4d2d2SMike Kravetz 43240549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 43360d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 43460d4d2d2SMike Kravetz 43560d4d2d2SMike Kravetz cond_resched(); 43660d4d2d2SMike Kravetz 4379e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 438d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 43960d4d2d2SMike Kravetz BUG_ON(!page); 44060d4d2d2SMike Kravetz 44160d4d2d2SMike Kravetz err = copy_huge_page_from_user(page, 44260d4d2d2SMike Kravetz (const void __user *)src_addr, 4434fb07ee6SWei Yang vma_hpagesize / PAGE_SIZE, 4444fb07ee6SWei Yang true); 44560d4d2d2SMike Kravetz if (unlikely(err)) { 44660d4d2d2SMike Kravetz err = -EFAULT; 44760d4d2d2SMike Kravetz goto out; 44860d4d2d2SMike Kravetz } 449d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 45060d4d2d2SMike Kravetz 45160d4d2d2SMike Kravetz dst_vma = NULL; 45260d4d2d2SMike Kravetz goto retry; 45360d4d2d2SMike Kravetz } else 45460d4d2d2SMike Kravetz BUG_ON(page); 45560d4d2d2SMike Kravetz 45660d4d2d2SMike Kravetz if (!err) { 45760d4d2d2SMike Kravetz dst_addr += vma_hpagesize; 45860d4d2d2SMike Kravetz src_addr += vma_hpagesize; 45960d4d2d2SMike Kravetz copied += vma_hpagesize; 46060d4d2d2SMike Kravetz 46160d4d2d2SMike Kravetz if (fatal_signal_pending(current)) 46260d4d2d2SMike Kravetz err = -EINTR; 46360d4d2d2SMike Kravetz } 46460d4d2d2SMike Kravetz if (err) 46560d4d2d2SMike Kravetz break; 46660d4d2d2SMike Kravetz } 46760d4d2d2SMike Kravetz 46860d4d2d2SMike Kravetz out_unlock: 469d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 47060d4d2d2SMike Kravetz out: 4718cc5fcbbSMina Almasry if (page) 47260d4d2d2SMike Kravetz put_page(page); 47360d4d2d2SMike Kravetz BUG_ON(copied < 0); 47460d4d2d2SMike Kravetz BUG_ON(err > 0); 47560d4d2d2SMike Kravetz BUG_ON(!copied && !err); 47660d4d2d2SMike Kravetz return copied ? copied : err; 47760d4d2d2SMike Kravetz } 47860d4d2d2SMike Kravetz #else /* !CONFIG_HUGETLB_PAGE */ 47960d4d2d2SMike Kravetz /* fail at build time if gcc attempts to use this */ 48060d4d2d2SMike Kravetz extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 48160d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 48260d4d2d2SMike Kravetz unsigned long dst_start, 48360d4d2d2SMike Kravetz unsigned long src_start, 48460d4d2d2SMike Kravetz unsigned long len, 4856041c691SPeter Xu enum mcopy_atomic_mode mode, 4866041c691SPeter Xu bool wp_copy); 48760d4d2d2SMike Kravetz #endif /* CONFIG_HUGETLB_PAGE */ 48860d4d2d2SMike Kravetz 4893217d3c7SMike Rapoport static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, 4903217d3c7SMike Rapoport pmd_t *dst_pmd, 4913217d3c7SMike Rapoport struct vm_area_struct *dst_vma, 4923217d3c7SMike Rapoport unsigned long dst_addr, 4933217d3c7SMike Rapoport unsigned long src_addr, 4943217d3c7SMike Rapoport struct page **page, 49515313257SAxel Rasmussen enum mcopy_atomic_mode mode, 49672981e0eSAndrea Arcangeli bool wp_copy) 4973217d3c7SMike Rapoport { 4983217d3c7SMike Rapoport ssize_t err; 4993217d3c7SMike Rapoport 50015313257SAxel Rasmussen if (mode == MCOPY_ATOMIC_CONTINUE) { 50115313257SAxel Rasmussen return mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 50215313257SAxel Rasmussen wp_copy); 50315313257SAxel Rasmussen } 50415313257SAxel Rasmussen 5055b51072eSAndrea Arcangeli /* 5065b51072eSAndrea Arcangeli * The normal page fault path for a shmem will invoke the 5075b51072eSAndrea Arcangeli * fault, fill the hole in the file and COW it right away. The 5085b51072eSAndrea Arcangeli * result generates plain anonymous memory. So when we are 5095b51072eSAndrea Arcangeli * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll 5105b51072eSAndrea Arcangeli * generate anonymous memory directly without actually filling 5115b51072eSAndrea Arcangeli * the hole. For the MAP_PRIVATE case the robustness check 5125b51072eSAndrea Arcangeli * only happens in the pagetable (to verify it's still none) 5135b51072eSAndrea Arcangeli * and not in the radix tree. 5145b51072eSAndrea Arcangeli */ 5155b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED)) { 51615313257SAxel Rasmussen if (mode == MCOPY_ATOMIC_NORMAL) 5173217d3c7SMike Rapoport err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, 51872981e0eSAndrea Arcangeli dst_addr, src_addr, page, 51972981e0eSAndrea Arcangeli wp_copy); 5203217d3c7SMike Rapoport else 5213217d3c7SMike Rapoport err = mfill_zeropage_pte(dst_mm, dst_pmd, 5223217d3c7SMike Rapoport dst_vma, dst_addr); 5233217d3c7SMike Rapoport } else { 5243460f6e5SAxel Rasmussen err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, 52515313257SAxel Rasmussen dst_addr, src_addr, 52615313257SAxel Rasmussen mode != MCOPY_ATOMIC_NORMAL, 5278ee79edfSPeter Xu wp_copy, page); 5283217d3c7SMike Rapoport } 5293217d3c7SMike Rapoport 5303217d3c7SMike Rapoport return err; 5313217d3c7SMike Rapoport } 5323217d3c7SMike Rapoport 533c1a4de99SAndrea Arcangeli static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, 534c1a4de99SAndrea Arcangeli unsigned long dst_start, 535c1a4de99SAndrea Arcangeli unsigned long src_start, 536c1a4de99SAndrea Arcangeli unsigned long len, 537f6191471SAxel Rasmussen enum mcopy_atomic_mode mcopy_mode, 538a759a909SNadav Amit atomic_t *mmap_changing, 53972981e0eSAndrea Arcangeli __u64 mode) 540c1a4de99SAndrea Arcangeli { 541c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma; 542c1a4de99SAndrea Arcangeli ssize_t err; 543c1a4de99SAndrea Arcangeli pmd_t *dst_pmd; 544c1a4de99SAndrea Arcangeli unsigned long src_addr, dst_addr; 545b6ebaedbSAndrea Arcangeli long copied; 546b6ebaedbSAndrea Arcangeli struct page *page; 54772981e0eSAndrea Arcangeli bool wp_copy; 548c1a4de99SAndrea Arcangeli 549c1a4de99SAndrea Arcangeli /* 550c1a4de99SAndrea Arcangeli * Sanitize the command parameters: 551c1a4de99SAndrea Arcangeli */ 552c1a4de99SAndrea Arcangeli BUG_ON(dst_start & ~PAGE_MASK); 553c1a4de99SAndrea Arcangeli BUG_ON(len & ~PAGE_MASK); 554c1a4de99SAndrea Arcangeli 555c1a4de99SAndrea Arcangeli /* Does the address range wrap, or is the span zero-sized? */ 556c1a4de99SAndrea Arcangeli BUG_ON(src_start + len <= src_start); 557c1a4de99SAndrea Arcangeli BUG_ON(dst_start + len <= dst_start); 558c1a4de99SAndrea Arcangeli 559b6ebaedbSAndrea Arcangeli src_addr = src_start; 560b6ebaedbSAndrea Arcangeli dst_addr = dst_start; 561b6ebaedbSAndrea Arcangeli copied = 0; 562b6ebaedbSAndrea Arcangeli page = NULL; 563b6ebaedbSAndrea Arcangeli retry: 564d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 565c1a4de99SAndrea Arcangeli 566c1a4de99SAndrea Arcangeli /* 567df2cc96eSMike Rapoport * If memory mappings are changing because of non-cooperative 568df2cc96eSMike Rapoport * operation (e.g. mremap) running in parallel, bail out and 569df2cc96eSMike Rapoport * request the user to retry later 570df2cc96eSMike Rapoport */ 571df2cc96eSMike Rapoport err = -EAGAIN; 572a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 573df2cc96eSMike Rapoport goto out_unlock; 574df2cc96eSMike Rapoport 575df2cc96eSMike Rapoport /* 576c1a4de99SAndrea Arcangeli * Make sure the vma is not shared, that the dst range is 577c1a4de99SAndrea Arcangeli * both valid and fully within a single existing vma. 578c1a4de99SAndrea Arcangeli */ 57927d02568SMike Rapoport err = -ENOENT; 580643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 58126071cedSMike Rapoport if (!dst_vma) 58226071cedSMike Rapoport goto out_unlock; 58327d02568SMike Rapoport 58427d02568SMike Rapoport err = -EINVAL; 58527d02568SMike Rapoport /* 58627d02568SMike Rapoport * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but 58727d02568SMike Rapoport * it will overwrite vm_ops, so vma_is_anonymous must return false. 58827d02568SMike Rapoport */ 58927d02568SMike Rapoport if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && 59027d02568SMike Rapoport dst_vma->vm_flags & VM_SHARED)) 59127d02568SMike Rapoport goto out_unlock; 59227d02568SMike Rapoport 59327d02568SMike Rapoport /* 59472981e0eSAndrea Arcangeli * validate 'mode' now that we know the dst_vma: don't allow 59572981e0eSAndrea Arcangeli * a wrprotect copy if the userfaultfd didn't register as WP. 59672981e0eSAndrea Arcangeli */ 59772981e0eSAndrea Arcangeli wp_copy = mode & UFFDIO_COPY_MODE_WP; 59872981e0eSAndrea Arcangeli if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) 59972981e0eSAndrea Arcangeli goto out_unlock; 60072981e0eSAndrea Arcangeli 60172981e0eSAndrea Arcangeli /* 60227d02568SMike Rapoport * If this is a HUGETLB vma, pass off to appropriate routine 60327d02568SMike Rapoport */ 60427d02568SMike Rapoport if (is_vm_hugetlb_page(dst_vma)) 60527d02568SMike Rapoport return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, 6066041c691SPeter Xu src_start, len, mcopy_mode, 6076041c691SPeter Xu wp_copy); 60827d02568SMike Rapoport 60926071cedSMike Rapoport if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) 610b6ebaedbSAndrea Arcangeli goto out_unlock; 61115313257SAxel Rasmussen if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) 612f6191471SAxel Rasmussen goto out_unlock; 613c1a4de99SAndrea Arcangeli 614c1a4de99SAndrea Arcangeli /* 615c1a4de99SAndrea Arcangeli * Ensure the dst_vma has a anon_vma or this page 616c1a4de99SAndrea Arcangeli * would get a NULL anon_vma when moved in the 617c1a4de99SAndrea Arcangeli * dst_vma. 618c1a4de99SAndrea Arcangeli */ 619c1a4de99SAndrea Arcangeli err = -ENOMEM; 6205b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED) && 6215b51072eSAndrea Arcangeli unlikely(anon_vma_prepare(dst_vma))) 622b6ebaedbSAndrea Arcangeli goto out_unlock; 623c1a4de99SAndrea Arcangeli 624b6ebaedbSAndrea Arcangeli while (src_addr < src_start + len) { 625c1a4de99SAndrea Arcangeli pmd_t dst_pmdval; 626b6ebaedbSAndrea Arcangeli 627c1a4de99SAndrea Arcangeli BUG_ON(dst_addr >= dst_start + len); 628b6ebaedbSAndrea Arcangeli 629c1a4de99SAndrea Arcangeli dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); 630c1a4de99SAndrea Arcangeli if (unlikely(!dst_pmd)) { 631c1a4de99SAndrea Arcangeli err = -ENOMEM; 632c1a4de99SAndrea Arcangeli break; 633c1a4de99SAndrea Arcangeli } 634c1a4de99SAndrea Arcangeli 635c1a4de99SAndrea Arcangeli dst_pmdval = pmd_read_atomic(dst_pmd); 636c1a4de99SAndrea Arcangeli /* 637c1a4de99SAndrea Arcangeli * If the dst_pmd is mapped as THP don't 638c1a4de99SAndrea Arcangeli * override it and just be strict. 639c1a4de99SAndrea Arcangeli */ 640c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(dst_pmdval))) { 641c1a4de99SAndrea Arcangeli err = -EEXIST; 642c1a4de99SAndrea Arcangeli break; 643c1a4de99SAndrea Arcangeli } 644c1a4de99SAndrea Arcangeli if (unlikely(pmd_none(dst_pmdval)) && 6454cf58924SJoel Fernandes (Google) unlikely(__pte_alloc(dst_mm, dst_pmd))) { 646c1a4de99SAndrea Arcangeli err = -ENOMEM; 647c1a4de99SAndrea Arcangeli break; 648c1a4de99SAndrea Arcangeli } 649c1a4de99SAndrea Arcangeli /* If an huge pmd materialized from under us fail */ 650c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(*dst_pmd))) { 651c1a4de99SAndrea Arcangeli err = -EFAULT; 652c1a4de99SAndrea Arcangeli break; 653c1a4de99SAndrea Arcangeli } 654c1a4de99SAndrea Arcangeli 655c1a4de99SAndrea Arcangeli BUG_ON(pmd_none(*dst_pmd)); 656c1a4de99SAndrea Arcangeli BUG_ON(pmd_trans_huge(*dst_pmd)); 657c1a4de99SAndrea Arcangeli 6583217d3c7SMike Rapoport err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 65915313257SAxel Rasmussen src_addr, &page, mcopy_mode, wp_copy); 660c1a4de99SAndrea Arcangeli cond_resched(); 661c1a4de99SAndrea Arcangeli 6629e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 663b6ebaedbSAndrea Arcangeli void *page_kaddr; 664b6ebaedbSAndrea Arcangeli 665d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 666b6ebaedbSAndrea Arcangeli BUG_ON(!page); 667b6ebaedbSAndrea Arcangeli 6685521de7dSIra Weiny page_kaddr = kmap_local_page(page); 669b6ebaedbSAndrea Arcangeli err = copy_from_user(page_kaddr, 670b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 671b6ebaedbSAndrea Arcangeli PAGE_SIZE); 6725521de7dSIra Weiny kunmap_local(page_kaddr); 673b6ebaedbSAndrea Arcangeli if (unlikely(err)) { 674b6ebaedbSAndrea Arcangeli err = -EFAULT; 675b6ebaedbSAndrea Arcangeli goto out; 676b6ebaedbSAndrea Arcangeli } 6777c25a0b8SMuchun Song flush_dcache_page(page); 678b6ebaedbSAndrea Arcangeli goto retry; 679b6ebaedbSAndrea Arcangeli } else 680b6ebaedbSAndrea Arcangeli BUG_ON(page); 681b6ebaedbSAndrea Arcangeli 682c1a4de99SAndrea Arcangeli if (!err) { 683c1a4de99SAndrea Arcangeli dst_addr += PAGE_SIZE; 684c1a4de99SAndrea Arcangeli src_addr += PAGE_SIZE; 685c1a4de99SAndrea Arcangeli copied += PAGE_SIZE; 686c1a4de99SAndrea Arcangeli 687c1a4de99SAndrea Arcangeli if (fatal_signal_pending(current)) 688c1a4de99SAndrea Arcangeli err = -EINTR; 689c1a4de99SAndrea Arcangeli } 690c1a4de99SAndrea Arcangeli if (err) 691c1a4de99SAndrea Arcangeli break; 692c1a4de99SAndrea Arcangeli } 693c1a4de99SAndrea Arcangeli 694b6ebaedbSAndrea Arcangeli out_unlock: 695d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 696b6ebaedbSAndrea Arcangeli out: 697b6ebaedbSAndrea Arcangeli if (page) 69809cbfeafSKirill A. Shutemov put_page(page); 699c1a4de99SAndrea Arcangeli BUG_ON(copied < 0); 700c1a4de99SAndrea Arcangeli BUG_ON(err > 0); 701c1a4de99SAndrea Arcangeli BUG_ON(!copied && !err); 702c1a4de99SAndrea Arcangeli return copied ? copied : err; 703c1a4de99SAndrea Arcangeli } 704c1a4de99SAndrea Arcangeli 705c1a4de99SAndrea Arcangeli ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, 706df2cc96eSMike Rapoport unsigned long src_start, unsigned long len, 707a759a909SNadav Amit atomic_t *mmap_changing, __u64 mode) 708c1a4de99SAndrea Arcangeli { 709f6191471SAxel Rasmussen return __mcopy_atomic(dst_mm, dst_start, src_start, len, 710f6191471SAxel Rasmussen MCOPY_ATOMIC_NORMAL, mmap_changing, mode); 711c1a4de99SAndrea Arcangeli } 712c1a4de99SAndrea Arcangeli 713c1a4de99SAndrea Arcangeli ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, 714a759a909SNadav Amit unsigned long len, atomic_t *mmap_changing) 715c1a4de99SAndrea Arcangeli { 716f6191471SAxel Rasmussen return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE, 717f6191471SAxel Rasmussen mmap_changing, 0); 718f6191471SAxel Rasmussen } 719f6191471SAxel Rasmussen 720f6191471SAxel Rasmussen ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long start, 721a759a909SNadav Amit unsigned long len, atomic_t *mmap_changing) 722f6191471SAxel Rasmussen { 723f6191471SAxel Rasmussen return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE, 724f6191471SAxel Rasmussen mmap_changing, 0); 725c1a4de99SAndrea Arcangeli } 726ffd05793SShaohua Li 727f369b07cSPeter Xu void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, 728f369b07cSPeter Xu unsigned long start, unsigned long len, bool enable_wp) 729f369b07cSPeter Xu { 730f369b07cSPeter Xu struct mmu_gather tlb; 731f369b07cSPeter Xu pgprot_t newprot; 732f369b07cSPeter Xu 733f369b07cSPeter Xu if (enable_wp) 734f369b07cSPeter Xu newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); 735f369b07cSPeter Xu else 736f369b07cSPeter Xu newprot = vm_get_page_prot(dst_vma->vm_flags); 737f369b07cSPeter Xu 738f369b07cSPeter Xu tlb_gather_mmu(&tlb, dst_mm); 739f369b07cSPeter Xu change_protection(&tlb, dst_vma, start, start + len, newprot, 740f369b07cSPeter Xu enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); 741f369b07cSPeter Xu tlb_finish_mmu(&tlb); 742f369b07cSPeter Xu } 743f369b07cSPeter Xu 744ffd05793SShaohua Li int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, 745a759a909SNadav Amit unsigned long len, bool enable_wp, 746a759a909SNadav Amit atomic_t *mmap_changing) 747ffd05793SShaohua Li { 748ffd05793SShaohua Li struct vm_area_struct *dst_vma; 7495a90d5a1SPeter Xu unsigned long page_mask; 750ffd05793SShaohua Li int err; 751ffd05793SShaohua Li 752ffd05793SShaohua Li /* 753ffd05793SShaohua Li * Sanitize the command parameters: 754ffd05793SShaohua Li */ 755ffd05793SShaohua Li BUG_ON(start & ~PAGE_MASK); 756ffd05793SShaohua Li BUG_ON(len & ~PAGE_MASK); 757ffd05793SShaohua Li 758ffd05793SShaohua Li /* Does the address range wrap, or is the span zero-sized? */ 759ffd05793SShaohua Li BUG_ON(start + len <= start); 760ffd05793SShaohua Li 761d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 762ffd05793SShaohua Li 763ffd05793SShaohua Li /* 764ffd05793SShaohua Li * If memory mappings are changing because of non-cooperative 765ffd05793SShaohua Li * operation (e.g. mremap) running in parallel, bail out and 766ffd05793SShaohua Li * request the user to retry later 767ffd05793SShaohua Li */ 768ffd05793SShaohua Li err = -EAGAIN; 769a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 770ffd05793SShaohua Li goto out_unlock; 771ffd05793SShaohua Li 772ffd05793SShaohua Li err = -ENOENT; 773ffd05793SShaohua Li dst_vma = find_dst_vma(dst_mm, start, len); 774b1f9e876SPeter Xu 775b1f9e876SPeter Xu if (!dst_vma) 776ffd05793SShaohua Li goto out_unlock; 777ffd05793SShaohua Li if (!userfaultfd_wp(dst_vma)) 778ffd05793SShaohua Li goto out_unlock; 779b1f9e876SPeter Xu if (!vma_can_userfault(dst_vma, dst_vma->vm_flags)) 780ffd05793SShaohua Li goto out_unlock; 781ffd05793SShaohua Li 7825a90d5a1SPeter Xu if (is_vm_hugetlb_page(dst_vma)) { 7835a90d5a1SPeter Xu err = -EINVAL; 7845a90d5a1SPeter Xu page_mask = vma_kernel_pagesize(dst_vma) - 1; 7855a90d5a1SPeter Xu if ((start & page_mask) || (len & page_mask)) 7865a90d5a1SPeter Xu goto out_unlock; 7875a90d5a1SPeter Xu } 7885a90d5a1SPeter Xu 789f369b07cSPeter Xu uffd_wp_range(dst_mm, dst_vma, start, len, enable_wp); 790ffd05793SShaohua Li 791ffd05793SShaohua Li err = 0; 792ffd05793SShaohua Li out_unlock: 793d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 794ffd05793SShaohua Li return err; 795ffd05793SShaohua Li } 796