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https://github.com/torvalds/linux
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![Axel Rasmussen](/assets/img/avatar_default.png)
The behavior here is the same as it is for anon/shmem. This is done separately because hugetlb pte marker handling is a bit different. Link: https://lkml.kernel.org/r/20230707215540.2324998-6-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Brian Geffon <bgeffon@google.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Gaosheng Cui <cuigaosheng1@huawei.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Houghton <jthoughton@google.com> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Jiaqi Yan <jiaqiyan@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nadav Amit <namit@vmware.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: ZhangPeng <zhangpeng362@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
845 lines
21 KiB
C
845 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/userfaultfd.c
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*
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* Copyright (C) 2015 Red Hat, Inc.
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*/
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#include <linux/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/pagemap.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/mmu_notifier.h>
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#include <linux/hugetlb.h>
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#include <linux/shmem_fs.h>
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#include <asm/tlbflush.h>
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#include <asm/tlb.h>
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#include "internal.h"
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static __always_inline
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struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm,
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unsigned long dst_start,
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unsigned long len)
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{
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/*
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* Make sure that the dst range is both valid and fully within a
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* single existing vma.
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*/
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struct vm_area_struct *dst_vma;
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dst_vma = find_vma(dst_mm, dst_start);
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if (!range_in_vma(dst_vma, dst_start, dst_start + len))
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return NULL;
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/*
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* Check the vma is registered in uffd, this is required to
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* enforce the VM_MAYWRITE check done at uffd registration
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* time.
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*/
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if (!dst_vma->vm_userfaultfd_ctx.ctx)
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return NULL;
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return dst_vma;
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}
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/* Check if dst_addr is outside of file's size. Must be called with ptl held. */
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static bool mfill_file_over_size(struct vm_area_struct *dst_vma,
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unsigned long dst_addr)
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{
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struct inode *inode;
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pgoff_t offset, max_off;
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if (!dst_vma->vm_file)
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return false;
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inode = dst_vma->vm_file->f_inode;
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offset = linear_page_index(dst_vma, dst_addr);
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max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
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return offset >= max_off;
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}
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/*
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* Install PTEs, to map dst_addr (within dst_vma) to page.
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*
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* This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem
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* and anon, and for both shared and private VMAs.
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*/
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int mfill_atomic_install_pte(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr, struct page *page,
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bool newly_allocated, uffd_flags_t flags)
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{
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int ret;
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struct mm_struct *dst_mm = dst_vma->vm_mm;
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pte_t _dst_pte, *dst_pte;
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bool writable = dst_vma->vm_flags & VM_WRITE;
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bool vm_shared = dst_vma->vm_flags & VM_SHARED;
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bool page_in_cache = page_mapping(page);
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spinlock_t *ptl;
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struct folio *folio;
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_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
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_dst_pte = pte_mkdirty(_dst_pte);
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if (page_in_cache && !vm_shared)
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writable = false;
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if (writable)
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_dst_pte = pte_mkwrite(_dst_pte);
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if (flags & MFILL_ATOMIC_WP)
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_dst_pte = pte_mkuffd_wp(_dst_pte);
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ret = -EAGAIN;
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dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
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if (!dst_pte)
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goto out;
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if (mfill_file_over_size(dst_vma, dst_addr)) {
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ret = -EFAULT;
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goto out_unlock;
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}
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ret = -EEXIST;
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/*
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* We allow to overwrite a pte marker: consider when both MISSING|WP
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* registered, we firstly wr-protect a none pte which has no page cache
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* page backing it, then access the page.
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*/
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if (!pte_none_mostly(ptep_get(dst_pte)))
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goto out_unlock;
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folio = page_folio(page);
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if (page_in_cache) {
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/* Usually, cache pages are already added to LRU */
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if (newly_allocated)
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folio_add_lru(folio);
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page_add_file_rmap(page, dst_vma, false);
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} else {
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page_add_new_anon_rmap(page, dst_vma, dst_addr);
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folio_add_lru_vma(folio, dst_vma);
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}
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/*
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* Must happen after rmap, as mm_counter() checks mapping (via
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* PageAnon()), which is set by __page_set_anon_rmap().
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*/
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inc_mm_counter(dst_mm, mm_counter(page));
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set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(dst_vma, dst_addr, dst_pte);
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ret = 0;
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out_unlock:
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pte_unmap_unlock(dst_pte, ptl);
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out:
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return ret;
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}
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static int mfill_atomic_pte_copy(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr,
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unsigned long src_addr,
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uffd_flags_t flags,
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struct folio **foliop)
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{
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void *kaddr;
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int ret;
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struct folio *folio;
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if (!*foliop) {
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ret = -ENOMEM;
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folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, dst_vma,
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dst_addr, false);
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if (!folio)
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goto out;
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kaddr = kmap_local_folio(folio, 0);
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/*
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* The read mmap_lock is held here. Despite the
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* mmap_lock being read recursive a deadlock is still
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* possible if a writer has taken a lock. For example:
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*
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* process A thread 1 takes read lock on own mmap_lock
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* process A thread 2 calls mmap, blocks taking write lock
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* process B thread 1 takes page fault, read lock on own mmap lock
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* process B thread 2 calls mmap, blocks taking write lock
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* process A thread 1 blocks taking read lock on process B
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* process B thread 1 blocks taking read lock on process A
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*
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* Disable page faults to prevent potential deadlock
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* and retry the copy outside the mmap_lock.
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*/
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pagefault_disable();
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ret = copy_from_user(kaddr, (const void __user *) src_addr,
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PAGE_SIZE);
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pagefault_enable();
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kunmap_local(kaddr);
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/* fallback to copy_from_user outside mmap_lock */
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if (unlikely(ret)) {
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ret = -ENOENT;
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*foliop = folio;
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/* don't free the page */
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goto out;
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}
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flush_dcache_folio(folio);
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} else {
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folio = *foliop;
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*foliop = NULL;
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}
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/*
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* The memory barrier inside __folio_mark_uptodate makes sure that
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* preceding stores to the page contents become visible before
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* the set_pte_at() write.
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*/
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__folio_mark_uptodate(folio);
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ret = -ENOMEM;
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if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL))
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goto out_release;
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ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
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&folio->page, true, flags);
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if (ret)
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goto out_release;
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out:
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return ret;
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out_release:
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folio_put(folio);
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goto out;
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}
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static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr)
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{
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pte_t _dst_pte, *dst_pte;
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spinlock_t *ptl;
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int ret;
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_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
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dst_vma->vm_page_prot));
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ret = -EAGAIN;
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dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl);
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if (!dst_pte)
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goto out;
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if (mfill_file_over_size(dst_vma, dst_addr)) {
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ret = -EFAULT;
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goto out_unlock;
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}
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ret = -EEXIST;
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if (!pte_none(ptep_get(dst_pte)))
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goto out_unlock;
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set_pte_at(dst_vma->vm_mm, dst_addr, dst_pte, _dst_pte);
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(dst_vma, dst_addr, dst_pte);
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ret = 0;
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out_unlock:
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pte_unmap_unlock(dst_pte, ptl);
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out:
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return ret;
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}
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/* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
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static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr,
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uffd_flags_t flags)
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{
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struct inode *inode = file_inode(dst_vma->vm_file);
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pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
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struct folio *folio;
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struct page *page;
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int ret;
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ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
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/* Our caller expects us to return -EFAULT if we failed to find folio */
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if (ret == -ENOENT)
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ret = -EFAULT;
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if (ret)
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goto out;
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if (!folio) {
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ret = -EFAULT;
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goto out;
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}
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page = folio_file_page(folio, pgoff);
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if (PageHWPoison(page)) {
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ret = -EIO;
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goto out_release;
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}
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ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
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page, false, flags);
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if (ret)
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goto out_release;
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folio_unlock(folio);
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ret = 0;
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out:
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return ret;
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out_release:
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folio_unlock(folio);
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folio_put(folio);
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goto out;
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}
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/* Handles UFFDIO_POISON for all non-hugetlb VMAs. */
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static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr,
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uffd_flags_t flags)
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{
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int ret;
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struct mm_struct *dst_mm = dst_vma->vm_mm;
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pte_t _dst_pte, *dst_pte;
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spinlock_t *ptl;
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_dst_pte = make_pte_marker(PTE_MARKER_POISONED);
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ret = -EAGAIN;
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dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
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if (!dst_pte)
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goto out;
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if (mfill_file_over_size(dst_vma, dst_addr)) {
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ret = -EFAULT;
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goto out_unlock;
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}
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ret = -EEXIST;
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/* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */
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if (!pte_none(*dst_pte))
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goto out_unlock;
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set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(dst_vma, dst_addr, dst_pte);
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ret = 0;
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out_unlock:
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pte_unmap_unlock(dst_pte, ptl);
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out:
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return ret;
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}
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static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
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{
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pgd = pgd_offset(mm, address);
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p4d = p4d_alloc(mm, pgd, address);
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if (!p4d)
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return NULL;
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pud = pud_alloc(mm, p4d, address);
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if (!pud)
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return NULL;
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/*
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* Note that we didn't run this because the pmd was
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* missing, the *pmd may be already established and in
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* turn it may also be a trans_huge_pmd.
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*/
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return pmd_alloc(mm, pud, address);
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}
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#ifdef CONFIG_HUGETLB_PAGE
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/*
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* mfill_atomic processing for HUGETLB vmas. Note that this routine is
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* called with mmap_lock held, it will release mmap_lock before returning.
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*/
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static __always_inline ssize_t mfill_atomic_hugetlb(
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struct vm_area_struct *dst_vma,
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unsigned long dst_start,
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unsigned long src_start,
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unsigned long len,
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uffd_flags_t flags)
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{
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struct mm_struct *dst_mm = dst_vma->vm_mm;
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int vm_shared = dst_vma->vm_flags & VM_SHARED;
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ssize_t err;
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pte_t *dst_pte;
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unsigned long src_addr, dst_addr;
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long copied;
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struct folio *folio;
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unsigned long vma_hpagesize;
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pgoff_t idx;
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u32 hash;
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struct address_space *mapping;
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|
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/*
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* There is no default zero huge page for all huge page sizes as
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* supported by hugetlb. A PMD_SIZE huge pages may exist as used
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* by THP. Since we can not reliably insert a zero page, this
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* feature is not supported.
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*/
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if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) {
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mmap_read_unlock(dst_mm);
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return -EINVAL;
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}
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src_addr = src_start;
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dst_addr = dst_start;
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copied = 0;
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folio = NULL;
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vma_hpagesize = vma_kernel_pagesize(dst_vma);
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/*
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* Validate alignment based on huge page size
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*/
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err = -EINVAL;
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if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
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goto out_unlock;
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|
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retry:
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/*
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* On routine entry dst_vma is set. If we had to drop mmap_lock and
|
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* retry, dst_vma will be set to NULL and we must lookup again.
|
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*/
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if (!dst_vma) {
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err = -ENOENT;
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dst_vma = find_dst_vma(dst_mm, dst_start, len);
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if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
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goto out_unlock;
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|
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err = -EINVAL;
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if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
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goto out_unlock;
|
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|
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vm_shared = dst_vma->vm_flags & VM_SHARED;
|
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}
|
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|
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/*
|
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* If not shared, ensure the dst_vma has a anon_vma.
|
|
*/
|
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err = -ENOMEM;
|
|
if (!vm_shared) {
|
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if (unlikely(anon_vma_prepare(dst_vma)))
|
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goto out_unlock;
|
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}
|
|
|
|
while (src_addr < src_start + len) {
|
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BUG_ON(dst_addr >= dst_start + len);
|
|
|
|
/*
|
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* Serialize via vma_lock and hugetlb_fault_mutex.
|
|
* vma_lock ensures the dst_pte remains valid even
|
|
* in the case of shared pmds. fault mutex prevents
|
|
* races with other faulting threads.
|
|
*/
|
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idx = linear_page_index(dst_vma, dst_addr);
|
|
mapping = dst_vma->vm_file->f_mapping;
|
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hash = hugetlb_fault_mutex_hash(mapping, idx);
|
|
mutex_lock(&hugetlb_fault_mutex_table[hash]);
|
|
hugetlb_vma_lock_read(dst_vma);
|
|
|
|
err = -ENOMEM;
|
|
dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize);
|
|
if (!dst_pte) {
|
|
hugetlb_vma_unlock_read(dst_vma);
|
|
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (!uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE) &&
|
|
!huge_pte_none_mostly(huge_ptep_get(dst_pte))) {
|
|
err = -EEXIST;
|
|
hugetlb_vma_unlock_read(dst_vma);
|
|
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
|
|
goto out_unlock;
|
|
}
|
|
|
|
err = hugetlb_mfill_atomic_pte(dst_pte, dst_vma, dst_addr,
|
|
src_addr, flags, &folio);
|
|
|
|
hugetlb_vma_unlock_read(dst_vma);
|
|
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
|
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|
|
cond_resched();
|
|
|
|
if (unlikely(err == -ENOENT)) {
|
|
mmap_read_unlock(dst_mm);
|
|
BUG_ON(!folio);
|
|
|
|
err = copy_folio_from_user(folio,
|
|
(const void __user *)src_addr, true);
|
|
if (unlikely(err)) {
|
|
err = -EFAULT;
|
|
goto out;
|
|
}
|
|
mmap_read_lock(dst_mm);
|
|
|
|
dst_vma = NULL;
|
|
goto retry;
|
|
} else
|
|
BUG_ON(folio);
|
|
|
|
if (!err) {
|
|
dst_addr += vma_hpagesize;
|
|
src_addr += vma_hpagesize;
|
|
copied += vma_hpagesize;
|
|
|
|
if (fatal_signal_pending(current))
|
|
err = -EINTR;
|
|
}
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
out:
|
|
if (folio)
|
|
folio_put(folio);
|
|
BUG_ON(copied < 0);
|
|
BUG_ON(err > 0);
|
|
BUG_ON(!copied && !err);
|
|
return copied ? copied : err;
|
|
}
|
|
#else /* !CONFIG_HUGETLB_PAGE */
|
|
/* fail at build time if gcc attempts to use this */
|
|
extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma,
|
|
unsigned long dst_start,
|
|
unsigned long src_start,
|
|
unsigned long len,
|
|
uffd_flags_t flags);
|
|
#endif /* CONFIG_HUGETLB_PAGE */
|
|
|
|
static __always_inline ssize_t mfill_atomic_pte(pmd_t *dst_pmd,
|
|
struct vm_area_struct *dst_vma,
|
|
unsigned long dst_addr,
|
|
unsigned long src_addr,
|
|
uffd_flags_t flags,
|
|
struct folio **foliop)
|
|
{
|
|
ssize_t err;
|
|
|
|
if (uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) {
|
|
return mfill_atomic_pte_continue(dst_pmd, dst_vma,
|
|
dst_addr, flags);
|
|
} else if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
|
|
return mfill_atomic_pte_poison(dst_pmd, dst_vma,
|
|
dst_addr, flags);
|
|
}
|
|
|
|
/*
|
|
* The normal page fault path for a shmem will invoke the
|
|
* fault, fill the hole in the file and COW it right away. The
|
|
* result generates plain anonymous memory. So when we are
|
|
* asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll
|
|
* generate anonymous memory directly without actually filling
|
|
* the hole. For the MAP_PRIVATE case the robustness check
|
|
* only happens in the pagetable (to verify it's still none)
|
|
* and not in the radix tree.
|
|
*/
|
|
if (!(dst_vma->vm_flags & VM_SHARED)) {
|
|
if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY))
|
|
err = mfill_atomic_pte_copy(dst_pmd, dst_vma,
|
|
dst_addr, src_addr,
|
|
flags, foliop);
|
|
else
|
|
err = mfill_atomic_pte_zeropage(dst_pmd,
|
|
dst_vma, dst_addr);
|
|
} else {
|
|
err = shmem_mfill_atomic_pte(dst_pmd, dst_vma,
|
|
dst_addr, src_addr,
|
|
flags, foliop);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm,
|
|
unsigned long dst_start,
|
|
unsigned long src_start,
|
|
unsigned long len,
|
|
atomic_t *mmap_changing,
|
|
uffd_flags_t flags)
|
|
{
|
|
struct vm_area_struct *dst_vma;
|
|
ssize_t err;
|
|
pmd_t *dst_pmd;
|
|
unsigned long src_addr, dst_addr;
|
|
long copied;
|
|
struct folio *folio;
|
|
|
|
/*
|
|
* Sanitize the command parameters:
|
|
*/
|
|
BUG_ON(dst_start & ~PAGE_MASK);
|
|
BUG_ON(len & ~PAGE_MASK);
|
|
|
|
/* Does the address range wrap, or is the span zero-sized? */
|
|
BUG_ON(src_start + len <= src_start);
|
|
BUG_ON(dst_start + len <= dst_start);
|
|
|
|
src_addr = src_start;
|
|
dst_addr = dst_start;
|
|
copied = 0;
|
|
folio = NULL;
|
|
retry:
|
|
mmap_read_lock(dst_mm);
|
|
|
|
/*
|
|
* If memory mappings are changing because of non-cooperative
|
|
* operation (e.g. mremap) running in parallel, bail out and
|
|
* request the user to retry later
|
|
*/
|
|
err = -EAGAIN;
|
|
if (mmap_changing && atomic_read(mmap_changing))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Make sure the vma is not shared, that the dst range is
|
|
* both valid and fully within a single existing vma.
|
|
*/
|
|
err = -ENOENT;
|
|
dst_vma = find_dst_vma(dst_mm, dst_start, len);
|
|
if (!dst_vma)
|
|
goto out_unlock;
|
|
|
|
err = -EINVAL;
|
|
/*
|
|
* shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but
|
|
* it will overwrite vm_ops, so vma_is_anonymous must return false.
|
|
*/
|
|
if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) &&
|
|
dst_vma->vm_flags & VM_SHARED))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* validate 'mode' now that we know the dst_vma: don't allow
|
|
* a wrprotect copy if the userfaultfd didn't register as WP.
|
|
*/
|
|
if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* If this is a HUGETLB vma, pass off to appropriate routine
|
|
*/
|
|
if (is_vm_hugetlb_page(dst_vma))
|
|
return mfill_atomic_hugetlb(dst_vma, dst_start,
|
|
src_start, len, flags);
|
|
|
|
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
|
|
goto out_unlock;
|
|
if (!vma_is_shmem(dst_vma) &&
|
|
uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Ensure the dst_vma has a anon_vma or this page
|
|
* would get a NULL anon_vma when moved in the
|
|
* dst_vma.
|
|
*/
|
|
err = -ENOMEM;
|
|
if (!(dst_vma->vm_flags & VM_SHARED) &&
|
|
unlikely(anon_vma_prepare(dst_vma)))
|
|
goto out_unlock;
|
|
|
|
while (src_addr < src_start + len) {
|
|
pmd_t dst_pmdval;
|
|
|
|
BUG_ON(dst_addr >= dst_start + len);
|
|
|
|
dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
|
|
if (unlikely(!dst_pmd)) {
|
|
err = -ENOMEM;
|
|
break;
|
|
}
|
|
|
|
dst_pmdval = pmdp_get_lockless(dst_pmd);
|
|
/*
|
|
* If the dst_pmd is mapped as THP don't
|
|
* override it and just be strict.
|
|
*/
|
|
if (unlikely(pmd_trans_huge(dst_pmdval))) {
|
|
err = -EEXIST;
|
|
break;
|
|
}
|
|
if (unlikely(pmd_none(dst_pmdval)) &&
|
|
unlikely(__pte_alloc(dst_mm, dst_pmd))) {
|
|
err = -ENOMEM;
|
|
break;
|
|
}
|
|
/* If an huge pmd materialized from under us fail */
|
|
if (unlikely(pmd_trans_huge(*dst_pmd))) {
|
|
err = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
BUG_ON(pmd_none(*dst_pmd));
|
|
BUG_ON(pmd_trans_huge(*dst_pmd));
|
|
|
|
err = mfill_atomic_pte(dst_pmd, dst_vma, dst_addr,
|
|
src_addr, flags, &folio);
|
|
cond_resched();
|
|
|
|
if (unlikely(err == -ENOENT)) {
|
|
void *kaddr;
|
|
|
|
mmap_read_unlock(dst_mm);
|
|
BUG_ON(!folio);
|
|
|
|
kaddr = kmap_local_folio(folio, 0);
|
|
err = copy_from_user(kaddr,
|
|
(const void __user *) src_addr,
|
|
PAGE_SIZE);
|
|
kunmap_local(kaddr);
|
|
if (unlikely(err)) {
|
|
err = -EFAULT;
|
|
goto out;
|
|
}
|
|
flush_dcache_folio(folio);
|
|
goto retry;
|
|
} else
|
|
BUG_ON(folio);
|
|
|
|
if (!err) {
|
|
dst_addr += PAGE_SIZE;
|
|
src_addr += PAGE_SIZE;
|
|
copied += PAGE_SIZE;
|
|
|
|
if (fatal_signal_pending(current))
|
|
err = -EINTR;
|
|
}
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
out:
|
|
if (folio)
|
|
folio_put(folio);
|
|
BUG_ON(copied < 0);
|
|
BUG_ON(err > 0);
|
|
BUG_ON(!copied && !err);
|
|
return copied ? copied : err;
|
|
}
|
|
|
|
ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start,
|
|
unsigned long src_start, unsigned long len,
|
|
atomic_t *mmap_changing, uffd_flags_t flags)
|
|
{
|
|
return mfill_atomic(dst_mm, dst_start, src_start, len, mmap_changing,
|
|
uffd_flags_set_mode(flags, MFILL_ATOMIC_COPY));
|
|
}
|
|
|
|
ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, atomic_t *mmap_changing)
|
|
{
|
|
return mfill_atomic(dst_mm, start, 0, len, mmap_changing,
|
|
uffd_flags_set_mode(0, MFILL_ATOMIC_ZEROPAGE));
|
|
}
|
|
|
|
ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, atomic_t *mmap_changing,
|
|
uffd_flags_t flags)
|
|
{
|
|
return mfill_atomic(dst_mm, start, 0, len, mmap_changing,
|
|
uffd_flags_set_mode(flags, MFILL_ATOMIC_CONTINUE));
|
|
}
|
|
|
|
ssize_t mfill_atomic_poison(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, atomic_t *mmap_changing,
|
|
uffd_flags_t flags)
|
|
{
|
|
return mfill_atomic(dst_mm, start, 0, len, mmap_changing,
|
|
uffd_flags_set_mode(flags, MFILL_ATOMIC_POISON));
|
|
}
|
|
|
|
long uffd_wp_range(struct vm_area_struct *dst_vma,
|
|
unsigned long start, unsigned long len, bool enable_wp)
|
|
{
|
|
unsigned int mm_cp_flags;
|
|
struct mmu_gather tlb;
|
|
long ret;
|
|
|
|
VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end,
|
|
"The address range exceeds VMA boundary.\n");
|
|
if (enable_wp)
|
|
mm_cp_flags = MM_CP_UFFD_WP;
|
|
else
|
|
mm_cp_flags = MM_CP_UFFD_WP_RESOLVE;
|
|
|
|
/*
|
|
* vma->vm_page_prot already reflects that uffd-wp is enabled for this
|
|
* VMA (see userfaultfd_set_vm_flags()) and that all PTEs are supposed
|
|
* to be write-protected as default whenever protection changes.
|
|
* Try upgrading write permissions manually.
|
|
*/
|
|
if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma))
|
|
mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
|
|
tlb_gather_mmu(&tlb, dst_vma->vm_mm);
|
|
ret = change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, bool enable_wp,
|
|
atomic_t *mmap_changing)
|
|
{
|
|
unsigned long end = start + len;
|
|
unsigned long _start, _end;
|
|
struct vm_area_struct *dst_vma;
|
|
unsigned long page_mask;
|
|
long err;
|
|
VMA_ITERATOR(vmi, dst_mm, start);
|
|
|
|
/*
|
|
* Sanitize the command parameters:
|
|
*/
|
|
BUG_ON(start & ~PAGE_MASK);
|
|
BUG_ON(len & ~PAGE_MASK);
|
|
|
|
/* Does the address range wrap, or is the span zero-sized? */
|
|
BUG_ON(start + len <= start);
|
|
|
|
mmap_read_lock(dst_mm);
|
|
|
|
/*
|
|
* If memory mappings are changing because of non-cooperative
|
|
* operation (e.g. mremap) running in parallel, bail out and
|
|
* request the user to retry later
|
|
*/
|
|
err = -EAGAIN;
|
|
if (mmap_changing && atomic_read(mmap_changing))
|
|
goto out_unlock;
|
|
|
|
err = -ENOENT;
|
|
for_each_vma_range(vmi, dst_vma, end) {
|
|
|
|
if (!userfaultfd_wp(dst_vma)) {
|
|
err = -ENOENT;
|
|
break;
|
|
}
|
|
|
|
if (is_vm_hugetlb_page(dst_vma)) {
|
|
err = -EINVAL;
|
|
page_mask = vma_kernel_pagesize(dst_vma) - 1;
|
|
if ((start & page_mask) || (len & page_mask))
|
|
break;
|
|
}
|
|
|
|
_start = max(dst_vma->vm_start, start);
|
|
_end = min(dst_vma->vm_end, end);
|
|
|
|
err = uffd_wp_range(dst_vma, _start, _end - _start, enable_wp);
|
|
|
|
/* Return 0 on success, <0 on failures */
|
|
if (err < 0)
|
|
break;
|
|
err = 0;
|
|
}
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
return err;
|
|
}
|