/* *  linux/arch/cris/mm/tlb.c * *  Copyright (C) 2000, 2001  Axis Communications AB *   *  Authors:   Bjorn Wesen (bjornw@axis.com) * */#include <linux/init.h>#include <asm/tlb.h>#define D(x)/* The TLB can host up to 64 different mm contexts at the same time. * The running context is R_MMU_CONTEXT, and each TLB entry contains a * page_id that has to match to give a hit. In page_id_map, we keep track * of which mm's we have assigned which page_id's, so that we know when * to invalidate TLB entries. * * The last page_id is never running - it is used as an invalid page_id * so we can make TLB entries that will never match. * * Notice that we need to make the flushes atomic, otherwise an interrupt * handler that uses vmalloced memory might cause a TLB load in the middle * of a flush causing. */struct mm_struct *page_id_map[NUM_PAGEID];static int map_replace_ptr = 1;  /* which page_id_map entry to replace next *//* the following functions are similar to those used in the PPC port */static inline voidalloc_context(struct mm_struct *mm){	struct mm_struct *old_mm;	D(printk("tlb: alloc context %d (%p)\n", map_replace_ptr, mm));	/* did we replace an mm ? */	old_mm = page_id_map[map_replace_ptr];	if(old_mm) {		/* throw out any TLB entries belonging to the mm we replace		 * in the map		 */		flush_tlb_mm(old_mm);		old_mm->context.page_id = NO_CONTEXT;	}	/* insert it into the page_id_map */	mm->context.page_id = map_replace_ptr;	page_id_map[map_replace_ptr] = mm;	map_replace_ptr++;	if(map_replace_ptr == INVALID_PAGEID)		map_replace_ptr = 0;         /* wrap around */	}/*  * if needed, get a new MMU context for the mm. otherwise nothing is done. */voidget_mmu_context(struct mm_struct *mm){	if(mm->context.page_id == NO_CONTEXT)		alloc_context(mm);}/* called by __exit_mm to destroy the used MMU context if any before * destroying the mm itself. this is only called when the last user of the mm * drops it. * * the only thing we really need to do here is mark the used PID slot * as empty. */voiddestroy_context(struct mm_struct *mm){	if(mm->context.page_id != NO_CONTEXT) {		D(printk("destroy_context %d (%p)\n", mm->context.page_id, mm));		flush_tlb_mm(mm);  /* TODO this might be redundant ? */		page_id_map[mm->context.page_id] = NULL;	}}/* called once during VM initialization, from init.c */void __inittlb_init(void){	int i;	/* clear the page_id map */	for (i = 1; i < sizeof (page_id_map) / sizeof (page_id_map[0]); i++)		page_id_map[i] = NULL;		/* invalidate the entire TLB */	flush_tlb_all();	/* the init_mm has context 0 from the boot */	page_id_map[0] = &init_mm;}