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 #include <asm/lmb.h>
  22 #include <asm/abs_addr.h>
  23
  24 struct stab_entry {
  25         unsigned long esid_data;
  26         unsigned long vsid_data;
  27 };
  28
  29 /* Both the segment table and SLB code uses the following cache */
  30 #define NR_STAB_CACHE_ENTRIES 8
  31 DEFINE_PER_CPU(long, stab_cache_ptr);
  32 DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
  33
  34 /*
  35  * Create a segment table entry for the given esid/vsid pair.
  36  */
  37 static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
  38 {
  39         unsigned long esid_data, vsid_data;
  40         unsigned long entry, group, old_esid, castout_entry, i;
  41         unsigned int global_entry;
  42         struct stab_entry *ste, *castout_ste;
  43         unsigned long kernel_segment = (esid << SID_SHIFT) >= KERNELBASE;
  44
  45         vsid_data = vsid << STE_VSID_SHIFT;
  46         esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
  47         if (! kernel_segment)
  48                 esid_data |= STE_ESID_KS;
  49
  50         /* Search the primary group first. */
  51         global_entry = (esid & 0x1f) << 3;
  52         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  53
  54         /* Find an empty entry, if one exists. */
  55         for (group = 0; group < 2; group++) {
  56                 for (entry = 0; entry < 8; entry++, ste++) {
  57                         if (!(ste->esid_data & STE_ESID_V)) {
  58                                 ste->vsid_data = vsid_data;
  59                                 asm volatile("eieio":::"memory");
  60                                 ste->esid_data = esid_data;
  61                                 return (global_entry | entry);
  62                         }
  63                 }
  64                 /* Now search the secondary group. */
  65                 global_entry = ((~esid) & 0x1f) << 3;
  66                 ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  67         }
  68
  69         /*
  70          * Could not find empty entry, pick one with a round robin selection.
  71          * Search all entries in the two groups.
  72          */
  73         castout_entry = get_paca()->stab_rr;
  74         for (i = 0; i < 16; i++) {
  75                 if (castout_entry < 8) {
  76                         global_entry = (esid & 0x1f) << 3;
  77                         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  78                         castout_ste = ste + castout_entry;
  79                 } else {
  80                         global_entry = ((~esid) & 0x1f) << 3;
  81                         ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  82                         castout_ste = ste + (castout_entry - 8);
  83                 }
  84
  85                 /* Dont cast out the first kernel segment */
  86                 if ((castout_ste->esid_data & ESID_MASK) != KERNELBASE)
  87                         break;
  88
  89                 castout_entry = (castout_entry + 1) & 0xf;
  90         }
  91
  92         get_paca()->stab_rr = (castout_entry + 1) & 0xf;
  93
  94         /* Modify the old entry to the new value. */
  95
  96         /* Force previous translations to complete. DRENG */
  97         asm volatile("isync" : : : "memory");
  98
  99         old_esid = castout_ste->esid_data >> SID_SHIFT;
 100         castout_ste->esid_data = 0;             /* Invalidate old entry */
 101
 102         asm volatile("sync" : : : "memory");    /* Order update */
 103
 104         castout_ste->vsid_data = vsid_data;
 105         asm volatile("eieio" : : : "memory");   /* Order update */
 106         castout_ste->esid_data = esid_data;
 107
 108         asm volatile("slbie  %0" : : "r" (old_esid << SID_SHIFT));
 109         /* Ensure completion of slbie */
 110         asm volatile("sync" : : : "memory");
 111
 112         return (global_entry | (castout_entry & 0x7));
 113 }
 114
 115 /*
 116  * Allocate a segment table entry for the given ea and mm
 117  */
 118 static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
 119 {
 120         unsigned long vsid;
 121         unsigned char stab_entry;
 122         unsigned long offset;
 123
 124         /* Kernel or user address? */
 125         if (ea >= KERNELBASE) {
 126                 vsid = get_kernel_vsid(ea);
 127         } else {
 128                 if ((ea >= TASK_SIZE_USER64) || (! mm))
 129                         return 1;
 130
 131                 vsid = get_vsid(mm->context.id, ea);
 132         }
 133
 134         stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
 135
 136         if (ea < KERNELBASE) {
 137                 offset = __get_cpu_var(stab_cache_ptr);
 138                 if (offset < NR_STAB_CACHE_ENTRIES)
 139                         __get_cpu_var(stab_cache[offset++]) = stab_entry;
 140                 else
 141                         offset = NR_STAB_CACHE_ENTRIES+1;
 142                 __get_cpu_var(stab_cache_ptr) = offset;
 143
 144                 /* Order update */
 145                 asm volatile("sync":::"memory");
 146         }
 147
 148         return 0;
 149 }
 150
 151 int ste_allocate(unsigned long ea)
 152 {
 153         return __ste_allocate(ea, current->mm);
 154 }
 155
 156 /*
 157  * Do the segment table work for a context switch: flush all user
 158  * entries from the table, then preload some probably useful entries
 159  * for the new task
 160  */
 161 void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
 162 {
 163         struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
 164         struct stab_entry *ste;
 165         unsigned long offset = __get_cpu_var(stab_cache_ptr);
 166         unsigned long pc = KSTK_EIP(tsk);
 167         unsigned long stack = KSTK_ESP(tsk);
 168         unsigned long unmapped_base;
 169
 170         /* Force previous translations to complete. DRENG */
 171         asm volatile("isync" : : : "memory");
 172
 173         if (offset <= NR_STAB_CACHE_ENTRIES) {
 174                 int i;
 175
 176                 for (i = 0; i < offset; i++) {
 177                         ste = stab + __get_cpu_var(stab_cache[i]);
 178                         ste->esid_data = 0; /* invalidate entry */
 179                 }
 180         } else {
 181                 unsigned long entry;
 182
 183                 /* Invalidate all entries. */
 184                 ste = stab;
 185
 186                 /* Never flush the first entry. */
 187                 ste += 1;
 188                 for (entry = 1;
 189                      entry < (PAGE_SIZE / sizeof(struct stab_entry));
 190                      entry++, ste++) {
 191                         unsigned long ea;
 192                         ea = ste->esid_data & ESID_MASK;
 193                         if (ea < KERNELBASE) {
 194                                 ste->esid_data = 0;
 195                         }
 196                 }
 197         }
 198
 199         asm volatile("sync; slbia; sync":::"memory");
 200
 201         __get_cpu_var(stab_cache_ptr) = 0;
 202
 203         /* Now preload some entries for the new task */
 204         if (test_tsk_thread_flag(tsk, TIF_32BIT))
 205                 unmapped_base = TASK_UNMAPPED_BASE_USER32;
 206         else
 207                 unmapped_base = TASK_UNMAPPED_BASE_USER64;
 208
 209         __ste_allocate(pc, mm);
 210
 211         if (GET_ESID(pc) == GET_ESID(stack))
 212                 return;
 213
 214         __ste_allocate(stack, mm);
 215
 216         if ((GET_ESID(pc) == GET_ESID(unmapped_base))
 217             || (GET_ESID(stack) == GET_ESID(unmapped_base)))
 218                 return;
 219
 220         __ste_allocate(unmapped_base, mm);
 221
 222         /* Order update */
 223         asm volatile("sync" : : : "memory");
 224 }
 225
 226 extern void slb_initialize(void);
 227
 228 /*
 229  * Allocate segment tables for secondary CPUs.  These must all go in
 230  * the first (bolted) segment, so that do_stab_bolted won't get a
 231  * recursive segment miss on the segment table itself.
 232  */
 233 void stabs_alloc(void)
 234 {
 235         int cpu;
 236
 237         if (cpu_has_feature(CPU_FTR_SLB))
 238                 return;
 239
 240         for_each_cpu(cpu) {
 241                 unsigned long newstab;
 242
 243                 if (cpu == 0)
 244                         continue; /* stab for CPU 0 is statically allocated */
 245
 246                 newstab = lmb_alloc_base(PAGE_SIZE, PAGE_SIZE, 1<<SID_SHIFT);
 247                 if (! newstab)
 248                         panic("Unable to allocate segment table for CPU %d.\n",
 249                               cpu);
 250
 251                 newstab += KERNELBASE;
 252
 253                 memset((void *)newstab, 0, PAGE_SIZE);
 254
 255                 paca[cpu].stab_addr = newstab;
 256                 paca[cpu].stab_real = virt_to_abs(newstab);
 257                 printk(KERN_DEBUG "Segment table for CPU %d at 0x%lx virtual, 0x%lx absolute\n", cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
 258         }
 259 }
 260
 261 /*
 262  * Build an entry for the base kernel segment and put it into
 263  * the segment table or SLB.  All other segment table or SLB
 264  * entries are faulted in.
 265  */
 266 void stab_initialize(unsigned long stab)
 267 {
 268         unsigned long vsid = get_kernel_vsid(KERNELBASE);
 269
 270         if (cpu_has_feature(CPU_FTR_SLB)) {
 271                 slb_initialize();
 272         } else {
 273                 asm volatile("isync; slbia; isync":::"memory");
 274                 make_ste(stab, GET_ESID(KERNELBASE), vsid);
 275
 276                 /* Order update */
 277                 asm volatile("sync":::"memory");
 278         }
 279 }