arch/openrisc/mm/tlb.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * OpenRISC tlb.c
   4  *
   5  * Linux architectural port borrowing liberally from similar works of
   6  * others.  All original copyrights apply as per the original source
   7  * declaration.
   8  *
   9  * Modifications for the OpenRISC architecture:
  10  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  11  * Copyright (C) 2010-2011 Julius Baxter <julius.baxter@orsoc.se>
  12  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  13  */
  14
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/string.h>
  19 #include <linux/types.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/mman.h>
  22 #include <linux/mm.h>
  23 #include <linux/init.h>
  24
  25 #include <asm/tlbflush.h>
  26 #include <asm/mmu_context.h>
  27 #include <asm/spr_defs.h>
  28
  29 #define NO_CONTEXT -1
  30
  31 #define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  32                             SPR_DMMUCFGR_NTS_OFF))
  33 #define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  34                             SPR_IMMUCFGR_NTS_OFF))
  35 #define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
  36 #define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
  37 /*
  38  * Invalidate all TLB entries.
  39  *
  40  * This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
  41  * Easiest way to accomplish this is to just zero out the xTLBMR register
  42  * completely.
  43  *
  44  */
  45
  46 void local_flush_tlb_all(void)
  47 {
  48         int i;
  49         unsigned long num_tlb_sets;
  50
  51         /* Determine number of sets for IMMU. */
  52         /* FIXME: Assumption is I & D nsets equal. */
  53         num_tlb_sets = NUM_ITLB_SETS;
  54
  55         for (i = 0; i < num_tlb_sets; i++) {
  56                 mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
  57                 mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
  58         }
  59 }
  60
  61 #define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
  62 #define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
  63
  64 /*
  65  * Invalidate a single page.  This is what the xTLBEIR register is for.
  66  *
  67  * There's no point in checking the vma for PAGE_EXEC to determine whether it's
  68  * the data or instruction TLB that should be flushed... that would take more
  69  * than the few instructions that the following compiles down to!
  70  *
  71  * The case where we don't have the xTLBEIR register really only works for
  72  * MMU's with a single way and is hard-coded that way.
  73  */
  74
  75 #define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
  76 #define flush_dtlb_page_no_eir(addr) \
  77         mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
  78
  79 #define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
  80 #define flush_itlb_page_no_eir(addr) \
  81         mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
  82
  83 void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
  84 {
  85         if (have_dtlbeir)
  86                 flush_dtlb_page_eir(addr);
  87         else
  88                 flush_dtlb_page_no_eir(addr);
  89
  90         if (have_itlbeir)
  91                 flush_itlb_page_eir(addr);
  92         else
  93                 flush_itlb_page_no_eir(addr);
  94 }
  95
  96 void local_flush_tlb_range(struct vm_area_struct *vma,
  97                            unsigned long start, unsigned long end)
  98 {
  99         int addr;
 100         bool dtlbeir;
 101         bool itlbeir;
 102
 103         dtlbeir = have_dtlbeir;
 104         itlbeir = have_itlbeir;
 105
 106         for (addr = start; addr < end; addr += PAGE_SIZE) {
 107                 if (dtlbeir)
 108                         flush_dtlb_page_eir(addr);
 109                 else
 110                         flush_dtlb_page_no_eir(addr);
 111
 112                 if (itlbeir)
 113                         flush_itlb_page_eir(addr);
 114                 else
 115                         flush_itlb_page_no_eir(addr);
 116         }
 117 }
 118
 119 /*
 120  * Invalidate the selected mm context only.
 121  *
 122  * FIXME: Due to some bug here, we're flushing everything for now.
 123  * This should be changed to loop over over mm and call flush_tlb_range.
 124  */
 125
 126 void local_flush_tlb_mm(struct mm_struct *mm)
 127 {
 128
 129         /* Was seeing bugs with the mm struct passed to us. Scrapped most of
 130            this function. */
 131         /* Several architctures do this */
 132         local_flush_tlb_all();
 133 }
 134
 135 /* called in schedule() just before actually doing the switch_to */
 136
 137 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 138                struct task_struct *next_tsk)
 139 {
 140         unsigned int cpu;
 141
 142         if (unlikely(prev == next))
 143                 return;
 144
 145         cpu = smp_processor_id();
 146
 147         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 148         cpumask_set_cpu(cpu, mm_cpumask(next));
 149
 150         /* remember the pgd for the fault handlers
 151          * this is similar to the pgd register in some other CPU's.
 152          * we need our own copy of it because current and active_mm
 153          * might be invalid at points where we still need to derefer
 154          * the pgd.
 155          */
 156         current_pgd[cpu] = next->pgd;
 157
 158         /* We don't have context support implemented, so flush all
 159          * entries belonging to previous map
 160          */
 161         local_flush_tlb_mm(prev);
 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 }