/*
   * arch/xtensa/mm/tlb.c
   *
   * Logic that manipulates the Xtensa MMU.  Derived from MIPS.
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2001 - 2003 Tensilica Inc.
   *
   * Joe Taylor
   * Chris Zankel	<chris@zankel.net>
   * Marc Gauthier
   */
  
  #include <linux/mm.h>
  #include <asm/processor.h>
  #include <asm/mmu_context.h>
  #include <asm/tlbflush.h>
  #include <asm/cacheflush.h>
  
  
  static inline void __flush_itlb_all (void)
  {
  	int w, i;
  
  	for (w = 0; w < ITLB_ARF_WAYS; w++) {
  		for (i = 0; i < (1 << XCHAL_ITLB_ARF_ENTRIES_LOG2); i++) {
  			int e = w + (i << PAGE_SHIFT);
  			invalidate_itlb_entry_no_isync(e);
  		}
  	}
  	asm volatile ("isync
  ");
  }
  
  static inline void __flush_dtlb_all (void)
  {
  	int w, i;
  
  	for (w = 0; w < DTLB_ARF_WAYS; w++) {
  		for (i = 0; i < (1 << XCHAL_DTLB_ARF_ENTRIES_LOG2); i++) {
  			int e = w + (i << PAGE_SHIFT);
  			invalidate_dtlb_entry_no_isync(e);
  		}
  	}
  	asm volatile ("isync
  ");
  }
  
  
  void local_flush_tlb_all(void)
  {
  	__flush_itlb_all();
  	__flush_dtlb_all();
  }
  
  /* If mm is current, we simply assign the current task a new ASID, thus,
   * invalidating all previous tlb entries. If mm is someone else's user mapping,
   * wie invalidate the context, thus, when that user mapping is swapped in,
   * a new context will be assigned to it.
   */
  
  void local_flush_tlb_mm(struct mm_struct *mm)
  {
  	int cpu = smp_processor_id();
  
  	if (mm == current->active_mm) {
  		unsigned long flags;
  		local_irq_save(flags);
  		mm->context.asid[cpu] = NO_CONTEXT;
  		activate_context(mm, cpu);
  		local_irq_restore(flags);
  	} else {
  		mm->context.asid[cpu] = NO_CONTEXT;
  		mm->context.cpu = -1;
  	}
  }
  
  
  #define _ITLB_ENTRIES (ITLB_ARF_WAYS << XCHAL_ITLB_ARF_ENTRIES_LOG2)
  #define _DTLB_ENTRIES (DTLB_ARF_WAYS << XCHAL_DTLB_ARF_ENTRIES_LOG2)
  #if _ITLB_ENTRIES > _DTLB_ENTRIES
  # define _TLB_ENTRIES _ITLB_ENTRIES
  #else
  # define _TLB_ENTRIES _DTLB_ENTRIES
  #endif
  
  void local_flush_tlb_range(struct vm_area_struct *vma,
  		unsigned long start, unsigned long end)
  {
  	int cpu = smp_processor_id();
  	struct mm_struct *mm = vma->vm_mm;
  	unsigned long flags;
  
  	if (mm->context.asid[cpu] == NO_CONTEXT)
  		return;
  
  #if 0
  	printk("[tlbrange<%02lx,%08lx,%08lx>]
  ",
  			(unsigned long)mm->context.asid[cpu], start, end);
  #endif
  	local_irq_save(flags);
  
  	if (end-start + (PAGE_SIZE-1) <= _TLB_ENTRIES << PAGE_SHIFT) {
  		int oldpid = get_rasid_register();
  
  		set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
  		start &= PAGE_MASK;
  		if (vma->vm_flags & VM_EXEC)
  			while(start < end) {
  				invalidate_itlb_mapping(start);
  				invalidate_dtlb_mapping(start);
  				start += PAGE_SIZE;
  			}
  		else
  			while(start < end) {
  				invalidate_dtlb_mapping(start);
  				start += PAGE_SIZE;
  			}
  
  		set_rasid_register(oldpid);
  	} else {
  		local_flush_tlb_mm(mm);
  	}
  	local_irq_restore(flags);
  }
  
  void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
  {
  	int cpu = smp_processor_id();
  	struct mm_struct* mm = vma->vm_mm;
  	unsigned long flags;
  	int oldpid;
  
  	if (mm->context.asid[cpu] == NO_CONTEXT)
  		return;
  
  	local_irq_save(flags);
  
  	oldpid = get_rasid_register();
  	set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
  
  	if (vma->vm_flags & VM_EXEC)
  		invalidate_itlb_mapping(page);
  	invalidate_dtlb_mapping(page);
  
  	set_rasid_register(oldpid);
  
  	local_irq_restore(flags);
  }
  
  #ifdef CONFIG_DEBUG_TLB_SANITY
  
  static unsigned get_pte_for_vaddr(unsigned vaddr)
  {
  	struct task_struct *task = get_current();
  	struct mm_struct *mm = task->mm;
  	pgd_t *pgd;
  	pmd_t *pmd;
  	pte_t *pte;
  
  	if (!mm)
  		mm = task->active_mm;
  	pgd = pgd_offset(mm, vaddr);
  	if (pgd_none_or_clear_bad(pgd))
  		return 0;
  	pmd = pmd_offset(pgd, vaddr);
  	if (pmd_none_or_clear_bad(pmd))
  		return 0;
  	pte = pte_offset_map(pmd, vaddr);
  	if (!pte)
  		return 0;
  	return pte_val(*pte);
  }
  
  enum {
  	TLB_SUSPICIOUS	= 1,
  	TLB_INSANE	= 2,
  };
  
  static void tlb_insane(void)
  {
  	BUG_ON(1);
  }
  
  static void tlb_suspicious(void)
  {
  	WARN_ON(1);
  }
  
  /*
   * Check that TLB entries with kernel ASID (1) have kernel VMA (>= TASK_SIZE),
   * and TLB entries with user ASID (>=4) have VMA < TASK_SIZE.
   *
   * Check that valid TLB entries either have the same PA as the PTE, or PTE is
   * marked as non-present. Non-present PTE and the page with non-zero refcount
   * and zero mapcount is normal for batched TLB flush operation. Zero refcount
   * means that the page was freed prematurely. Non-zero mapcount is unusual,
   * but does not necessary means an error, thus marked as suspicious.
   */
  static int check_tlb_entry(unsigned w, unsigned e, bool dtlb)
  {
  	unsigned tlbidx = w | (e << PAGE_SHIFT);
  	unsigned r0 = dtlb ?
  		read_dtlb_virtual(tlbidx) : read_itlb_virtual(tlbidx);
  	unsigned vpn = (r0 & PAGE_MASK) | (e << PAGE_SHIFT);
  	unsigned pte = get_pte_for_vaddr(vpn);
  	unsigned mm_asid = (get_rasid_register() >> 8) & ASID_MASK;
  	unsigned tlb_asid = r0 & ASID_MASK;
  	bool kernel = tlb_asid == 1;
  	int rc = 0;
  
  	if (tlb_asid > 0 && ((vpn < TASK_SIZE) == kernel)) {
  		pr_err("%cTLB: way: %u, entry: %u, VPN %08x in %s PTE
  ",
  				dtlb ? 'D' : 'I', w, e, vpn,
  				kernel ? "kernel" : "user");
  		rc |= TLB_INSANE;
  	}
  
  	if (tlb_asid == mm_asid) {
  		unsigned r1 = dtlb ? read_dtlb_translation(tlbidx) :
  			read_itlb_translation(tlbidx);
  		if ((pte ^ r1) & PAGE_MASK) {
  			pr_err("%cTLB: way: %u, entry: %u, mapping: %08x->%08x, PTE: %08x
  ",
  					dtlb ? 'D' : 'I', w, e, r0, r1, pte);
  			if (pte == 0 || !pte_present(__pte(pte))) {
  				struct page *p = pfn_to_page(r1 >> PAGE_SHIFT);
  				pr_err("page refcount: %d, mapcount: %d
  ",
  						page_count(p),
  						page_mapcount(p));
  				if (!page_count(p))
  					rc |= TLB_INSANE;
  				else if (page_mapped(p))
  					rc |= TLB_SUSPICIOUS;
  			} else {
  				rc |= TLB_INSANE;
  			}
  		}
  	}
  	return rc;
  }
  
  void check_tlb_sanity(void)
  {
  	unsigned long flags;
  	unsigned w, e;
  	int bug = 0;
  
  	local_irq_save(flags);
  	for (w = 0; w < DTLB_ARF_WAYS; ++w)
  		for (e = 0; e < (1 << XCHAL_DTLB_ARF_ENTRIES_LOG2); ++e)
  			bug |= check_tlb_entry(w, e, true);
  	for (w = 0; w < ITLB_ARF_WAYS; ++w)
  		for (e = 0; e < (1 << XCHAL_ITLB_ARF_ENTRIES_LOG2); ++e)
  			bug |= check_tlb_entry(w, e, false);
  	if (bug & TLB_INSANE)
  		tlb_insane();
  	if (bug & TLB_SUSPICIOUS)
  		tlb_suspicious();
  	local_irq_restore(flags);
  }
  
  #endif /* CONFIG_DEBUG_TLB_SANITY */