/* * linux/arch/cris/mm/tlb.c * * Copyright (C) 2000, 2001 Axis Communications AB * * Authors: Bjorn Wesen (bjornw@axis.com) * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define D(x) /* CRIS in Etrax100LX TLB */ #define NUM_TLB_ENTRIES 64 #define NUM_PAGEID 64 #define INVALID_PAGEID 63 #define NO_CONTEXT -1 /* 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 */ /* invalidate all TLB entries */ void flush_tlb_all(void) { int i; unsigned long flags; /* the vpn of i & 0xf is so we dont write similar TLB entries * in the same 4-way entry group. details.. */ save_and_cli(flags); /* flush needs to be atomic */ for(i = 0; i < NUM_TLB_ENTRIES; i++) { *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) ); *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) | IO_FIELD(R_TLB_HI, vpn, i & 0xf ) ); *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) | IO_STATE(R_TLB_LO, valid, no ) | IO_STATE(R_TLB_LO, kernel,no ) | IO_STATE(R_TLB_LO, we, no ) | IO_FIELD(R_TLB_LO, pfn, 0 ) ); } restore_flags(flags); D(printk("tlb: flushed all\n")); } /* invalidate the selected mm context only */ void flush_tlb_mm(struct mm_struct *mm) { int i; int page_id = mm->context; unsigned long flags; D(printk("tlb: flush mm context %d (%p)\n", page_id, mm)); if(page_id == NO_CONTEXT) return; /* mark the TLB entries that match the page_id as invalid. * here we could also check the _PAGE_GLOBAL bit and NOT flush * global pages. is it worth the extra I/O ? */ save_and_cli(flags); /* flush needs to be atomic */ for(i = 0; i < NUM_TLB_ENTRIES; i++) { *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i); if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) { *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) | IO_FIELD(R_TLB_HI, vpn, i & 0xf ) ); *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) | IO_STATE(R_TLB_LO, valid, no ) | IO_STATE(R_TLB_LO, kernel,no ) | IO_STATE(R_TLB_LO, we, no ) | IO_FIELD(R_TLB_LO, pfn, 0 ) ); } } restore_flags(flags); } /* invalidate a single page */ void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr) { struct mm_struct *mm = vma->vm_mm; int page_id = mm->context; int i; unsigned long flags; D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm)); if(page_id == NO_CONTEXT) return; addr &= PAGE_MASK; /* perhaps not necessary */ /* invalidate those TLB entries that match both the mm context * and the virtual address requested */ save_and_cli(flags); /* flush needs to be atomic */ for(i = 0; i < NUM_TLB_ENTRIES; i++) { unsigned long tlb_hi; *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i); tlb_hi = *R_TLB_HI; if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id && (tlb_hi & PAGE_MASK) == addr) { *R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) | addr; /* same addr as before works. */ *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) | IO_STATE(R_TLB_LO, valid, no ) | IO_STATE(R_TLB_LO, kernel,no ) | IO_STATE(R_TLB_LO, we, no ) | IO_FIELD(R_TLB_LO, pfn, 0 ) ); } } restore_flags(flags); } /* invalidate a page range */ void flush_tlb_range(struct mm_struct *mm, unsigned long start, unsigned long end) { int page_id = mm->context; int i; unsigned long flags; D(printk("tlb: flush range %p<->%p in context %d (%p)\n", start, end, page_id, mm)); if(page_id == NO_CONTEXT) return; start &= PAGE_MASK; /* probably not necessary */ end &= PAGE_MASK; /* dito */ /* invalidate those TLB entries that match both the mm context * and the virtual address range */ save_and_cli(flags); /* flush needs to be atomic */ for(i = 0; i < NUM_TLB_ENTRIES; i++) { unsigned long tlb_hi, vpn; *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i); tlb_hi = *R_TLB_HI; vpn = tlb_hi & PAGE_MASK; if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id && vpn >= start && vpn < end) { *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) | IO_FIELD(R_TLB_HI, vpn, i & 0xf ) ); *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) | IO_STATE(R_TLB_LO, valid, no ) | IO_STATE(R_TLB_LO, kernel,no ) | IO_STATE(R_TLB_LO, we, no ) | IO_FIELD(R_TLB_LO, pfn, 0 ) ); } } restore_flags(flags); } /* dump the entire TLB for debug purposes */ #if 0 void dump_tlb_all(void) { int i; unsigned long flags; printk("TLB dump. LO is: pfn | reserved | global | valid | kernel | we |\n"); save_and_cli(flags); for(i = 0; i < NUM_TLB_ENTRIES; i++) { *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) ); printk("Entry %d: HI 0x%08lx, LO 0x%08lx\n", i, *R_TLB_HI, *R_TLB_LO); } restore_flags(flags); } #endif /* * 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 in schedule() just before actually doing the switch_to */ void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk, int cpu) { /* make sure we have a context */ get_mmu_context(next); /* remember the pgd for the fault handlers * this is similar to the pgd register in some other CPU's. * we need our own copy of it because current and active_mm * might be invalid at points where we still need to derefer * the pgd. */ current_pgd = next->pgd; /* switch context in the MMU */ D(printk("switching mmu_context to %d (%p)\n", next->context, next)); *R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT, page_id, next->context); } /* 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; }