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Diffstat (limited to 'arch/cris/mm/tlb.c')
-rw-r--r-- | arch/cris/mm/tlb.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/arch/cris/mm/tlb.c b/arch/cris/mm/tlb.c new file mode 100644 index 000000000000..23eca5ad7389 --- /dev/null +++ b/arch/cris/mm/tlb.c @@ -0,0 +1,126 @@ +/* + * 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 */ + +/* + * Initialize the context related info for a new mm_struct + * instance. + */ + +int +init_new_context(struct task_struct *tsk, struct mm_struct *mm) +{ + mm->context = NO_CONTEXT; + return 0; +} + +/* 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 = NO_CONTEXT; + } + + /* insert it into the page_id_map */ + + mm->context = 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 == 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 != NO_CONTEXT) { + D(printk("destroy_context %d (%p)\n", mm->context, mm)); + flush_tlb_mm(mm); /* TODO this might be redundant ? */ + page_id_map[mm->context] = NULL; + /* mm->context = NO_CONTEXT; redundant.. mm will be freed */ + } +} + +/* called once during VM initialization, from init.c */ + +void __init +tlb_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; +} |