/*
* Based on arch/arm/include/asm/tlb.h
*
* Copyright (C) 2002 Russell King
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_TLB_H
#define __ASM_TLB_H

#include <linux/pagemap.h>
#include <linux/swap.h>

#include <asm/pgalloc.h>
#include <asm/tlbflush.h>

#define MMU_GATHER_BUNDLE 8

/*
* TLB handling. This allows us to remove pages from the page
* tables, and efficiently handle the TLB issues.
*/
struct mmu_gather {
struct mm_struct *mm;
unsigned int fullmm;
struct vm_area_struct *vma;
unsigned long start, end;
unsigned long range_start;
unsigned long range_end;
unsigned int nr;
unsigned int max;
struct page **pages;
struct page *local[MMU_GATHER_BUNDLE];
};

/*
* This is unnecessarily complex. There's three ways the TLB shootdown
* code is used:
* 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
* tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
* tlb->vma will be non-NULL.
* 2. Unmapping all vmas. See exit_mmap().
* tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
* tlb->vma will be non-NULL. Additionally, page tables will be freed.
* 3. Unmapping argument pages. See shift_arg_pages().
* tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
* tlb->vma will be NULL.
*/
static inline void tlb_flush(struct mmu_gather *tlb)
{
if (tlb->fullmm || !tlb->vma)
flush_tlb_mm(tlb->mm);
else if (tlb->range_end > 0) {
flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
tlb->range_start = TASK_SIZE;
tlb->range_end = 0;
}
}

static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
{
if (!tlb->fullmm) {
if (addr < tlb->range_start)
tlb->range_start = addr;
if (addr + PAGE_SIZE > tlb->range_end)
tlb->range_end = addr + PAGE_SIZE;
}
}

static inline void __tlb_alloc_page(struct mmu_gather *tlb)
{
unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);

if (addr) {
tlb->pages = (void *)addr;
tlb->max = PAGE_SIZE / sizeof(struct page *);
}
}

static inline void tlb_flush_mmu(struct mmu_gather *tlb)
{
tlb_flush(tlb);
free_pages_and_swap_cache(tlb->pages, tlb->nr);
tlb->nr = 0;
if (tlb->pages == tlb->local)
__tlb_alloc_page(tlb);
}

static inline void
tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
{
tlb->mm = mm;
tlb->fullmm = !(start | (end+1));
tlb->start = start;
tlb->end = end;
tlb->vma = NULL;
tlb->max = ARRAY_SIZE(tlb->local);
tlb->pages = tlb->local;
tlb->nr = 0;
__tlb_alloc_page(tlb);
}

static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
tlb_flush_mmu(tlb);

/* keep the page table cache within bounds */
check_pgt_cache();

if (tlb->pages != tlb->local)
free_pages((unsigned long)tlb->pages, 0);
}

/*
* Memorize the range for the TLB flush.
*/
static inline void
tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
{
tlb_add_flush(tlb, addr);
}

/*
* In the case of tlb vma handling, we can optimise these away in the
* case where we're doing a full MM flush. When we're doing a munmap,
* the vmas are adjusted to only cover the region to be torn down.
*/
static inline void
tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
{
if (!tlb->fullmm) {
tlb->vma = vma;
tlb->range_start = TASK_SIZE;
tlb->range_end = 0;
}
}

static inline void
tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
{
if (!tlb->fullmm)
tlb_flush(tlb);
}

static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
tlb->pages[tlb->nr++] = page;
VM_BUG_ON(tlb->nr > tlb->max);
return tlb->max - tlb->nr;
}

static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
if (!__tlb_remove_page(tlb, page))
tlb_flush_mmu(tlb);
}

static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long addr)
{
pgtable_page_dtor(pte);
tlb_add_flush(tlb, addr);
tlb_remove_page(tlb, pte);
}

#ifndef CONFIG_ARM64_64K_PAGES
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
unsigned long addr)
{
tlb_add_flush(tlb, addr);
tlb_remove_page(tlb, virt_to_page(pmdp));
}
#endif

#define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
#define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr)
#define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp)

#define tlb_migrate_finish(mm) do { } while (0)

static inline void
tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
{
tlb_add_flush(tlb, addr);
}

#endif