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> 19c1a4de99SAndrea Arcangeli #include "internal.h" 20c1a4de99SAndrea Arcangeli 21643aa36eSWei Yang static __always_inline 22643aa36eSWei Yang struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, 23643aa36eSWei Yang unsigned long dst_start, 24643aa36eSWei Yang unsigned long len) 25643aa36eSWei Yang { 26643aa36eSWei Yang /* 27643aa36eSWei Yang * Make sure that the dst range is both valid and fully within a 28643aa36eSWei Yang * single existing vma. 29643aa36eSWei Yang */ 30643aa36eSWei Yang struct vm_area_struct *dst_vma; 31643aa36eSWei Yang 32643aa36eSWei Yang dst_vma = find_vma(dst_mm, dst_start); 33643aa36eSWei Yang if (!dst_vma) 34643aa36eSWei Yang return NULL; 35643aa36eSWei Yang 36643aa36eSWei Yang if (dst_start < dst_vma->vm_start || 37643aa36eSWei Yang dst_start + len > dst_vma->vm_end) 38643aa36eSWei Yang return NULL; 39643aa36eSWei Yang 40643aa36eSWei Yang /* 41643aa36eSWei Yang * Check the vma is registered in uffd, this is required to 42643aa36eSWei Yang * enforce the VM_MAYWRITE check done at uffd registration 43643aa36eSWei Yang * time. 44643aa36eSWei Yang */ 45643aa36eSWei Yang if (!dst_vma->vm_userfaultfd_ctx.ctx) 46643aa36eSWei Yang return NULL; 47643aa36eSWei Yang 48643aa36eSWei Yang return dst_vma; 49643aa36eSWei Yang } 50643aa36eSWei Yang 51c1a4de99SAndrea Arcangeli static int mcopy_atomic_pte(struct mm_struct *dst_mm, 52c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 53c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 54c1a4de99SAndrea Arcangeli unsigned long dst_addr, 55b6ebaedbSAndrea Arcangeli unsigned long src_addr, 5672981e0eSAndrea Arcangeli struct page **pagep, 5772981e0eSAndrea Arcangeli bool wp_copy) 58c1a4de99SAndrea Arcangeli { 59c1a4de99SAndrea Arcangeli struct mem_cgroup *memcg; 60c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 61c1a4de99SAndrea Arcangeli spinlock_t *ptl; 62c1a4de99SAndrea Arcangeli void *page_kaddr; 63c1a4de99SAndrea Arcangeli int ret; 64b6ebaedbSAndrea Arcangeli struct page *page; 65e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 66e2a50c1fSAndrea Arcangeli struct inode *inode; 67c1a4de99SAndrea Arcangeli 68b6ebaedbSAndrea Arcangeli if (!*pagep) { 69c1a4de99SAndrea Arcangeli ret = -ENOMEM; 70c1a4de99SAndrea Arcangeli page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); 71c1a4de99SAndrea Arcangeli if (!page) 72c1a4de99SAndrea Arcangeli goto out; 73c1a4de99SAndrea Arcangeli 74b6ebaedbSAndrea Arcangeli page_kaddr = kmap_atomic(page); 75b6ebaedbSAndrea Arcangeli ret = copy_from_user(page_kaddr, 76b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 77b6ebaedbSAndrea Arcangeli PAGE_SIZE); 78b6ebaedbSAndrea Arcangeli kunmap_atomic(page_kaddr); 79b6ebaedbSAndrea Arcangeli 80b6ebaedbSAndrea Arcangeli /* fallback to copy_from_user outside mmap_sem */ 81b6ebaedbSAndrea Arcangeli if (unlikely(ret)) { 829e368259SAndrea Arcangeli ret = -ENOENT; 83b6ebaedbSAndrea Arcangeli *pagep = page; 84b6ebaedbSAndrea Arcangeli /* don't free the page */ 85b6ebaedbSAndrea Arcangeli goto out; 86b6ebaedbSAndrea Arcangeli } 87b6ebaedbSAndrea Arcangeli } else { 88b6ebaedbSAndrea Arcangeli page = *pagep; 89b6ebaedbSAndrea Arcangeli *pagep = NULL; 90b6ebaedbSAndrea Arcangeli } 91c1a4de99SAndrea Arcangeli 92c1a4de99SAndrea Arcangeli /* 93c1a4de99SAndrea Arcangeli * The memory barrier inside __SetPageUptodate makes sure that 94f4f5329dSWei Yang * preceding stores to the page contents become visible before 95c1a4de99SAndrea Arcangeli * the set_pte_at() write. 96c1a4de99SAndrea Arcangeli */ 97c1a4de99SAndrea Arcangeli __SetPageUptodate(page); 98c1a4de99SAndrea Arcangeli 99c1a4de99SAndrea Arcangeli ret = -ENOMEM; 100f627c2f5SKirill A. Shutemov if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) 101c1a4de99SAndrea Arcangeli goto out_release; 102c1a4de99SAndrea Arcangeli 10372981e0eSAndrea Arcangeli _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); 104292924b2SPeter Xu if (dst_vma->vm_flags & VM_WRITE) { 105292924b2SPeter Xu if (wp_copy) 106292924b2SPeter Xu _dst_pte = pte_mkuffd_wp(_dst_pte); 107292924b2SPeter Xu else 10872981e0eSAndrea Arcangeli _dst_pte = pte_mkwrite(_dst_pte); 109292924b2SPeter Xu } 110c1a4de99SAndrea Arcangeli 111c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 112e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 113e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 114e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 115e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 116e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 117e2a50c1fSAndrea Arcangeli ret = -EFAULT; 118e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 119e2a50c1fSAndrea Arcangeli goto out_release_uncharge_unlock; 120e2a50c1fSAndrea Arcangeli } 121e2a50c1fSAndrea Arcangeli ret = -EEXIST; 122c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 123c1a4de99SAndrea Arcangeli goto out_release_uncharge_unlock; 124c1a4de99SAndrea Arcangeli 125c1a4de99SAndrea Arcangeli inc_mm_counter(dst_mm, MM_ANONPAGES); 126d281ee61SKirill A. Shutemov page_add_new_anon_rmap(page, dst_vma, dst_addr, false); 127f627c2f5SKirill A. Shutemov mem_cgroup_commit_charge(page, memcg, false, false); 128c1a4de99SAndrea Arcangeli lru_cache_add_active_or_unevictable(page, dst_vma); 129c1a4de99SAndrea Arcangeli 130c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 131c1a4de99SAndrea Arcangeli 132c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 133c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 134c1a4de99SAndrea Arcangeli 135c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 136c1a4de99SAndrea Arcangeli ret = 0; 137c1a4de99SAndrea Arcangeli out: 138c1a4de99SAndrea Arcangeli return ret; 139c1a4de99SAndrea Arcangeli out_release_uncharge_unlock: 140c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 141f627c2f5SKirill A. Shutemov mem_cgroup_cancel_charge(page, memcg, false); 142c1a4de99SAndrea Arcangeli out_release: 14309cbfeafSKirill A. Shutemov put_page(page); 144c1a4de99SAndrea Arcangeli goto out; 145c1a4de99SAndrea Arcangeli } 146c1a4de99SAndrea Arcangeli 147c1a4de99SAndrea Arcangeli static int mfill_zeropage_pte(struct mm_struct *dst_mm, 148c1a4de99SAndrea Arcangeli pmd_t *dst_pmd, 149c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma, 150c1a4de99SAndrea Arcangeli unsigned long dst_addr) 151c1a4de99SAndrea Arcangeli { 152c1a4de99SAndrea Arcangeli pte_t _dst_pte, *dst_pte; 153c1a4de99SAndrea Arcangeli spinlock_t *ptl; 154c1a4de99SAndrea Arcangeli int ret; 155e2a50c1fSAndrea Arcangeli pgoff_t offset, max_off; 156e2a50c1fSAndrea Arcangeli struct inode *inode; 157c1a4de99SAndrea Arcangeli 158c1a4de99SAndrea Arcangeli _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), 159c1a4de99SAndrea Arcangeli dst_vma->vm_page_prot)); 160c1a4de99SAndrea Arcangeli dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); 161e2a50c1fSAndrea Arcangeli if (dst_vma->vm_file) { 162e2a50c1fSAndrea Arcangeli /* the shmem MAP_PRIVATE case requires checking the i_size */ 163e2a50c1fSAndrea Arcangeli inode = dst_vma->vm_file->f_inode; 164e2a50c1fSAndrea Arcangeli offset = linear_page_index(dst_vma, dst_addr); 165e2a50c1fSAndrea Arcangeli max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); 166e2a50c1fSAndrea Arcangeli ret = -EFAULT; 167e2a50c1fSAndrea Arcangeli if (unlikely(offset >= max_off)) 168e2a50c1fSAndrea Arcangeli goto out_unlock; 169e2a50c1fSAndrea Arcangeli } 170e2a50c1fSAndrea Arcangeli ret = -EEXIST; 171c1a4de99SAndrea Arcangeli if (!pte_none(*dst_pte)) 172c1a4de99SAndrea Arcangeli goto out_unlock; 173c1a4de99SAndrea Arcangeli set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); 174c1a4de99SAndrea Arcangeli /* No need to invalidate - it was non-present before */ 175c1a4de99SAndrea Arcangeli update_mmu_cache(dst_vma, dst_addr, dst_pte); 176c1a4de99SAndrea Arcangeli ret = 0; 177c1a4de99SAndrea Arcangeli out_unlock: 178c1a4de99SAndrea Arcangeli pte_unmap_unlock(dst_pte, ptl); 179c1a4de99SAndrea Arcangeli return ret; 180c1a4de99SAndrea Arcangeli } 181c1a4de99SAndrea Arcangeli 182c1a4de99SAndrea Arcangeli static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) 183c1a4de99SAndrea Arcangeli { 184c1a4de99SAndrea Arcangeli pgd_t *pgd; 185c2febafcSKirill A. Shutemov p4d_t *p4d; 186c1a4de99SAndrea Arcangeli pud_t *pud; 187c1a4de99SAndrea Arcangeli 188c1a4de99SAndrea Arcangeli pgd = pgd_offset(mm, address); 189c2febafcSKirill A. Shutemov p4d = p4d_alloc(mm, pgd, address); 190c2febafcSKirill A. Shutemov if (!p4d) 191c2febafcSKirill A. Shutemov return NULL; 192c2febafcSKirill A. Shutemov pud = pud_alloc(mm, p4d, address); 193c2febafcSKirill A. Shutemov if (!pud) 194c2febafcSKirill A. Shutemov return NULL; 195c1a4de99SAndrea Arcangeli /* 196c1a4de99SAndrea Arcangeli * Note that we didn't run this because the pmd was 197c1a4de99SAndrea Arcangeli * missing, the *pmd may be already established and in 198c1a4de99SAndrea Arcangeli * turn it may also be a trans_huge_pmd. 199c1a4de99SAndrea Arcangeli */ 200c2febafcSKirill A. Shutemov return pmd_alloc(mm, pud, address); 201c1a4de99SAndrea Arcangeli } 202c1a4de99SAndrea Arcangeli 20360d4d2d2SMike Kravetz #ifdef CONFIG_HUGETLB_PAGE 20460d4d2d2SMike Kravetz /* 20560d4d2d2SMike Kravetz * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is 20660d4d2d2SMike Kravetz * called with mmap_sem held, it will release mmap_sem before returning. 20760d4d2d2SMike Kravetz */ 20860d4d2d2SMike Kravetz static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 20960d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 21060d4d2d2SMike Kravetz unsigned long dst_start, 21160d4d2d2SMike Kravetz unsigned long src_start, 21260d4d2d2SMike Kravetz unsigned long len, 21360d4d2d2SMike Kravetz bool zeropage) 21460d4d2d2SMike Kravetz { 2151c9e8defSMike Kravetz int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; 2161c9e8defSMike Kravetz int vm_shared = dst_vma->vm_flags & VM_SHARED; 21760d4d2d2SMike Kravetz ssize_t err; 21860d4d2d2SMike Kravetz pte_t *dst_pte; 21960d4d2d2SMike Kravetz unsigned long src_addr, dst_addr; 22060d4d2d2SMike Kravetz long copied; 22160d4d2d2SMike Kravetz struct page *page; 22260d4d2d2SMike Kravetz unsigned long vma_hpagesize; 22360d4d2d2SMike Kravetz pgoff_t idx; 22460d4d2d2SMike Kravetz u32 hash; 22560d4d2d2SMike Kravetz struct address_space *mapping; 22660d4d2d2SMike Kravetz 22760d4d2d2SMike Kravetz /* 22860d4d2d2SMike Kravetz * There is no default zero huge page for all huge page sizes as 22960d4d2d2SMike Kravetz * supported by hugetlb. A PMD_SIZE huge pages may exist as used 23060d4d2d2SMike Kravetz * by THP. Since we can not reliably insert a zero page, this 23160d4d2d2SMike Kravetz * feature is not supported. 23260d4d2d2SMike Kravetz */ 23360d4d2d2SMike Kravetz if (zeropage) { 23460d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 23560d4d2d2SMike Kravetz return -EINVAL; 23660d4d2d2SMike Kravetz } 23760d4d2d2SMike Kravetz 23860d4d2d2SMike Kravetz src_addr = src_start; 23960d4d2d2SMike Kravetz dst_addr = dst_start; 24060d4d2d2SMike Kravetz copied = 0; 24160d4d2d2SMike Kravetz page = NULL; 24260d4d2d2SMike Kravetz vma_hpagesize = vma_kernel_pagesize(dst_vma); 24360d4d2d2SMike Kravetz 24460d4d2d2SMike Kravetz /* 24560d4d2d2SMike Kravetz * Validate alignment based on huge page size 24660d4d2d2SMike Kravetz */ 24760d4d2d2SMike Kravetz err = -EINVAL; 24860d4d2d2SMike Kravetz if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) 24960d4d2d2SMike Kravetz goto out_unlock; 25060d4d2d2SMike Kravetz 25160d4d2d2SMike Kravetz retry: 25260d4d2d2SMike Kravetz /* 25360d4d2d2SMike Kravetz * On routine entry dst_vma is set. If we had to drop mmap_sem and 25460d4d2d2SMike Kravetz * retry, dst_vma will be set to NULL and we must lookup again. 25560d4d2d2SMike Kravetz */ 25660d4d2d2SMike Kravetz if (!dst_vma) { 25727d02568SMike Rapoport err = -ENOENT; 258643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 25960d4d2d2SMike Kravetz if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) 26060d4d2d2SMike Kravetz goto out_unlock; 2611c9e8defSMike Kravetz 26227d02568SMike Rapoport err = -EINVAL; 26327d02568SMike Rapoport if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) 26427d02568SMike Rapoport goto out_unlock; 26527d02568SMike Rapoport 2661c9e8defSMike Kravetz vm_shared = dst_vma->vm_flags & VM_SHARED; 26760d4d2d2SMike Kravetz } 26860d4d2d2SMike Kravetz 26960d4d2d2SMike Kravetz /* 2701c9e8defSMike Kravetz * If not shared, ensure the dst_vma has a anon_vma. 27160d4d2d2SMike Kravetz */ 27260d4d2d2SMike Kravetz err = -ENOMEM; 2731c9e8defSMike Kravetz if (!vm_shared) { 27460d4d2d2SMike Kravetz if (unlikely(anon_vma_prepare(dst_vma))) 27560d4d2d2SMike Kravetz goto out_unlock; 2761c9e8defSMike Kravetz } 27760d4d2d2SMike Kravetz 27860d4d2d2SMike Kravetz while (src_addr < src_start + len) { 27960d4d2d2SMike Kravetz pte_t dst_pteval; 28060d4d2d2SMike Kravetz 28160d4d2d2SMike Kravetz BUG_ON(dst_addr >= dst_start + len); 28260d4d2d2SMike Kravetz 28360d4d2d2SMike Kravetz /* 284c0d0381aSMike Kravetz * Serialize via i_mmap_rwsem and hugetlb_fault_mutex. 285c0d0381aSMike Kravetz * i_mmap_rwsem ensures the dst_pte remains valid even 286c0d0381aSMike Kravetz * in the case of shared pmds. fault mutex prevents 287c0d0381aSMike Kravetz * races with other faulting threads. 28860d4d2d2SMike Kravetz */ 289ddeaab32SMike Kravetz mapping = dst_vma->vm_file->f_mapping; 290c0d0381aSMike Kravetz i_mmap_lock_read(mapping); 291c0d0381aSMike Kravetz idx = linear_page_index(dst_vma, dst_addr); 292188b04a7SWei Yang hash = hugetlb_fault_mutex_hash(mapping, idx); 29360d4d2d2SMike Kravetz mutex_lock(&hugetlb_fault_mutex_table[hash]); 29460d4d2d2SMike Kravetz 29560d4d2d2SMike Kravetz err = -ENOMEM; 2964fb07ee6SWei Yang dst_pte = huge_pte_alloc(dst_mm, dst_addr, vma_hpagesize); 29760d4d2d2SMike Kravetz if (!dst_pte) { 29860d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 299c0d0381aSMike Kravetz i_mmap_unlock_read(mapping); 30060d4d2d2SMike Kravetz goto out_unlock; 30160d4d2d2SMike Kravetz } 30260d4d2d2SMike Kravetz 30360d4d2d2SMike Kravetz err = -EEXIST; 30460d4d2d2SMike Kravetz dst_pteval = huge_ptep_get(dst_pte); 30560d4d2d2SMike Kravetz if (!huge_pte_none(dst_pteval)) { 30660d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 307c0d0381aSMike Kravetz i_mmap_unlock_read(mapping); 30860d4d2d2SMike Kravetz goto out_unlock; 30960d4d2d2SMike Kravetz } 31060d4d2d2SMike Kravetz 31160d4d2d2SMike Kravetz err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, 31260d4d2d2SMike Kravetz dst_addr, src_addr, &page); 31360d4d2d2SMike Kravetz 31460d4d2d2SMike Kravetz mutex_unlock(&hugetlb_fault_mutex_table[hash]); 315c0d0381aSMike Kravetz i_mmap_unlock_read(mapping); 3161c9e8defSMike Kravetz vm_alloc_shared = vm_shared; 31760d4d2d2SMike Kravetz 31860d4d2d2SMike Kravetz cond_resched(); 31960d4d2d2SMike Kravetz 3209e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 32160d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 32260d4d2d2SMike Kravetz BUG_ON(!page); 32360d4d2d2SMike Kravetz 32460d4d2d2SMike Kravetz err = copy_huge_page_from_user(page, 32560d4d2d2SMike Kravetz (const void __user *)src_addr, 3264fb07ee6SWei Yang vma_hpagesize / PAGE_SIZE, 3274fb07ee6SWei Yang true); 32860d4d2d2SMike Kravetz if (unlikely(err)) { 32960d4d2d2SMike Kravetz err = -EFAULT; 33060d4d2d2SMike Kravetz goto out; 33160d4d2d2SMike Kravetz } 33260d4d2d2SMike Kravetz down_read(&dst_mm->mmap_sem); 33360d4d2d2SMike Kravetz 33460d4d2d2SMike Kravetz dst_vma = NULL; 33560d4d2d2SMike Kravetz goto retry; 33660d4d2d2SMike Kravetz } else 33760d4d2d2SMike Kravetz BUG_ON(page); 33860d4d2d2SMike Kravetz 33960d4d2d2SMike Kravetz if (!err) { 34060d4d2d2SMike Kravetz dst_addr += vma_hpagesize; 34160d4d2d2SMike Kravetz src_addr += vma_hpagesize; 34260d4d2d2SMike Kravetz copied += vma_hpagesize; 34360d4d2d2SMike Kravetz 34460d4d2d2SMike Kravetz if (fatal_signal_pending(current)) 34560d4d2d2SMike Kravetz err = -EINTR; 34660d4d2d2SMike Kravetz } 34760d4d2d2SMike Kravetz if (err) 34860d4d2d2SMike Kravetz break; 34960d4d2d2SMike Kravetz } 35060d4d2d2SMike Kravetz 35160d4d2d2SMike Kravetz out_unlock: 35260d4d2d2SMike Kravetz up_read(&dst_mm->mmap_sem); 35360d4d2d2SMike Kravetz out: 35421205bf8SMike Kravetz if (page) { 35521205bf8SMike Kravetz /* 35621205bf8SMike Kravetz * We encountered an error and are about to free a newly 3571c9e8defSMike Kravetz * allocated huge page. 3581c9e8defSMike Kravetz * 3591c9e8defSMike Kravetz * Reservation handling is very subtle, and is different for 3601c9e8defSMike Kravetz * private and shared mappings. See the routine 3611c9e8defSMike Kravetz * restore_reserve_on_error for details. Unfortunately, we 3621c9e8defSMike Kravetz * can not call restore_reserve_on_error now as it would 3631c9e8defSMike Kravetz * require holding mmap_sem. 3641c9e8defSMike Kravetz * 3651c9e8defSMike Kravetz * If a reservation for the page existed in the reservation 3661c9e8defSMike Kravetz * map of a private mapping, the map was modified to indicate 3671c9e8defSMike Kravetz * the reservation was consumed when the page was allocated. 3681c9e8defSMike Kravetz * We clear the PagePrivate flag now so that the global 36921205bf8SMike Kravetz * reserve count will not be incremented in free_huge_page. 37021205bf8SMike Kravetz * The reservation map will still indicate the reservation 37121205bf8SMike Kravetz * was consumed and possibly prevent later page allocation. 3721c9e8defSMike Kravetz * This is better than leaking a global reservation. If no 3731c9e8defSMike Kravetz * reservation existed, it is still safe to clear PagePrivate 3741c9e8defSMike Kravetz * as no adjustments to reservation counts were made during 3751c9e8defSMike Kravetz * allocation. 3761c9e8defSMike Kravetz * 3771c9e8defSMike Kravetz * The reservation map for shared mappings indicates which 3781c9e8defSMike Kravetz * pages have reservations. When a huge page is allocated 3791c9e8defSMike Kravetz * for an address with a reservation, no change is made to 3801c9e8defSMike Kravetz * the reserve map. In this case PagePrivate will be set 3811c9e8defSMike Kravetz * to indicate that the global reservation count should be 3821c9e8defSMike Kravetz * incremented when the page is freed. This is the desired 3831c9e8defSMike Kravetz * behavior. However, when a huge page is allocated for an 3841c9e8defSMike Kravetz * address without a reservation a reservation entry is added 3851c9e8defSMike Kravetz * to the reservation map, and PagePrivate will not be set. 3861c9e8defSMike Kravetz * When the page is freed, the global reserve count will NOT 3871c9e8defSMike Kravetz * be incremented and it will appear as though we have leaked 3881c9e8defSMike Kravetz * reserved page. In this case, set PagePrivate so that the 3891c9e8defSMike Kravetz * global reserve count will be incremented to match the 3901c9e8defSMike Kravetz * reservation map entry which was created. 3911c9e8defSMike Kravetz * 3921c9e8defSMike Kravetz * Note that vm_alloc_shared is based on the flags of the vma 3931c9e8defSMike Kravetz * for which the page was originally allocated. dst_vma could 3941c9e8defSMike Kravetz * be different or NULL on error. 39521205bf8SMike Kravetz */ 3961c9e8defSMike Kravetz if (vm_alloc_shared) 3971c9e8defSMike Kravetz SetPagePrivate(page); 3981c9e8defSMike Kravetz else 39921205bf8SMike Kravetz ClearPagePrivate(page); 40060d4d2d2SMike Kravetz put_page(page); 40121205bf8SMike Kravetz } 40260d4d2d2SMike Kravetz BUG_ON(copied < 0); 40360d4d2d2SMike Kravetz BUG_ON(err > 0); 40460d4d2d2SMike Kravetz BUG_ON(!copied && !err); 40560d4d2d2SMike Kravetz return copied ? copied : err; 40660d4d2d2SMike Kravetz } 40760d4d2d2SMike Kravetz #else /* !CONFIG_HUGETLB_PAGE */ 40860d4d2d2SMike Kravetz /* fail at build time if gcc attempts to use this */ 40960d4d2d2SMike Kravetz extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 41060d4d2d2SMike Kravetz struct vm_area_struct *dst_vma, 41160d4d2d2SMike Kravetz unsigned long dst_start, 41260d4d2d2SMike Kravetz unsigned long src_start, 41360d4d2d2SMike Kravetz unsigned long len, 41460d4d2d2SMike Kravetz bool zeropage); 41560d4d2d2SMike Kravetz #endif /* CONFIG_HUGETLB_PAGE */ 41660d4d2d2SMike Kravetz 4173217d3c7SMike Rapoport static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, 4183217d3c7SMike Rapoport pmd_t *dst_pmd, 4193217d3c7SMike Rapoport struct vm_area_struct *dst_vma, 4203217d3c7SMike Rapoport unsigned long dst_addr, 4213217d3c7SMike Rapoport unsigned long src_addr, 4223217d3c7SMike Rapoport struct page **page, 42372981e0eSAndrea Arcangeli bool zeropage, 42472981e0eSAndrea Arcangeli bool wp_copy) 4253217d3c7SMike Rapoport { 4263217d3c7SMike Rapoport ssize_t err; 4273217d3c7SMike Rapoport 4285b51072eSAndrea Arcangeli /* 4295b51072eSAndrea Arcangeli * The normal page fault path for a shmem will invoke the 4305b51072eSAndrea Arcangeli * fault, fill the hole in the file and COW it right away. The 4315b51072eSAndrea Arcangeli * result generates plain anonymous memory. So when we are 4325b51072eSAndrea Arcangeli * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll 4335b51072eSAndrea Arcangeli * generate anonymous memory directly without actually filling 4345b51072eSAndrea Arcangeli * the hole. For the MAP_PRIVATE case the robustness check 4355b51072eSAndrea Arcangeli * only happens in the pagetable (to verify it's still none) 4365b51072eSAndrea Arcangeli * and not in the radix tree. 4375b51072eSAndrea Arcangeli */ 4385b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED)) { 4393217d3c7SMike Rapoport if (!zeropage) 4403217d3c7SMike Rapoport err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, 44172981e0eSAndrea Arcangeli dst_addr, src_addr, page, 44272981e0eSAndrea Arcangeli wp_copy); 4433217d3c7SMike Rapoport else 4443217d3c7SMike Rapoport err = mfill_zeropage_pte(dst_mm, dst_pmd, 4453217d3c7SMike Rapoport dst_vma, dst_addr); 4463217d3c7SMike Rapoport } else { 44772981e0eSAndrea Arcangeli VM_WARN_ON_ONCE(wp_copy); 4488fb44e54SMike Rapoport if (!zeropage) 4493217d3c7SMike Rapoport err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, 4503217d3c7SMike Rapoport dst_vma, dst_addr, 4513217d3c7SMike Rapoport src_addr, page); 4528fb44e54SMike Rapoport else 4538fb44e54SMike Rapoport err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, 4548fb44e54SMike Rapoport dst_vma, dst_addr); 4553217d3c7SMike Rapoport } 4563217d3c7SMike Rapoport 4573217d3c7SMike Rapoport return err; 4583217d3c7SMike Rapoport } 4593217d3c7SMike Rapoport 460c1a4de99SAndrea Arcangeli static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, 461c1a4de99SAndrea Arcangeli unsigned long dst_start, 462c1a4de99SAndrea Arcangeli unsigned long src_start, 463c1a4de99SAndrea Arcangeli unsigned long len, 464df2cc96eSMike Rapoport bool zeropage, 46572981e0eSAndrea Arcangeli bool *mmap_changing, 46672981e0eSAndrea Arcangeli __u64 mode) 467c1a4de99SAndrea Arcangeli { 468c1a4de99SAndrea Arcangeli struct vm_area_struct *dst_vma; 469c1a4de99SAndrea Arcangeli ssize_t err; 470c1a4de99SAndrea Arcangeli pmd_t *dst_pmd; 471c1a4de99SAndrea Arcangeli unsigned long src_addr, dst_addr; 472b6ebaedbSAndrea Arcangeli long copied; 473b6ebaedbSAndrea Arcangeli struct page *page; 47472981e0eSAndrea Arcangeli bool wp_copy; 475c1a4de99SAndrea Arcangeli 476c1a4de99SAndrea Arcangeli /* 477c1a4de99SAndrea Arcangeli * Sanitize the command parameters: 478c1a4de99SAndrea Arcangeli */ 479c1a4de99SAndrea Arcangeli BUG_ON(dst_start & ~PAGE_MASK); 480c1a4de99SAndrea Arcangeli BUG_ON(len & ~PAGE_MASK); 481c1a4de99SAndrea Arcangeli 482c1a4de99SAndrea Arcangeli /* Does the address range wrap, or is the span zero-sized? */ 483c1a4de99SAndrea Arcangeli BUG_ON(src_start + len <= src_start); 484c1a4de99SAndrea Arcangeli BUG_ON(dst_start + len <= dst_start); 485c1a4de99SAndrea Arcangeli 486b6ebaedbSAndrea Arcangeli src_addr = src_start; 487b6ebaedbSAndrea Arcangeli dst_addr = dst_start; 488b6ebaedbSAndrea Arcangeli copied = 0; 489b6ebaedbSAndrea Arcangeli page = NULL; 490b6ebaedbSAndrea Arcangeli retry: 491c1a4de99SAndrea Arcangeli down_read(&dst_mm->mmap_sem); 492c1a4de99SAndrea Arcangeli 493c1a4de99SAndrea Arcangeli /* 494df2cc96eSMike Rapoport * If memory mappings are changing because of non-cooperative 495df2cc96eSMike Rapoport * operation (e.g. mremap) running in parallel, bail out and 496df2cc96eSMike Rapoport * request the user to retry later 497df2cc96eSMike Rapoport */ 498df2cc96eSMike Rapoport err = -EAGAIN; 499df2cc96eSMike Rapoport if (mmap_changing && READ_ONCE(*mmap_changing)) 500df2cc96eSMike Rapoport goto out_unlock; 501df2cc96eSMike Rapoport 502df2cc96eSMike Rapoport /* 503c1a4de99SAndrea Arcangeli * Make sure the vma is not shared, that the dst range is 504c1a4de99SAndrea Arcangeli * both valid and fully within a single existing vma. 505c1a4de99SAndrea Arcangeli */ 50627d02568SMike Rapoport err = -ENOENT; 507643aa36eSWei Yang dst_vma = find_dst_vma(dst_mm, dst_start, len); 50826071cedSMike Rapoport if (!dst_vma) 50926071cedSMike Rapoport goto out_unlock; 51027d02568SMike Rapoport 51127d02568SMike Rapoport err = -EINVAL; 51227d02568SMike Rapoport /* 51327d02568SMike Rapoport * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but 51427d02568SMike Rapoport * it will overwrite vm_ops, so vma_is_anonymous must return false. 51527d02568SMike Rapoport */ 51627d02568SMike Rapoport if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && 51727d02568SMike Rapoport dst_vma->vm_flags & VM_SHARED)) 51827d02568SMike Rapoport goto out_unlock; 51927d02568SMike Rapoport 52027d02568SMike Rapoport /* 52172981e0eSAndrea Arcangeli * validate 'mode' now that we know the dst_vma: don't allow 52272981e0eSAndrea Arcangeli * a wrprotect copy if the userfaultfd didn't register as WP. 52372981e0eSAndrea Arcangeli */ 52472981e0eSAndrea Arcangeli wp_copy = mode & UFFDIO_COPY_MODE_WP; 52572981e0eSAndrea Arcangeli if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) 52672981e0eSAndrea Arcangeli goto out_unlock; 52772981e0eSAndrea Arcangeli 52872981e0eSAndrea Arcangeli /* 52927d02568SMike Rapoport * If this is a HUGETLB vma, pass off to appropriate routine 53027d02568SMike Rapoport */ 53127d02568SMike Rapoport if (is_vm_hugetlb_page(dst_vma)) 53227d02568SMike Rapoport return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, 53327d02568SMike Rapoport src_start, len, zeropage); 53427d02568SMike Rapoport 53526071cedSMike Rapoport if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) 536b6ebaedbSAndrea Arcangeli goto out_unlock; 537c1a4de99SAndrea Arcangeli 538c1a4de99SAndrea Arcangeli /* 539c1a4de99SAndrea Arcangeli * Ensure the dst_vma has a anon_vma or this page 540c1a4de99SAndrea Arcangeli * would get a NULL anon_vma when moved in the 541c1a4de99SAndrea Arcangeli * dst_vma. 542c1a4de99SAndrea Arcangeli */ 543c1a4de99SAndrea Arcangeli err = -ENOMEM; 5445b51072eSAndrea Arcangeli if (!(dst_vma->vm_flags & VM_SHARED) && 5455b51072eSAndrea Arcangeli unlikely(anon_vma_prepare(dst_vma))) 546b6ebaedbSAndrea Arcangeli goto out_unlock; 547c1a4de99SAndrea Arcangeli 548b6ebaedbSAndrea Arcangeli while (src_addr < src_start + len) { 549c1a4de99SAndrea Arcangeli pmd_t dst_pmdval; 550b6ebaedbSAndrea Arcangeli 551c1a4de99SAndrea Arcangeli BUG_ON(dst_addr >= dst_start + len); 552b6ebaedbSAndrea Arcangeli 553c1a4de99SAndrea Arcangeli dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); 554c1a4de99SAndrea Arcangeli if (unlikely(!dst_pmd)) { 555c1a4de99SAndrea Arcangeli err = -ENOMEM; 556c1a4de99SAndrea Arcangeli break; 557c1a4de99SAndrea Arcangeli } 558c1a4de99SAndrea Arcangeli 559c1a4de99SAndrea Arcangeli dst_pmdval = pmd_read_atomic(dst_pmd); 560c1a4de99SAndrea Arcangeli /* 561c1a4de99SAndrea Arcangeli * If the dst_pmd is mapped as THP don't 562c1a4de99SAndrea Arcangeli * override it and just be strict. 563c1a4de99SAndrea Arcangeli */ 564c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(dst_pmdval))) { 565c1a4de99SAndrea Arcangeli err = -EEXIST; 566c1a4de99SAndrea Arcangeli break; 567c1a4de99SAndrea Arcangeli } 568c1a4de99SAndrea Arcangeli if (unlikely(pmd_none(dst_pmdval)) && 5694cf58924SJoel Fernandes (Google) unlikely(__pte_alloc(dst_mm, dst_pmd))) { 570c1a4de99SAndrea Arcangeli err = -ENOMEM; 571c1a4de99SAndrea Arcangeli break; 572c1a4de99SAndrea Arcangeli } 573c1a4de99SAndrea Arcangeli /* If an huge pmd materialized from under us fail */ 574c1a4de99SAndrea Arcangeli if (unlikely(pmd_trans_huge(*dst_pmd))) { 575c1a4de99SAndrea Arcangeli err = -EFAULT; 576c1a4de99SAndrea Arcangeli break; 577c1a4de99SAndrea Arcangeli } 578c1a4de99SAndrea Arcangeli 579c1a4de99SAndrea Arcangeli BUG_ON(pmd_none(*dst_pmd)); 580c1a4de99SAndrea Arcangeli BUG_ON(pmd_trans_huge(*dst_pmd)); 581c1a4de99SAndrea Arcangeli 5823217d3c7SMike Rapoport err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, 58372981e0eSAndrea Arcangeli src_addr, &page, zeropage, wp_copy); 584c1a4de99SAndrea Arcangeli cond_resched(); 585c1a4de99SAndrea Arcangeli 5869e368259SAndrea Arcangeli if (unlikely(err == -ENOENT)) { 587b6ebaedbSAndrea Arcangeli void *page_kaddr; 588b6ebaedbSAndrea Arcangeli 589b6ebaedbSAndrea Arcangeli up_read(&dst_mm->mmap_sem); 590b6ebaedbSAndrea Arcangeli BUG_ON(!page); 591b6ebaedbSAndrea Arcangeli 592b6ebaedbSAndrea Arcangeli page_kaddr = kmap(page); 593b6ebaedbSAndrea Arcangeli err = copy_from_user(page_kaddr, 594b6ebaedbSAndrea Arcangeli (const void __user *) src_addr, 595b6ebaedbSAndrea Arcangeli PAGE_SIZE); 596b6ebaedbSAndrea Arcangeli kunmap(page); 597b6ebaedbSAndrea Arcangeli if (unlikely(err)) { 598b6ebaedbSAndrea Arcangeli err = -EFAULT; 599b6ebaedbSAndrea Arcangeli goto out; 600b6ebaedbSAndrea Arcangeli } 601b6ebaedbSAndrea Arcangeli goto retry; 602b6ebaedbSAndrea Arcangeli } else 603b6ebaedbSAndrea Arcangeli BUG_ON(page); 604b6ebaedbSAndrea Arcangeli 605c1a4de99SAndrea Arcangeli if (!err) { 606c1a4de99SAndrea Arcangeli dst_addr += PAGE_SIZE; 607c1a4de99SAndrea Arcangeli src_addr += PAGE_SIZE; 608c1a4de99SAndrea Arcangeli copied += PAGE_SIZE; 609c1a4de99SAndrea Arcangeli 610c1a4de99SAndrea Arcangeli if (fatal_signal_pending(current)) 611c1a4de99SAndrea Arcangeli err = -EINTR; 612c1a4de99SAndrea Arcangeli } 613c1a4de99SAndrea Arcangeli if (err) 614c1a4de99SAndrea Arcangeli break; 615c1a4de99SAndrea Arcangeli } 616c1a4de99SAndrea Arcangeli 617b6ebaedbSAndrea Arcangeli out_unlock: 618c1a4de99SAndrea Arcangeli up_read(&dst_mm->mmap_sem); 619b6ebaedbSAndrea Arcangeli out: 620b6ebaedbSAndrea Arcangeli if (page) 62109cbfeafSKirill A. Shutemov put_page(page); 622c1a4de99SAndrea Arcangeli BUG_ON(copied < 0); 623c1a4de99SAndrea Arcangeli BUG_ON(err > 0); 624c1a4de99SAndrea Arcangeli BUG_ON(!copied && !err); 625c1a4de99SAndrea Arcangeli return copied ? copied : err; 626c1a4de99SAndrea Arcangeli } 627c1a4de99SAndrea Arcangeli 628c1a4de99SAndrea Arcangeli ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, 629df2cc96eSMike Rapoport unsigned long src_start, unsigned long len, 63072981e0eSAndrea Arcangeli bool *mmap_changing, __u64 mode) 631c1a4de99SAndrea Arcangeli { 632df2cc96eSMike Rapoport return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, 63372981e0eSAndrea Arcangeli mmap_changing, mode); 634c1a4de99SAndrea Arcangeli } 635c1a4de99SAndrea Arcangeli 636c1a4de99SAndrea Arcangeli ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, 637df2cc96eSMike Rapoport unsigned long len, bool *mmap_changing) 638c1a4de99SAndrea Arcangeli { 63972981e0eSAndrea Arcangeli return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); 640c1a4de99SAndrea Arcangeli } 641*ffd05793SShaohua Li 642*ffd05793SShaohua Li int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, 643*ffd05793SShaohua Li unsigned long len, bool enable_wp, bool *mmap_changing) 644*ffd05793SShaohua Li { 645*ffd05793SShaohua Li struct vm_area_struct *dst_vma; 646*ffd05793SShaohua Li pgprot_t newprot; 647*ffd05793SShaohua Li int err; 648*ffd05793SShaohua Li 649*ffd05793SShaohua Li /* 650*ffd05793SShaohua Li * Sanitize the command parameters: 651*ffd05793SShaohua Li */ 652*ffd05793SShaohua Li BUG_ON(start & ~PAGE_MASK); 653*ffd05793SShaohua Li BUG_ON(len & ~PAGE_MASK); 654*ffd05793SShaohua Li 655*ffd05793SShaohua Li /* Does the address range wrap, or is the span zero-sized? */ 656*ffd05793SShaohua Li BUG_ON(start + len <= start); 657*ffd05793SShaohua Li 658*ffd05793SShaohua Li down_read(&dst_mm->mmap_sem); 659*ffd05793SShaohua Li 660*ffd05793SShaohua Li /* 661*ffd05793SShaohua Li * If memory mappings are changing because of non-cooperative 662*ffd05793SShaohua Li * operation (e.g. mremap) running in parallel, bail out and 663*ffd05793SShaohua Li * request the user to retry later 664*ffd05793SShaohua Li */ 665*ffd05793SShaohua Li err = -EAGAIN; 666*ffd05793SShaohua Li if (mmap_changing && READ_ONCE(*mmap_changing)) 667*ffd05793SShaohua Li goto out_unlock; 668*ffd05793SShaohua Li 669*ffd05793SShaohua Li err = -ENOENT; 670*ffd05793SShaohua Li dst_vma = find_dst_vma(dst_mm, start, len); 671*ffd05793SShaohua Li /* 672*ffd05793SShaohua Li * Make sure the vma is not shared, that the dst range is 673*ffd05793SShaohua Li * both valid and fully within a single existing vma. 674*ffd05793SShaohua Li */ 675*ffd05793SShaohua Li if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) 676*ffd05793SShaohua Li goto out_unlock; 677*ffd05793SShaohua Li if (!userfaultfd_wp(dst_vma)) 678*ffd05793SShaohua Li goto out_unlock; 679*ffd05793SShaohua Li if (!vma_is_anonymous(dst_vma)) 680*ffd05793SShaohua Li goto out_unlock; 681*ffd05793SShaohua Li 682*ffd05793SShaohua Li if (enable_wp) 683*ffd05793SShaohua Li newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); 684*ffd05793SShaohua Li else 685*ffd05793SShaohua Li newprot = vm_get_page_prot(dst_vma->vm_flags); 686*ffd05793SShaohua Li 687*ffd05793SShaohua Li change_protection(dst_vma, start, start + len, newprot, 688*ffd05793SShaohua Li enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); 689*ffd05793SShaohua Li 690*ffd05793SShaohua Li err = 0; 691*ffd05793SShaohua Li out_unlock: 692*ffd05793SShaohua Li up_read(&dst_mm->mmap_sem); 693*ffd05793SShaohua Li return err; 694*ffd05793SShaohua Li } 695