arch/openrisc/mm/tlb.c

   1 /*
   2  * OpenRISC tlb.c
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10  * Copyright (C) 2010-2011 Julius Baxter <julius.baxter@orsoc.se>
  11  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  12  *
  13  *      This program is free software; you can redistribute it and/or
  14  *      modify it under the terms of the GNU General Public License
  15  *      as published by the Free Software Foundation; either version
  16  *      2 of the License, or (at your option) any later version.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/kernel.h>
  21 #include <linux/errno.h>
  22 #include <linux/string.h>
  23 #include <linux/types.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/mman.h>
  26 #include <linux/mm.h>
  27 #include <linux/init.h>
  28
  29 #include <asm/segment.h>
  30 #include <asm/tlbflush.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/mmu_context.h>
  33 #include <asm/spr_defs.h>
  34
  35 #define NO_CONTEXT -1
  36
  37 #define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  38                             SPR_DMMUCFGR_NTS_OFF))
  39 #define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  40                             SPR_IMMUCFGR_NTS_OFF))
  41 #define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
  42 #define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
  43 /*
  44  * Invalidate all TLB entries.
  45  *
  46  * This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
  47  * Easiest way to accomplish this is to just zero out the xTLBMR register
  48  * completely.
  49  *
  50  */
  51
  52 void flush_tlb_all(void)
  53 {
  54         int i;
  55         unsigned long num_tlb_sets;
  56
  57         /* Determine number of sets for IMMU. */
  58         /* FIXME: Assumption is I & D nsets equal. */
  59         num_tlb_sets = NUM_ITLB_SETS;
  60
  61         for (i = 0; i < num_tlb_sets; i++) {
  62                 mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
  63                 mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
  64         }
  65 }
  66
  67 #define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
  68 #define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
  69
  70 /*
  71  * Invalidate a single page.  This is what the xTLBEIR register is for.
  72  *
  73  * There's no point in checking the vma for PAGE_EXEC to determine whether it's
  74  * the data or instruction TLB that should be flushed... that would take more
  75  * than the few instructions that the following compiles down to!
  76  *
  77  * The case where we don't have the xTLBEIR register really only works for
  78  * MMU's with a single way and is hard-coded that way.
  79  */
  80
  81 #define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
  82 #define flush_dtlb_page_no_eir(addr) \
  83         mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
  84
  85 #define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
  86 #define flush_itlb_page_no_eir(addr) \
  87         mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
  88
  89 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
  90 {
  91         if (have_dtlbeir)
  92                 flush_dtlb_page_eir(addr);
  93         else
  94                 flush_dtlb_page_no_eir(addr);
  95
  96         if (have_itlbeir)
  97                 flush_itlb_page_eir(addr);
  98         else
  99                 flush_itlb_page_no_eir(addr);
 100 }
 101
 102 void flush_tlb_range(struct vm_area_struct *vma,
 103                      unsigned long start, unsigned long end)
 104 {
 105         int addr;
 106         bool dtlbeir;
 107         bool itlbeir;
 108
 109         dtlbeir = have_dtlbeir;
 110         itlbeir = have_itlbeir;
 111
 112         for (addr = start; addr < end; addr += PAGE_SIZE) {
 113                 if (dtlbeir)
 114                         flush_dtlb_page_eir(addr);
 115                 else
 116                         flush_dtlb_page_no_eir(addr);
 117
 118                 if (itlbeir)
 119                         flush_itlb_page_eir(addr);
 120                 else
 121                         flush_itlb_page_no_eir(addr);
 122         }
 123 }
 124
 125 /*
 126  * Invalidate the selected mm context only.
 127  *
 128  * FIXME: Due to some bug here, we're flushing everything for now.
 129  * This should be changed to loop over over mm and call flush_tlb_range.
 130  */
 131
 132 void flush_tlb_mm(struct mm_struct *mm)
 133 {
 134
 135         /* Was seeing bugs with the mm struct passed to us. Scrapped most of
 136            this function. */
 137         /* Several architctures do this */
 138         flush_tlb_all();
 139 }
 140
 141 /* called in schedule() just before actually doing the switch_to */
 142
 143 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 144                struct task_struct *next_tsk)
 145 {
 146         /* remember the pgd for the fault handlers
 147          * this is similar to the pgd register in some other CPU's.
 148          * we need our own copy of it because current and active_mm
 149          * might be invalid at points where we still need to derefer
 150          * the pgd.
 151          */
 152         current_pgd = next->pgd;
 153
 154         /* We don't have context support implemented, so flush all
 155          * entries belonging to previous map
 156          */
 157
 158         if (prev != next)
 159                 flush_tlb_mm(prev);
 160
 161 }
 162
 163 /*
 164  * Initialize the context related info for a new mm_struct
 165  * instance.
 166  */
 167
 168 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 169 {
 170         mm->context = NO_CONTEXT;
 171         return 0;
 172 }
 173
 174 /* called by __exit_mm to destroy the used MMU context if any before
 175  * destroying the mm itself. this is only called when the last user of the mm
 176  * drops it.
 177  */
 178
 179 void destroy_context(struct mm_struct *mm)
 180 {
 181         flush_tlb_mm(mm);
 182
 183 }
 184
 185 /* called once during VM initialization, from init.c */
 186
 187 void __init tlb_init(void)
 188 {
 189         /* Do nothing... */
 190         /* invalidate the entire TLB */
 191         /* flush_tlb_all(); */
 192 }