mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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df57721f9a
Convert IBT selftest to asm to fix objtool warning -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmTv1QQACgkQaDWVMHDJ krAUwhAAn6TOwHJK8BSkHeiQhON1nrlP3c5cv0AyZ2NP8RYDrZrSZvhpYBJ6wgKC Cx5CGq5nn9twYsYS3KsktLKDfR3lRdsQ7K9qtyFtYiaeaVKo+7gEKl/K+klwai8/ gninQWHk0zmSCja8Vi77q52WOMkQKapT8+vaON9EVDO8dVEi+CvhAIfPwMafuiwO Rk4X86SzoZu9FP79LcCg9XyGC/XbM2OG9eNUTSCKT40qTTKm5y4gix687NvAlaHR ko5MTsdl0Wfp6Qk0ohT74LnoA2c1g/FluvZIM33ci/2rFpkf9Hw7ip3lUXqn6CPx rKiZ+pVRc0xikVWkraMfIGMJfUd2rhelp8OyoozD7DB7UZw40Q4RW4N5tgq9Fhe9 MQs3p1v9N8xHdRKl365UcOczUxNAmv4u0nV5gY/4FMC6VjldCl2V9fmqYXyzFS4/ Ogg4FSd7c2JyGFKPs+5uXyi+RY2qOX4+nzHOoKD7SY616IYqtgKoz5usxETLwZ6s VtJOmJL0h//z0A7tBliB0zd+SQ5UQQBDC2XouQH2fNX2isJMn0UDmWJGjaHgK6Hh 8jVp6LNqf+CEQS387UxckOyj7fu438hDky1Ggaw4YqowEOhQeqLVO4++x+HITrbp AupXfbJw9h9cMN63Yc0gVxXQ9IMZ+M7UxLtZ3Cd8/PVztNy/clA= =3UUm -----END PGP SIGNATURE----- Merge tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 shadow stack support from Dave Hansen: "This is the long awaited x86 shadow stack support, part of Intel's Control-flow Enforcement Technology (CET). CET consists of two related security features: shadow stacks and indirect branch tracking. This series implements just the shadow stack part of this feature, and just for userspace. The main use case for shadow stack is providing protection against return oriented programming attacks. It works by maintaining a secondary (shadow) stack using a special memory type that has protections against modification. When executing a CALL instruction, the processor pushes the return address to both the normal stack and to the special permission shadow stack. Upon RET, the processor pops the shadow stack copy and compares it to the normal stack copy. For more information, refer to the links below for the earlier versions of this patch set" Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/ Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/ * tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits) x86/shstk: Change order of __user in type x86/ibt: Convert IBT selftest to asm x86/shstk: Don't retry vm_munmap() on -EINTR x86/kbuild: Fix Documentation/ reference x86/shstk: Move arch detail comment out of core mm x86/shstk: Add ARCH_SHSTK_STATUS x86/shstk: Add ARCH_SHSTK_UNLOCK x86: Add PTRACE interface for shadow stack selftests/x86: Add shadow stack test x86/cpufeatures: Enable CET CR4 bit for shadow stack x86/shstk: Wire in shadow stack interface x86: Expose thread features in /proc/$PID/status x86/shstk: Support WRSS for userspace x86/shstk: Introduce map_shadow_stack syscall x86/shstk: Check that signal frame is shadow stack mem x86/shstk: Check that SSP is aligned on sigreturn x86/shstk: Handle signals for shadow stack x86/shstk: Introduce routines modifying shstk x86/shstk: Handle thread shadow stack x86/shstk: Add user-mode shadow stack support ...
844 lines
21 KiB
C
844 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
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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, dst_vma);
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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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|
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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;
|
|
}
|
|
|
|
ret = -EEXIST;
|
|
/* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */
|
|
if (!pte_none(*dst_pte))
|
|
goto out_unlock;
|
|
|
|
set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
|
|
|
|
/* No need to invalidate - it was non-present before */
|
|
update_mmu_cache(dst_vma, dst_addr, dst_pte);
|
|
ret = 0;
|
|
out_unlock:
|
|
pte_unmap_unlock(dst_pte, ptl);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
p4d = p4d_alloc(mm, pgd, address);
|
|
if (!p4d)
|
|
return NULL;
|
|
pud = pud_alloc(mm, p4d, address);
|
|
if (!pud)
|
|
return NULL;
|
|
/*
|
|
* Note that we didn't run this because the pmd was
|
|
* missing, the *pmd may be already established and in
|
|
* turn it may also be a trans_huge_pmd.
|
|
*/
|
|
return pmd_alloc(mm, pud, address);
|
|
}
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
/*
|
|
* mfill_atomic processing for HUGETLB vmas. Note that this routine is
|
|
* called with mmap_lock held, it will release mmap_lock before returning.
|
|
*/
|
|
static __always_inline 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)
|
|
{
|
|
struct mm_struct *dst_mm = dst_vma->vm_mm;
|
|
int vm_shared = dst_vma->vm_flags & VM_SHARED;
|
|
ssize_t err;
|
|
pte_t *dst_pte;
|
|
unsigned long src_addr, dst_addr;
|
|
long copied;
|
|
struct folio *folio;
|
|
unsigned long vma_hpagesize;
|
|
pgoff_t idx;
|
|
u32 hash;
|
|
struct address_space *mapping;
|
|
|
|
/*
|
|
* There is no default zero huge page for all huge page sizes as
|
|
* supported by hugetlb. A PMD_SIZE huge pages may exist as used
|
|
* by THP. Since we can not reliably insert a zero page, this
|
|
* feature is not supported.
|
|
*/
|
|
if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) {
|
|
mmap_read_unlock(dst_mm);
|
|
return -EINVAL;
|
|
}
|
|
|
|
src_addr = src_start;
|
|
dst_addr = dst_start;
|
|
copied = 0;
|
|
folio = NULL;
|
|
vma_hpagesize = vma_kernel_pagesize(dst_vma);
|
|
|
|
/*
|
|
* Validate alignment based on huge page size
|
|
*/
|
|
err = -EINVAL;
|
|
if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
|
|
goto out_unlock;
|
|
|
|
retry:
|
|
/*
|
|
* On routine entry dst_vma is set. If we had to drop mmap_lock and
|
|
* retry, dst_vma will be set to NULL and we must lookup again.
|
|
*/
|
|
if (!dst_vma) {
|
|
err = -ENOENT;
|
|
dst_vma = find_dst_vma(dst_mm, dst_start, len);
|
|
if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
|
|
goto out_unlock;
|
|
|
|
err = -EINVAL;
|
|
if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
|
|
goto out_unlock;
|
|
|
|
vm_shared = dst_vma->vm_flags & VM_SHARED;
|
|
}
|
|
|
|
/*
|
|
* If not shared, ensure the dst_vma has a anon_vma.
|
|
*/
|
|
err = -ENOMEM;
|
|
if (!vm_shared) {
|
|
if (unlikely(anon_vma_prepare(dst_vma)))
|
|
goto out_unlock;
|
|
}
|
|
|
|
while (src_addr < src_start + len) {
|
|
BUG_ON(dst_addr >= dst_start + len);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
idx = linear_page_index(dst_vma, dst_addr);
|
|
mapping = dst_vma->vm_file->f_mapping;
|
|
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]);
|
|
|
|
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;
|
|
}
|