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/* 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.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_GENERIC__TLB_H
#define _ASM_GENERIC__TLB_H
#include <linux/config.h>
#ifdef CONFIG_SMP
/* aim for something that fits in the L1 cache */
#define FREE_PTE_NR 508
/* mmu_gather_t is an opaque type used by the mm code for passing around any
* data needed by arch specific code for tlb_remove_page. This structure can
* be per-CPU or per-MM as the page table lock is held for the duration of TLB
* shootdown.
*/
typedef struct free_pte_ctx {
struct mm_struct *mm;
unsigned long nr; /* set to ~0UL means fast mode */
unsigned long start_addr, end_addr;
pte_t ptes[FREE_PTE_NR];
} mmu_gather_t;
/* Users of the generic TLB shootdown code must declare this storage space. */
extern mmu_gather_t mmu_gathers[NR_CPUS];
/* tlb_gather_mmu
* Return a pointer to an initialized mmu_gather_t.
*/
static inline mmu_gather_t *tlb_gather_mmu(struct mm_struct *mm)
{
mmu_gather_t *tlb = &mmu_gathers[smp_processor_id()];
tlb->mm = mm;
/* Use fast mode if there is only one user of this mm (this process) */
tlb->nr = (atomic_read(&(mm)->mm_users) == 1) ? ~0UL : 0UL;
return tlb;
}
/* void tlb_remove_page(mmu_gather_t *tlb, pte_t *ptep, unsigned long addr)
* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
* handling the additional races in SMP caused by other CPUs caching valid
* mappings in their TLBs.
*/
#define tlb_remove_page(ctxp, pte, addr) do {\
/* Handle the common case fast, first. */\
if ((ctxp)->nr == ~0UL) {\
__free_pte(*(pte));\
pte_clear((pte));\
break;\
}\
if (!(ctxp)->nr) \
(ctxp)->start_addr = (addr);\
(ctxp)->ptes[(ctxp)->nr++] = ptep_get_and_clear(pte);\
(ctxp)->end_addr = (addr) + PAGE_SIZE;\
if ((ctxp)->nr >= FREE_PTE_NR)\
tlb_finish_mmu((ctxp), 0, 0);\
} while (0)
/* tlb_finish_mmu
* Called at the end of the shootdown operation to free up any resources
* that were required. The page talbe lock is still held at this point.
*/
static inline void tlb_finish_mmu(struct free_pte_ctx *ctx, unsigned long start, unsigned long end)
{
unsigned long i, nr;
/* Handle the fast case first. */
if (ctx->nr == ~0UL) {
flush_tlb_range(ctx->mm, start, end);
return;
}
nr = ctx->nr;
ctx->nr = 0;
if (nr)
flush_tlb_range(ctx->mm, ctx->start_addr, ctx->end_addr);
for (i=0; i < nr; i++) {
pte_t pte = ctx->ptes[i];
__free_pte(pte);
}
}
#else
/* The uniprocessor functions are quite simple and are inline macros in an
* attempt to get gcc to generate optimal code since this code is run on each
* page in a process at exit.
*/
typedef struct mm_struct mmu_gather_t;
#define tlb_gather_mmu(mm) (mm)
#define tlb_finish_mmu(tlb, start, end) flush_tlb_range(tlb, start, end)
#define tlb_remove_page(tlb, ptep, addr) do {\
pte_t __pte = *(ptep);\
pte_clear(ptep);\
__free_pte(__pte);\
} while (0)
#endif
#endif /* _ASM_GENERIC__TLB_H */
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