mirror of https://gitee.com/openkylin/linux.git
191 lines
4.7 KiB
C
191 lines
4.7 KiB
C
/*
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* arch/arm/include/asm/tlb.h
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*
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* Copyright (C) 2002 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Experimentation shows that on a StrongARM, it appears to be faster
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* to use the "invalidate whole tlb" rather than "invalidate single
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* tlb" for this.
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*
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* This appears true for both the process fork+exit case, as well as
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* the munmap-large-area case.
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*/
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#ifndef __ASMARM_TLB_H
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#define __ASMARM_TLB_H
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#include <asm/cacheflush.h>
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#ifndef CONFIG_MMU
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#include <linux/pagemap.h>
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#define tlb_flush(tlb) ((void) tlb)
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#include <asm-generic/tlb.h>
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#else /* !CONFIG_MMU */
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#include <linux/swap.h>
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#include <asm/pgalloc.h>
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#include <asm/tlbflush.h>
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/*
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* We need to delay page freeing for SMP as other CPUs can access pages
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* which have been removed but not yet had their TLB entries invalidated.
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* Also, as ARMv7 speculative prefetch can drag new entries into the TLB,
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* we need to apply this same delaying tactic to ensure correct operation.
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*/
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#if defined(CONFIG_SMP) || defined(CONFIG_CPU_32v7)
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#define tlb_fast_mode(tlb) 0
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#define FREE_PTE_NR 500
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#else
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#define tlb_fast_mode(tlb) 1
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#define FREE_PTE_NR 0
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#endif
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/*
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* TLB handling. This allows us to remove pages from the page
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* tables, and efficiently handle the TLB issues.
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*/
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struct mmu_gather {
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struct mm_struct *mm;
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unsigned int fullmm;
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struct vm_area_struct *vma;
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unsigned long range_start;
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unsigned long range_end;
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unsigned int nr;
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struct page *pages[FREE_PTE_NR];
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};
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DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
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/*
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* This is unnecessarily complex. There's three ways the TLB shootdown
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* code is used:
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* 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
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* tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
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* tlb->vma will be non-NULL.
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* 2. Unmapping all vmas. See exit_mmap().
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* tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
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* tlb->vma will be non-NULL. Additionally, page tables will be freed.
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* 3. Unmapping argument pages. See shift_arg_pages().
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* tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
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* tlb->vma will be NULL.
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*/
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static inline void tlb_flush(struct mmu_gather *tlb)
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{
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if (tlb->fullmm || !tlb->vma)
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flush_tlb_mm(tlb->mm);
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else if (tlb->range_end > 0) {
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flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
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tlb->range_start = TASK_SIZE;
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tlb->range_end = 0;
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}
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}
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static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
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{
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if (!tlb->fullmm) {
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if (addr < tlb->range_start)
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tlb->range_start = addr;
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if (addr + PAGE_SIZE > tlb->range_end)
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tlb->range_end = addr + PAGE_SIZE;
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}
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}
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static inline void tlb_flush_mmu(struct mmu_gather *tlb)
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{
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tlb_flush(tlb);
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if (!tlb_fast_mode(tlb)) {
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free_pages_and_swap_cache(tlb->pages, tlb->nr);
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tlb->nr = 0;
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}
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}
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static inline struct mmu_gather *
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tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
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{
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struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
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tlb->mm = mm;
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tlb->fullmm = full_mm_flush;
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tlb->vma = NULL;
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tlb->nr = 0;
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return tlb;
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}
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static inline void
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tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
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{
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tlb_flush_mmu(tlb);
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/* keep the page table cache within bounds */
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check_pgt_cache();
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put_cpu_var(mmu_gathers);
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}
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/*
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* Memorize the range for the TLB flush.
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*/
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static inline void
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tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
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{
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tlb_add_flush(tlb, addr);
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}
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/*
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* In the case of tlb vma handling, we can optimise these away in the
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* case where we're doing a full MM flush. When we're doing a munmap,
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* the vmas are adjusted to only cover the region to be torn down.
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*/
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static inline void
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tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
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{
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if (!tlb->fullmm) {
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flush_cache_range(vma, vma->vm_start, vma->vm_end);
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tlb->vma = vma;
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tlb->range_start = TASK_SIZE;
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tlb->range_end = 0;
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}
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}
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static inline void
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tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
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{
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if (!tlb->fullmm)
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tlb_flush(tlb);
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}
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static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
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{
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if (tlb_fast_mode(tlb)) {
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free_page_and_swap_cache(page);
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} else {
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tlb->pages[tlb->nr++] = page;
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if (tlb->nr >= FREE_PTE_NR)
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tlb_flush_mmu(tlb);
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}
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}
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static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
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unsigned long addr)
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{
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pgtable_page_dtor(pte);
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tlb_add_flush(tlb, addr);
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tlb_remove_page(tlb, pte);
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}
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#define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
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#define pmd_free_tlb(tlb, pmdp, addr) pmd_free((tlb)->mm, pmdp)
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#define tlb_migrate_finish(mm) do { } while (0)
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#endif /* CONFIG_MMU */
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#endif
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