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 */ 5861c50040SAxel Rasmussen int mfill_atomic_install_pte(pmd_t *dst_pmd, 5915313257SAxel Rasmussen struct vm_area_struct *dst_vma, 6015313257SAxel Rasmussen unsigned long dst_addr, struct page *page, 61d9712937SAxel Rasmussen bool newly_allocated, uffd_flags_t flags) 6215313257SAxel Rasmussen { 6315313257SAxel Rasmussen int ret; 6461c50040SAxel Rasmussen struct mm_struct *dst_mm = dst_vma->vm_mm; 6515313257SAxel Rasmussen pte_t _dst_pte, *dst_pte; 6615313257SAxel Rasmussen bool writable = dst_vma->vm_flags & VM_WRITE; 6715313257SAxel Rasmussen bool vm_shared = dst_vma->vm_flags & VM_SHARED; 6893b0d917SPeter Xu bool page_in_cache = page_mapping(page); 6915313257SAxel Rasmussen spinlock_t *ptl; 7028965f0fSVishal Moola (Oracle) struct folio *folio; 7115313257SAxel Rasmussen struct inode *inode; 7215313257SAxel Rasmussen pgoff_t offset, max_off; 7315313257SAxel Rasmussen 7415313257SAxel Rasmussen _dst_pte = mk_pte(page, dst_vma->vm_page_prot); 759ae0f87dSPeter Xu _dst_pte = pte_mkdirty(_dst_pte); 7615313257SAxel Rasmussen if (page_in_cache && !vm_shared) 7715313257SAxel Rasmussen writable = false; 788ee79edfSPeter Xu if (writable) 7915313257SAxel Rasmussen _dst_pte = pte_mkwrite(_dst_pte); 80d9712937SAxel Rasmussen if (flags & MFILL_ATOMIC_WP) 81f1eb1bacSPeter Xu _dst_pte = pte_mkuffd_wp(_dst_pte); 8215313257SAxel Rasmussen 8315313257SAxel Rasmussen dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 8415313257SAxel Rasmussen 8515313257SAxel Rasmussen if (vma_is_shmem(dst_vma)) { 8615313257SAxel Rasmussen /* serialize against truncate with the page table lock */ 8715313257SAxel Rasmussen inode = dst_vma->vm_file->f_inode; 8815313257SAxel Rasmussen offset = linear_page_index(dst_vma, dst_addr); 8915313257SAxel Rasmussen max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 9015313257SAxel Rasmussen ret = -EFAULT; 9115313257SAxel Rasmussen if (unlikely(offset >= max_off)) 9215313257SAxel Rasmussen goto out_unlock; 9315313257SAxel Rasmussen } 9415313257SAxel Rasmussen 9515313257SAxel Rasmussen ret = -EEXIST; 968ee79edfSPeter Xu /* 978ee79edfSPeter Xu * We allow to overwrite a pte marker: consider when both MISSING|WP 988ee79edfSPeter Xu * registered, we firstly wr-protect a none pte which has no page cache 998ee79edfSPeter Xu * page backing it, then access the page. 1008ee79edfSPeter Xu */ 1018ee79edfSPeter Xu if (!pte_none_mostly(*dst_pte)) 10215313257SAxel Rasmussen goto out_unlock; 10315313257SAxel Rasmussen 10428965f0fSVishal Moola (Oracle) folio = page_folio(page); 105cea86fe2SHugh Dickins if (page_in_cache) { 106cea86fe2SHugh Dickins /* Usually, cache pages are already added to LRU */ 107cea86fe2SHugh Dickins if (newly_allocated) 10828965f0fSVishal Moola (Oracle) folio_add_lru(folio); 109cea86fe2SHugh Dickins page_add_file_rmap(page, dst_vma, false); 110cea86fe2SHugh Dickins } else { 11140f2bbf7SDavid Hildenbrand page_add_new_anon_rmap(page, dst_vma, dst_addr); 11228965f0fSVishal Moola (Oracle) folio_add_lru_vma(folio, dst_vma); 113cea86fe2SHugh Dickins } 11415313257SAxel Rasmussen 11515313257SAxel Rasmussen /* 11615313257SAxel Rasmussen * Must happen after rmap, as mm_counter() checks mapping (via 11715313257SAxel Rasmussen * PageAnon()), which is set by __page_set_anon_rmap(). 11815313257SAxel Rasmussen */ 11915313257SAxel Rasmussen inc_mm_counter(dst_mm, mm_counter(page)); 12015313257SAxel Rasmussen 12115313257SAxel Rasmussen set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 12215313257SAxel Rasmussen 12315313257SAxel Rasmussen /* No need to invalidate - it was non-present before */ 12415313257SAxel Rasmussen update_mmu_cache(dst_vma, dst_addr, dst_pte); 12515313257SAxel Rasmussen ret = 0; 12615313257SAxel Rasmussen out_unlock: 12715313257SAxel Rasmussen pte_unmap_unlock(dst_pte, ptl); 12815313257SAxel Rasmussen return ret; 12915313257SAxel Rasmussen } 13015313257SAxel Rasmussen 13161c50040SAxel Rasmussen static int mfill_atomic_pte_copy(pmd_t *dst_pmd, 132c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 133c1a4de99SAndrea Arcangeli unsigned long dst_addr, 134b6ebaedbSAndrea Arcangeli unsigned long src_addr, 135d9712937SAxel Rasmussen uffd_flags_t flags, 136*d7be6d7eSZhangPeng struct folio **foliop) 137c1a4de99SAndrea Arcangeli { 13807e6d409SZhangPeng void *kaddr; 139c1a4de99SAndrea Arcangeli int ret; 14007e6d409SZhangPeng struct folio *folio; 141c1a4de99SAndrea Arcangeli 142*d7be6d7eSZhangPeng if (!*foliop) { 143c1a4de99SAndrea Arcangeli ret = -ENOMEM; 14407e6d409SZhangPeng folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, dst_vma, 14507e6d409SZhangPeng dst_addr, false); 14607e6d409SZhangPeng if (!folio) 147c1a4de99SAndrea Arcangeli goto out; 148c1a4de99SAndrea Arcangeli 14907e6d409SZhangPeng kaddr = kmap_local_folio(folio, 0); 1505521de7dSIra Weiny /* 1515521de7dSIra Weiny * The read mmap_lock is held here. Despite the 1525521de7dSIra Weiny * mmap_lock being read recursive a deadlock is still 1535521de7dSIra Weiny * possible if a writer has taken a lock. For example: 1545521de7dSIra Weiny * 1555521de7dSIra Weiny * process A thread 1 takes read lock on own mmap_lock 1565521de7dSIra Weiny * process A thread 2 calls mmap, blocks taking write lock 1575521de7dSIra Weiny * process B thread 1 takes page fault, read lock on own mmap lock 1585521de7dSIra Weiny * process B thread 2 calls mmap, blocks taking write lock 1595521de7dSIra Weiny * process A thread 1 blocks taking read lock on process B 1605521de7dSIra Weiny * process B thread 1 blocks taking read lock on process A 1615521de7dSIra Weiny * 1625521de7dSIra Weiny * Disable page faults to prevent potential deadlock 1635521de7dSIra Weiny * and retry the copy outside the mmap_lock. 1645521de7dSIra Weiny */ 1655521de7dSIra Weiny pagefault_disable(); 16607e6d409SZhangPeng ret = copy_from_user(kaddr, (const void __user *) src_addr, 167b6ebaedbSAndrea Arcangeli PAGE_SIZE); 1685521de7dSIra Weiny pagefault_enable(); 16907e6d409SZhangPeng kunmap_local(kaddr); 170b6ebaedbSAndrea Arcangeli 171c1e8d7c6SMichel Lespinasse /* fallback to copy_from_user outside mmap_lock */ 172b6ebaedbSAndrea Arcangeli if (unlikely(ret)) { 1739e368259SAndrea Arcangeli ret = -ENOENT; 174*d7be6d7eSZhangPeng *foliop = folio; 175b6ebaedbSAndrea Arcangeli /* don't free the page */ 176b6ebaedbSAndrea Arcangeli goto out; 177b6ebaedbSAndrea Arcangeli } 1787c25a0b8SMuchun Song 17907e6d409SZhangPeng flush_dcache_folio(folio); 180b6ebaedbSAndrea Arcangeli } else { 181*d7be6d7eSZhangPeng folio = *foliop; 182*d7be6d7eSZhangPeng *foliop = NULL; 183b6ebaedbSAndrea Arcangeli } 184c1a4de99SAndrea Arcangeli 185c1a4de99SAndrea Arcangeli /* 18607e6d409SZhangPeng * The memory barrier inside __folio_mark_uptodate makes sure that 187f4f5329dSWei Yang * preceding stores to the page contents become visible before 188c1a4de99SAndrea Arcangeli * the set_pte_at() write. 189c1a4de99SAndrea Arcangeli */ 19007e6d409SZhangPeng __folio_mark_uptodate(folio); 191c1a4de99SAndrea Arcangeli 192c1a4de99SAndrea Arcangeli ret = -ENOMEM; 19307e6d409SZhangPeng if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL)) 194c1a4de99SAndrea Arcangeli goto out_release; 195c1a4de99SAndrea Arcangeli 19661c50040SAxel Rasmussen ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, 19707e6d409SZhangPeng &folio->page, true, flags); 19815313257SAxel Rasmussen if (ret) 19915313257SAxel Rasmussen goto out_release; 200c1a4de99SAndrea Arcangeli out: 201c1a4de99SAndrea Arcangeli return ret; 202c1a4de99SAndrea Arcangeli out_release: 20307e6d409SZhangPeng folio_put(folio); 204c1a4de99SAndrea Arcangeli goto out; 205c1a4de99SAndrea Arcangeli } 206c1a4de99SAndrea Arcangeli 20761c50040SAxel Rasmussen static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd, 208c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 209c1a4de99SAndrea Arcangeli unsigned long dst_addr) 210c1a4de99SAndrea Arcangeli { 211c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 212c1a4de99SAndrea Arcangeli spinlock_t *ptl; 213c1a4de99SAndrea Arcangeli int ret; 214e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 215e2a50c1fSAndrea Arcangeli struct inode *inode; 216c1a4de99SAndrea Arcangeli 217c1a4de99SAndrea Arcangeli _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), 218c1a4de99SAndrea Arcangeli dst_vma->vm_page_prot)); 21961c50040SAxel Rasmussen dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl); 220e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 221e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 222e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 223e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 224e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 225e2a50c1fSAndrea Arcangeli ret = -EFAULT; 226e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 227e2a50c1fSAndrea Arcangeli goto out_unlock; 228e2a50c1fSAndrea Arcangeli } 229e2a50c1fSAndrea Arcangeli ret = -EEXIST; 230c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 231c1a4de99SAndrea Arcangeli goto out_unlock; 23261c50040SAxel Rasmussen set_pte_at(dst_vma->vm_mm, dst_addr, dst_pte, _dst_pte); 233c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 234c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 235c1a4de99SAndrea Arcangeli ret = 0; 236c1a4de99SAndrea Arcangeli out_unlock: 237c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 238c1a4de99SAndrea Arcangeli return ret; 239c1a4de99SAndrea Arcangeli } 240c1a4de99SAndrea Arcangeli 24115313257SAxel Rasmussen /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */ 24261c50040SAxel Rasmussen static int mfill_atomic_pte_continue(pmd_t *dst_pmd, 24315313257SAxel Rasmussen struct vm_area_struct *dst_vma, 24415313257SAxel Rasmussen unsigned long dst_addr, 245d9712937SAxel Rasmussen uffd_flags_t flags) 24615313257SAxel Rasmussen { 24715313257SAxel Rasmussen struct inode *inode = file_inode(dst_vma->vm_file); 24815313257SAxel Rasmussen pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); 24912acf4fbSMatthew Wilcox (Oracle) struct folio *folio; 25015313257SAxel Rasmussen struct page *page; 25115313257SAxel Rasmussen int ret; 25215313257SAxel Rasmussen 25312acf4fbSMatthew Wilcox (Oracle) ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); 25412acf4fbSMatthew Wilcox (Oracle) /* Our caller expects us to return -EFAULT if we failed to find folio */ 25573f37dbcSAxel Rasmussen if (ret == -ENOENT) 25673f37dbcSAxel Rasmussen ret = -EFAULT; 25715313257SAxel Rasmussen if (ret) 25815313257SAxel Rasmussen goto out; 25912acf4fbSMatthew Wilcox (Oracle) if (!folio) { 26015313257SAxel Rasmussen ret = -EFAULT; 26115313257SAxel Rasmussen goto out; 26215313257SAxel Rasmussen } 26315313257SAxel Rasmussen 26412acf4fbSMatthew Wilcox (Oracle) page = folio_file_page(folio, pgoff); 265a7605426SYang Shi if (PageHWPoison(page)) { 266a7605426SYang Shi ret = -EIO; 267a7605426SYang Shi goto out_release; 268a7605426SYang Shi } 269a7605426SYang Shi 27061c50040SAxel Rasmussen ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, 271d9712937SAxel Rasmussen page, false, flags); 27215313257SAxel Rasmussen if (ret) 27315313257SAxel Rasmussen goto out_release; 27415313257SAxel Rasmussen 27512acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 27615313257SAxel Rasmussen ret = 0; 27715313257SAxel Rasmussen out: 27815313257SAxel Rasmussen return ret; 27915313257SAxel Rasmussen out_release: 28012acf4fbSMatthew Wilcox (Oracle) folio_unlock(folio); 28112acf4fbSMatthew Wilcox (Oracle) folio_put(folio); 28215313257SAxel Rasmussen goto out; 28315313257SAxel Rasmussen } 28415313257SAxel Rasmussen 285c1a4de99SAndrea Arcangeli static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) 286c1a4de99SAndrea Arcangeli { 287c1a4de99SAndrea Arcangeli pgd_t *pgd; 288c2febafcSKirill A. Shutemov p4d_t *p4d; 289c1a4de99SAndrea Arcangeli pud_t *pud; 290c1a4de99SAndrea Arcangeli 291c1a4de99SAndrea Arcangeli pgd = pgd_offset(mm, address); 292c2febafcSKirill A. Shutemov p4d = p4d_alloc(mm, pgd, address); 293c2febafcSKirill A. Shutemov if (!p4d) 294c2febafcSKirill A. Shutemov return NULL; 295c2febafcSKirill A. Shutemov pud = pud_alloc(mm, p4d, address); 296c2febafcSKirill A. Shutemov if (!pud) 297c2febafcSKirill A. Shutemov return NULL; 298c1a4de99SAndrea Arcangeli /* 299c1a4de99SAndrea Arcangeli * Note that we didn't run this because the pmd was 300c1a4de99SAndrea Arcangeli * missing, the *pmd may be already established and in 301c1a4de99SAndrea Arcangeli * turn it may also be a trans_huge_pmd. 302c1a4de99SAndrea Arcangeli */ 303c2febafcSKirill A. Shutemov return pmd_alloc(mm, pud, address); 304c1a4de99SAndrea Arcangeli } 305c1a4de99SAndrea Arcangeli 30660d4d2d2SMike Kravetz #ifdef CONFIG_HUGETLB_PAGE 30760d4d2d2SMike Kravetz /* 308a734991cSAxel Rasmussen * mfill_atomic processing for HUGETLB vmas. Note that this routine is 309c1e8d7c6SMichel Lespinasse * called with mmap_lock held, it will release mmap_lock before returning. 31060d4d2d2SMike Kravetz */ 31161c50040SAxel Rasmussen static __always_inline ssize_t mfill_atomic_hugetlb( 31260d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 31360d4d2d2SMike Kravetz unsigned long dst_start, 31460d4d2d2SMike Kravetz unsigned long src_start, 31560d4d2d2SMike Kravetz unsigned long len, 316d9712937SAxel Rasmussen uffd_flags_t flags) 31760d4d2d2SMike Kravetz { 31861c50040SAxel Rasmussen struct mm_struct *dst_mm = dst_vma->vm_mm; 3191c9e8defSMike Kravetz int vm_shared = dst_vma->vm_flags & VM_SHARED; 32060d4d2d2SMike Kravetz ssize_t err; 32160d4d2d2SMike Kravetz pte_t *dst_pte; 32260d4d2d2SMike Kravetz unsigned long src_addr, dst_addr; 32360d4d2d2SMike Kravetz long copied; 3240169fd51SZhangPeng struct folio *folio; 32560d4d2d2SMike Kravetz unsigned long vma_hpagesize; 32660d4d2d2SMike Kravetz pgoff_t idx; 32760d4d2d2SMike Kravetz u32 hash; 32860d4d2d2SMike Kravetz struct address_space *mapping; 32960d4d2d2SMike Kravetz 33060d4d2d2SMike Kravetz /* 33160d4d2d2SMike Kravetz * There is no default zero huge page for all huge page sizes as 33260d4d2d2SMike Kravetz * supported by hugetlb. A PMD_SIZE huge pages may exist as used 33360d4d2d2SMike Kravetz * by THP. Since we can not reliably insert a zero page, this 33460d4d2d2SMike Kravetz * feature is not supported. 33560d4d2d2SMike Kravetz */ 336d9712937SAxel Rasmussen if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) { 337d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 33860d4d2d2SMike Kravetz return -EINVAL; 33960d4d2d2SMike Kravetz } 34060d4d2d2SMike Kravetz 34160d4d2d2SMike Kravetz src_addr = src_start; 34260d4d2d2SMike Kravetz dst_addr = dst_start; 34360d4d2d2SMike Kravetz copied = 0; 3440169fd51SZhangPeng folio = NULL; 34560d4d2d2SMike Kravetz vma_hpagesize = vma_kernel_pagesize(dst_vma); 34660d4d2d2SMike Kravetz 34760d4d2d2SMike Kravetz /* 34860d4d2d2SMike Kravetz * Validate alignment based on huge page size 34960d4d2d2SMike Kravetz */ 35060d4d2d2SMike Kravetz err = -EINVAL; 35160d4d2d2SMike Kravetz if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) 35260d4d2d2SMike Kravetz goto out_unlock; 35360d4d2d2SMike Kravetz 35460d4d2d2SMike Kravetz retry: 35560d4d2d2SMike Kravetz /* 356c1e8d7c6SMichel Lespinasse * On routine entry dst_vma is set. If we had to drop mmap_lock and 35760d4d2d2SMike Kravetz * retry, dst_vma will be set to NULL and we must lookup again. 35860d4d2d2SMike Kravetz */ 35960d4d2d2SMike Kravetz if (!dst_vma) { 36027d02568SMike Rapoport err = -ENOENT; 361643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 36260d4d2d2SMike Kravetz if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) 36360d4d2d2SMike Kravetz goto out_unlock; 3641c9e8defSMike Kravetz 36527d02568SMike Rapoport err = -EINVAL; 36627d02568SMike Rapoport if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) 36727d02568SMike Rapoport goto out_unlock; 36827d02568SMike Rapoport 3691c9e8defSMike Kravetz vm_shared = dst_vma->vm_flags & VM_SHARED; 37060d4d2d2SMike Kravetz } 37160d4d2d2SMike Kravetz 37260d4d2d2SMike Kravetz /* 3731c9e8defSMike Kravetz * If not shared, ensure the dst_vma has a anon_vma. 37460d4d2d2SMike Kravetz */ 37560d4d2d2SMike Kravetz err = -ENOMEM; 3761c9e8defSMike Kravetz if (!vm_shared) { 37760d4d2d2SMike Kravetz if (unlikely(anon_vma_prepare(dst_vma))) 37860d4d2d2SMike Kravetz goto out_unlock; 3791c9e8defSMike Kravetz } 38060d4d2d2SMike Kravetz 38160d4d2d2SMike Kravetz while (src_addr < src_start + len) { 38260d4d2d2SMike Kravetz BUG_ON(dst_addr >= dst_start + len); 38360d4d2d2SMike Kravetz 38460d4d2d2SMike Kravetz /* 38540549ba8SMike Kravetz * Serialize via vma_lock and hugetlb_fault_mutex. 38640549ba8SMike Kravetz * vma_lock ensures the dst_pte remains valid even 38740549ba8SMike Kravetz * in the case of shared pmds. fault mutex prevents 38840549ba8SMike Kravetz * races with other faulting threads. 38960d4d2d2SMike Kravetz */ 390c0d0381aSMike Kravetz idx = linear_page_index(dst_vma, dst_addr); 3913a47c54fSMike Kravetz mapping = dst_vma->vm_file->f_mapping; 392188b04a7SWei Yang hash = hugetlb_fault_mutex_hash(mapping, idx); 39360d4d2d2SMike Kravetz mutex_lock(&hugetlb_fault_mutex_table[hash]); 39440549ba8SMike Kravetz hugetlb_vma_lock_read(dst_vma); 39560d4d2d2SMike Kravetz 39660d4d2d2SMike Kravetz err = -ENOMEM; 397aec44e0fSPeter Xu dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); 39860d4d2d2SMike Kravetz if (!dst_pte) { 39940549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 40060d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 40160d4d2d2SMike Kravetz goto out_unlock; 40260d4d2d2SMike Kravetz } 40360d4d2d2SMike Kravetz 404d9712937SAxel Rasmussen if (!uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE) && 4056041c691SPeter Xu !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { 40660d4d2d2SMike Kravetz err = -EEXIST; 40740549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 40860d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 40960d4d2d2SMike Kravetz goto out_unlock; 41060d4d2d2SMike Kravetz } 41160d4d2d2SMike Kravetz 412d9712937SAxel Rasmussen err = hugetlb_mfill_atomic_pte(dst_pte, dst_vma, dst_addr, 4130169fd51SZhangPeng src_addr, flags, &folio); 41460d4d2d2SMike Kravetz 41540549ba8SMike Kravetz hugetlb_vma_unlock_read(dst_vma); 41660d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 41760d4d2d2SMike Kravetz 41860d4d2d2SMike Kravetz cond_resched(); 41960d4d2d2SMike Kravetz 4209e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 421d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 4220169fd51SZhangPeng BUG_ON(!folio); 42360d4d2d2SMike Kravetz 4240169fd51SZhangPeng err = copy_folio_from_user(folio, 425e87340caSZhangPeng (const void __user *)src_addr, true); 42660d4d2d2SMike Kravetz if (unlikely(err)) { 42760d4d2d2SMike Kravetz err = -EFAULT; 42860d4d2d2SMike Kravetz goto out; 42960d4d2d2SMike Kravetz } 430d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 43160d4d2d2SMike Kravetz 43260d4d2d2SMike Kravetz dst_vma = NULL; 43360d4d2d2SMike Kravetz goto retry; 43460d4d2d2SMike Kravetz } else 4350169fd51SZhangPeng BUG_ON(folio); 43660d4d2d2SMike Kravetz 43760d4d2d2SMike Kravetz if (!err) { 43860d4d2d2SMike Kravetz dst_addr += vma_hpagesize; 43960d4d2d2SMike Kravetz src_addr += vma_hpagesize; 44060d4d2d2SMike Kravetz copied += vma_hpagesize; 44160d4d2d2SMike Kravetz 44260d4d2d2SMike Kravetz if (fatal_signal_pending(current)) 44360d4d2d2SMike Kravetz err = -EINTR; 44460d4d2d2SMike Kravetz } 44560d4d2d2SMike Kravetz if (err) 44660d4d2d2SMike Kravetz break; 44760d4d2d2SMike Kravetz } 44860d4d2d2SMike Kravetz 44960d4d2d2SMike Kravetz out_unlock: 450d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 45160d4d2d2SMike Kravetz out: 4520169fd51SZhangPeng if (folio) 4530169fd51SZhangPeng folio_put(folio); 45460d4d2d2SMike Kravetz BUG_ON(copied < 0); 45560d4d2d2SMike Kravetz BUG_ON(err > 0); 45660d4d2d2SMike Kravetz BUG_ON(!copied && !err); 45760d4d2d2SMike Kravetz return copied ? copied : err; 45860d4d2d2SMike Kravetz } 45960d4d2d2SMike Kravetz #else /* !CONFIG_HUGETLB_PAGE */ 46060d4d2d2SMike Kravetz /* fail at build time if gcc attempts to use this */ 46161c50040SAxel Rasmussen extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma, 46260d4d2d2SMike Kravetz unsigned long dst_start, 46360d4d2d2SMike Kravetz unsigned long src_start, 46460d4d2d2SMike Kravetz unsigned long len, 465d9712937SAxel Rasmussen uffd_flags_t flags); 46660d4d2d2SMike Kravetz #endif /* CONFIG_HUGETLB_PAGE */ 46760d4d2d2SMike Kravetz 46861c50040SAxel Rasmussen static __always_inline ssize_t mfill_atomic_pte(pmd_t *dst_pmd, 4693217d3c7SMike Rapoport struct vm_area_struct *dst_vma, 4703217d3c7SMike Rapoport unsigned long dst_addr, 4713217d3c7SMike Rapoport unsigned long src_addr, 472d9712937SAxel Rasmussen uffd_flags_t flags, 473*d7be6d7eSZhangPeng struct folio **foliop) 4743217d3c7SMike Rapoport { 4753217d3c7SMike Rapoport ssize_t err; 4763217d3c7SMike Rapoport 477d9712937SAxel Rasmussen if (uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) { 47861c50040SAxel Rasmussen return mfill_atomic_pte_continue(dst_pmd, dst_vma, 479d9712937SAxel Rasmussen dst_addr, flags); 48015313257SAxel Rasmussen } 48115313257SAxel Rasmussen 4825b51072eSAndrea Arcangeli /* 4835b51072eSAndrea Arcangeli * The normal page fault path for a shmem will invoke the 4845b51072eSAndrea Arcangeli * fault, fill the hole in the file and COW it right away. The 4855b51072eSAndrea Arcangeli * result generates plain anonymous memory. So when we are 4865b51072eSAndrea Arcangeli * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll 4875b51072eSAndrea Arcangeli * generate anonymous memory directly without actually filling 4885b51072eSAndrea Arcangeli * the hole. For the MAP_PRIVATE case the robustness check 4895b51072eSAndrea Arcangeli * only happens in the pagetable (to verify it's still none) 4905b51072eSAndrea Arcangeli * and not in the radix tree. 4915b51072eSAndrea Arcangeli */ 4925b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED)) { 493d9712937SAxel Rasmussen if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) 49461c50040SAxel Rasmussen err = mfill_atomic_pte_copy(dst_pmd, dst_vma, 495d9712937SAxel Rasmussen dst_addr, src_addr, 496*d7be6d7eSZhangPeng flags, foliop); 4973217d3c7SMike Rapoport else 49861c50040SAxel Rasmussen err = mfill_atomic_pte_zeropage(dst_pmd, 4993217d3c7SMike Rapoport dst_vma, dst_addr); 5003217d3c7SMike Rapoport } else { 50161c50040SAxel Rasmussen err = shmem_mfill_atomic_pte(dst_pmd, dst_vma, 50215313257SAxel Rasmussen dst_addr, src_addr, 503*d7be6d7eSZhangPeng flags, foliop); 5043217d3c7SMike Rapoport } 5053217d3c7SMike Rapoport 5063217d3c7SMike Rapoport return err; 5073217d3c7SMike Rapoport } 5083217d3c7SMike Rapoport 509a734991cSAxel Rasmussen static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, 510c1a4de99SAndrea Arcangeli unsigned long dst_start, 511c1a4de99SAndrea Arcangeli unsigned long src_start, 512c1a4de99SAndrea Arcangeli unsigned long len, 513a759a909SNadav Amit atomic_t *mmap_changing, 514d9712937SAxel Rasmussen uffd_flags_t flags) 515c1a4de99SAndrea Arcangeli { 516c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma; 517c1a4de99SAndrea Arcangeli ssize_t err; 518c1a4de99SAndrea Arcangeli pmd_t *dst_pmd; 519c1a4de99SAndrea Arcangeli unsigned long src_addr, dst_addr; 520b6ebaedbSAndrea Arcangeli long copied; 521*d7be6d7eSZhangPeng struct folio *folio; 522c1a4de99SAndrea Arcangeli 523c1a4de99SAndrea Arcangeli /* 524c1a4de99SAndrea Arcangeli * Sanitize the command parameters: 525c1a4de99SAndrea Arcangeli */ 526c1a4de99SAndrea Arcangeli BUG_ON(dst_start & ~PAGE_MASK); 527c1a4de99SAndrea Arcangeli BUG_ON(len & ~PAGE_MASK); 528c1a4de99SAndrea Arcangeli 529c1a4de99SAndrea Arcangeli /* Does the address range wrap, or is the span zero-sized? */ 530c1a4de99SAndrea Arcangeli BUG_ON(src_start + len <= src_start); 531c1a4de99SAndrea Arcangeli BUG_ON(dst_start + len <= dst_start); 532c1a4de99SAndrea Arcangeli 533b6ebaedbSAndrea Arcangeli src_addr = src_start; 534b6ebaedbSAndrea Arcangeli dst_addr = dst_start; 535b6ebaedbSAndrea Arcangeli copied = 0; 536*d7be6d7eSZhangPeng folio = NULL; 537b6ebaedbSAndrea Arcangeli retry: 538d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 539c1a4de99SAndrea Arcangeli 540c1a4de99SAndrea Arcangeli /* 541df2cc96eSMike Rapoport * If memory mappings are changing because of non-cooperative 542df2cc96eSMike Rapoport * operation (e.g. mremap) running in parallel, bail out and 543df2cc96eSMike Rapoport * request the user to retry later 544df2cc96eSMike Rapoport */ 545df2cc96eSMike Rapoport err = -EAGAIN; 546a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 547df2cc96eSMike Rapoport goto out_unlock; 548df2cc96eSMike Rapoport 549df2cc96eSMike Rapoport /* 550c1a4de99SAndrea Arcangeli * Make sure the vma is not shared, that the dst range is 551c1a4de99SAndrea Arcangeli * both valid and fully within a single existing vma. 552c1a4de99SAndrea Arcangeli */ 55327d02568SMike Rapoport err = -ENOENT; 554643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 55526071cedSMike Rapoport if (!dst_vma) 55626071cedSMike Rapoport goto out_unlock; 55727d02568SMike Rapoport 55827d02568SMike Rapoport err = -EINVAL; 55927d02568SMike Rapoport /* 56027d02568SMike Rapoport * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but 56127d02568SMike Rapoport * it will overwrite vm_ops, so vma_is_anonymous must return false. 56227d02568SMike Rapoport */ 56327d02568SMike Rapoport if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && 56427d02568SMike Rapoport dst_vma->vm_flags & VM_SHARED)) 56527d02568SMike Rapoport goto out_unlock; 56627d02568SMike Rapoport 56727d02568SMike Rapoport /* 56872981e0eSAndrea Arcangeli * validate 'mode' now that we know the dst_vma: don't allow 56972981e0eSAndrea Arcangeli * a wrprotect copy if the userfaultfd didn't register as WP. 57072981e0eSAndrea Arcangeli */ 571d9712937SAxel Rasmussen if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP)) 57272981e0eSAndrea Arcangeli goto out_unlock; 57372981e0eSAndrea Arcangeli 57472981e0eSAndrea Arcangeli /* 57527d02568SMike Rapoport * If this is a HUGETLB vma, pass off to appropriate routine 57627d02568SMike Rapoport */ 57727d02568SMike Rapoport if (is_vm_hugetlb_page(dst_vma)) 57861c50040SAxel Rasmussen return mfill_atomic_hugetlb(dst_vma, dst_start, 579d9712937SAxel Rasmussen src_start, len, flags); 58027d02568SMike Rapoport 58126071cedSMike Rapoport if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) 582b6ebaedbSAndrea Arcangeli goto out_unlock; 583d9712937SAxel Rasmussen if (!vma_is_shmem(dst_vma) && 584d9712937SAxel Rasmussen uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) 585f6191471SAxel Rasmussen goto out_unlock; 586c1a4de99SAndrea Arcangeli 587c1a4de99SAndrea Arcangeli /* 588c1a4de99SAndrea Arcangeli * Ensure the dst_vma has a anon_vma or this page 589c1a4de99SAndrea Arcangeli * would get a NULL anon_vma when moved in the 590c1a4de99SAndrea Arcangeli * dst_vma. 591c1a4de99SAndrea Arcangeli */ 592c1a4de99SAndrea Arcangeli err = -ENOMEM; 5935b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED) && 5945b51072eSAndrea Arcangeli unlikely(anon_vma_prepare(dst_vma))) 595b6ebaedbSAndrea Arcangeli goto out_unlock; 596c1a4de99SAndrea Arcangeli 597b6ebaedbSAndrea Arcangeli while (src_addr < src_start + len) { 598c1a4de99SAndrea Arcangeli pmd_t dst_pmdval; 599b6ebaedbSAndrea Arcangeli 600c1a4de99SAndrea Arcangeli BUG_ON(dst_addr >= dst_start + len); 601b6ebaedbSAndrea Arcangeli 602c1a4de99SAndrea Arcangeli dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); 603c1a4de99SAndrea Arcangeli if (unlikely(!dst_pmd)) { 604c1a4de99SAndrea Arcangeli err = -ENOMEM; 605c1a4de99SAndrea Arcangeli break; 606c1a4de99SAndrea Arcangeli } 607c1a4de99SAndrea Arcangeli 608dab6e717SPeter Zijlstra dst_pmdval = pmdp_get_lockless(dst_pmd); 609c1a4de99SAndrea Arcangeli /* 610c1a4de99SAndrea Arcangeli * If the dst_pmd is mapped as THP don't 611c1a4de99SAndrea Arcangeli * override it and just be strict. 612c1a4de99SAndrea Arcangeli */ 613c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(dst_pmdval))) { 614c1a4de99SAndrea Arcangeli err = -EEXIST; 615c1a4de99SAndrea Arcangeli break; 616c1a4de99SAndrea Arcangeli } 617c1a4de99SAndrea Arcangeli if (unlikely(pmd_none(dst_pmdval)) && 6184cf58924SJoel Fernandes (Google) unlikely(__pte_alloc(dst_mm, dst_pmd))) { 619c1a4de99SAndrea Arcangeli err = -ENOMEM; 620c1a4de99SAndrea Arcangeli break; 621c1a4de99SAndrea Arcangeli } 622c1a4de99SAndrea Arcangeli /* If an huge pmd materialized from under us fail */ 623c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(*dst_pmd))) { 624c1a4de99SAndrea Arcangeli err = -EFAULT; 625c1a4de99SAndrea Arcangeli break; 626c1a4de99SAndrea Arcangeli } 627c1a4de99SAndrea Arcangeli 628c1a4de99SAndrea Arcangeli BUG_ON(pmd_none(*dst_pmd)); 629c1a4de99SAndrea Arcangeli BUG_ON(pmd_trans_huge(*dst_pmd)); 630c1a4de99SAndrea Arcangeli 63161c50040SAxel Rasmussen err = mfill_atomic_pte(dst_pmd, dst_vma, dst_addr, 632*d7be6d7eSZhangPeng src_addr, flags, &folio); 633c1a4de99SAndrea Arcangeli cond_resched(); 634c1a4de99SAndrea Arcangeli 6359e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 636*d7be6d7eSZhangPeng void *kaddr; 637b6ebaedbSAndrea Arcangeli 638d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 639*d7be6d7eSZhangPeng BUG_ON(!folio); 640b6ebaedbSAndrea Arcangeli 641*d7be6d7eSZhangPeng kaddr = kmap_local_folio(folio, 0); 642*d7be6d7eSZhangPeng err = copy_from_user(kaddr, 643b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 644b6ebaedbSAndrea Arcangeli PAGE_SIZE); 645*d7be6d7eSZhangPeng kunmap_local(kaddr); 646b6ebaedbSAndrea Arcangeli if (unlikely(err)) { 647b6ebaedbSAndrea Arcangeli err = -EFAULT; 648b6ebaedbSAndrea Arcangeli goto out; 649b6ebaedbSAndrea Arcangeli } 650*d7be6d7eSZhangPeng flush_dcache_folio(folio); 651b6ebaedbSAndrea Arcangeli goto retry; 652b6ebaedbSAndrea Arcangeli } else 653*d7be6d7eSZhangPeng BUG_ON(folio); 654b6ebaedbSAndrea Arcangeli 655c1a4de99SAndrea Arcangeli if (!err) { 656c1a4de99SAndrea Arcangeli dst_addr += PAGE_SIZE; 657c1a4de99SAndrea Arcangeli src_addr += PAGE_SIZE; 658c1a4de99SAndrea Arcangeli copied += PAGE_SIZE; 659c1a4de99SAndrea Arcangeli 660c1a4de99SAndrea Arcangeli if (fatal_signal_pending(current)) 661c1a4de99SAndrea Arcangeli err = -EINTR; 662c1a4de99SAndrea Arcangeli } 663c1a4de99SAndrea Arcangeli if (err) 664c1a4de99SAndrea Arcangeli break; 665c1a4de99SAndrea Arcangeli } 666c1a4de99SAndrea Arcangeli 667b6ebaedbSAndrea Arcangeli out_unlock: 668d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 669b6ebaedbSAndrea Arcangeli out: 670*d7be6d7eSZhangPeng if (folio) 671*d7be6d7eSZhangPeng folio_put(folio); 672c1a4de99SAndrea Arcangeli BUG_ON(copied < 0); 673c1a4de99SAndrea Arcangeli BUG_ON(err > 0); 674c1a4de99SAndrea Arcangeli BUG_ON(!copied && !err); 675c1a4de99SAndrea Arcangeli return copied ? copied : err; 676c1a4de99SAndrea Arcangeli } 677c1a4de99SAndrea Arcangeli 678a734991cSAxel Rasmussen ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, 679df2cc96eSMike Rapoport unsigned long src_start, unsigned long len, 680d9712937SAxel Rasmussen atomic_t *mmap_changing, uffd_flags_t flags) 681c1a4de99SAndrea Arcangeli { 682d9712937SAxel Rasmussen return mfill_atomic(dst_mm, dst_start, src_start, len, mmap_changing, 683d9712937SAxel Rasmussen uffd_flags_set_mode(flags, MFILL_ATOMIC_COPY)); 684c1a4de99SAndrea Arcangeli } 685c1a4de99SAndrea Arcangeli 686a734991cSAxel Rasmussen ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start, 687a759a909SNadav Amit unsigned long len, atomic_t *mmap_changing) 688c1a4de99SAndrea Arcangeli { 689d9712937SAxel Rasmussen return mfill_atomic(dst_mm, start, 0, len, mmap_changing, 690d9712937SAxel Rasmussen uffd_flags_set_mode(0, MFILL_ATOMIC_ZEROPAGE)); 691f6191471SAxel Rasmussen } 692f6191471SAxel Rasmussen 693a734991cSAxel Rasmussen ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start, 69402891844SAxel Rasmussen unsigned long len, atomic_t *mmap_changing, 69502891844SAxel Rasmussen uffd_flags_t flags) 696f6191471SAxel Rasmussen { 697d9712937SAxel Rasmussen return mfill_atomic(dst_mm, start, 0, len, mmap_changing, 69802891844SAxel Rasmussen uffd_flags_set_mode(flags, MFILL_ATOMIC_CONTINUE)); 699c1a4de99SAndrea Arcangeli } 700ffd05793SShaohua Li 70161c50040SAxel Rasmussen long uffd_wp_range(struct vm_area_struct *dst_vma, 702f369b07cSPeter Xu unsigned long start, unsigned long len, bool enable_wp) 703f369b07cSPeter Xu { 704931298e1SDavid Hildenbrand unsigned int mm_cp_flags; 705f369b07cSPeter Xu struct mmu_gather tlb; 706d1751118SPeter Xu long ret; 707f369b07cSPeter Xu 708a1b92a3fSMuhammad Usama Anjum VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end, 709a1b92a3fSMuhammad Usama Anjum "The address range exceeds VMA boundary.\n"); 710f369b07cSPeter Xu if (enable_wp) 711931298e1SDavid Hildenbrand mm_cp_flags = MM_CP_UFFD_WP; 712f369b07cSPeter Xu else 713931298e1SDavid Hildenbrand mm_cp_flags = MM_CP_UFFD_WP_RESOLVE; 714f369b07cSPeter Xu 715931298e1SDavid Hildenbrand /* 716931298e1SDavid Hildenbrand * vma->vm_page_prot already reflects that uffd-wp is enabled for this 717931298e1SDavid Hildenbrand * VMA (see userfaultfd_set_vm_flags()) and that all PTEs are supposed 718931298e1SDavid Hildenbrand * to be write-protected as default whenever protection changes. 719931298e1SDavid Hildenbrand * Try upgrading write permissions manually. 720931298e1SDavid Hildenbrand */ 721931298e1SDavid Hildenbrand if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma)) 722931298e1SDavid Hildenbrand mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 72361c50040SAxel Rasmussen tlb_gather_mmu(&tlb, dst_vma->vm_mm); 724d1751118SPeter Xu ret = change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); 725f369b07cSPeter Xu tlb_finish_mmu(&tlb); 726d1751118SPeter Xu 727d1751118SPeter Xu return ret; 728f369b07cSPeter Xu } 729f369b07cSPeter Xu 730ffd05793SShaohua Li int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, 731a759a909SNadav Amit unsigned long len, bool enable_wp, 732a759a909SNadav Amit atomic_t *mmap_changing) 733ffd05793SShaohua Li { 734a1b92a3fSMuhammad Usama Anjum unsigned long end = start + len; 735a1b92a3fSMuhammad Usama Anjum unsigned long _start, _end; 736ffd05793SShaohua Li struct vm_area_struct *dst_vma; 7375a90d5a1SPeter Xu unsigned long page_mask; 738d1751118SPeter Xu long err; 739a1b92a3fSMuhammad Usama Anjum VMA_ITERATOR(vmi, dst_mm, start); 740ffd05793SShaohua Li 741ffd05793SShaohua Li /* 742ffd05793SShaohua Li * Sanitize the command parameters: 743ffd05793SShaohua Li */ 744ffd05793SShaohua Li BUG_ON(start & ~PAGE_MASK); 745ffd05793SShaohua Li BUG_ON(len & ~PAGE_MASK); 746ffd05793SShaohua Li 747ffd05793SShaohua Li /* Does the address range wrap, or is the span zero-sized? */ 748ffd05793SShaohua Li BUG_ON(start + len <= start); 749ffd05793SShaohua Li 750d8ed45c5SMichel Lespinasse mmap_read_lock(dst_mm); 751ffd05793SShaohua Li 752ffd05793SShaohua Li /* 753ffd05793SShaohua Li * If memory mappings are changing because of non-cooperative 754ffd05793SShaohua Li * operation (e.g. mremap) running in parallel, bail out and 755ffd05793SShaohua Li * request the user to retry later 756ffd05793SShaohua Li */ 757ffd05793SShaohua Li err = -EAGAIN; 758a759a909SNadav Amit if (mmap_changing && atomic_read(mmap_changing)) 759ffd05793SShaohua Li goto out_unlock; 760ffd05793SShaohua Li 761ffd05793SShaohua Li err = -ENOENT; 762a1b92a3fSMuhammad Usama Anjum for_each_vma_range(vmi, dst_vma, end) { 763b1f9e876SPeter Xu 764a1b92a3fSMuhammad Usama Anjum if (!userfaultfd_wp(dst_vma)) { 765a1b92a3fSMuhammad Usama Anjum err = -ENOENT; 766a1b92a3fSMuhammad Usama Anjum break; 767a1b92a3fSMuhammad Usama Anjum } 768ffd05793SShaohua Li 7695a90d5a1SPeter Xu if (is_vm_hugetlb_page(dst_vma)) { 7705a90d5a1SPeter Xu err = -EINVAL; 7715a90d5a1SPeter Xu page_mask = vma_kernel_pagesize(dst_vma) - 1; 7725a90d5a1SPeter Xu if ((start & page_mask) || (len & page_mask)) 773a1b92a3fSMuhammad Usama Anjum break; 7745a90d5a1SPeter Xu } 7755a90d5a1SPeter Xu 776a1b92a3fSMuhammad Usama Anjum _start = max(dst_vma->vm_start, start); 777a1b92a3fSMuhammad Usama Anjum _end = min(dst_vma->vm_end, end); 778a1b92a3fSMuhammad Usama Anjum 77961c50040SAxel Rasmussen err = uffd_wp_range(dst_vma, _start, _end - _start, enable_wp); 780ffd05793SShaohua Li 781d1751118SPeter Xu /* Return 0 on success, <0 on failures */ 782a1b92a3fSMuhammad Usama Anjum if (err < 0) 783a1b92a3fSMuhammad Usama Anjum break; 784ffd05793SShaohua Li err = 0; 785a1b92a3fSMuhammad Usama Anjum } 786ffd05793SShaohua Li out_unlock: 787d8ed45c5SMichel Lespinasse mmap_read_unlock(dst_mm); 788ffd05793SShaohua Li return err; 789ffd05793SShaohua Li } 790