| #ifndef _ASM_GENERIC_PGTABLE_H | 
 | #define _ASM_GENERIC_PGTABLE_H | 
 |  | 
 | #ifndef __ASSEMBLY__ | 
 | #ifdef CONFIG_MMU | 
 |  | 
 | #include <linux/mm_types.h> | 
 | #include <linux/bug.h> | 
 |  | 
 | /* | 
 |  * On almost all architectures and configurations, 0 can be used as the | 
 |  * upper ceiling to free_pgtables(): on many architectures it has the same | 
 |  * effect as using TASK_SIZE.  However, there is one configuration which | 
 |  * must impose a more careful limit, to avoid freeing kernel pgtables. | 
 |  */ | 
 | #ifndef USER_PGTABLES_CEILING | 
 | #define USER_PGTABLES_CEILING	0UL | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS | 
 | extern int ptep_set_access_flags(struct vm_area_struct *vma, | 
 | 				 unsigned long address, pte_t *ptep, | 
 | 				 pte_t entry, int dirty); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS | 
 | extern int pmdp_set_access_flags(struct vm_area_struct *vma, | 
 | 				 unsigned long address, pmd_t *pmdp, | 
 | 				 pmd_t entry, int dirty); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG | 
 | static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, | 
 | 					    unsigned long address, | 
 | 					    pte_t *ptep) | 
 | { | 
 | 	pte_t pte = *ptep; | 
 | 	int r = 1; | 
 | 	if (!pte_young(pte)) | 
 | 		r = 0; | 
 | 	else | 
 | 		set_pte_at(vma->vm_mm, address, ptep, pte_mkold(pte)); | 
 | 	return r; | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, | 
 | 					    unsigned long address, | 
 | 					    pmd_t *pmdp) | 
 | { | 
 | 	pmd_t pmd = *pmdp; | 
 | 	int r = 1; | 
 | 	if (!pmd_young(pmd)) | 
 | 		r = 0; | 
 | 	else | 
 | 		set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd)); | 
 | 	return r; | 
 | } | 
 | #else /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, | 
 | 					    unsigned long address, | 
 | 					    pmd_t *pmdp) | 
 | { | 
 | 	BUG(); | 
 | 	return 0; | 
 | } | 
 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH | 
 | int ptep_clear_flush_young(struct vm_area_struct *vma, | 
 | 			   unsigned long address, pte_t *ptep); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH | 
 | int pmdp_clear_flush_young(struct vm_area_struct *vma, | 
 | 			   unsigned long address, pmd_t *pmdp); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR | 
 | static inline pte_t ptep_get_and_clear(struct mm_struct *mm, | 
 | 				       unsigned long address, | 
 | 				       pte_t *ptep) | 
 | { | 
 | 	pte_t pte = *ptep; | 
 | 	pte_clear(mm, address, ptep); | 
 | 	return pte; | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, | 
 | 				       unsigned long address, | 
 | 				       pmd_t *pmdp) | 
 | { | 
 | 	pmd_t pmd = *pmdp; | 
 | 	pmd_clear(pmdp); | 
 | 	return pmd; | 
 | } | 
 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL | 
 | static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, | 
 | 					    unsigned long address, pte_t *ptep, | 
 | 					    int full) | 
 | { | 
 | 	pte_t pte; | 
 | 	pte = ptep_get_and_clear(mm, address, ptep); | 
 | 	return pte; | 
 | } | 
 | #endif | 
 |  | 
 | /* | 
 |  * Some architectures may be able to avoid expensive synchronization | 
 |  * primitives when modifications are made to PTE's which are already | 
 |  * not present, or in the process of an address space destruction. | 
 |  */ | 
 | #ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL | 
 | static inline void pte_clear_not_present_full(struct mm_struct *mm, | 
 | 					      unsigned long address, | 
 | 					      pte_t *ptep, | 
 | 					      int full) | 
 | { | 
 | 	pte_clear(mm, address, ptep); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH | 
 | extern pte_t ptep_clear_flush(struct vm_area_struct *vma, | 
 | 			      unsigned long address, | 
 | 			      pte_t *ptep); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_CLEAR_FLUSH | 
 | extern pmd_t pmdp_clear_flush(struct vm_area_struct *vma, | 
 | 			      unsigned long address, | 
 | 			      pmd_t *pmdp); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT | 
 | struct mm_struct; | 
 | static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep) | 
 | { | 
 | 	pte_t old_pte = *ptep; | 
 | 	set_pte_at(mm, address, ptep, pte_wrprotect(old_pte)); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | static inline void pmdp_set_wrprotect(struct mm_struct *mm, | 
 | 				      unsigned long address, pmd_t *pmdp) | 
 | { | 
 | 	pmd_t old_pmd = *pmdp; | 
 | 	set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd)); | 
 | } | 
 | #else /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | static inline void pmdp_set_wrprotect(struct mm_struct *mm, | 
 | 				      unsigned long address, pmd_t *pmdp) | 
 | { | 
 | 	BUG(); | 
 | } | 
 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH | 
 | extern void pmdp_splitting_flush(struct vm_area_struct *vma, | 
 | 				 unsigned long address, pmd_t *pmdp); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT | 
 | extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, | 
 | 				       pgtable_t pgtable); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PGTABLE_WITHDRAW | 
 | extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMDP_INVALIDATE | 
 | extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, | 
 | 			    pmd_t *pmdp); | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PTE_SAME | 
 | static inline int pte_same(pte_t pte_a, pte_t pte_b) | 
 | { | 
 | 	return pte_val(pte_a) == pte_val(pte_b); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PMD_SAME | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) | 
 | { | 
 | 	return pmd_val(pmd_a) == pmd_val(pmd_b); | 
 | } | 
 | #else /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) | 
 | { | 
 | 	BUG(); | 
 | 	return 0; | 
 | } | 
 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG | 
 | #define page_test_and_clear_young(pfn) (0) | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_PGD_OFFSET_GATE | 
 | #define pgd_offset_gate(mm, addr)	pgd_offset(mm, addr) | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_ARCH_MOVE_PTE | 
 | #define move_pte(pte, prot, old_addr, new_addr)	(pte) | 
 | #endif | 
 |  | 
 | #ifndef pte_accessible | 
 | # define pte_accessible(pte)		((void)(pte),1) | 
 | #endif | 
 |  | 
 | #ifndef flush_tlb_fix_spurious_fault | 
 | #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address) | 
 | #endif | 
 |  | 
 | #ifndef pgprot_noncached | 
 | #define pgprot_noncached(prot)	(prot) | 
 | #endif | 
 |  | 
 | #ifndef pgprot_writecombine | 
 | #define pgprot_writecombine pgprot_noncached | 
 | #endif | 
 |  | 
 | /* | 
 |  * When walking page tables, get the address of the next boundary, | 
 |  * or the end address of the range if that comes earlier.  Although no | 
 |  * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout. | 
 |  */ | 
 |  | 
 | #define pgd_addr_end(addr, end)						\ | 
 | ({	unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK;	\ | 
 | 	(__boundary - 1 < (end) - 1)? __boundary: (end);		\ | 
 | }) | 
 |  | 
 | #ifndef pud_addr_end | 
 | #define pud_addr_end(addr, end)						\ | 
 | ({	unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK;	\ | 
 | 	(__boundary - 1 < (end) - 1)? __boundary: (end);		\ | 
 | }) | 
 | #endif | 
 |  | 
 | #ifndef pmd_addr_end | 
 | #define pmd_addr_end(addr, end)						\ | 
 | ({	unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK;	\ | 
 | 	(__boundary - 1 < (end) - 1)? __boundary: (end);		\ | 
 | }) | 
 | #endif | 
 |  | 
 | /* | 
 |  * When walking page tables, we usually want to skip any p?d_none entries; | 
 |  * and any p?d_bad entries - reporting the error before resetting to none. | 
 |  * Do the tests inline, but report and clear the bad entry in mm/memory.c. | 
 |  */ | 
 | void pgd_clear_bad(pgd_t *); | 
 | void pud_clear_bad(pud_t *); | 
 | void pmd_clear_bad(pmd_t *); | 
 |  | 
 | static inline int pgd_none_or_clear_bad(pgd_t *pgd) | 
 | { | 
 | 	if (pgd_none(*pgd)) | 
 | 		return 1; | 
 | 	if (unlikely(pgd_bad(*pgd))) { | 
 | 		pgd_clear_bad(pgd); | 
 | 		return 1; | 
 | 	} | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline int pud_none_or_clear_bad(pud_t *pud) | 
 | { | 
 | 	if (pud_none(*pud)) | 
 | 		return 1; | 
 | 	if (unlikely(pud_bad(*pud))) { | 
 | 		pud_clear_bad(pud); | 
 | 		return 1; | 
 | 	} | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline int pmd_none_or_clear_bad(pmd_t *pmd) | 
 | { | 
 | 	if (pmd_none(*pmd)) | 
 | 		return 1; | 
 | 	if (unlikely(pmd_bad(*pmd))) { | 
 | 		pmd_clear_bad(pmd); | 
 | 		return 1; | 
 | 	} | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm, | 
 | 					     unsigned long addr, | 
 | 					     pte_t *ptep) | 
 | { | 
 | 	/* | 
 | 	 * Get the current pte state, but zero it out to make it | 
 | 	 * non-present, preventing the hardware from asynchronously | 
 | 	 * updating it. | 
 | 	 */ | 
 | 	return ptep_get_and_clear(mm, addr, ptep); | 
 | } | 
 |  | 
 | static inline void __ptep_modify_prot_commit(struct mm_struct *mm, | 
 | 					     unsigned long addr, | 
 | 					     pte_t *ptep, pte_t pte) | 
 | { | 
 | 	/* | 
 | 	 * The pte is non-present, so there's no hardware state to | 
 | 	 * preserve. | 
 | 	 */ | 
 | 	set_pte_at(mm, addr, ptep, pte); | 
 | } | 
 |  | 
 | #ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION | 
 | /* | 
 |  * Start a pte protection read-modify-write transaction, which | 
 |  * protects against asynchronous hardware modifications to the pte. | 
 |  * The intention is not to prevent the hardware from making pte | 
 |  * updates, but to prevent any updates it may make from being lost. | 
 |  * | 
 |  * This does not protect against other software modifications of the | 
 |  * pte; the appropriate pte lock must be held over the transation. | 
 |  * | 
 |  * Note that this interface is intended to be batchable, meaning that | 
 |  * ptep_modify_prot_commit may not actually update the pte, but merely | 
 |  * queue the update to be done at some later time.  The update must be | 
 |  * actually committed before the pte lock is released, however. | 
 |  */ | 
 | static inline pte_t ptep_modify_prot_start(struct mm_struct *mm, | 
 | 					   unsigned long addr, | 
 | 					   pte_t *ptep) | 
 | { | 
 | 	return __ptep_modify_prot_start(mm, addr, ptep); | 
 | } | 
 |  | 
 | /* | 
 |  * Commit an update to a pte, leaving any hardware-controlled bits in | 
 |  * the PTE unmodified. | 
 |  */ | 
 | static inline void ptep_modify_prot_commit(struct mm_struct *mm, | 
 | 					   unsigned long addr, | 
 | 					   pte_t *ptep, pte_t pte) | 
 | { | 
 | 	__ptep_modify_prot_commit(mm, addr, ptep, pte); | 
 | } | 
 | #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */ | 
 | #endif /* CONFIG_MMU */ | 
 |  | 
 | /* | 
 |  * A facility to provide lazy MMU batching.  This allows PTE updates and | 
 |  * page invalidations to be delayed until a call to leave lazy MMU mode | 
 |  * is issued.  Some architectures may benefit from doing this, and it is | 
 |  * beneficial for both shadow and direct mode hypervisors, which may batch | 
 |  * the PTE updates which happen during this window.  Note that using this | 
 |  * interface requires that read hazards be removed from the code.  A read | 
 |  * hazard could result in the direct mode hypervisor case, since the actual | 
 |  * write to the page tables may not yet have taken place, so reads though | 
 |  * a raw PTE pointer after it has been modified are not guaranteed to be | 
 |  * up to date.  This mode can only be entered and left under the protection of | 
 |  * the page table locks for all page tables which may be modified.  In the UP | 
 |  * case, this is required so that preemption is disabled, and in the SMP case, | 
 |  * it must synchronize the delayed page table writes properly on other CPUs. | 
 |  */ | 
 | #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE | 
 | #define arch_enter_lazy_mmu_mode()	do {} while (0) | 
 | #define arch_leave_lazy_mmu_mode()	do {} while (0) | 
 | #define arch_flush_lazy_mmu_mode()	do {} while (0) | 
 | #endif | 
 |  | 
 | /* | 
 |  * A facility to provide batching of the reload of page tables and | 
 |  * other process state with the actual context switch code for | 
 |  * paravirtualized guests.  By convention, only one of the batched | 
 |  * update (lazy) modes (CPU, MMU) should be active at any given time, | 
 |  * entry should never be nested, and entry and exits should always be | 
 |  * paired.  This is for sanity of maintaining and reasoning about the | 
 |  * kernel code.  In this case, the exit (end of the context switch) is | 
 |  * in architecture-specific code, and so doesn't need a generic | 
 |  * definition. | 
 |  */ | 
 | #ifndef __HAVE_ARCH_START_CONTEXT_SWITCH | 
 | #define arch_start_context_switch(prev)	do {} while (0) | 
 | #endif | 
 |  | 
 | #ifndef CONFIG_HAVE_ARCH_SOFT_DIRTY | 
 | static inline int pte_soft_dirty(pte_t pte) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline int pmd_soft_dirty(pmd_t pmd) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline pte_t pte_mksoft_dirty(pte_t pte) | 
 | { | 
 | 	return pte; | 
 | } | 
 |  | 
 | static inline pmd_t pmd_mksoft_dirty(pmd_t pmd) | 
 | { | 
 | 	return pmd; | 
 | } | 
 |  | 
 | static inline pte_t pte_swp_mksoft_dirty(pte_t pte) | 
 | { | 
 | 	return pte; | 
 | } | 
 |  | 
 | static inline int pte_swp_soft_dirty(pte_t pte) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) | 
 | { | 
 | 	return pte; | 
 | } | 
 |  | 
 | static inline pte_t pte_file_clear_soft_dirty(pte_t pte) | 
 | { | 
 |        return pte; | 
 | } | 
 |  | 
 | static inline pte_t pte_file_mksoft_dirty(pte_t pte) | 
 | { | 
 |        return pte; | 
 | } | 
 |  | 
 | static inline int pte_file_soft_dirty(pte_t pte) | 
 | { | 
 |        return 0; | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef __HAVE_PFNMAP_TRACKING | 
 | /* | 
 |  * Interfaces that can be used by architecture code to keep track of | 
 |  * memory type of pfn mappings specified by the remap_pfn_range, | 
 |  * vm_insert_pfn. | 
 |  */ | 
 |  | 
 | /* | 
 |  * track_pfn_remap is called when a _new_ pfn mapping is being established | 
 |  * by remap_pfn_range() for physical range indicated by pfn and size. | 
 |  */ | 
 | static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot, | 
 | 				  unsigned long pfn, unsigned long addr, | 
 | 				  unsigned long size) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | /* | 
 |  * track_pfn_insert is called when a _new_ single pfn is established | 
 |  * by vm_insert_pfn(). | 
 |  */ | 
 | static inline int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, | 
 | 				   unsigned long pfn) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | /* | 
 |  * track_pfn_copy is called when vma that is covering the pfnmap gets | 
 |  * copied through copy_page_range(). | 
 |  */ | 
 | static inline int track_pfn_copy(struct vm_area_struct *vma) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | /* | 
 |  * untrack_pfn_vma is called while unmapping a pfnmap for a region. | 
 |  * untrack can be called for a specific region indicated by pfn and size or | 
 |  * can be for the entire vma (in which case pfn, size are zero). | 
 |  */ | 
 | static inline void untrack_pfn(struct vm_area_struct *vma, | 
 | 			       unsigned long pfn, unsigned long size) | 
 | { | 
 | } | 
 | #else | 
 | extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot, | 
 | 			   unsigned long pfn, unsigned long addr, | 
 | 			   unsigned long size); | 
 | extern int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, | 
 | 			    unsigned long pfn); | 
 | extern int track_pfn_copy(struct vm_area_struct *vma); | 
 | extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, | 
 | 			unsigned long size); | 
 | #endif | 
 |  | 
 | #ifdef __HAVE_COLOR_ZERO_PAGE | 
 | static inline int is_zero_pfn(unsigned long pfn) | 
 | { | 
 | 	extern unsigned long zero_pfn; | 
 | 	unsigned long offset_from_zero_pfn = pfn - zero_pfn; | 
 | 	return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT); | 
 | } | 
 |  | 
 | #define my_zero_pfn(addr)	page_to_pfn(ZERO_PAGE(addr)) | 
 |  | 
 | #else | 
 | static inline int is_zero_pfn(unsigned long pfn) | 
 | { | 
 | 	extern unsigned long zero_pfn; | 
 | 	return pfn == zero_pfn; | 
 | } | 
 |  | 
 | static inline unsigned long my_zero_pfn(unsigned long addr) | 
 | { | 
 | 	extern unsigned long zero_pfn; | 
 | 	return zero_pfn; | 
 | } | 
 | #endif | 
 |  | 
 | #ifdef CONFIG_MMU | 
 |  | 
 | #ifndef CONFIG_TRANSPARENT_HUGEPAGE | 
 | static inline int pmd_trans_huge(pmd_t pmd) | 
 | { | 
 | 	return 0; | 
 | } | 
 | static inline int pmd_trans_splitting(pmd_t pmd) | 
 | { | 
 | 	return 0; | 
 | } | 
 | #ifndef __HAVE_ARCH_PMD_WRITE | 
 | static inline int pmd_write(pmd_t pmd) | 
 | { | 
 | 	BUG(); | 
 | 	return 0; | 
 | } | 
 | #endif /* __HAVE_ARCH_PMD_WRITE */ | 
 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | 
 |  | 
 | #ifndef pmd_read_atomic | 
 | static inline pmd_t pmd_read_atomic(pmd_t *pmdp) | 
 | { | 
 | 	/* | 
 | 	 * Depend on compiler for an atomic pmd read. NOTE: this is | 
 | 	 * only going to work, if the pmdval_t isn't larger than | 
 | 	 * an unsigned long. | 
 | 	 */ | 
 | 	return *pmdp; | 
 | } | 
 | #endif | 
 |  | 
 | /* | 
 |  * This function is meant to be used by sites walking pagetables with | 
 |  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and | 
 |  * transhuge page faults. MADV_DONTNEED can convert a transhuge pmd | 
 |  * into a null pmd and the transhuge page fault can convert a null pmd | 
 |  * into an hugepmd or into a regular pmd (if the hugepage allocation | 
 |  * fails). While holding the mmap_sem in read mode the pmd becomes | 
 |  * stable and stops changing under us only if it's not null and not a | 
 |  * transhuge pmd. When those races occurs and this function makes a | 
 |  * difference vs the standard pmd_none_or_clear_bad, the result is | 
 |  * undefined so behaving like if the pmd was none is safe (because it | 
 |  * can return none anyway). The compiler level barrier() is critically | 
 |  * important to compute the two checks atomically on the same pmdval. | 
 |  * | 
 |  * For 32bit kernels with a 64bit large pmd_t this automatically takes | 
 |  * care of reading the pmd atomically to avoid SMP race conditions | 
 |  * against pmd_populate() when the mmap_sem is hold for reading by the | 
 |  * caller (a special atomic read not done by "gcc" as in the generic | 
 |  * version above, is also needed when THP is disabled because the page | 
 |  * fault can populate the pmd from under us). | 
 |  */ | 
 | static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd) | 
 | { | 
 | 	pmd_t pmdval = pmd_read_atomic(pmd); | 
 | 	/* | 
 | 	 * The barrier will stabilize the pmdval in a register or on | 
 | 	 * the stack so that it will stop changing under the code. | 
 | 	 * | 
 | 	 * When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE, | 
 | 	 * pmd_read_atomic is allowed to return a not atomic pmdval | 
 | 	 * (for example pointing to an hugepage that has never been | 
 | 	 * mapped in the pmd). The below checks will only care about | 
 | 	 * the low part of the pmd with 32bit PAE x86 anyway, with the | 
 | 	 * exception of pmd_none(). So the important thing is that if | 
 | 	 * the low part of the pmd is found null, the high part will | 
 | 	 * be also null or the pmd_none() check below would be | 
 | 	 * confused. | 
 | 	 */ | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | 	barrier(); | 
 | #endif | 
 | 	if (pmd_none(pmdval)) | 
 | 		return 1; | 
 | 	if (unlikely(pmd_bad(pmdval))) { | 
 | 		if (!pmd_trans_huge(pmdval)) | 
 | 			pmd_clear_bad(pmd); | 
 | 		return 1; | 
 | 	} | 
 | 	return 0; | 
 | } | 
 |  | 
 | /* | 
 |  * This is a noop if Transparent Hugepage Support is not built into | 
 |  * the kernel. Otherwise it is equivalent to | 
 |  * pmd_none_or_trans_huge_or_clear_bad(), and shall only be called in | 
 |  * places that already verified the pmd is not none and they want to | 
 |  * walk ptes while holding the mmap sem in read mode (write mode don't | 
 |  * need this). If THP is not enabled, the pmd can't go away under the | 
 |  * code even if MADV_DONTNEED runs, but if THP is enabled we need to | 
 |  * run a pmd_trans_unstable before walking the ptes after | 
 |  * split_huge_page_pmd returns (because it may have run when the pmd | 
 |  * become null, but then a page fault can map in a THP and not a | 
 |  * regular page). | 
 |  */ | 
 | static inline int pmd_trans_unstable(pmd_t *pmd) | 
 | { | 
 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | 
 | 	return pmd_none_or_trans_huge_or_clear_bad(pmd); | 
 | #else | 
 | 	return 0; | 
 | #endif | 
 | } | 
 |  | 
 | #ifdef CONFIG_NUMA_BALANCING | 
 | #ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE | 
 | /* | 
 |  * _PAGE_NUMA works identical to _PAGE_PROTNONE (it's actually the | 
 |  * same bit too). It's set only when _PAGE_PRESET is not set and it's | 
 |  * never set if _PAGE_PRESENT is set. | 
 |  * | 
 |  * pte/pmd_present() returns true if pte/pmd_numa returns true. Page | 
 |  * fault triggers on those regions if pte/pmd_numa returns true | 
 |  * (because _PAGE_PRESENT is not set). | 
 |  */ | 
 | #ifndef pte_numa | 
 | static inline int pte_numa(pte_t pte) | 
 | { | 
 | 	return (pte_flags(pte) & | 
 | 		(_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA; | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef pmd_numa | 
 | static inline int pmd_numa(pmd_t pmd) | 
 | { | 
 | 	return (pmd_flags(pmd) & | 
 | 		(_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA; | 
 | } | 
 | #endif | 
 |  | 
 | /* | 
 |  * pte/pmd_mknuma sets the _PAGE_ACCESSED bitflag automatically | 
 |  * because they're called by the NUMA hinting minor page fault. If we | 
 |  * wouldn't set the _PAGE_ACCESSED bitflag here, the TLB miss handler | 
 |  * would be forced to set it later while filling the TLB after we | 
 |  * return to userland. That would trigger a second write to memory | 
 |  * that we optimize away by setting _PAGE_ACCESSED here. | 
 |  */ | 
 | #ifndef pte_mknonnuma | 
 | static inline pte_t pte_mknonnuma(pte_t pte) | 
 | { | 
 | 	pte = pte_clear_flags(pte, _PAGE_NUMA); | 
 | 	return pte_set_flags(pte, _PAGE_PRESENT|_PAGE_ACCESSED); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef pmd_mknonnuma | 
 | static inline pmd_t pmd_mknonnuma(pmd_t pmd) | 
 | { | 
 | 	pmd = pmd_clear_flags(pmd, _PAGE_NUMA); | 
 | 	return pmd_set_flags(pmd, _PAGE_PRESENT|_PAGE_ACCESSED); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef pte_mknuma | 
 | static inline pte_t pte_mknuma(pte_t pte) | 
 | { | 
 | 	pte = pte_set_flags(pte, _PAGE_NUMA); | 
 | 	return pte_clear_flags(pte, _PAGE_PRESENT); | 
 | } | 
 | #endif | 
 |  | 
 | #ifndef pmd_mknuma | 
 | static inline pmd_t pmd_mknuma(pmd_t pmd) | 
 | { | 
 | 	pmd = pmd_set_flags(pmd, _PAGE_NUMA); | 
 | 	return pmd_clear_flags(pmd, _PAGE_PRESENT); | 
 | } | 
 | #endif | 
 | #else | 
 | extern int pte_numa(pte_t pte); | 
 | extern int pmd_numa(pmd_t pmd); | 
 | extern pte_t pte_mknonnuma(pte_t pte); | 
 | extern pmd_t pmd_mknonnuma(pmd_t pmd); | 
 | extern pte_t pte_mknuma(pte_t pte); | 
 | extern pmd_t pmd_mknuma(pmd_t pmd); | 
 | #endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */ | 
 | #else | 
 | static inline int pmd_numa(pmd_t pmd) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline int pte_numa(pte_t pte) | 
 | { | 
 | 	return 0; | 
 | } | 
 |  | 
 | static inline pte_t pte_mknonnuma(pte_t pte) | 
 | { | 
 | 	return pte; | 
 | } | 
 |  | 
 | static inline pmd_t pmd_mknonnuma(pmd_t pmd) | 
 | { | 
 | 	return pmd; | 
 | } | 
 |  | 
 | static inline pte_t pte_mknuma(pte_t pte) | 
 | { | 
 | 	return pte; | 
 | } | 
 |  | 
 | static inline pmd_t pmd_mknuma(pmd_t pmd) | 
 | { | 
 | 	return pmd; | 
 | } | 
 | #endif /* CONFIG_NUMA_BALANCING */ | 
 |  | 
 | #endif /* CONFIG_MMU */ | 
 |  | 
 | #endif /* !__ASSEMBLY__ */ | 
 |  | 
 | #ifndef io_remap_pfn_range | 
 | #define io_remap_pfn_range remap_pfn_range | 
 | #endif | 
 |  | 
 | #endif /* _ASM_GENERIC_PGTABLE_H */ |