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     mˆÊÔ„.:É¿Ñ ?÷     m/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MMU_NOTIFIER_H
#define _LINUX_MMU_NOTIFIER_H

#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mm_types.h>
#include <linux/mmap_lock.h>
#include <linux/srcu.h>
#include <linux/interval_tree.h>

struct mmu_notifier_subscriptions;
struct mmu_notifier;
struct mmu_notifier_range;
struct mmu_interval_notifier;

/**
 * enum mmu_notifier_event - reason for the mmu notifier callback
 * @MMU_NOTIFY_UNMAP: either munmap() that unmap the range or a mremap() that
 * move the range
 *
 * @MMU_NOTIFY_CLEAR: clear page table entry (many reasons for this like
 * madvise() or replacing a page by another one, ...).
 *
 * @MMU_NOTIFY_PROTECTION_VMA: update is due to protection change for the range
 * ie using the vma access permission (vm_page_prot) to update the whole range
 * is enough no need to inspect changes to the CPU page table (mprotect()
 * syscall)
 *
 * @MMU_NOTIFY_PROTECTION_PAGE: update is due to change in read/write flag for
 * pages in the range so to mirror those changes the user must inspect the CPU
 * page table (from the end callback).
 *
 * @MMU_NOTIFY_SOFT_DIRTY: soft dirty accounting (still same page and same
 * access flags). User should soft dirty the page in the end callback to make
 * sure that anyone relying on soft dirtiness catch pages that might be written
 * through non CPU mappings.
 *
 * @MMU_NOTIFY_RELEASE: used during mmu_interval_notifier invalidate to signal
 * that the mm refcount is zero and the range is no longer accessible.
 *
 * @MMU_NOTIFY_MIGRATE: used during migrate_vma_collect() invalidate to signal
 * a device driver to possibly ignore the invalidation if the
 * owner field matches the driver's device private pgmap owner.
 *
 * @MMU_NOTIFY_EXCLUSIVE: to signal a device driver that the device will no
 * longer have exclusive access to the page. When sent during creation of an
 * exclusive range the owner will be initialised to the value provided by the
 * caller of make_device_exclusive_range(), otherwise the owner will be NULL.
 */
enum mmu_notifier_event {
	MMU_NOTIFY_UNMAP = 0,
	MMU_NOTIFY_CLEAR,
	MMU_NOTIFY_PROTECTION_VMA,
	MMU_NOTIFY_PROTECTION_PAGE,
	MMU_NOTIFY_SOFT_DIRTY,
	MMU_NOTIFY_RELEASE,
	MMU_NOTIFY_MIGRATE,
	MMU_NOTIFY_EXCLUSIVE,
};

#define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0)

struct mmu_notifier_ops {
	/*
	 * Called either by mmu_notifier_unregister or when the mm is
	 * being destroyed by exit_mmap, always before all pages are
	 * freed. This can run concurrently with other mmu notifier
	 * methods (the ones invoked outside the mm context) and it
	 * should tear down all secondary mmu mappings and freeze the
	 * secondary mmu. If this method isn't implemented you've to
	 * be sure that nothing could possibly write to the pages
	 * through the secondary mmu by the time the last thread with
	 * tsk->mm == mm exits.
	 *
	 * As side note: the pages freed after ->release returns could
	 * be immediately reallocated by the gart at an alias physical
	 * address with a different cache model, so if ->release isn't
	 * implemented because all _software_ driven memory accesses
	 * through the secondary mmu are terminated by the time the
	 * last thread of this mm quits, you've also to be sure that
	 * speculative _hardware_ operations can't allocate dirty
	 * cachelines in the cpu that could not be snooped and made
	 * coherent with the other read and write operations happening
	 * through the gart alias address, so leading to memory
	 * corruption.
	 */
	void (*release)(struct mmu_notifier *subscription,
			struct mm_struct *mm);

	/*
	 * clear_flush_young is called after the VM is
	 * test-and-clearing the young/accessed bitflag in the
	 * pte. This way the VM will provide proper aging to the
	 * accesses to the page through the secondary MMUs and not
	 * only to the ones through the Linux pte.
	 * Start-end is necessary in case the secondary MMU is mapping the page
	 * at a smaller granularity than the primary MMU.
	 */
	int (*clea