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/system.h>
  30 #include <asm/segment.h>
  31 #include <asm/tlbflush.h>
  32 #include <asm/pgtable.h>
  33 #include <asm/mmu_context.h>
  34 #include <asm/spr_defs.h>
  35
  36 #define NO_CONTEXT -1
  37
  38 #define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  39                             SPR_DMMUCFGR_NTS_OFF))
  40 #define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  41                             SPR_IMMUCFGR_NTS_OFF))
  42 #define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
  43 #define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
  44 /*
  45  * Invalidate all TLB entries.
  46  *
  47  * This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
  48  * Easiest way to accomplish this is to just zero out the xTLBMR register
  49  * completely.
  50  *
  51  */
  52
  53 void flush_tlb_all(void)
  54 {
  55         int i;
  56         unsigned long num_tlb_sets;
  57
  58         /* Determine number of sets for IMMU. */
  59         /* FIXME: Assumption is I & D nsets equal. */
  60         num_tlb_sets = NUM_ITLB_SETS;
  61
  62         for (i = 0; i < num_tlb_sets; i++) {
  63                 mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
  64                 mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
  65         }
  66 }
  67
  68 #define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
  69 #define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
  70
  71 /*
  72  * Invalidate a single page.  This is what the xTLBEIR register is for.
  73  *
  74  * There's no point in checking the vma for PAGE_EXEC to determine whether it's
  75  * the data or instruction TLB that should be flushed... that would take more
  76  * than the few instructions that the following compiles down to!
  77  *
  78  * The case where we don't have the xTLBEIR register really only works for
  79  * MMU's with a single way and is hard-coded that way.
  80  */
  81
  82 #define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
  83 #define flush_dtlb_page_no_eir(addr) \
  84         mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
  85
  86 #define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
  87 #define flush_itlb_page_no_eir(addr) \
  88         mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
  89
  90 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
  91 {
  92         if (have_dtlbeir)
  93                 flush_dtlb_page_eir(addr);
  94         else
  95                 flush_dtlb_page_no_eir(addr);
  96
  97         if (have_itlbeir)
  98                 flush_itlb_page_eir(addr);
  99         else
 100                 flush_itlb_page_no_eir(addr);
 101 }
 102
 103 void flush_tlb_range(struct vm_area_struct *vma,
 104                      unsigned long start, unsigned long end)
 105 {
 106         int addr;
 107         bool dtlbeir;
 108         bool itlbeir;
 109
 110         dtlbeir = have_dtlbeir;
 111         itlbeir = have_itlbeir;
 112
 113         for (addr = start; addr < end; addr += PAGE_SIZE) {
 114                 if (dtlbeir)
 115                         flush_dtlb_page_eir(addr);
 116                 else
 117                         flush_dtlb_page_no_eir(addr);
 118
 119                 if (itlbeir)
 120                         flush_itlb_page_eir(addr);
 121                 else
 122                         flush_itlb_page_no_eir(addr);
 123         }
 124 }
 125
 126 /*
 127  * Invalidate the selected mm context only.
 128  *
 129  * FIXME: Due to some bug here, we're flushing everything for now.
 130  * This should be changed to loop over over mm and call flush_tlb_range.
 131  */
 132
 133 void flush_tlb_mm(struct mm_struct *mm)
 134 {
 135
 136         /* Was seeing bugs with the mm struct passed to us. Scrapped most of
 137            this function. */
 138         /* Several architctures do this */
 139         flush_tlb_all();
 140 }
 141
 142 /* called in schedule() just before actually doing the switch_to */
 143
 144 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 145                struct task_struct *next_tsk)
 146 {
 147         /* remember the pgd for the fault handlers
 148          * this is similar to the pgd register in some other CPU's.
 149          * we need our own copy of it because current and active_mm
 150          * might be invalid at points where we still need to derefer
 151          * the pgd.
 152          */
 153         current_pgd = next->pgd;
 154
 155         /* We don't have context support implemented, so flush all
 156          * entries belonging to previous map
 157          */
 158
 159         if (prev != next)
 160                 flush_tlb_mm(prev);
 161
 162 }
 163
 164 /*
 165  * Initialize the context related info for a new mm_struct
 166  * instance.
 167  */
 168
 169 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 170 {
 171         mm->context = NO_CONTEXT;
 172         return 0;
 173 }
 174
 175 /* called by __exit_mm to destroy the used MMU context if any before
 176  * destroying the mm itself. this is only called when the last user of the mm
 177  * drops it.
 178  */
 179
 180 void destroy_context(struct mm_struct *mm)
 181 {
 182         flush_tlb_mm(mm);
 183
 184 }
 185
 186 /* called once during VM initialization, from init.c */
 187
 188 void __init tlb_init(void)
 189 {
 190         /* Do nothing... */
 191         /* invalidate the entire TLB */
 192         /* flush_tlb_all(); */
 193 }