/* SPDX-License-Identifier: GPL-2.0-or-later *//* include/asm-generic/tlb.h * *	Generic TLB shootdown code * * Copyright 2001 Red Hat, Inc. * Based on code from mm/memory.c Copyright Linus Torvalds and others. * * Copyright 2011 Red Hat, Inc., Peter Zijlstra */#ifndef _ASM_GENERIC__TLB_H#define _ASM_GENERIC__TLB_H #include <linux/mmu_notifier.h>#include <linux/swap.h>#include <linux/hugetlb_inline.h>#include <asm/tlbflush.h>#include <asm/cacheflush.h> /* * Blindly accessing user memory from NMI context can be dangerous * if we're in the middle of switching the current user task or switching * the loaded mm. */#ifndef nmi_uaccess_okay# define nmi_uaccess_okay() true#endif #ifdef CONFIG_MMU /* * Generic MMU-gather implementation. * * The mmu_gather data structure is used by the mm code to implement the * correct and efficient ordering of freeing pages and TLB invalidations. * * This correct ordering is: * *  1) unhook page *  2) TLB invalidate page *  3) free page * * That is, we must never free a page before we have ensured there are no live * translations left to it. Otherwise it might be possible to observe (or * worse, change) the page content after it has been reused. * * The mmu_gather API consists of: * *  - tlb_gather_mmu() / tlb_finish_mmu(); start and finish a mmu_gather * *    Finish in particular will issue a (final) TLB invalidate and free *    all (remaining) queued pages. * *  - tlb_start_vma() / tlb_end_vma(); marks the start / end of a VMA * *    Defaults to flushing at tlb_end_vma() to reset the range; helps when *    there's large holes between the VMAs. * *  - tlb_remove_table() * *    tlb_remove_table() is the basic primitive to free page-table directories *    (__p*_free_tlb()).  In it's most primitive form it is an alias for *    tlb_remove_page() below, for when page directories are pages and have no *    additional constraints. * *    See also MMU_GATHER_TABLE_FREE and MMU_GATHER_RCU_TABLE_FREE. * *  - tlb_remove_page() / __tlb_remove_page() *  - tlb_remove_page_size() / __tlb_remove_page_size() * *    __tlb_remove_page_size() is the basic primitive that queues a page for *    freeing. __tlb_remove_page() assumes PAGE_SIZE. Both will return a *    boolean indicating if the queue is (now) full and a call to *    tlb_flush_mmu() is required. * *    tlb_remove_page() and tlb_remove_page_size() imply the call to *    tlb_flush_mmu() when required and has no return value. * *  - tlb_change_page_size() * *    call before __tlb_remove_page*() to set the current page-size; implies a *    possible tlb_flush_mmu() call. * *  - tlb_flush_mmu() / tlb_flush_mmu_tlbonly() * *    tlb_flush_mmu_tlbonly() - does the TLB invalidate (and resets *                              related state, like the range) * *    tlb_flush_mmu() - in addition to the above TLB invalidate, also frees *			whatever pages are still batched. * *  - mmu_gather::fullmm * *    A flag set by tlb_gather_mmu() to indicate we're going to free *    the entire mm; this allows a number of optimizations. * *    - We can ignore tlb_{start,end}_vma(); because we don't *      care about ranges. Everything will be shot down. * *    - (RISC) architectures that use ASIDs can cycle to a new ASID *      and delay the invalidation until ASID space runs out. * *  - mmu_gather::need_flush_all * *    A flag that can be set by the arch code if it wants to force *    flush the entire TLB irrespective of the range. For instance *    x86-PAE needs this when changing top-level entries. * * And allows the architecture to provide and implement tlb_flush(): * * tlb_flush() may, in addition to the above mentioned mmu_gather fields, make * use of: * *  - mmu_gather::start / mmu_gather::end * *    which provides the range that needs to be flushed to cover the pages to *    be freed. * *  - mmu_gather::freed_tables * *    set when we freed page table pages * *  - tlb_get_unmap_shift() / tlb_get_unmap_size() * *    returns the smallest TLB entry size unmapped in this range. * * If an architecture does not provide tlb_flush() a default implementation * based on flush_tlb_range() will be used, unless MMU_GATHER_NO_RANGE is * specified, in which case we'll default to flush_tlb_mm(). * * Additionally there are a few opt-in features: * *  MMU_GATHER_PAGE_SIZE * *  This ensures we call tlb_flush() every time tlb_change_page_size() actually *  changes the size and provides mmu_gather::page_size to tlb_flush(). * *  This might be useful if your architecture has size specific TLB *  invalidation instructions. * *  MMU_GATHER_TABLE_FREE * *  This provides tlb_remove_table(), to be used instead of tlb_remove_page() *  for page directores (__p*_free_tlb()). * *  Useful if your architecture has non-page page directories. * *  When used, an architecture is expected to provide __tlb_remove_table() *  which does the actual freeing of these pages. * *  MMU_GATHER_RCU_TABLE_FREE * *  Like MMU_GATHER_TABLE_FREE, and adds semi-RCU semantics to the free (see *  comment below). * *  Useful if your architecture doesn't use IPIs for remote TLB invalidates *  and therefore doesn't naturally serialize with software page-table walkers. * *  MMU_GATHER_NO_RANGE * *  Use this if your architecture lacks an efficient flush_tlb_range(). * *  MMU_GATHER_NO_GATHER * *  If the option is set the mmu_gather will not track individual pages for *  delayed page free anymore. A platform that enables the option needs to *  provide its own implementation of the __tlb_remove_page_size() function to *  free pages. * *  This is useful if your architecture already flushes TLB entries in the *  various ptep_get_and_clear() functions. */ #ifdef CONFIG_MMU_GATHER_TABLE_FREE struct mmu_table_batch {#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE	struct rcu_head		rcu;#endif	unsigned int		nr;	void			*tables[0];}; #define MAX_TABLE_BATCH		\	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *)) extern void tlb_remove_table(struct mmu_gather *tlb, void *table); #else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */ /* * Without MMU_GATHER_TABLE_FREE the architecture is assumed to have page based * page directories and we can use the normal page batching to free them. */#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page)) #endif /* CONFIG_MMU_GATHER_TABLE_FREE */ #ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE/* * This allows an architecture that does not use the linux page-tables for * hardware to skip the TLBI when freeing page tables. */#ifndef tlb_needs_table_invalidate#define tlb_needs_table_invalidate() (true)#endif #else #ifdef tlb_needs_table_invalidate#error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE#endif #endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */  #ifndef CONFIG_MMU_GATHER_NO_GATHER/* * If we can't allocate a page to make a big batch of page pointers * to work on, then just handle a few from the on-stack structure. */#define MMU_GATHER_BUNDLE	8 struct mmu_gather_batch {	struct mmu_gather_batch	*next;	unsigned int		nr;	unsigned int		max;	struct page		*pages[0];}; #define MAX_GATHER_BATCH	\	((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) /* * Limit the maximum number of mmu_gather batches to reduce a risk of soft * lockups for non-preemptible kernels on huge machines when a lot of memory * is zapped during unmapping. * 10K pages freed at once should be safe even without a preemption point. */#define MAX_GATHER_BATCH_COUNT	(10000UL/MAX_GATHER_BATCH) extern bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page,				   int page_size);#endif /* * struct mmu_gather is an opaque type used by the mm code for passing around * any data needed by arch specific code for tlb_remove_page. */struct mmu_gather {	struct mm_struct	*mm; #ifdef CONFIG_MMU_GATHER_TABLE_FREE	struct mmu_table_batch	*batch;#endif 	unsigned long		start;	unsigned long		end;	/*	 * we are in the middle of an operation to clear	 * a full mm and can make some optimizations	 */	unsigned int		fullmm : 1; 	/*	 * we have performed an operation which	 * requires a complete flush of the tlb	 */	unsigned int		need_flush_all : 1; 	/*	 * we have removed page directories	 */	unsigned int		freed_tables : 1; 	/*	 * at which levels have we cleared entries?	 */	unsigned int		cleared_ptes : 1;	unsigned int		cleared_pmds : 1;	unsigned int		cleared_puds : 1;	unsigned int		cleared_p4ds : 1; 	/*	 * tracks VM_EXEC | VM_HUGETLB in tlb_start_vma	 */	unsigned int		vma_exec : 1;	unsigned int		vma_huge : 1; 	unsigned int		batch_count; #ifndef CONFIG_MMU_GATHER_NO_GATHER	struct mmu_gather_batch *active;	struct mmu_gather_batch	local;	struct page		*__pages[MMU_GATHER_BUNDLE]; #ifdef CONFIG_MMU_GATHER_PAGE_SIZE	unsigned int page_size;#endif#endif}; void tlb_flush_mmu(struct mmu_gather *tlb); static inline void __tlb_adjust_range(struct mmu_gather *tlb,				      unsigned long address,				      unsigned int range_size){	tlb->start = min(tlb->start, address);	tlb->end = max(tlb->end, address + range_size);} static inline void __tlb_reset_range(struct mmu_gather *tlb){	if (tlb->fullmm) {		tlb->start = tlb->end = ~0;	} else {		tlb->start = TASK_SIZE;		tlb->end = 0;	}	tlb->freed_tables = 0;	tlb->cleared_ptes = 0;	tlb->cleared_pmds = 0;	tlb->cleared_puds = 0;	tlb->cleared_p4ds = 0;	/*	 * Do not reset mmu_gather::vma_* fields here, we do not	 * call into tlb_start_vma() again to set them if there is an	 * intermediate flush.	 */} #ifdef CONFIG_MMU_GATHER_NO_RANGE #if defined(tlb_flush) || defined(tlb_start_vma) || defined(tlb_end_vma)#error MMU_GATHER_NO_RANGE relies on default tlb_flush(), tlb_start_vma() and tlb_end_vma()#endif /* * When an architecture does not have efficient means of range flushing TLBs * there is no point in doing intermediate flushes on tlb_end_vma() to keep the * range small. We equally don't have to worry about page granularity or other * things. * * All we need to do is issue a full flush for any !0 range. */static inline void tlb_flush(struct mmu_gather *tlb){	if (tlb->end)		flush_tlb_mm(tlb->mm);} static inline voidtlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { } #define tlb_end_vma tlb_end_vmastatic inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) { } #else /* CONFIG_MMU_GATHER_NO_RANGE */ #ifndef tlb_flush #if defined(tlb_start_vma) || defined(tlb_end_vma)#error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma()#endif /* * When an architecture does not provide its own tlb_flush() implementation * but does have a reasonably efficient flush_vma_range() implementation * use that. */static inline void tlb_flush(struct mmu_gather *tlb){	if (tlb->fullmm || tlb->need_flush_all) {		flush_tlb_mm(tlb->mm);	} else if (tlb->end) {		struct vm_area_struct vma = {			.vm_mm = tlb->mm,			.vm_flags = (tlb->vma_exec ? VM_EXEC    : 0) |				    (tlb->vma_huge ? VM_HUGETLB : 0),		}; 		flush_tlb_range(&vma, tlb->start, tlb->end);	}} static inline voidtlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma){	/*	 * flush_tlb_range() implementations that look at VM_HUGETLB (tile,	 * mips-4k) flush only large pages.	 *	 * flush_tlb_range() implementations that flush I-TLB also flush D-TLB	 * (tile, xtensa, arm), so it's ok to just add VM_EXEC to an existing	 * range.	 *	 * We rely on tlb_end_vma() to issue a flush, such that when we reset	 * these values the batch is empty.	 */	tlb->vma_huge = is_vm_hugetlb_page(vma);	tlb->vma_exec = !!(vma->vm_flags & VM_EXEC);} #else static inline voidtlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { } #endif #endif /* CONFIG_MMU_GATHER_NO_RANGE */ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb){	/*	 * Anything calling __tlb_adjust_range() also sets at least one of	 * these bits.	 */	if (!(tlb->freed_tables || tlb->cleared_ptes || tlb->cleared_pmds ||	      tlb->cleared_puds || tlb->cleared_p4ds))		return; 	tlb_flush(tlb);	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);	__tlb_reset_range(tlb);} static inline void tlb_remove_page_size(struct mmu_gather *tlb,					struct page *page, int page_size){	if (__tlb_remove_page_size(tlb, page, page_size))		tlb_flush_mmu(tlb);} static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page){	return __tlb_remove_page_size(tlb, page, PAGE_SIZE);} /* tlb_remove_page *	Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when *	required. */static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page){	return tlb_remove_page_size(tlb, page, PAGE_SIZE);} static inline void tlb_change_page_size(struct mmu_gather *tlb,						     unsigned int page_size){#ifdef CONFIG_MMU_GATHER_PAGE_SIZE	if (tlb->page_size && tlb->page_size != page_size) {		if (!tlb->fullmm && !tlb->need_flush_all)			tlb_flush_mmu(tlb);	} 	tlb->page_size = page_size;#endif} static inline unsigned long tlb_get_unmap_shift(struct mmu_gather *tlb){	if (tlb->cleared_ptes)		return PAGE_SHIFT;	if (tlb->cleared_pmds)		return PMD_SHIFT;	if (tlb->cleared_puds)		return PUD_SHIFT;	if (tlb->cleared_p4ds)		return P4D_SHIFT; 	return PAGE_SHIFT;} static inline unsigned long tlb_get_unmap_size(struct mmu_gather *tlb){	return 1UL << tlb_get_unmap_shift(tlb);} /* * In the case of tlb vma handling, we can optimise these away in the * case where we're doing a full MM flush.  When we're doing a munmap, * the vmas are adjusted to only cover the region to be torn down. */#ifndef tlb_start_vmastatic inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma){	if (tlb->fullmm)		return; 	tlb_update_vma_flags(tlb, vma);	flush_cache_range(vma, vma->vm_start, vma->vm_end);}#endif #ifndef tlb_end_vmastatic inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma){

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