/* * linux/arch/cris/mm/tlb.c * * Copyright (C) 2000, 2001 Axis Communications AB * * Authors: Bjorn Wesen (bjornw@axis.com) * */ #include #include #include #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 we have assigned to which page_id, 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 void alloc_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. */ void get_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. */ void destroy_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 __init tlb_init(void) { int i; /* clear the page_id map */ for (i = 1; i < ARRAY_SIZE(page_id_map); 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; } 2d8f040b8d8db0b86d42806e0c417f7ccf'>root/arch/sparc/kernel/prom.h

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