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; 6928965f0fSVishal 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; 778ee79edfSPeter Xu if (writable) 7815313257SAxel Rasmussen _dst_pte = pte_mkwrite(_dst_pte); 79f1eb1bacSPeter Xu if (wp_copy) 80f1eb1bacSPeter Xu _dst_pte = pte_mkuffd_wp(_dst_pte); 8115313257SAxel Rasmussen 8215313257SAxel Rasmussen dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 8315313257SAxel Rasmussen 8415313257SAxel Rasmussen if (vma_is_shmem(dst_vma)) { 8515313257SAxel Rasmussen /* serialize against truncate with the page table lock */ 8615313257SAxel Rasmussen inode = dst_vma->vm_file->f_inode; 8715313257SAxel Rasmussen offset = linear_page_index(dst_vma, dst_addr); 8815313257SAxel Rasmussen max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 8915313257SAxel Rasmussen ret = -EFAULT; 9015313257SAxel Rasmussen if (unlikely(offset >= max_off)) 9115313257SAxel Rasmussen goto out_unlock; 9215313257SAxel Rasmussen } 9315313257SAxel Rasmussen 9415313257SAxel Rasmussen ret = -EEXIST; 958ee79edfSPeter Xu /* 968ee79edfSPeter Xu * We allow to overwrite a pte marker: consider when both MISSING|WP 978ee79edfSPeter Xu * registered, we firstly wr-protect a none pte which has no page cache 988ee79edfSPeter Xu * page backing it, then access the page. 998ee79edfSPeter Xu */ 1008ee79edfSPeter Xu if (!pte_none_mostly(*dst_pte)) 10115313257SAxel Rasmussen goto out_unlock; 10215313257SAxel Rasmussen 10328965f0fSVishal Moola (Oracle) folio = page_folio(page); 104cea86fe2SHugh Dickins if (page_in_cache) { 105cea86fe2SHugh Dickins /* Usually, cache pages are already added to LRU */ 106cea86fe2SHugh Dickins if (newly_allocated) 10728965f0fSVishal Moola (Oracle) folio_add_lru(folio); 108cea86fe2SHugh Dickins page_add_file_rmap(page, dst_vma, false); 109cea86fe2SHugh Dickins } else { 11040f2bbf7SDavid Hildenbrand page_add_new_anon_rmap(page, dst_vma, dst_addr); 11128965f0fSVishal Moola (Oracle) folio_add_lru_vma(folio, dst_vma); 112cea86fe2SHugh Dickins } 11315313257SAxel Rasmussen 11415313257SAxel Rasmussen /* 11515313257SAxel Rasmussen * Must happen after rmap, as mm_counter() checks mapping (via 11615313257SAxel Rasmussen * PageAnon()), which is set by __page_set_anon_rmap(). 11715313257SAxel Rasmussen */ 11815313257SAxel Rasmussen inc_mm_counter(dst_mm, mm_counter(page)); 11915313257SAxel Rasmussen 12015313257SAxel Rasmussen set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 12115313257SAxel Rasmussen 12215313257SAxel Rasmussen /* No need to invalidate - it was non-present before */ 12315313257SAxel Rasmussen update_mmu_cache(dst_vma, dst_addr, dst_pte); 12415313257SAxel Rasmussen ret = 0; 12515313257SAxel Rasmussen out_unlock: 12615313257SAxel Rasmussen pte_unmap_unlock(dst_pte, ptl); 12715313257SAxel Rasmussen return ret; 12815313257SAxel Rasmussen } 12915313257SAxel Rasmussen 130*a734991cSAxel Rasmussen static int mfill_atomic_pte_copy(struct mm_struct *dst_mm, 131c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 132c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 133c1a4de99SAndrea Arcangeli unsigned long dst_addr, 134b6ebaedbSAndrea Arcangeli unsigned long src_addr, 13572981e0eSAndrea Arcangeli struct page **pagep, 13672981e0eSAndrea Arcangeli bool wp_copy) 137c1a4de99SAndrea Arcangeli { 138c1a4de99SAndrea Arcangeli void *page_kaddr; 139c1a4de99SAndrea Arcangeli int ret; 140b6ebaedbSAndrea Arcangeli struct page *page; 141c1a4de99SAndrea Arcangeli 142b6ebaedbSAndrea Arcangeli if (!*pagep) { 143c1a4de99SAndrea Arcangeli ret = -ENOMEM; 144c1a4de99SAndrea Arcangeli page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); 145c1a4de99SAndrea Arcangeli if (!page) 146c1a4de99SAndrea Arcangeli goto out; 147c1a4de99SAndrea Arcangeli 1485521de7dSIra Weiny page_kaddr = kmap_local_page(page); 1495521de7dSIra Weiny /* 1505521de7dSIra Weiny * The read mmap_lock is held here. Despite the 1515521de7dSIra Weiny * mmap_lock being read recursive a deadlock is still 1525521de7dSIra Weiny * possible if a writer has taken a lock. For example: 1535521de7dSIra Weiny * 1545521de7dSIra Weiny * process A thread 1 takes read lock on own mmap_lock 1555521de7dSIra Weiny * process A thread 2 calls mmap, blocks taking write lock 1565521de7dSIra Weiny * process B thread 1 takes page fault, read lock on own mmap lock 1575521de7dSIra Weiny * process B thread 2 calls mmap, blocks taking write lock 1585521de7dSIra Weiny * process A thread 1 blocks taking read lock on process B 1595521de7dSIra Weiny * process B thread 1 blocks taking read lock on process A 1605521de7dSIra Weiny * 1615521de7dSIra Weiny * Disable page faults to prevent potential deadlock 1625521de7dSIra Weiny * and retry the copy outside the mmap_lock. 1635521de7dSIra Weiny */ 1645521de7dSIra Weiny pagefault_disable(); 165b6ebaedbSAndrea Arcangeli ret = copy_from_user(page_kaddr, 166b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 167b6ebaedbSAndrea Arcangeli PAGE_SIZE); 1685521de7dSIra Weiny pagefault_enable(); 1695521de7dSIra Weiny kunmap_local(page_kaddr); 170b6ebaedbSAndrea Arcangeli 171c1e8d7c6SMichel Lespinasse /* fallback to copy_from_user outside mmap_lock */ 172b6ebaedbSAndrea Arcangeli if (unlikely(ret)) { 1739e368259SAndrea Arcangeli ret = -ENOENT; 174b6ebaedbSAndrea Arcangeli *pagep = page; 175b6ebaedbSAndrea Arcangeli /* don't free the page */ 176b6ebaedbSAndrea Arcangeli goto out; 177b6ebaedbSAndrea Arcangeli } 1787c25a0b8SMuchun Song 1797c25a0b8SMuchun Song flush_dcache_page(page); 180b6ebaedbSAndrea Arcangeli } else { 181b6ebaedbSAndrea Arcangeli page = *pagep; 182b6ebaedbSAndrea Arcangeli *pagep = NULL; 183b6ebaedbSAndrea Arcangeli } 184c1a4de99SAndrea Arcangeli 185c1a4de99SAndrea Arcangeli /* 186c1a4de99SAndrea Arcangeli * The memory barrier inside __SetPageUptodate makes sure that 187f4f5329dSWei Yang * preceding stores to the page contents become visible before 188c1a4de99SAndrea Arcangeli * the set_pte_at() write. 189c1a4de99SAndrea Arcangeli */ 190c1a4de99SAndrea Arcangeli __SetPageUptodate(page); 191c1a4de99SAndrea Arcangeli 192c1a4de99SAndrea Arcangeli ret = -ENOMEM; 1938f425e4eSMatthew Wilcox (Oracle) if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL)) 194c1a4de99SAndrea Arcangeli goto out_release; 195c1a4de99SAndrea Arcangeli 19615313257SAxel Rasmussen ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 19715313257SAxel Rasmussen page, true, wp_copy); 19815313257SAxel Rasmussen if (ret) 19915313257SAxel Rasmussen goto out_release; 200c1a4de99SAndrea Arcangeli out: 201c1a4de99SAndrea Arcangeli return ret; 202c1a4de99SAndrea Arcangeli out_release: 20309cbfeafSKirill A. Shutemov put_page(page); 204c1a4de99SAndrea Arcangeli goto out; 205c1a4de99SAndrea Arcangeli } 206c1a4de99SAndrea Arcangeli 207*a734991cSAxel Rasmussen static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm, 208c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 209c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 210c1a4de99SAndrea Arcangeli unsigned long dst_addr) 211c1a4de99SAndrea Arcangeli { 212c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 213c1a4de99SAndrea Arcangeli spinlock_t *ptl; 214c1a4de99SAndrea Arcangeli int ret; 215e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 216e2a50c1fSAndrea Arcangeli struct inode *inode; 217c1a4de99SAndrea Arcangeli 218c1a4de99SAndrea Arcangeli _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), 219c1a4de99SAndrea Arcangeli dst_vma->vm_page_prot)); 220c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 221e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 222e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 223e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 224e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 225e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 226e2a50c1fSAndrea Arcangeli ret = -EFAULT; 227e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 228e2a50c1fSAndrea Arcangeli goto out_unlock; 229e2a50c1fSAndrea Arcangeli } 230e2a50c1fSAndrea Arcangeli ret = -EEXIST; 231c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 232c1a4de99SAndrea Arcangeli goto out_unlock; 233c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 234c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 235c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 236c1a4de99SAndrea Arcangeli ret = 0; 237c1a4de99SAndrea Arcangeli out_unlock: 238c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 239c1a4de99SAndrea Arcangeli return ret; 240c1a4de99SAndrea Arcangeli } 241c1a4de99SAndrea Arcangeli 24215313257SAxel Rasmussen /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */ 243*a734991cSAxel Rasmussen static int mfill_atomic_pte_continue(struct mm_struct *dst_mm, 24415313257SAxel Rasmussen pmd_t *dst_pmd, 24515313257SAxel Rasmussen struct vm_area_struct *dst_vma, 24615313257SAxel Rasmussen unsigned long dst_addr, 24715313257SAxel Rasmussen bool wp_copy) 24815313257SAxel Rasmussen { 24915313257SAxel Rasmussen struct inode *inode = file_inode(dst_vma->vm_file); 25015313257SAxel Rasmussen pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); 25112acf4fbSMatthew Wilcox (Oracle) struct folio *folio; 25215313257SAxel Rasmussen struct page *page; 25315313257SAxel Rasmussen int ret; 25415313257SAxel Rasmussen 25512acf4fbSMatthew Wilcox (Oracle) ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); 25612acf4fbSMatthew Wilcox (Oracle) /* Our caller expects us to return -EFAULT if we failed to find folio */ 25773f37dbcSAxel Rasmussen if (ret == -ENOENT) 25873f37dbcSAxel Rasmussen ret = -EFAULT; 25915313257SAxel Rasmussen if (ret) 26015313257SAxel Rasmussen goto out; 26112acf4fbSMatthew Wilcox (Oracle) if (!folio) { 26215313257SAxel Rasmussen ret = -EFAULT; 26315313257SAxel Rasmussen goto out; 26415313257SAxel Rasmussen } 26515313257SAxel Rasmussen 26612acf4fbSMatthew Wilcox (Oracle) page = folio_file_page(folio, pgoff); 267a7605426SYang Shi if (PageHWPoison(page)) { 268a7605426SYang Shi ret = -EIO; 269a7605426SYang Shi goto out_release; 270a7605426SYang Shi } 271a7605426SYang Shi 27215313257SAxel Rasmussen ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 27315313257SAxel Rasmussen page, false, wp_copy); 27415313257SAxel Rasmussen if (ret) 27515313257SAxel Rasmussen goto out_release; 27615313257SAxel Rasmussen 27712acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 27815313257SAxel Rasmussen ret = 0; 27915313257SAxel Rasmussen out: 28015313257SAxel Rasmussen return ret; 28115313257SAxel Rasmussen out_release: 28212acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 28312acf4fbSMatthew Wilcox (Oracle) folio_put(folio); 28415313257SAxel Rasmussen goto out; 28515313257SAxel Rasmussen } 28615313257SAxel Rasmussen 287c1a4de99SAndrea Arcangeli static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) 288c1a4de99SAndrea Arcangeli { 289c1a4de99SAndrea Arcangeli pgd_t *pgd; 290c2febafcSKirill A. Shutemov p4d_t *p4d; 291c1a4de99SAndrea Arcangeli pud_t *pud; 292c1a4de99SAndrea Arcangeli 293c1a4de99SAndrea Arcangeli pgd = pgd_offset(mm, address); 294c2febafcSKirill A. Shutemov p4d = p4d_alloc(mm, pgd, address); 295c2febafcSKirill A. Shutemov if (!p4d) 296c2febafcSKirill A. Shutemov return NULL; 297c2febafcSKirill A. Shutemov pud = pud_alloc(mm, p4d, address); 298c2febafcSKirill A. Shutemov if (!pud) 299c2febafcSKirill A. Shutemov return NULL; 300c1a4de99SAndrea Arcangeli /* 301c1a4de99SAndrea Arcangeli * Note that we didn't run this because the pmd was 302c1a4de99SAndrea Arcangeli * missing, the *pmd may be already established and in 303c1a4de99SAndrea Arcangeli * turn it may also be a trans_huge_pmd. 304c1a4de99SAndrea Arcangeli */ 305c2febafcSKirill A. Shutemov return pmd_alloc(mm, pud, address); 306c1a4de99SAndrea Arcangeli } 307c1a4de99SAndrea Arcangeli 30860d4d2d2SMike Kravetz #ifdef CONFIG_HUGETLB_PAGE 30960d4d2d2SMike Kravetz /* 310*a734991cSAxel Rasmussen * mfill_atomic processing for HUGETLB vmas. Note that this routine is 311c1e8d7c6SMichel Lespinasse * called with mmap_lock held, it will release mmap_lock before returning. 31260d4d2d2SMike Kravetz */ 313*a734991cSAxel Rasmussen static __always_inline ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm, 31460d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 31560d4d2d2SMike Kravetz unsigned long dst_start, 31660d4d2d2SMike Kravetz unsigned long src_start, 31760d4d2d2SMike Kravetz unsigned long len, 3186041c691SPeter Xu enum mcopy_atomic_mode mode, 3196041c691SPeter Xu bool wp_copy) 32060d4d2d2SMike Kravetz { 3211c9e8defSMike Kravetz int vm_shared = dst_vma->vm_flags & VM_SHARED; 32260d4d2d2SMike Kravetz ssize_t err; 32360d4d2d2SMike Kravetz pte_t *dst_pte; 32460d4d2d2SMike Kravetz unsigned long src_addr, dst_addr; 32560d4d2d2SMike Kravetz long copied; 32660d4d2d2SMike Kravetz struct page *page; 32760d4d2d2SMike Kravetz unsigned long vma_hpagesize; 32860d4d2d2SMike Kravetz pgoff_t idx; 32960d4d2d2SMike Kravetz u32 hash; 33060d4d2d2SMike Kravetz struct address_space *mapping; 33160d4d2d2SMike Kravetz 33260d4d2d2SMike Kravetz /* 33360d4d2d2SMike Kravetz * There is no default zero huge page for all huge page sizes as 33460d4d2d2SMike Kravetz * supported by hugetlb. A PMD_SIZE huge pages may exist as used 33560d4d2d2SMike Kravetz * by THP. Since we can not reliably insert a zero page, this 33660d4d2d2SMike Kravetz * feature is not supported. 33760d4d2d2SMike Kravetz */ 338f6191471SAxel Rasmussen if (mode == MCOPY_ATOMIC_ZEROPAGE) { 339d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 34060d4d2d2SMike Kravetz return -EINVAL; 34160d4d2d2SMike Kravetz } 34260d4d2d2SMike Kravetz 34360d4d2d2SMike Kravetz src_addr = src_start; 34460d4d2d2SMike Kravetz dst_addr = dst_start; 34560d4d2d2SMike Kravetz copied = 0; 34660d4d2d2SMike Kravetz page = NULL; 34760d4d2d2SMike Kravetz vma_hpagesize = vma_kernel_pagesize(dst_vma); 34860d4d2d2SMike Kravetz 34960d4d2d2SMike Kravetz /* 35060d4d2d2SMike Kravetz * Validate alignment based on huge page size 35160d4d2d2SMike Kravetz */ 35260d4d2d2SMike Kravetz err = -EINVAL; 35360d4d2d2SMike Kravetz if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) 35460d4d2d2SMike Kravetz goto out_unlock; 35560d4d2d2SMike Kravetz 35660d4d2d2SMike Kravetz retry: 35760d4d2d2SMike Kravetz /* 358c1e8d7c6SMichel Lespinasse * On routine entry dst_vma is set. If we had to drop mmap_lock and 35960d4d2d2SMike Kravetz * retry, dst_vma will be set to NULL and we must lookup again. 36060d4d2d2SMike Kravetz */ 36160d4d2d2SMike Kravetz if (!dst_vma) { 36227d02568SMike Rapoport err = -ENOENT; 363643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 36460d4d2d2SMike Kravetz if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) 36560d4d2d2SMike Kravetz goto out_unlock; 3661c9e8defSMike Kravetz 36727d02568SMike Rapoport err = -EINVAL; 36827d02568SMike Rapoport if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) 36927d02568SMike Rapoport goto out_unlock; 37027d02568SMike Rapoport 3711c9e8defSMike Kravetz vm_shared = dst_vma->vm_flags & VM_SHARED; 37260d4d2d2SMike Kravetz } 37360d4d2d2SMike Kravetz 37460d4d2d2SMike Kravetz /* 3751c9e8defSMike Kravetz * If not shared, ensure the dst_vma has a anon_vma. 37660d4d2d2SMike Kravetz */ 37760d4d2d2SMike Kravetz err = -ENOMEM; 3781c9e8defSMike Kravetz if (!vm_shared) { 37960d4d2d2SMike Kravetz if (unlikely(anon_vma_prepare(dst_vma))) 38060d4d2d2SMike Kravetz goto out_unlock; 3811c9e8defSMike Kravetz } 38260d4d2d2SMike Kravetz 38360d4d2d2SMike Kravetz while (src_addr < src_start + len) { 38460d4d2d2SMike Kravetz BUG_ON(dst_addr >= dst_start + len); 38560d4d2d2SMike Kravetz 38660d4d2d2SMike Kravetz /* 38740549ba8SMike Kravetz * Serialize via vma_lock and hugetlb_fault_mutex. 38840549ba8SMike Kravetz * vma_lock ensures the dst_pte remains valid even 38940549ba8SMike Kravetz * in the case of shared pmds. fault mutex prevents 39040549ba8SMike Kravetz * races with other faulting threads. 39160d4d2d2SMike Kravetz */ 392c0d0381aSMike Kravetz idx = linear_page_index(dst_vma, dst_addr); 3933a47c54fSMike Kravetz mapping = dst_vma->vm_file->f_mapping; 394188b04a7SWei Yang hash = hugetlb_fault_mutex_hash(mapping, idx); 39560d4d2d2SMike Kravetz mutex_lock(&hugetlb_fault_mutex_table[hash]); 39640549ba8SMike Kravetz hugetlb_vma_lock_read(dst_vma); 39760d4d2d2SMike Kravetz 39860d4d2d2SMike Kravetz err = -ENOMEM; 399aec44e0fSPeter Xu dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); 40060d4d2d2SMike Kravetz if (!dst_pte) { 40140549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 40260d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 40360d4d2d2SMike Kravetz goto out_unlock; 40460d4d2d2SMike Kravetz } 40560d4d2d2SMike Kravetz 406f6191471SAxel Rasmussen if (mode != MCOPY_ATOMIC_CONTINUE && 4076041c691SPeter Xu !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { 40860d4d2d2SMike Kravetz err = -EEXIST; 40940549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 41060d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 41160d4d2d2SMike Kravetz goto out_unlock; 41260d4d2d2SMike Kravetz } 41360d4d2d2SMike Kravetz 414*a734991cSAxel Rasmussen err = hugetlb_mfill_atomic_pte(dst_mm, dst_pte, dst_vma, 4156041c691SPeter Xu dst_addr, src_addr, mode, &page, 4166041c691SPeter Xu wp_copy); 41760d4d2d2SMike Kravetz 41840549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 41960d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 42060d4d2d2SMike Kravetz 42160d4d2d2SMike Kravetz cond_resched(); 42260d4d2d2SMike Kravetz 4239e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 424d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 42560d4d2d2SMike Kravetz BUG_ON(!page); 42660d4d2d2SMike Kravetz 42760d4d2d2SMike Kravetz err = copy_huge_page_from_user(page, 42860d4d2d2SMike Kravetz (const void __user *)src_addr, 4294fb07ee6SWei Yang vma_hpagesize / PAGE_SIZE, 4304fb07ee6SWei Yang true); 43160d4d2d2SMike Kravetz if (unlikely(err)) { 43260d4d2d2SMike Kravetz err = -EFAULT; 43360d4d2d2SMike Kravetz goto out; 43460d4d2d2SMike Kravetz } 435d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 43660d4d2d2SMike Kravetz 43760d4d2d2SMike Kravetz dst_vma = NULL; 43860d4d2d2SMike Kravetz goto retry; 43960d4d2d2SMike Kravetz } else 44060d4d2d2SMike Kravetz BUG_ON(page); 44160d4d2d2SMike Kravetz 44260d4d2d2SMike Kravetz if (!err) { 44360d4d2d2SMike Kravetz dst_addr += vma_hpagesize; 44460d4d2d2SMike Kravetz src_addr += vma_hpagesize; 44560d4d2d2SMike Kravetz copied += vma_hpagesize; 44660d4d2d2SMike Kravetz 44760d4d2d2SMike Kravetz if (fatal_signal_pending(current)) 44860d4d2d2SMike Kravetz err = -EINTR; 44960d4d2d2SMike Kravetz } 45060d4d2d2SMike Kravetz if (err) 45160d4d2d2SMike Kravetz break; 45260d4d2d2SMike Kravetz } 45360d4d2d2SMike Kravetz 45460d4d2d2SMike Kravetz out_unlock: 455d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 45660d4d2d2SMike Kravetz out: 4578cc5fcbbSMina Almasry if (page) 45860d4d2d2SMike Kravetz put_page(page); 45960d4d2d2SMike Kravetz BUG_ON(copied < 0); 46060d4d2d2SMike Kravetz BUG_ON(err > 0); 46160d4d2d2SMike Kravetz BUG_ON(!copied && !err); 46260d4d2d2SMike Kravetz return copied ? copied : err; 46360d4d2d2SMike Kravetz } 46460d4d2d2SMike Kravetz #else /* !CONFIG_HUGETLB_PAGE */ 46560d4d2d2SMike Kravetz /* fail at build time if gcc attempts to use this */ 466*a734991cSAxel Rasmussen extern ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm, 46760d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 46860d4d2d2SMike Kravetz unsigned long dst_start, 46960d4d2d2SMike Kravetz unsigned long src_start, 47060d4d2d2SMike Kravetz unsigned long len, 4716041c691SPeter Xu enum mcopy_atomic_mode mode, 4726041c691SPeter Xu bool wp_copy); 47360d4d2d2SMike Kravetz #endif /* CONFIG_HUGETLB_PAGE */ 47460d4d2d2SMike Kravetz 4753217d3c7SMike Rapoport static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, 4763217d3c7SMike Rapoport pmd_t *dst_pmd, 4773217d3c7SMike Rapoport struct vm_area_struct *dst_vma, 4783217d3c7SMike Rapoport unsigned long dst_addr, 4793217d3c7SMike Rapoport unsigned long src_addr, 4803217d3c7SMike Rapoport struct page **page, 48115313257SAxel Rasmussen enum mcopy_atomic_mode mode, 48272981e0eSAndrea Arcangeli bool wp_copy) 4833217d3c7SMike Rapoport { 4843217d3c7SMike Rapoport ssize_t err; 4853217d3c7SMike Rapoport 48615313257SAxel Rasmussen if (mode == MCOPY_ATOMIC_CONTINUE) { 487*a734991cSAxel Rasmussen return mfill_atomic_pte_continue(dst_mm, dst_pmd, dst_vma, 488*a734991cSAxel Rasmussen dst_addr, wp_copy); 48915313257SAxel Rasmussen } 49015313257SAxel Rasmussen 4915b51072eSAndrea Arcangeli /* 4925b51072eSAndrea Arcangeli * The normal page fault path for a shmem will invoke the 4935b51072eSAndrea Arcangeli * fault, fill the hole in the file and COW it right away. The 4945b51072eSAndrea Arcangeli * result generates plain anonymous memory. So when we are 4955b51072eSAndrea Arcangeli * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll 4965b51072eSAndrea Arcangeli * generate anonymous memory directly without actually filling 4975b51072eSAndrea Arcangeli * the hole. For the MAP_PRIVATE case the robustness check 4985b51072eSAndrea Arcangeli * only happens in the pagetable (to verify it's still none) 4995b51072eSAndrea Arcangeli * and not in the radix tree. 5005b51072eSAndrea Arcangeli */ 5015b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED)) { 50215313257SAxel Rasmussen if (mode == MCOPY_ATOMIC_NORMAL) 503*a734991cSAxel Rasmussen err = mfill_atomic_pte_copy(dst_mm, dst_pmd, dst_vma, 50472981e0eSAndrea Arcangeli dst_addr, src_addr, page, 50572981e0eSAndrea Arcangeli wp_copy); 5063217d3c7SMike Rapoport else 507*a734991cSAxel Rasmussen err = mfill_atomic_pte_zeropage(dst_mm, dst_pmd, 5083217d3c7SMike Rapoport dst_vma, dst_addr); 5093217d3c7SMike Rapoport } else { 5103460f6e5SAxel Rasmussen err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, 51115313257SAxel Rasmussen dst_addr, src_addr, 51215313257SAxel Rasmussen mode != MCOPY_ATOMIC_NORMAL, 5138ee79edfSPeter Xu wp_copy, page); 5143217d3c7SMike Rapoport } 5153217d3c7SMike Rapoport 5163217d3c7SMike Rapoport return err; 5173217d3c7SMike Rapoport } 5183217d3c7SMike Rapoport 519*a734991cSAxel Rasmussen static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, 520c1a4de99SAndrea Arcangeli unsigned long dst_start, 521c1a4de99SAndrea Arcangeli unsigned long src_start, 522c1a4de99SAndrea Arcangeli unsigned long len, 523f6191471SAxel Rasmussen enum mcopy_atomic_mode mcopy_mode, 524a759a909SNadav Amit atomic_t *mmap_changing, 52572981e0eSAndrea Arcangeli __u64 mode) 526c1a4de99SAndrea Arcangeli { 527c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma; 528c1a4de99SAndrea Arcangeli ssize_t err; 529c1a4de99SAndrea Arcangeli pmd_t *dst_pmd; 530c1a4de99SAndrea Arcangeli unsigned long src_addr, dst_addr; 531b6ebaedbSAndrea Arcangeli long copied; 532b6ebaedbSAndrea Arcangeli struct page *page; 53372981e0eSAndrea Arcangeli bool wp_copy; 534c1a4de99SAndrea Arcangeli 535c1a4de99SAndrea Arcangeli /* 536c1a4de99SAndrea Arcangeli * Sanitize the command parameters: 537c1a4de99SAndrea Arcangeli */ 538c1a4de99SAndrea Arcangeli BUG_ON(dst_start & ~PAGE_MASK); 539c1a4de99SAndrea Arcangeli BUG_ON(len & ~PAGE_MASK); 540c1a4de99SAndrea Arcangeli 541c1a4de99SAndrea Arcangeli /* Does the address range wrap, or is the span zero-sized? */ 542c1a4de99SAndrea Arcangeli BUG_ON(src_start + len <= src_start); 543c1a4de99SAndrea Arcangeli BUG_ON(dst_start + len <= dst_start); 544c1a4de99SAndrea Arcangeli 545b6ebaedbSAndrea Arcangeli src_addr = src_start; 546b6ebaedbSAndrea Arcangeli dst_addr = dst_start; 547b6ebaedbSAndrea Arcangeli copied = 0; 548b6ebaedbSAndrea Arcangeli page = NULL; 549b6ebaedbSAndrea Arcangeli retry: 550d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 551c1a4de99SAndrea Arcangeli 552c1a4de99SAndrea Arcangeli /* 553df2cc96eSMike Rapoport * If memory mappings are changing because of non-cooperative 554df2cc96eSMike Rapoport * operation (e.g. mremap) running in parallel, bail out and 555df2cc96eSMike Rapoport * request the user to retry later 556df2cc96eSMike Rapoport */ 557df2cc96eSMike Rapoport err = -EAGAIN; 558a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 559df2cc96eSMike Rapoport goto out_unlock; 560df2cc96eSMike Rapoport 561df2cc96eSMike Rapoport /* 562c1a4de99SAndrea Arcangeli * Make sure the vma is not shared, that the dst range is 563c1a4de99SAndrea Arcangeli * both valid and fully within a single existing vma. 564c1a4de99SAndrea Arcangeli */ 56527d02568SMike Rapoport err = -ENOENT; 566643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 56726071cedSMike Rapoport if (!dst_vma) 56826071cedSMike Rapoport goto out_unlock; 56927d02568SMike Rapoport 57027d02568SMike Rapoport err = -EINVAL; 57127d02568SMike Rapoport /* 57227d02568SMike Rapoport * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but 57327d02568SMike Rapoport * it will overwrite vm_ops, so vma_is_anonymous must return false. 57427d02568SMike Rapoport */ 57527d02568SMike Rapoport if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && 57627d02568SMike Rapoport dst_vma->vm_flags & VM_SHARED)) 57727d02568SMike Rapoport goto out_unlock; 57827d02568SMike Rapoport 57927d02568SMike Rapoport /* 58072981e0eSAndrea Arcangeli * validate 'mode' now that we know the dst_vma: don't allow 58172981e0eSAndrea Arcangeli * a wrprotect copy if the userfaultfd didn't register as WP. 58272981e0eSAndrea Arcangeli */ 58372981e0eSAndrea Arcangeli wp_copy = mode & UFFDIO_COPY_MODE_WP; 58472981e0eSAndrea Arcangeli if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) 58572981e0eSAndrea Arcangeli goto out_unlock; 58672981e0eSAndrea Arcangeli 58772981e0eSAndrea Arcangeli /* 58827d02568SMike Rapoport * If this is a HUGETLB vma, pass off to appropriate routine 58927d02568SMike Rapoport */ 59027d02568SMike Rapoport if (is_vm_hugetlb_page(dst_vma)) 591*a734991cSAxel Rasmussen return mfill_atomic_hugetlb(dst_mm, dst_vma, dst_start, 5926041c691SPeter Xu src_start, len, mcopy_mode, 5936041c691SPeter Xu wp_copy); 59427d02568SMike Rapoport 59526071cedSMike Rapoport if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) 596b6ebaedbSAndrea Arcangeli goto out_unlock; 59715313257SAxel Rasmussen if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) 598f6191471SAxel Rasmussen goto out_unlock; 599c1a4de99SAndrea Arcangeli 600c1a4de99SAndrea Arcangeli /* 601c1a4de99SAndrea Arcangeli * Ensure the dst_vma has a anon_vma or this page 602c1a4de99SAndrea Arcangeli * would get a NULL anon_vma when moved in the 603c1a4de99SAndrea Arcangeli * dst_vma. 604c1a4de99SAndrea Arcangeli */ 605c1a4de99SAndrea Arcangeli err = -ENOMEM; 6065b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED) && 6075b51072eSAndrea Arcangeli unlikely(anon_vma_prepare(dst_vma))) 608b6ebaedbSAndrea Arcangeli goto out_unlock; 609c1a4de99SAndrea Arcangeli 610b6ebaedbSAndrea Arcangeli while (src_addr < src_start + len) { 611c1a4de99SAndrea Arcangeli pmd_t dst_pmdval; 612b6ebaedbSAndrea Arcangeli 613c1a4de99SAndrea Arcangeli BUG_ON(dst_addr >= dst_start + len); 614b6ebaedbSAndrea Arcangeli 615c1a4de99SAndrea Arcangeli dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); 616c1a4de99SAndrea Arcangeli if (unlikely(!dst_pmd)) { 617c1a4de99SAndrea Arcangeli err = -ENOMEM; 618c1a4de99SAndrea Arcangeli break; 619c1a4de99SAndrea Arcangeli } 620c1a4de99SAndrea Arcangeli 621dab6e717SPeter Zijlstra dst_pmdval = pmdp_get_lockless(dst_pmd); 622c1a4de99SAndrea Arcangeli /* 623c1a4de99SAndrea Arcangeli * If the dst_pmd is mapped as THP don't 624c1a4de99SAndrea Arcangeli * override it and just be strict. 625c1a4de99SAndrea Arcangeli */ 626c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(dst_pmdval))) { 627c1a4de99SAndrea Arcangeli err = -EEXIST; 628c1a4de99SAndrea Arcangeli break; 629c1a4de99SAndrea Arcangeli } 630c1a4de99SAndrea Arcangeli if (unlikely(pmd_none(dst_pmdval)) && 6314cf58924SJoel Fernandes (Google) unlikely(__pte_alloc(dst_mm, dst_pmd))) { 632c1a4de99SAndrea Arcangeli err = -ENOMEM; 633c1a4de99SAndrea Arcangeli break; 634c1a4de99SAndrea Arcangeli } 635c1a4de99SAndrea Arcangeli /* If an huge pmd materialized from under us fail */ 636c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(*dst_pmd))) { 637c1a4de99SAndrea Arcangeli err = -EFAULT; 638c1a4de99SAndrea Arcangeli break; 639c1a4de99SAndrea Arcangeli } 640c1a4de99SAndrea Arcangeli 641c1a4de99SAndrea Arcangeli BUG_ON(pmd_none(*dst_pmd)); 642c1a4de99SAndrea Arcangeli BUG_ON(pmd_trans_huge(*dst_pmd)); 643c1a4de99SAndrea Arcangeli 6443217d3c7SMike Rapoport err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 64515313257SAxel Rasmussen src_addr, &page, mcopy_mode, wp_copy); 646c1a4de99SAndrea Arcangeli cond_resched(); 647c1a4de99SAndrea Arcangeli 6489e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 649b6ebaedbSAndrea Arcangeli void *page_kaddr; 650b6ebaedbSAndrea Arcangeli 651d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 652b6ebaedbSAndrea Arcangeli BUG_ON(!page); 653b6ebaedbSAndrea Arcangeli 6545521de7dSIra Weiny page_kaddr = kmap_local_page(page); 655b6ebaedbSAndrea Arcangeli err = copy_from_user(page_kaddr, 656b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 657b6ebaedbSAndrea Arcangeli PAGE_SIZE); 6585521de7dSIra Weiny kunmap_local(page_kaddr); 659b6ebaedbSAndrea Arcangeli if (unlikely(err)) { 660b6ebaedbSAndrea Arcangeli err = -EFAULT; 661b6ebaedbSAndrea Arcangeli goto out; 662b6ebaedbSAndrea Arcangeli } 6637c25a0b8SMuchun Song flush_dcache_page(page); 664b6ebaedbSAndrea Arcangeli goto retry; 665b6ebaedbSAndrea Arcangeli } else 666b6ebaedbSAndrea Arcangeli BUG_ON(page); 667b6ebaedbSAndrea Arcangeli 668c1a4de99SAndrea Arcangeli if (!err) { 669c1a4de99SAndrea Arcangeli dst_addr += PAGE_SIZE; 670c1a4de99SAndrea Arcangeli src_addr += PAGE_SIZE; 671c1a4de99SAndrea Arcangeli copied += PAGE_SIZE; 672c1a4de99SAndrea Arcangeli 673c1a4de99SAndrea Arcangeli if (fatal_signal_pending(current)) 674c1a4de99SAndrea Arcangeli err = -EINTR; 675c1a4de99SAndrea Arcangeli } 676c1a4de99SAndrea Arcangeli if (err) 677c1a4de99SAndrea Arcangeli break; 678c1a4de99SAndrea Arcangeli } 679c1a4de99SAndrea Arcangeli 680b6ebaedbSAndrea Arcangeli out_unlock: 681d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 682b6ebaedbSAndrea Arcangeli out: 683b6ebaedbSAndrea Arcangeli if (page) 68409cbfeafSKirill A. Shutemov put_page(page); 685c1a4de99SAndrea Arcangeli BUG_ON(copied < 0); 686c1a4de99SAndrea Arcangeli BUG_ON(err > 0); 687c1a4de99SAndrea Arcangeli BUG_ON(!copied && !err); 688c1a4de99SAndrea Arcangeli return copied ? copied : err; 689c1a4de99SAndrea Arcangeli } 690c1a4de99SAndrea Arcangeli 691*a734991cSAxel Rasmussen ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, 692df2cc96eSMike Rapoport unsigned long src_start, unsigned long len, 693a759a909SNadav Amit atomic_t *mmap_changing, __u64 mode) 694c1a4de99SAndrea Arcangeli { 695*a734991cSAxel Rasmussen return mfill_atomic(dst_mm, dst_start, src_start, len, 696f6191471SAxel Rasmussen MCOPY_ATOMIC_NORMAL, mmap_changing, mode); 697c1a4de99SAndrea Arcangeli } 698c1a4de99SAndrea Arcangeli 699*a734991cSAxel Rasmussen ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start, 700a759a909SNadav Amit unsigned long len, atomic_t *mmap_changing) 701c1a4de99SAndrea Arcangeli { 702*a734991cSAxel Rasmussen return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE, 703f6191471SAxel Rasmussen mmap_changing, 0); 704f6191471SAxel Rasmussen } 705f6191471SAxel Rasmussen 706*a734991cSAxel Rasmussen ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start, 707a759a909SNadav Amit unsigned long len, atomic_t *mmap_changing) 708f6191471SAxel Rasmussen { 709*a734991cSAxel Rasmussen return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE, 710f6191471SAxel Rasmussen mmap_changing, 0); 711c1a4de99SAndrea Arcangeli } 712ffd05793SShaohua Li 713d1751118SPeter Xu long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, 714f369b07cSPeter Xu unsigned long start, unsigned long len, bool enable_wp) 715f369b07cSPeter Xu { 716931298e1SDavid Hildenbrand unsigned int mm_cp_flags; 717f369b07cSPeter Xu struct mmu_gather tlb; 718d1751118SPeter Xu long ret; 719f369b07cSPeter Xu 720a1b92a3fSMuhammad Usama Anjum VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end, 721a1b92a3fSMuhammad Usama Anjum "The address range exceeds VMA boundary.\n"); 722f369b07cSPeter Xu if (enable_wp) 723931298e1SDavid Hildenbrand mm_cp_flags = MM_CP_UFFD_WP; 724f369b07cSPeter Xu else 725931298e1SDavid Hildenbrand mm_cp_flags = MM_CP_UFFD_WP_RESOLVE; 726f369b07cSPeter Xu 727931298e1SDavid Hildenbrand /* 728931298e1SDavid Hildenbrand * vma->vm_page_prot already reflects that uffd-wp is enabled for this 729931298e1SDavid Hildenbrand * VMA (see userfaultfd_set_vm_flags()) and that all PTEs are supposed 730931298e1SDavid Hildenbrand * to be write-protected as default whenever protection changes. 731931298e1SDavid Hildenbrand * Try upgrading write permissions manually. 732931298e1SDavid Hildenbrand */ 733931298e1SDavid Hildenbrand if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma)) 734931298e1SDavid Hildenbrand mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 735f369b07cSPeter Xu tlb_gather_mmu(&tlb, dst_mm); 736d1751118SPeter Xu ret = change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); 737f369b07cSPeter Xu tlb_finish_mmu(&tlb); 738d1751118SPeter Xu 739d1751118SPeter Xu return ret; 740f369b07cSPeter Xu } 741f369b07cSPeter Xu 742ffd05793SShaohua Li int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, 743a759a909SNadav Amit unsigned long len, bool enable_wp, 744a759a909SNadav Amit atomic_t *mmap_changing) 745ffd05793SShaohua Li { 746a1b92a3fSMuhammad Usama Anjum unsigned long end = start + len; 747a1b92a3fSMuhammad Usama Anjum unsigned long _start, _end; 748ffd05793SShaohua Li struct vm_area_struct *dst_vma; 7495a90d5a1SPeter Xu unsigned long page_mask; 750d1751118SPeter Xu long err; 751a1b92a3fSMuhammad Usama Anjum VMA_ITERATOR(vmi, dst_mm, start); 752ffd05793SShaohua Li 753ffd05793SShaohua Li /* 754ffd05793SShaohua Li * Sanitize the command parameters: 755ffd05793SShaohua Li */ 756ffd05793SShaohua Li BUG_ON(start & ~PAGE_MASK); 757ffd05793SShaohua Li BUG_ON(len & ~PAGE_MASK); 758ffd05793SShaohua Li 759ffd05793SShaohua Li /* Does the address range wrap, or is the span zero-sized? */ 760ffd05793SShaohua Li BUG_ON(start + len <= start); 761ffd05793SShaohua Li 762d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 763ffd05793SShaohua Li 764ffd05793SShaohua Li /* 765ffd05793SShaohua Li * If memory mappings are changing because of non-cooperative 766ffd05793SShaohua Li * operation (e.g. mremap) running in parallel, bail out and 767ffd05793SShaohua Li * request the user to retry later 768ffd05793SShaohua Li */ 769ffd05793SShaohua Li err = -EAGAIN; 770a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 771ffd05793SShaohua Li goto out_unlock; 772ffd05793SShaohua Li 773ffd05793SShaohua Li err = -ENOENT; 774a1b92a3fSMuhammad Usama Anjum for_each_vma_range(vmi, dst_vma, end) { 775b1f9e876SPeter Xu 776a1b92a3fSMuhammad Usama Anjum if (!userfaultfd_wp(dst_vma)) { 777a1b92a3fSMuhammad Usama Anjum err = -ENOENT; 778a1b92a3fSMuhammad Usama Anjum break; 779a1b92a3fSMuhammad Usama Anjum } 780ffd05793SShaohua Li 7815a90d5a1SPeter Xu if (is_vm_hugetlb_page(dst_vma)) { 7825a90d5a1SPeter Xu err = -EINVAL; 7835a90d5a1SPeter Xu page_mask = vma_kernel_pagesize(dst_vma) - 1; 7845a90d5a1SPeter Xu if ((start & page_mask) || (len & page_mask)) 785a1b92a3fSMuhammad Usama Anjum break; 7865a90d5a1SPeter Xu } 7875a90d5a1SPeter Xu 788a1b92a3fSMuhammad Usama Anjum _start = max(dst_vma->vm_start, start); 789a1b92a3fSMuhammad Usama Anjum _end = min(dst_vma->vm_end, end); 790a1b92a3fSMuhammad Usama Anjum 791a1b92a3fSMuhammad Usama Anjum err = uffd_wp_range(dst_mm, dst_vma, _start, _end - _start, enable_wp); 792ffd05793SShaohua Li 793d1751118SPeter Xu /* Return 0 on success, <0 on failures */ 794a1b92a3fSMuhammad Usama Anjum if (err < 0) 795a1b92a3fSMuhammad Usama Anjum break; 796ffd05793SShaohua Li err = 0; 797a1b92a3fSMuhammad Usama Anjum } 798ffd05793SShaohua Li out_unlock: 799d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 800ffd05793SShaohua Li return err; 801ffd05793SShaohua Li } 802