/* arch/sparc64/mm/tlb.c
   *
   * Copyright (C) 2004 David S. Miller <davem@redhat.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/percpu.h>
  #include <linux/mm.h>
  #include <linux/swap.h>
  #include <linux/preempt.h>
  
  #include <asm/pgtable.h>
  #include <asm/pgalloc.h>
  #include <asm/tlbflush.h>
  #include <asm/cacheflush.h>
  #include <asm/mmu_context.h>
  #include <asm/tlb.h>
  
  /* Heavily inspired by the ppc64 code.  */
  
  static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);
  
  void flush_tlb_pending(void)
  {
  	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
  	struct mm_struct *mm = tb->mm;
  
  	if (!tb->tlb_nr)
  		goto out;
  
  	flush_tsb_user(tb);
  
  	if (CTX_VALID(mm->context)) {
  		if (tb->tlb_nr == 1) {
  			global_flush_tlb_page(mm, tb->vaddrs[0]);
  		} else {
  #ifdef CONFIG_SMP
  			smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
  					      &tb->vaddrs[0]);
  #else
  			__flush_tlb_pending(CTX_HWBITS(tb->mm->context),
  					    tb->tlb_nr, &tb->vaddrs[0]);
  #endif
  		}
  	}
  
  	tb->tlb_nr = 0;
  
  out:
  	put_cpu_var(tlb_batch);
  }
  
  void arch_enter_lazy_mmu_mode(void)
  {
  	struct tlb_batch *tb = &__get_cpu_var(tlb_batch);
  
  	tb->active = 1;
  }
  
  void arch_leave_lazy_mmu_mode(void)
  {
  	struct tlb_batch *tb = &__get_cpu_var(tlb_batch);
  
  	if (tb->tlb_nr)
  		flush_tlb_pending();
  	tb->active = 0;
  }
  
  static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
  			      bool exec)
  {
  	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
  	unsigned long nr;
  
  	vaddr &= PAGE_MASK;
  	if (exec)
  		vaddr |= 0x1UL;
  
  	nr = tb->tlb_nr;
  
  	if (unlikely(nr != 0 && mm != tb->mm)) {
  		flush_tlb_pending();
  		nr = 0;
  	}
  
  	if (!tb->active) {
  		flush_tsb_user_page(mm, vaddr);
  		global_flush_tlb_page(mm, vaddr);
  		goto out;
  	}
  
  	if (nr == 0)
  		tb->mm = mm;
  
  	tb->vaddrs[nr] = vaddr;
  	tb->tlb_nr = ++nr;
  	if (nr >= TLB_BATCH_NR)
  		flush_tlb_pending();
  
  out:
  	put_cpu_var(tlb_batch);
  }
  
  void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
  		   pte_t *ptep, pte_t orig, int fullmm)
  {
  	if (tlb_type != hypervisor &&
  	    pte_dirty(orig)) {
  		unsigned long paddr, pfn = pte_pfn(orig);
  		struct address_space *mapping;
  		struct page *page;
  
  		if (!pfn_valid(pfn))
  			goto no_cache_flush;
  
  		page = pfn_to_page(pfn);
  		if (PageReserved(page))
  			goto no_cache_flush;
  
  		/* A real file page? */
  		mapping = page_mapping(page);
  		if (!mapping)
  			goto no_cache_flush;
  
  		paddr = (unsigned long) page_address(page);
  		if ((paddr ^ vaddr) & (1 << 13))
  			flush_dcache_page_all(mm, page);
  	}
  
  no_cache_flush:
  	if (!fullmm)
  		tlb_batch_add_one(mm, vaddr, pte_exec(orig));
  }
  
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  static void tlb_batch_pmd_scan(struct mm_struct *mm, unsigned long vaddr,
  			       pmd_t pmd)
  {
  	unsigned long end;
  	pte_t *pte;
  
  	pte = pte_offset_map(&pmd, vaddr);
  	end = vaddr + HPAGE_SIZE;
  	while (vaddr < end) {
  		if (pte_val(*pte) & _PAGE_VALID) {
  			bool exec = pte_exec(*pte);
  
  			tlb_batch_add_one(mm, vaddr, exec);
  		}
  		pte++;
  		vaddr += PAGE_SIZE;
  	}
  	pte_unmap(pte);
  }
  
  void set_pmd_at(struct mm_struct *mm, unsigned long addr,
  		pmd_t *pmdp, pmd_t pmd)
  {
  	pmd_t orig = *pmdp;
  
  	*pmdp = pmd;
  
  	if (mm == &init_mm)
  		return;
  
  	if ((pmd_val(pmd) ^ pmd_val(orig)) & _PAGE_PMD_HUGE) {
  		if (pmd_val(pmd) & _PAGE_PMD_HUGE)
  			mm->context.huge_pte_count++;
  		else
  			mm->context.huge_pte_count--;
  
  		/* Do not try to allocate the TSB hash table if we
  		 * don't have one already.  We have various locks held
  		 * and thus we'll end up doing a GFP_KERNEL allocation
  		 * in an atomic context.
  		 *
  		 * Instead, we let the first TLB miss on a hugepage
  		 * take care of this.
  		 */
  	}
  
  	if (!pmd_none(orig)) {
  		addr &= HPAGE_MASK;
  		if (pmd_trans_huge(orig)) {
  			pte_t orig_pte = __pte(pmd_val(orig));
  			bool exec = pte_exec(orig_pte);
  
  			tlb_batch_add_one(mm, addr, exec);
  			tlb_batch_add_one(mm, addr + REAL_HPAGE_SIZE, exec);
  		} else {
  			tlb_batch_pmd_scan(mm, addr, orig);
  		}
  	}
  }
  
  void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
  		     pmd_t *pmdp)
  {
  	pmd_t entry = *pmdp;
  
  	pmd_val(entry) &= ~_PAGE_VALID;
  
  	set_pmd_at(vma->vm_mm, address, pmdp, entry);
  	flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
  }
  
  void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
  				pgtable_t pgtable)
  {
  	struct list_head *lh = (struct list_head *) pgtable;
  
  	assert_spin_locked(&mm->page_table_lock);
  
  	/* FIFO */
  	if (!pmd_huge_pte(mm, pmdp))
  		INIT_LIST_HEAD(lh);
  	else
  		list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
  	pmd_huge_pte(mm, pmdp) = pgtable;
  }
  
  pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
  {
  	struct list_head *lh;
  	pgtable_t pgtable;
  
  	assert_spin_locked(&mm->page_table_lock);
  
  	/* FIFO */
  	pgtable = pmd_huge_pte(mm, pmdp);
  	lh = (struct list_head *) pgtable;
  	if (list_empty(lh))
  		pmd_huge_pte(mm, pmdp) = NULL;
  	else {
  		pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
  		list_del(lh);
  	}
  	pte_val(pgtable[0]) = 0;
  	pte_val(pgtable[1]) = 0;
  
  	return pgtable;
  }
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */