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phoenix |
/* 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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* 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/config.h>
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#ifdef CONFIG_SMP
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/* aim for something that fits in the L1 cache */
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#define FREE_PTE_NR 508
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/* mmu_gather_t is an opaque type used by the mm code for passing around any
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* data needed by arch specific code for tlb_remove_page. This structure can
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* be per-CPU or per-MM as the page table lock is held for the duration of TLB
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* shootdown.
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*/
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typedef struct free_pte_ctx {
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struct mm_struct *mm;
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unsigned long nr; /* set to ~0UL means fast mode */
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unsigned long start_addr, end_addr;
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pte_t ptes[FREE_PTE_NR];
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} mmu_gather_t;
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/* Users of the generic TLB shootdown code must declare this storage space. */
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extern mmu_gather_t mmu_gathers[NR_CPUS];
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/* tlb_gather_mmu
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* Return a pointer to an initialized mmu_gather_t.
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*/
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static inline mmu_gather_t *tlb_gather_mmu(struct mm_struct *mm)
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{
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mmu_gather_t *tlb = &mmu_gathers[smp_processor_id()];
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tlb->mm = mm;
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/* Use fast mode if there is only one user of this mm (this process) */
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tlb->nr = (atomic_read(&(mm)->mm_users) == 1) ? ~0UL : 0UL;
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return tlb;
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}
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/* void tlb_remove_page(mmu_gather_t *tlb, pte_t *ptep, unsigned long addr)
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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.
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*/
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#define tlb_remove_page(ctxp, pte, addr) do {\
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/* Handle the common case fast, first. */\
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if ((ctxp)->nr == ~0UL) {\
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pte_t __pte = *(pte);\
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pte_clear(pte);\
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__free_pte(__pte);\
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break;\
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}\
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if (!(ctxp)->nr) \
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(ctxp)->start_addr = (addr);\
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(ctxp)->ptes[(ctxp)->nr++] = ptep_get_and_clear(pte);\
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(ctxp)->end_addr = (addr) + PAGE_SIZE;\
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if ((ctxp)->nr >= FREE_PTE_NR)\
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tlb_finish_mmu((ctxp), 0, 0);\
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} while (0)
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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. The page talbe lock is still held at this point.
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*/
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static inline void tlb_finish_mmu(struct free_pte_ctx *ctx, unsigned long start, unsigned long end)
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{
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unsigned long i, nr;
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/* Handle the fast case first. */
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if (ctx->nr == ~0UL) {
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flush_tlb_range(ctx->mm, start, end);
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return;
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}
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nr = ctx->nr;
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ctx->nr = 0;
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if (nr)
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flush_tlb_range(ctx->mm, ctx->start_addr, ctx->end_addr);
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for (i=0; i < nr; i++) {
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pte_t pte = ctx->ptes[i];
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__free_pte(pte);
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}
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}
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#else
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/* The uniprocessor functions are quite simple and are inline macros in an
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* attempt to get gcc to generate optimal code since this code is run on each
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* page in a process at exit.
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*/
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typedef struct mm_struct mmu_gather_t;
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#define tlb_gather_mmu(mm) (mm)
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#define tlb_finish_mmu(tlb, start, end) flush_tlb_range(tlb, start, end)
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#define tlb_remove_page(tlb, ptep, addr) do {\
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pte_t __pte = *(ptep);\
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pte_clear(ptep);\
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__free_pte(__pte);\
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} while (0)
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#endif
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#endif /* _ASM_GENERIC__TLB_H */
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