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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>
#include <linux/swap.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
/*
* For UP we don't need to worry about TLB flush
* and page free order so much..
*/
#ifdef CONFIG_SMP
#define FREE_PTE_NR 506
#define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
#else
#define FREE_PTE_NR 1
#define tlb_fast_mode(tlb) 1
#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. This structure
* can be per-CPU or per-MM as the page table lock is held for the duration of
* TLB shootdown.
*/
struct mmu_gather {
struct mm_struct *mm;
unsigned int nr; /* set to ~0U means fast mode */
unsigned int need_flush;/* Really unmapped some ptes? */
unsigned int fullmm; /* non-zero means full mm flush */
unsigned long freed;
struct page * pages[FREE_PTE_NR];
};
/* Users of the generic TLB shootdown code must declare this storage space. */
DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
/* tlb_gather_mmu
* Return a pointer to an initialized struct mmu_gather.
*/
static inline struct mmu_gather *
tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
{
struct mmu_gather *tlb = &per_cpu(mmu_gathers, smp_processor_id());
tlb->mm = mm;
/* Use fast mode if only one CPU is online */
tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
tlb->fullmm = full_mm_flush;
tlb->freed = 0;
return tlb;
}
static inline void
tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
if (!tlb->need_flush)
return;
tlb->need_flush = 0;
tlb_flush(tlb);
if (!tlb_fast_mode(tlb)) {
free_pages_and_swap_cache(tlb->pages, tlb->nr);
tlb->nr = 0;
}
}
/* tlb_finish_mmu
* Called at the end of the shootdown operation to free up any resources
* that were required. The page table lock is still held at this point.
*/
static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
int freed = tlb->freed;
struct mm_struct *mm = tlb->mm;
int rss = get_mm_counter(mm, rss);
if (rss < freed)
freed = rss;
add_mm_counter(mm, rss, -freed);
tlb_flush_mmu(tlb, start, end);
/* keep the page table cache within bounds */
check_pgt_cache();
}
static inline unsigned int
tlb_is_full_mm(struct mmu_gather *tlb)
{
return tlb->fullmm;
}
/* tlb_remove_page
* 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.
*/
static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
tlb->need_flush = 1;
if (tlb_fast_mode(tlb)) {
free_page_and_swap_cache(page);
return;
}
tlb->pages[tlb->nr++] = page;
if (tlb->nr >= FREE_PTE_NR)
tlb_flush_mmu(tlb, 0, 0);
}
/**
* tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
*
* Record the fact that pte's were really umapped in ->need_flush, so we can
* later optimise away the tlb invalidate. This helps when userspace is
* unmapping already-unmapped pages, which happens quite a lot.
*/
#define tlb_remove_tlb_entry(tlb, ptep, address) \
do { \
tlb->need_flush = 1; \
__tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
#define pte_free_tlb(tlb, ptep) \
do { \
tlb->need_flush = 1; \
__pte_free_tlb(tlb, ptep); \
} while (0)
#ifndef __ARCH_HAS_4LEVEL_HACK
#define pud_free_tlb(tlb, pudp) \
do { \
tlb->need_flush = 1; \
__pud_free_tlb(tlb, pudp); \
} while (0)
#endif
#define pmd_free_tlb(tlb, pmdp) \
do { \
tlb->need_flush = 1; \
__pmd_free_tlb(tlb, pmdp); \
} while (0)
#define tlb_migrate_finish(mm) do {} while (0)
#endif /* _ASM_GENERIC__TLB_H */
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