191 lines
5.0 KiB
C
191 lines
5.0 KiB
C
/* include/asm-generic/tlb.h
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*
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* Generic TLB shootdown code
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*
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* Copyright 2001 Red Hat, Inc.
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* Based on code from mm/memory.c Copyright Linus Torvalds and others.
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*
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* Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_GENERIC__TLB_H
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#define _ASM_GENERIC__TLB_H
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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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* For UP we don't need to worry about TLB flush
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* and page free order so much..
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*/
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#ifdef CONFIG_SMP
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#define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
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#else
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#define tlb_fast_mode(tlb) 1
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#endif
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/*
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* If we can't allocate a page to make a big batch of page pointers
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* to work on, then just handle a few from the on-stack structure.
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*/
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#define MMU_GATHER_BUNDLE 8
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/* struct mmu_gather is an opaque type used by the mm code for passing around
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* any data needed by arch specific code for tlb_remove_page.
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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 nr; /* set to ~0U means fast mode */
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unsigned int max; /* nr < max */
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unsigned int need_flush;/* Really unmapped some ptes? */
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unsigned int fullmm; /* non-zero means full mm flush */
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#ifdef HAVE_ARCH_MMU_GATHER
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struct arch_mmu_gather arch;
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#endif
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struct page **pages;
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struct page *local[MMU_GATHER_BUNDLE];
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};
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static inline void __tlb_alloc_page(struct mmu_gather *tlb)
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{
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unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
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if (addr) {
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tlb->pages = (void *)addr;
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tlb->max = PAGE_SIZE / sizeof(struct page *);
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}
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}
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/* tlb_gather_mmu
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* Called to initialize an (on-stack) mmu_gather structure for page-table
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* tear-down from @mm. The @fullmm argument is used when @mm is without
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* users and we're going to destroy the full address space (exit/execve).
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*/
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static inline void
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tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
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{
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tlb->mm = mm;
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tlb->max = ARRAY_SIZE(tlb->local);
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tlb->pages = tlb->local;
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if (num_online_cpus() > 1) {
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tlb->nr = 0;
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__tlb_alloc_page(tlb);
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} else /* Use fast mode if only one CPU is online */
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tlb->nr = ~0U;
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tlb->fullmm = fullmm;
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#ifdef HAVE_ARCH_MMU_GATHER
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tlb->arch = ARCH_MMU_GATHER_INIT;
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#endif
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}
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static inline void
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tlb_flush_mmu(struct mmu_gather *tlb)
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{
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if (!tlb->need_flush)
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return;
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tlb->need_flush = 0;
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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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* If we are using the local on-stack array of pages for MMU
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* gather, try allocating an off-stack array again as we have
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* recently freed pages.
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*/
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if (tlb->pages == tlb->local)
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__tlb_alloc_page(tlb);
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}
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}
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/* tlb_finish_mmu
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* Called at the end of the shootdown operation to free up any resources
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* that were required.
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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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if (tlb->pages != tlb->local)
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free_pages((unsigned long)tlb->pages, 0);
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}
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/* __tlb_remove_page
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* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
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* handling the additional races in SMP caused by other CPUs caching valid
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* mappings in their TLBs. Returns the number of free page slots left.
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* When out of page slots we must call tlb_flush_mmu().
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*/
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static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
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{
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tlb->need_flush = 1;
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if (tlb_fast_mode(tlb)) {
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free_page_and_swap_cache(page);
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return 1; /* avoid calling tlb_flush_mmu() */
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}
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tlb->pages[tlb->nr++] = page;
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VM_BUG_ON(tlb->nr > tlb->max);
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return tlb->max - tlb->nr;
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}
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/* tlb_remove_page
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* Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when
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* required.
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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_remove_page(tlb, page))
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tlb_flush_mmu(tlb);
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}
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/**
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* tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
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*
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* Record the fact that pte's were really umapped in ->need_flush, so we can
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* later optimise away the tlb invalidate. This helps when userspace is
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* unmapping already-unmapped pages, which happens quite a lot.
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*/
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#define tlb_remove_tlb_entry(tlb, ptep, address) \
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do { \
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tlb->need_flush = 1; \
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__tlb_remove_tlb_entry(tlb, ptep, address); \
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} while (0)
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#define pte_free_tlb(tlb, ptep, address) \
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do { \
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tlb->need_flush = 1; \
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__pte_free_tlb(tlb, ptep, address); \
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} while (0)
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#ifndef __ARCH_HAS_4LEVEL_HACK
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#define pud_free_tlb(tlb, pudp, address) \
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do { \
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tlb->need_flush = 1; \
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__pud_free_tlb(tlb, pudp, address); \
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} while (0)
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#endif
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#define pmd_free_tlb(tlb, pmdp, address) \
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do { \
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tlb->need_flush = 1; \
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__pmd_free_tlb(tlb, pmdp, address); \
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} while (0)
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#define tlb_migrate_finish(mm) do {} while (0)
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#endif /* _ASM_GENERIC__TLB_H */
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