Edit File: mmu_notifier.h
#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/srcu.h> struct mmu_notifier; struct mmu_notifier_rhel7; struct mmu_notifier_ops; struct mmu_notifier_ops_rhel7; #ifdef CONFIG_MMU_NOTIFIER /* * The mmu notifier_mm structure is allocated and installed in * mm->mmu_notifier_mm inside the mm_take_all_locks() protected * critical section and it's released only when mm_count reaches zero * in mmdrop(). */ struct mmu_notifier_mm { /* all mmu notifiers registerd in this mm are queued in this list */ struct hlist_head list; /* to serialize the list modifications and hlist_unhashed */ spinlock_t lock; }; 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 *mn, 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. */ int (*clear_flush_young)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address); /* * test_young is called to check the young/accessed bitflag in * the secondary pte. This is used to know if the page is * frequently used without actually clearing the flag or tearing * down the secondary mapping on the page. */ int (*test_young)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address); /* * change_pte is called in cases that pte mapping to page is changed: * for example, when ksm remaps pte to point to a new shared page. */ void (*change_pte)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address, pte_t pte); /* * Before this is invoked any secondary MMU is still ok to * read/write to the page previously pointed to by the Linux * pte because the page hasn't been freed yet and it won't be * freed until this returns. If required set_page_dirty has to * be called internally to this method. */ void (*invalidate_page)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address); /* * invalidate_range_start() and invalidate_range_end() must be * paired and are called only when the mmap_sem and/or the * locks protecting the reverse maps are held. If the subsystem * can't guarantee that no additional references are taken to * the pages in the range, it has to implement the * invalidate_range() notifier from rhel7 interface (see below * for updated mmu_notifier_ops structure) to remove any * references taken after invalidate_range_start(). * * * Invalidation of multiple concurrent ranges may be * optionally permitted by the driver. Either way the * establishment of sptes is forbidden in the range passed to * invalidate_range_begin/end for the whole duration of the * invalidate_range_begin/end critical section. * * invalidate_range_start() is called when all pages in the * range are still mapped and have at least a refcount of one. * * invalidate_range_end() is called when all pages in the * range have been unmapped and the pages have been freed by * the VM. * * The VM will remove the page table entries and potentially * the page between invalidate_range_start() and * invalidate_range_end(). If the page must not be freed * because of pending I/O or other circumstances then the * invalidate_range_start() callback (or the initial mapping * by the driver) must make sure that the refcount is kept * elevated. * * If the driver increases the refcount when the pages are * initially mapped into an address space then either * invalidate_range_start() or invalidate_range_end() may * decrease the refcount. If the refcount is decreased on * invalidate_range_start() then the VM can free pages as page * table entries are removed. If the refcount is only * droppped on invalidate_range_end() then the driver itself * will drop the last refcount but it must take care to flush * any secondary tlb before doing the final free on the * page. Pages will no longer be referenced by the linux * address space but may still be referenced by sptes until * the last refcount is dropped. */ void (*invalidate_range_start)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end); void (*invalidate_range_end)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end); }; struct mmu_notifier_ops_rhel7 { void (*release)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm); int (*clear_flush_young)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long address); int (*test_young)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long address); void (*change_pte)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long address, pte_t pte); void (*invalidate_page)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long address); void (*invalidate_range_start)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long start, unsigned long end); void (*invalidate_range_end)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long start, unsigned long end); /* * invalidate_range() is either called between * invalidate_range_start() and invalidate_range_end() when the * VM has to free pages that where unmapped, but before the * pages are actually freed, or outside of _start()/_end() when * a (remote) TLB is necessary. * * If invalidate_range() is used to manage a non-CPU TLB with * shared page-tables, it not necessary to implement the * invalidate_range_start()/end() notifiers, as * invalidate_range() alread catches the points in time when an * external TLB range needs to be flushed. * * The invalidate_range() function is called under the ptl * spin-lock and not allowed to sleep. * * Note that this function might be called with just a sub-range * of what was passed to invalidate_range_start()/end(), if * called between those functions. */ void (*invalidate_range)(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm, unsigned long start, unsigned long end); }; struct mmu_notifier_rhel7 { struct hlist_node hlist; const struct mmu_notifier_ops_rhel7 *ops; }; /* * The notifier chains are protected by mmap_sem and/or the reverse map * semaphores. Notifier chains are only changed when all reverse maps and * the mmap_sem locks are taken. * * Therefore notifier chains can only be traversed when either * * 1. mmap_sem is held. * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->rwsem). * 3. No other concurrent thread can access the list (release) */ struct mmu_notifier { struct hlist_node hlist; const struct mmu_notifier_ops *ops; }; static inline int mm_has_notifiers(struct mm_struct *mm) { return unlikely(mm->mmu_notifier_mm); } extern int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm); extern int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm); extern void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm); extern void mmu_notifier_unregister_no_release(struct mmu_notifier *mn, struct mm_struct *mm); extern int mmu_notifier_register_rhel7(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm); extern int __mmu_notifier_register_rhel7(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm); extern void mmu_notifier_unregister_rhel7(struct mmu_notifier_rhel7 *mn, struct mm_struct *mm); extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); extern void __mmu_notifier_release(struct mm_struct *mm); extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address); extern int __mmu_notifier_test_young(struct mm_struct *mm, unsigned long address); extern void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, pte_t pte); extern void __mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address); extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end); extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end); extern void __mmu_notifier_invalidate_range(struct mm_struct *mm, unsigned long start, unsigned long end); static inline void mmu_notifier_release(struct mm_struct *mm) { if (mm_has_notifiers(mm)) __mmu_notifier_release(mm); } static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address) { if (mm_has_notifiers(mm)) return __mmu_notifier_clear_flush_young(mm, address); return 0; } static inline int mmu_notifier_test_young(struct mm_struct *mm, unsigned long address) { if (mm_has_notifiers(mm)) return __mmu_notifier_test_young(mm, address); return 0; } static inline void mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, pte_t pte) { if (mm_has_notifiers(mm)) __mmu_notifier_change_pte(mm, address, pte); } static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_page(mm, address); } static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_range_start(mm, start, end); } static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_range_end(mm, start, end); } static inline void mmu_notifier_invalidate_range(struct mm_struct *mm, unsigned long start, unsigned long end) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_range(mm, start, end); } static inline void mmu_notifier_mm_init(struct mm_struct *mm) { mm->mmu_notifier_mm = NULL; } static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) { if (mm_has_notifiers(mm)) __mmu_notifier_mm_destroy(mm); } #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \ ({ \ int __young; \ struct vm_area_struct *___vma = __vma; \ unsigned long ___address = __address; \ __young = ptep_clear_flush_young(___vma, ___address, __ptep); \ __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ ___address); \ __young; \ }) #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \ ({ \ int __young; \ struct vm_area_struct *___vma = __vma; \ unsigned long ___address = __address; \ __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \ __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ ___address); \ __young; \ }) #define ptep_clear_flush_notify(__vma, __address, __ptep) \ ({ \ unsigned long ___addr = __address & PAGE_MASK; \ struct mm_struct *___mm = (__vma)->vm_mm; \ pte_t ___pte; \ \ ___pte = ptep_clear_flush(__vma, __address, __ptep); \ mmu_notifier_invalidate_range(___mm, ___addr, \ ___addr + PAGE_SIZE); \ \ ___pte; \ }) #define pmdp_clear_flush_notify(__vma, __haddr, __pmd) \ ({ \ unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \ struct mm_struct *___mm = (__vma)->vm_mm; \ pmd_t ___pmd; \ \ ___pmd = pmdp_clear_flush(__vma, __haddr, __pmd); \ mmu_notifier_invalidate_range(___mm, ___haddr, \ ___haddr + HPAGE_PMD_SIZE); \ \ ___pmd; \ }) #define pudp_clear_flush_notify(__vma, __haddr, __pud) \ ({ \ unsigned long ___haddr = __haddr & HPAGE_PUD_MASK; \ struct mm_struct *___mm = (__vma)->vm_mm; \ pud_t ___pud; \ \ ___pud = pudp_clear_flush(__vma, __haddr, __pud); \ mmu_notifier_invalidate_range(___mm, ___haddr, \ ___haddr + HPAGE_PUD_SIZE); \ \ ___pud; \ }) #define pmdp_get_and_clear_notify(__mm, __haddr, __pmd) \ ({ \ unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \ pmd_t ___pmd; \ \ ___pmd = pmdp_get_and_clear(__mm, __haddr, __pmd); \ mmu_notifier_invalidate_range(__mm, ___haddr, \ ___haddr + HPAGE_PMD_SIZE); \ \ ___pmd; \ }) /* * set_pte_at_notify() sets the pte _after_ running the notifier. * This is safe to start by updating the secondary MMUs, because the primary MMU * pte invalidate must have already happened with a ptep_clear_flush() before * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is * required when we change both the protection of the mapping from read-only to * read-write and the pfn (like during copy on write page faults). Otherwise the * old page would remain mapped readonly in the secondary MMUs after the new * page is already writable by some CPU through the primary MMU. */ #define set_pte_at_notify(__mm, __address, __ptep, __pte) \ ({ \ struct mm_struct *___mm = __mm; \ unsigned long ___address = __address; \ pte_t ___pte = __pte; \ \ mmu_notifier_change_pte(___mm, ___address, ___pte); \ set_pte_at(___mm, ___address, __ptep, ___pte); \ }) #define ptep_clear_young_notify ptep_test_and_clear_young #define pmdp_clear_young_notify pmdp_test_and_clear_young extern void mmu_notifier_call_srcu(struct rcu_head *rcu, void (*func)(struct rcu_head *rcu)); extern void mmu_notifier_synchronize(void); #else /* CONFIG_MMU_NOTIFIER */ static inline void mmu_notifier_release(struct mm_struct *mm) { } static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address) { return 0; } static inline int mmu_notifier_test_young(struct mm_struct *mm, unsigned long address) { return 0; } static inline void mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, pte_t pte) { } static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address) { } static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end) { } static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end) { } static inline void mmu_notifier_invalidate_range(struct mm_struct *mm, unsigned long start, unsigned long end) { } static inline void mmu_notifier_mm_init(struct mm_struct *mm) { } static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) { } #define ptep_clear_flush_young_notify ptep_clear_flush_young #define pmdp_clear_flush_young_notify pmdp_clear_flush_young #define ptep_clear_young_notify ptep_test_and_clear_young #define pmdp_clear_young_notify pmdp_test_and_clear_young #define ptep_clear_flush_notify ptep_clear_flush #define pmdp_clear_flush_notify pmdp_clear_flush #define pmdp_get_and_clear_notify pmdp_get_and_clear #define set_pte_at_notify set_pte_at #endif /* CONFIG_MMU_NOTIFIER */ #endif /* _LINUX_MMU_NOTIFIER_H */