arch/ppc64/mm/stab.c

   1 /*
   2  * PowerPC64 Segment Translation Support.
   3  *
   4  * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
   5  *    Copyright (c) 2001 Dave Engebretsen
   6  *
   7  * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  */
  14
  15 #include <linux/config.h>
  16 #include <asm/pgtable.h>
  17 #include <asm/mmu.h>
  18 #include <asm/mmu_context.h>
  19 #include <asm/paca.h>
  20 #include <asm/cputable.h>
  21
  22 /* Both the segment table and SLB code uses the following cache */
  23 #define NR_STAB_CACHE_ENTRIES 8
  24 DEFINE_PER_CPU(long, stab_cache_ptr);
  25 DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
  26
  27 /*
  28  * Create a segment table entry for the given esid/vsid pair.
  29  */
  30 static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
  31 {
  32         unsigned long esid_data, vsid_data;
  33         unsigned long entry, group, old_esid, castout_entry, i;
  34         unsigned int global_entry;
  35         struct stab_entry *ste, *castout_ste;
  36         unsigned long kernel_segment = (esid << SID_SHIFT) >= KERNELBASE;
  37
  38         vsid_data = vsid << STE_VSID_SHIFT;
  39         esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
  40         if (! kernel_segment)
  41                 esid_data |= STE_ESID_KS;
  42
  43         /* Search the primary group first. */
  44         global_entry = (esid & 0x1f) << 3;
  45         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  46
  47         /* Find an empty entry, if one exists. */
  48         for (group = 0; group < 2; group++) {
  49                 for (entry = 0; entry < 8; entry++, ste++) {
  50                         if (!(ste->esid_data & STE_ESID_V)) {
  51                                 ste->vsid_data = vsid_data;
  52                                 asm volatile("eieio":::"memory");
  53                                 ste->esid_data = esid_data;
  54                                 return (global_entry | entry);
  55                         }
  56                 }
  57                 /* Now search the secondary group. */
  58                 global_entry = ((~esid) & 0x1f) << 3;
  59                 ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  60         }
  61
  62         /*
  63          * Could not find empty entry, pick one with a round robin selection.
  64          * Search all entries in the two groups.
  65          */
  66         castout_entry = get_paca()->stab_rr;
  67         for (i = 0; i < 16; i++) {
  68                 if (castout_entry < 8) {
  69                         global_entry = (esid & 0x1f) << 3;
  70                         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  71                         castout_ste = ste + castout_entry;
  72                 } else {
  73                         global_entry = ((~esid) & 0x1f) << 3;
  74                         ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  75                         castout_ste = ste + (castout_entry - 8);
  76                 }
  77
  78                 /* Dont cast out the first kernel segment */
  79                 if ((castout_ste->esid_data & ESID_MASK) != KERNELBASE)
  80                         break;
  81
  82                 castout_entry = (castout_entry + 1) & 0xf;
  83         }
  84
  85         get_paca()->stab_rr = (castout_entry + 1) & 0xf;
  86
  87         /* Modify the old entry to the new value. */
  88
  89         /* Force previous translations to complete. DRENG */
  90         asm volatile("isync" : : : "memory");
  91
  92         old_esid = castout_ste->esid_data >> SID_SHIFT;
  93         castout_ste->esid_data = 0;             /* Invalidate old entry */
  94
  95         asm volatile("sync" : : : "memory");    /* Order update */
  96
  97         castout_ste->vsid_data = vsid_data;
  98         asm volatile("eieio" : : : "memory");   /* Order update */
  99         castout_ste->esid_data = esid_data;
 100
 101         asm volatile("slbie  %0" : : "r" (old_esid << SID_SHIFT));
 102         /* Ensure completion of slbie */
 103         asm volatile("sync" : : : "memory");
 104
 105         return (global_entry | (castout_entry & 0x7));
 106 }
 107
 108 /*
 109  * Allocate a segment table entry for the given ea and mm
 110  */
 111 static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
 112 {
 113         unsigned long vsid;
 114         unsigned char stab_entry;
 115         unsigned long offset;
 116
 117         /* Kernel or user address? */
 118         if (ea >= KERNELBASE) {
 119                 vsid = get_kernel_vsid(ea);
 120         } else {
 121                 if ((ea >= TASK_SIZE_USER64) || (! mm))
 122                         return 1;
 123
 124                 vsid = get_vsid(mm->context.id, ea);
 125         }
 126
 127         stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
 128
 129         if (ea < KERNELBASE) {
 130                 offset = __get_cpu_var(stab_cache_ptr);
 131                 if (offset < NR_STAB_CACHE_ENTRIES)
 132                         __get_cpu_var(stab_cache[offset++]) = stab_entry;
 133                 else
 134                         offset = NR_STAB_CACHE_ENTRIES+1;
 135                 __get_cpu_var(stab_cache_ptr) = offset;
 136
 137                 /* Order update */
 138                 asm volatile("sync":::"memory");
 139         }
 140
 141         return 0;
 142 }
 143
 144 int ste_allocate(unsigned long ea)
 145 {
 146         return __ste_allocate(ea, current->mm);
 147 }
 148
 149 /*
 150  * Do the segment table work for a context switch: flush all user
 151  * entries from the table, then preload some probably useful entries
 152  * for the new task
 153  */
 154 void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
 155 {
 156         struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
 157         struct stab_entry *ste;
 158         unsigned long offset = __get_cpu_var(stab_cache_ptr);
 159         unsigned long pc = KSTK_EIP(tsk);
 160         unsigned long stack = KSTK_ESP(tsk);
 161         unsigned long unmapped_base;
 162
 163         /* Force previous translations to complete. DRENG */
 164         asm volatile("isync" : : : "memory");
 165
 166         if (offset <= NR_STAB_CACHE_ENTRIES) {
 167                 int i;
 168
 169                 for (i = 0; i < offset; i++) {
 170                         ste = stab + __get_cpu_var(stab_cache[i]);
 171                         ste->esid_data = 0; /* invalidate entry */
 172                 }
 173         } else {
 174                 unsigned long entry;
 175
 176                 /* Invalidate all entries. */
 177                 ste = stab;
 178
 179                 /* Never flush the first entry. */
 180                 ste += 1;
 181                 for (entry = 1;
 182                      entry < (PAGE_SIZE / sizeof(struct stab_entry));
 183                      entry++, ste++) {
 184                         unsigned long ea;
 185                         ea = ste->esid_data & ESID_MASK;
 186                         if (ea < KERNELBASE) {
 187                                 ste->esid_data = 0;
 188                         }
 189                 }
 190         }
 191
 192         asm volatile("sync; slbia; sync":::"memory");
 193
 194         __get_cpu_var(stab_cache_ptr) = 0;
 195
 196         /* Now preload some entries for the new task */
 197         if (test_tsk_thread_flag(tsk, TIF_32BIT))
 198                 unmapped_base = TASK_UNMAPPED_BASE_USER32;
 199         else
 200                 unmapped_base = TASK_UNMAPPED_BASE_USER64;
 201
 202         __ste_allocate(pc, mm);
 203
 204         if (GET_ESID(pc) == GET_ESID(stack))
 205                 return;
 206
 207         __ste_allocate(stack, mm);
 208
 209         if ((GET_ESID(pc) == GET_ESID(unmapped_base))
 210             || (GET_ESID(stack) == GET_ESID(unmapped_base)))
 211                 return;
 212
 213         __ste_allocate(unmapped_base, mm);
 214
 215         /* Order update */
 216         asm volatile("sync" : : : "memory");
 217 }
 218
 219 extern void slb_initialize(void);
 220
 221 /*
 222  * Build an entry for the base kernel segment and put it into
 223  * the segment table or SLB.  All other segment table or SLB
 224  * entries are faulted in.
 225  */
 226 void stab_initialize(unsigned long stab)
 227 {
 228         unsigned long vsid = get_kernel_vsid(KERNELBASE);
 229
 230         if (cpu_has_feature(CPU_FTR_SLB)) {
 231                 slb_initialize();
 232         } else {
 233                 asm volatile("isync; slbia; isync":::"memory");
 234                 make_ste(stab, GET_ESID(KERNELBASE), vsid);
 235
 236                 /* Order update */
 237                 asm volatile("sync":::"memory");
 238         }
 239 }