/* include/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/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

  #ifdef ARCH_FREE_PTR_NR

    #define FREE_PTR_NR   ARCH_FREE_PTR_NR

  #else

    #define FREE_PTE_NR	506

  #endif

  #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.

 */

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 */

	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 = &get_cpu_var(mmu_gathers);

	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;

	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.

 */

static inline void

tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)

{

	tlb_flush_mmu(tlb, start, end);

	/* keep the page table cache within bounds */

	check_pgt_cache();

	put_cpu_var(mmu_gathers);

}

/* 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 */