500 lines
16 KiB
C
500 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_MMU_NOTIFIER_H
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#define _LINUX_MMU_NOTIFIER_H
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/mm_types.h>
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#include <linux/srcu.h>
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struct mmu_notifier;
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struct mmu_notifier_ops;
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#ifdef CONFIG_MMU_NOTIFIER
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/*
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* The mmu notifier_mm structure is allocated and installed in
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* mm->mmu_notifier_mm inside the mm_take_all_locks() protected
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* critical section and it's released only when mm_count reaches zero
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* in mmdrop().
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*/
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struct mmu_notifier_mm {
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/* all mmu notifiers registerd in this mm are queued in this list */
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struct hlist_head list;
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/* to serialize the list modifications and hlist_unhashed */
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spinlock_t lock;
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};
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struct mmu_notifier_ops {
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/*
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* Called either by mmu_notifier_unregister or when the mm is
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* being destroyed by exit_mmap, always before all pages are
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* freed. This can run concurrently with other mmu notifier
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* methods (the ones invoked outside the mm context) and it
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* should tear down all secondary mmu mappings and freeze the
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* secondary mmu. If this method isn't implemented you've to
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* be sure that nothing could possibly write to the pages
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* through the secondary mmu by the time the last thread with
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* tsk->mm == mm exits.
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*
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* As side note: the pages freed after ->release returns could
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* be immediately reallocated by the gart at an alias physical
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* address with a different cache model, so if ->release isn't
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* implemented because all _software_ driven memory accesses
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* through the secondary mmu are terminated by the time the
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* last thread of this mm quits, you've also to be sure that
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* speculative _hardware_ operations can't allocate dirty
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* cachelines in the cpu that could not be snooped and made
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* coherent with the other read and write operations happening
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* through the gart alias address, so leading to memory
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* corruption.
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*/
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void (*release)(struct mmu_notifier *mn,
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struct mm_struct *mm);
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/*
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* clear_flush_young is called after the VM is
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* test-and-clearing the young/accessed bitflag in the
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* pte. This way the VM will provide proper aging to the
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* accesses to the page through the secondary MMUs and not
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* only to the ones through the Linux pte.
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* Start-end is necessary in case the secondary MMU is mapping the page
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* at a smaller granularity than the primary MMU.
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*/
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int (*clear_flush_young)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long start,
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unsigned long end);
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/*
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* clear_young is a lightweight version of clear_flush_young. Like the
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* latter, it is supposed to test-and-clear the young/accessed bitflag
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* in the secondary pte, but it may omit flushing the secondary tlb.
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*/
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int (*clear_young)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long start,
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unsigned long end);
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/*
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* test_young is called to check the young/accessed bitflag in
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* the secondary pte. This is used to know if the page is
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* frequently used without actually clearing the flag or tearing
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* down the secondary mapping on the page.
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*/
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int (*test_young)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long address);
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/*
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* change_pte is called in cases that pte mapping to page is changed:
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* for example, when ksm remaps pte to point to a new shared page.
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*/
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void (*change_pte)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long address,
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pte_t pte);
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/*
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* invalidate_range_start() and invalidate_range_end() must be
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* paired and are called only when the mmap_sem and/or the
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* locks protecting the reverse maps are held. If the subsystem
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* can't guarantee that no additional references are taken to
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* the pages in the range, it has to implement the
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* invalidate_range() notifier to remove any references taken
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* after invalidate_range_start().
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*
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* Invalidation of multiple concurrent ranges may be
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* optionally permitted by the driver. Either way the
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* establishment of sptes is forbidden in the range passed to
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* invalidate_range_begin/end for the whole duration of the
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* invalidate_range_begin/end critical section.
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*
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* invalidate_range_start() is called when all pages in the
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* range are still mapped and have at least a refcount of one.
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*
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* invalidate_range_end() is called when all pages in the
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* range have been unmapped and the pages have been freed by
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* the VM.
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*
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* The VM will remove the page table entries and potentially
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* the page between invalidate_range_start() and
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* invalidate_range_end(). If the page must not be freed
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* because of pending I/O or other circumstances then the
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* invalidate_range_start() callback (or the initial mapping
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* by the driver) must make sure that the refcount is kept
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* elevated.
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*
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* If the driver increases the refcount when the pages are
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* initially mapped into an address space then either
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* invalidate_range_start() or invalidate_range_end() may
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* decrease the refcount. If the refcount is decreased on
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* invalidate_range_start() then the VM can free pages as page
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* table entries are removed. If the refcount is only
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* droppped on invalidate_range_end() then the driver itself
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* will drop the last refcount but it must take care to flush
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* any secondary tlb before doing the final free on the
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* page. Pages will no longer be referenced by the linux
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* address space but may still be referenced by sptes until
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* the last refcount is dropped.
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*
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* If blockable argument is set to false then the callback cannot
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* sleep and has to return with -EAGAIN. 0 should be returned
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* otherwise. Please note that if invalidate_range_start approves
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* a non-blocking behavior then the same applies to
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* invalidate_range_end.
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*
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*/
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int (*invalidate_range_start)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long start, unsigned long end,
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bool blockable);
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void (*invalidate_range_end)(struct mmu_notifier *mn,
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struct mm_struct *mm,
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unsigned long start, unsigned long end);
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/*
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* invalidate_range() is either called between
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* invalidate_range_start() and invalidate_range_end() when the
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* VM has to free pages that where unmapped, but before the
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* pages are actually freed, or outside of _start()/_end() when
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* a (remote) TLB is necessary.
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*
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* If invalidate_range() is used to manage a non-CPU TLB with
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* shared page-tables, it not necessary to implement the
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* invalidate_range_start()/end() notifiers, as
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* invalidate_range() alread catches the points in time when an
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* external TLB range needs to be flushed. For more in depth
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* discussion on this see Documentation/vm/mmu_notifier.rst
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*
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* Note that this function might be called with just a sub-range
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* of what was passed to invalidate_range_start()/end(), if
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* called between those functions.
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*/
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void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
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unsigned long start, unsigned long end);
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};
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/*
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* The notifier chains are protected by mmap_sem and/or the reverse map
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* semaphores. Notifier chains are only changed when all reverse maps and
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* the mmap_sem locks are taken.
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*
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* Therefore notifier chains can only be traversed when either
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*
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* 1. mmap_sem is held.
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* 2. One of the reverse map locks is held (i_mmap_rwsem or anon_vma->rwsem).
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* 3. No other concurrent thread can access the list (release)
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*/
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struct mmu_notifier {
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struct hlist_node hlist;
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const struct mmu_notifier_ops *ops;
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};
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static inline int mm_has_notifiers(struct mm_struct *mm)
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{
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return unlikely(mm->mmu_notifier_mm);
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}
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extern int mmu_notifier_register(struct mmu_notifier *mn,
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struct mm_struct *mm);
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extern int __mmu_notifier_register(struct mmu_notifier *mn,
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struct mm_struct *mm);
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extern void mmu_notifier_unregister(struct mmu_notifier *mn,
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struct mm_struct *mm);
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extern void mmu_notifier_unregister_no_release(struct mmu_notifier *mn,
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struct mm_struct *mm);
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extern void __mmu_notifier_mm_destroy(struct mm_struct *mm);
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extern void __mmu_notifier_release(struct mm_struct *mm);
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extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
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unsigned long start,
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unsigned long end);
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extern int __mmu_notifier_clear_young(struct mm_struct *mm,
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unsigned long start,
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unsigned long end);
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extern int __mmu_notifier_test_young(struct mm_struct *mm,
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unsigned long address);
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extern void __mmu_notifier_change_pte(struct mm_struct *mm,
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unsigned long address, pte_t pte);
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extern int __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
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unsigned long start, unsigned long end,
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bool blockable);
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extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
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unsigned long start, unsigned long end,
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bool only_end);
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extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
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unsigned long start, unsigned long end);
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static inline void mmu_notifier_release(struct mm_struct *mm)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_release(mm);
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}
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static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
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unsigned long start,
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unsigned long end)
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{
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if (mm_has_notifiers(mm))
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return __mmu_notifier_clear_flush_young(mm, start, end);
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return 0;
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}
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static inline int mmu_notifier_clear_young(struct mm_struct *mm,
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unsigned long start,
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unsigned long end)
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{
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if (mm_has_notifiers(mm))
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return __mmu_notifier_clear_young(mm, start, end);
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return 0;
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}
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static inline int mmu_notifier_test_young(struct mm_struct *mm,
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unsigned long address)
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{
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if (mm_has_notifiers(mm))
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return __mmu_notifier_test_young(mm, address);
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return 0;
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}
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static inline void mmu_notifier_change_pte(struct mm_struct *mm,
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unsigned long address, pte_t pte)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_change_pte(mm, address, pte);
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}
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static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_invalidate_range_start(mm, start, end, true);
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}
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static inline int mmu_notifier_invalidate_range_start_nonblock(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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if (mm_has_notifiers(mm))
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return __mmu_notifier_invalidate_range_start(mm, start, end, false);
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return 0;
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}
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static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_invalidate_range_end(mm, start, end, false);
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}
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static inline void mmu_notifier_invalidate_range_only_end(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_invalidate_range_end(mm, start, end, true);
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}
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static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_invalidate_range(mm, start, end);
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}
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static inline void mmu_notifier_mm_init(struct mm_struct *mm)
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{
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mm->mmu_notifier_mm = NULL;
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}
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static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
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{
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if (mm_has_notifiers(mm))
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__mmu_notifier_mm_destroy(mm);
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}
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#define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
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({ \
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int __young; \
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struct vm_area_struct *___vma = __vma; \
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unsigned long ___address = __address; \
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__young = ptep_clear_flush_young(___vma, ___address, __ptep); \
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__young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
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___address, \
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___address + \
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PAGE_SIZE); \
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__young; \
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})
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#define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \
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({ \
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int __young; \
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struct vm_area_struct *___vma = __vma; \
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unsigned long ___address = __address; \
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__young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \
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__young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
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___address, \
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___address + \
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PMD_SIZE); \
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__young; \
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})
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#define ptep_clear_young_notify(__vma, __address, __ptep) \
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({ \
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int __young; \
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struct vm_area_struct *___vma = __vma; \
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unsigned long ___address = __address; \
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__young = ptep_test_and_clear_young(___vma, ___address, __ptep);\
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__young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
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___address + PAGE_SIZE); \
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__young; \
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})
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#define pmdp_clear_young_notify(__vma, __address, __pmdp) \
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({ \
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int __young; \
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struct vm_area_struct *___vma = __vma; \
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unsigned long ___address = __address; \
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__young = pmdp_test_and_clear_young(___vma, ___address, __pmdp);\
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__young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
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___address + PMD_SIZE); \
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__young; \
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})
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#define ptep_clear_flush_notify(__vma, __address, __ptep) \
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({ \
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unsigned long ___addr = __address & PAGE_MASK; \
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struct mm_struct *___mm = (__vma)->vm_mm; \
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pte_t ___pte; \
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\
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___pte = ptep_clear_flush(__vma, __address, __ptep); \
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mmu_notifier_invalidate_range(___mm, ___addr, \
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___addr + PAGE_SIZE); \
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\
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___pte; \
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})
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#define pmdp_huge_clear_flush_notify(__vma, __haddr, __pmd) \
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({ \
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unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \
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struct mm_struct *___mm = (__vma)->vm_mm; \
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pmd_t ___pmd; \
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\
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___pmd = pmdp_huge_clear_flush(__vma, __haddr, __pmd); \
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mmu_notifier_invalidate_range(___mm, ___haddr, \
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___haddr + HPAGE_PMD_SIZE); \
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\
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___pmd; \
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})
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#define pudp_huge_clear_flush_notify(__vma, __haddr, __pud) \
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({ \
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unsigned long ___haddr = __haddr & HPAGE_PUD_MASK; \
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struct mm_struct *___mm = (__vma)->vm_mm; \
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pud_t ___pud; \
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\
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___pud = pudp_huge_clear_flush(__vma, __haddr, __pud); \
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mmu_notifier_invalidate_range(___mm, ___haddr, \
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___haddr + HPAGE_PUD_SIZE); \
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\
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___pud; \
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})
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/*
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* set_pte_at_notify() sets the pte _after_ running the notifier.
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* This is safe to start by updating the secondary MMUs, because the primary MMU
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* pte invalidate must have already happened with a ptep_clear_flush() before
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* set_pte_at_notify() has been invoked. Updating the secondary MMUs first is
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* required when we change both the protection of the mapping from read-only to
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* read-write and the pfn (like during copy on write page faults). Otherwise the
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* old page would remain mapped readonly in the secondary MMUs after the new
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* page is already writable by some CPU through the primary MMU.
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*/
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#define set_pte_at_notify(__mm, __address, __ptep, __pte) \
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({ \
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struct mm_struct *___mm = __mm; \
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unsigned long ___address = __address; \
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pte_t ___pte = __pte; \
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\
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mmu_notifier_change_pte(___mm, ___address, ___pte); \
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set_pte_at(___mm, ___address, __ptep, ___pte); \
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})
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extern void mmu_notifier_call_srcu(struct rcu_head *rcu,
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void (*func)(struct rcu_head *rcu));
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extern void mmu_notifier_synchronize(void);
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#else /* CONFIG_MMU_NOTIFIER */
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static inline int mm_has_notifiers(struct mm_struct *mm)
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{
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return 0;
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}
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static inline void mmu_notifier_release(struct mm_struct *mm)
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{
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}
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static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
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unsigned long start,
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unsigned long end)
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{
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return 0;
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}
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static inline int mmu_notifier_test_young(struct mm_struct *mm,
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unsigned long address)
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{
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return 0;
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}
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static inline void mmu_notifier_change_pte(struct mm_struct *mm,
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unsigned long address, pte_t pte)
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{
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}
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static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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}
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static inline int mmu_notifier_invalidate_range_start_nonblock(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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return 0;
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}
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static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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}
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static inline void mmu_notifier_invalidate_range_only_end(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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}
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static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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}
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static inline void mmu_notifier_mm_init(struct mm_struct *mm)
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{
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}
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static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
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{
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}
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#define ptep_clear_flush_young_notify ptep_clear_flush_young
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#define pmdp_clear_flush_young_notify pmdp_clear_flush_young
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#define ptep_clear_young_notify ptep_test_and_clear_young
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#define pmdp_clear_young_notify pmdp_test_and_clear_young
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#define ptep_clear_flush_notify ptep_clear_flush
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#define pmdp_huge_clear_flush_notify pmdp_huge_clear_flush
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#define pudp_huge_clear_flush_notify pudp_huge_clear_flush
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#define set_pte_at_notify set_pte_at
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#endif /* CONFIG_MMU_NOTIFIER */
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#endif /* _LINUX_MMU_NOTIFIER_H */
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