root/arch/openrisc/mm/tlb.c

DEFINITIONS

1. local_flush_tlb_all
2. local_flush_tlb_page
3. local_flush_tlb_range
4. local_flush_tlb_mm
5. switch_mm
6. init_new_context
7. destroy_context
8. tlb_init

   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/pgtable.h>
  27 #include <asm/mmu_context.h>
  28 #include <asm/spr_defs.h>
  29 
  30 #define NO_CONTEXT -1
  31 
  32 #define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  33                             SPR_DMMUCFGR_NTS_OFF))
  34 #define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
  35                             SPR_IMMUCFGR_NTS_OFF))
  36 #define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
  37 #define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
  38 /*
  39  * Invalidate all TLB entries.
  40  *
  41  * This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
  42  * Easiest way to accomplish this is to just zero out the xTLBMR register
  43  * completely.
  44  *
  45  */
  46 
  47 void local_flush_tlb_all(void)
  48 {
  49         int i;
  50         unsigned long num_tlb_sets;
  51 
  52         /* Determine number of sets for IMMU. */
  53         /* FIXME: Assumption is I & D nsets equal. */
  54         num_tlb_sets = NUM_ITLB_SETS;
  55 
  56         for (i = 0; i < num_tlb_sets; i++) {
  57                 mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
  58                 mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
  59         }
  60 }
  61 
  62 #define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
  63 #define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
  64 
  65 /*
  66  * Invalidate a single page.  This is what the xTLBEIR register is for.
  67  *
  68  * There's no point in checking the vma for PAGE_EXEC to determine whether it's
  69  * the data or instruction TLB that should be flushed... that would take more
  70  * than the few instructions that the following compiles down to!
  71  *
  72  * The case where we don't have the xTLBEIR register really only works for
  73  * MMU's with a single way and is hard-coded that way.
  74  */
  75 
  76 #define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
  77 #define flush_dtlb_page_no_eir(addr) \
  78         mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
  79 
  80 #define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
  81 #define flush_itlb_page_no_eir(addr) \
  82         mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
  83 
  84 void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
  85 {
  86         if (have_dtlbeir)
  87                 flush_dtlb_page_eir(addr);
  88         else
  89                 flush_dtlb_page_no_eir(addr);
  90 
  91         if (have_itlbeir)
  92                 flush_itlb_page_eir(addr);
  93         else
  94                 flush_itlb_page_no_eir(addr);
  95 }
  96 
  97 void local_flush_tlb_range(struct vm_area_struct *vma,
  98                            unsigned long start, unsigned long end)
  99 {
 100         int addr;
 101         bool dtlbeir;
 102         bool itlbeir;
 103 
 104         dtlbeir = have_dtlbeir;
 105         itlbeir = have_itlbeir;
 106 
 107         for (addr = start; addr < end; addr += PAGE_SIZE) {
 108                 if (dtlbeir)
 109                         flush_dtlb_page_eir(addr);
 110                 else
 111                         flush_dtlb_page_no_eir(addr);
 112 
 113                 if (itlbeir)
 114                         flush_itlb_page_eir(addr);
 115                 else
 116                         flush_itlb_page_no_eir(addr);
 117         }
 118 }
 119 
 120 /*
 121  * Invalidate the selected mm context only.
 122  *
 123  * FIXME: Due to some bug here, we're flushing everything for now.
 124  * This should be changed to loop over over mm and call flush_tlb_range.
 125  */
 126 
 127 void local_flush_tlb_mm(struct mm_struct *mm)
 128 {
 129 
 130         /* Was seeing bugs with the mm struct passed to us. Scrapped most of
 131            this function. */
 132         /* Several architctures do this */
 133         local_flush_tlb_all();
 134 }
 135 
 136 /* called in schedule() just before actually doing the switch_to */
 137 
 138 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 139                struct task_struct *next_tsk)
 140 {
 141         /* remember the pgd for the fault handlers
 142          * this is similar to the pgd register in some other CPU's.
 143          * we need our own copy of it because current and active_mm
 144          * might be invalid at points where we still need to derefer
 145          * the pgd.
 146          */
 147         current_pgd[smp_processor_id()] = next->pgd;
 148 
 149         /* We don't have context support implemented, so flush all
 150          * entries belonging to previous map
 151          */
 152 
 153         if (prev != next)
 154                 local_flush_tlb_mm(prev);
 155 
 156 }
 157 
 158 /*
 159  * Initialize the context related info for a new mm_struct
 160  * instance.
 161  */
 162 
 163 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 164 {
 165         mm->context = NO_CONTEXT;
 166         return 0;
 167 }
 168 
 169 /* called by __exit_mm to destroy the used MMU context if any before
 170  * destroying the mm itself. this is only called when the last user of the mm
 171  * drops it.
 172  */
 173 
 174 void destroy_context(struct mm_struct *mm)
 175 {
 176         flush_tlb_mm(mm);
 177 
 178 }
 179 
 180 /* called once during VM initialization, from init.c */
 181 
 182 void __init tlb_init(void)
 183 {
 184         /* Do nothing... */
 185         /* invalidate the entire TLB */
 186         /* flush_tlb_all(); */
 187 }