text: /*
   *  S390 version
   *
   *  Derived from "include/asm-i386/mmu_context.h"
   */
  
  #ifndef __S390_MMU_CONTEXT_H
  #define __S390_MMU_CONTEXT_H
  
  #include <asm/pgalloc.h>
  #include <asm/uaccess.h>
  #include <asm/tlbflush.h>
  #include <asm/ctl_reg.h>
  
  static inline int init_new_context(struct task_struct *tsk,
  				   struct mm_struct *mm)
  {
  	atomic_set(&mm->context.attach_count, 0);
  	mm->context.flush_mm = 0;
  	mm->context.asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
  #ifdef CONFIG_64BIT
  	mm->context.asce_bits |= _ASCE_TYPE_REGION3;
  #endif
  	if (current->mm && current->mm->context.alloc_pgste) {
  		/*
  		 * alloc_pgste indicates, that any NEW context will be created
  		 * with extended page tables. The old context is unchanged. The
  		 * page table allocation and the page table operations will
  		 * look at has_pgste to distinguish normal and extended page
  		 * tables. The only way to create extended page tables is to
  		 * set alloc_pgste and then create a new context (e.g. dup_mm).
  		 * The page table allocation is called after init_new_context
  		 * and if has_pgste is set, it will create extended page
  		 * tables.
  		 */
  		mm->context.has_pgste = 1;
  		mm->context.alloc_pgste = 1;
  	} else {
  		mm->context.has_pgste = 0;
  		mm->context.alloc_pgste = 0;
  	}
  	mm->context.asce_limit = STACK_TOP_MAX;
  	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
  	return 0;
  }
  
  #define destroy_context(mm)             do { } while (0)
  
  #ifndef CONFIG_64BIT
  #define LCTL_OPCODE "lctl"
  #else
  #define LCTL_OPCODE "lctlg"
  #endif
  
  static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
  {
  	pgd_t *pgd = mm->pgd;
  
  	S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
  	if (addressing_mode != HOME_SPACE_MODE) {
  		/* Load primary space page table origin. */
  		asm volatile(LCTL_OPCODE" 1,1,%0\n"
  			     : : "m" (S390_lowcore.user_asce) );
  	} else
  		/* Load home space page table origin. */
  		asm volatile(LCTL_OPCODE" 13,13,%0"
  			     : : "m" (S390_lowcore.user_asce) );
  	set_fs(current->thread.mm_segment);
  }
  
  static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  			     struct task_struct *tsk)
  {
  	cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
  	update_mm(next, tsk);
  	atomic_dec(&prev->context.attach_count);
  	WARN_ON(atomic_read(&prev->context.attach_count) < 0);
  	atomic_inc(&next->context.attach_count);
  	/* Check for TLBs not flushed yet */
  	if (next->context.flush_mm)
  		__tlb_flush_mm(next);
  }
  
  #define enter_lazy_tlb(mm,tsk)	do { } while (0)
  #define deactivate_mm(tsk,mm)	do { } while (0)
  
  static inline void activate_mm(struct mm_struct *prev,
                                 struct mm_struct *next)
  {
          switch_mm(prev, next, current);
  }
  
  static inline void arch_dup_mmap(struct mm_struct *oldmm,
  				 struct mm_struct *mm)
  {
  #ifdef CONFIG_64BIT
  	if (oldmm->context.asce_limit < mm->context.asce_limit)
  		crst_table_downgrade(mm, oldmm->context.asce_limit);
  #endif
  }
  
  static inline void arch_exit_mmap(struct mm_struct *mm)
  {
  }
  
  #endif /* __S390_MMU_CONTEXT_H */
  