arch/powerpc/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/memblock.h>
  16
  17 #include <asm/pgtable.h>
  18 #include <asm/mmu.h>
  19 #include <asm/mmu_context.h>
  20 #include <asm/paca.h>
  21 #include <asm/cputable.h>
  22 #include <asm/prom.h>
  23 #include <asm/abs_addr.h>
  24 #include <asm/firmware.h>
  25 #include <asm/iseries/hv_call.h>
  26
  27 struct stab_entry {
  28         unsigned long esid_data;
  29         unsigned long vsid_data;
  30 };
  31
  32 #define NR_STAB_CACHE_ENTRIES 8
  33 static DEFINE_PER_CPU(long, stab_cache_ptr);
  34 static DEFINE_PER_CPU(long [NR_STAB_CACHE_ENTRIES], stab_cache);
  35
  36 /*
  37  * Create a segment table entry for the given esid/vsid pair.
  38  */
  39 static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
  40 {
  41         unsigned long esid_data, vsid_data;
  42         unsigned long entry, group, old_esid, castout_entry, i;
  43         unsigned int global_entry;
  44         struct stab_entry *ste, *castout_ste;
  45         unsigned long kernel_segment = (esid << SID_SHIFT) >= PAGE_OFFSET;
  46
  47         vsid_data = vsid << STE_VSID_SHIFT;
  48         esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
  49         if (! kernel_segment)
  50                 esid_data |= STE_ESID_KS;
  51
  52         /* Search the primary group first. */
  53         global_entry = (esid & 0x1f) << 3;
  54         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  55
  56         /* Find an empty entry, if one exists. */
  57         for (group = 0; group < 2; group++) {
  58                 for (entry = 0; entry < 8; entry++, ste++) {
  59                         if (!(ste->esid_data & STE_ESID_V)) {
  60                                 ste->vsid_data = vsid_data;
  61                                 eieio();
  62                                 ste->esid_data = esid_data;
  63                                 return (global_entry | entry);
  64                         }
  65                 }
  66                 /* Now search the secondary group. */
  67                 global_entry = ((~esid) & 0x1f) << 3;
  68                 ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  69         }
  70
  71         /*
  72          * Could not find empty entry, pick one with a round robin selection.
  73          * Search all entries in the two groups.
  74          */
  75         castout_entry = get_paca()->stab_rr;
  76         for (i = 0; i < 16; i++) {
  77                 if (castout_entry < 8) {
  78                         global_entry = (esid & 0x1f) << 3;
  79                         ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
  80                         castout_ste = ste + castout_entry;
  81                 } else {
  82                         global_entry = ((~esid) & 0x1f) << 3;
  83                         ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
  84                         castout_ste = ste + (castout_entry - 8);
  85                 }
  86
  87                 /* Dont cast out the first kernel segment */
  88                 if ((castout_ste->esid_data & ESID_MASK) != PAGE_OFFSET)
  89                         break;
  90
  91                 castout_entry = (castout_entry + 1) & 0xf;
  92         }
  93
  94         get_paca()->stab_rr = (castout_entry + 1) & 0xf;
  95
  96         /* Modify the old entry to the new value. */
  97
  98         /* Force previous translations to complete. DRENG */
  99         asm volatile("isync" : : : "memory");
 100
 101         old_esid = castout_ste->esid_data >> SID_SHIFT;
 102         castout_ste->esid_data = 0;             /* Invalidate old entry */
 103
 104         asm volatile("sync" : : : "memory");    /* Order update */
 105
 106         castout_ste->vsid_data = vsid_data;
 107         eieio();                                /* Order update */
 108         castout_ste->esid_data = esid_data;
 109
 110         asm volatile("slbie  %0" : : "r" (old_esid << SID_SHIFT));
 111         /* Ensure completion of slbie */
 112         asm volatile("sync" : : : "memory");
 113
 114         return (global_entry | (castout_entry & 0x7));
 115 }
 116
 117 /*
 118  * Allocate a segment table entry for the given ea and mm
 119  */
 120 static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
 121 {
 122         unsigned long vsid;
 123         unsigned char stab_entry;
 124         unsigned long offset;
 125
 126         /* Kernel or user address? */
 127         if (is_kernel_addr(ea)) {
 128                 vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M);
 129         } else {
 130                 if ((ea >= TASK_SIZE_USER64) || (! mm))
 131                         return 1;
 132
 133                 vsid = get_vsid(mm->context.id, ea, MMU_SEGSIZE_256M);
 134         }
 135
 136         stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
 137
 138         if (!is_kernel_addr(ea)) {
 139                 offset = __get_cpu_var(stab_cache_ptr);
 140                 if (offset < NR_STAB_CACHE_ENTRIES)
 141                         __get_cpu_var(stab_cache[offset++]) = stab_entry;
 142                 else
 143                         offset = NR_STAB_CACHE_ENTRIES+1;
 144                 __get_cpu_var(stab_cache_ptr) = offset;
 145
 146                 /* Order update */
 147                 asm volatile("sync":::"memory");
 148         }
 149
 150         return 0;
 151 }
 152
 153 int ste_allocate(unsigned long ea)
 154 {
 155         return __ste_allocate(ea, current->mm);
 156 }
 157
 158 /*
 159  * Do the segment table work for a context switch: flush all user
 160  * entries from the table, then preload some probably useful entries
 161  * for the new task
 162  */
 163 void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
 164 {
 165         struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
 166         struct stab_entry *ste;
 167         unsigned long offset;
 168         unsigned long pc = KSTK_EIP(tsk);
 169         unsigned long stack = KSTK_ESP(tsk);
 170         unsigned long unmapped_base;
 171
 172         /* Force previous translations to complete. DRENG */
 173         asm volatile("isync" : : : "memory");
 174
 175         /*
 176          * We need interrupts hard-disabled here, not just soft-disabled,
 177          * so that a PMU interrupt can't occur, which might try to access
 178          * user memory (to get a stack trace) and possible cause an STAB miss
 179          * which would update the stab_cache/stab_cache_ptr per-cpu variables.
 180          */
 181         hard_irq_disable();
 182
 183         offset = __get_cpu_var(stab_cache_ptr);
 184         if (offset <= NR_STAB_CACHE_ENTRIES) {
 185                 int i;
 186
 187                 for (i = 0; i < offset; i++) {
 188                         ste = stab + __get_cpu_var(stab_cache[i]);
 189                         ste->esid_data = 0; /* invalidate entry */
 190                 }
 191         } else {
 192                 unsigned long entry;
 193
 194                 /* Invalidate all entries. */
 195                 ste = stab;
 196
 197                 /* Never flush the first entry. */
 198                 ste += 1;
 199                 for (entry = 1;
 200                      entry < (HW_PAGE_SIZE / sizeof(struct stab_entry));
 201                      entry++, ste++) {
 202                         unsigned long ea;
 203                         ea = ste->esid_data & ESID_MASK;
 204                         if (!is_kernel_addr(ea)) {
 205                                 ste->esid_data = 0;
 206                         }
 207                 }
 208         }
 209
 210         asm volatile("sync; slbia; sync":::"memory");
 211
 212         __get_cpu_var(stab_cache_ptr) = 0;
 213
 214         /* Now preload some entries for the new task */
 215         if (test_tsk_thread_flag(tsk, TIF_32BIT))
 216                 unmapped_base = TASK_UNMAPPED_BASE_USER32;
 217         else
 218                 unmapped_base = TASK_UNMAPPED_BASE_USER64;
 219
 220         __ste_allocate(pc, mm);
 221
 222         if (GET_ESID(pc) == GET_ESID(stack))
 223                 return;
 224
 225         __ste_allocate(stack, mm);
 226
 227         if ((GET_ESID(pc) == GET_ESID(unmapped_base))
 228             || (GET_ESID(stack) == GET_ESID(unmapped_base)))
 229                 return;
 230
 231         __ste_allocate(unmapped_base, mm);
 232
 233         /* Order update */
 234         asm volatile("sync" : : : "memory");
 235 }
 236
 237 /*
 238  * Allocate segment tables for secondary CPUs.  These must all go in
 239  * the first (bolted) segment, so that do_stab_bolted won't get a
 240  * recursive segment miss on the segment table itself.
 241  */
 242 void __init stabs_alloc(void)
 243 {
 244         int cpu;
 245
 246         if (mmu_has_feature(MMU_FTR_SLB))
 247                 return;
 248
 249         for_each_possible_cpu(cpu) {
 250                 unsigned long newstab;
 251
 252                 if (cpu == 0)
 253                         continue; /* stab for CPU 0 is statically allocated */
 254
 255                 newstab = memblock_alloc_base(HW_PAGE_SIZE, HW_PAGE_SIZE,
 256                                          1<<SID_SHIFT);
 257                 newstab = (unsigned long)__va(newstab);
 258
 259                 memset((void *)newstab, 0, HW_PAGE_SIZE);
 260
 261                 paca[cpu].stab_addr = newstab;
 262                 paca[cpu].stab_real = virt_to_abs(newstab);
 263                 printk(KERN_INFO "Segment table for CPU %d at 0x%llx "
 264                        "virtual, 0x%llx absolute\n",
 265                        cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
 266         }
 267 }
 268
 269 /*
 270  * Build an entry for the base kernel segment and put it into
 271  * the segment table or SLB.  All other segment table or SLB
 272  * entries are faulted in.
 273  */
 274 void stab_initialize(unsigned long stab)
 275 {
 276         unsigned long vsid = get_kernel_vsid(PAGE_OFFSET, MMU_SEGSIZE_256M);
 277         unsigned long stabreal;
 278
 279         asm volatile("isync; slbia; isync":::"memory");
 280         make_ste(stab, GET_ESID(PAGE_OFFSET), vsid);
 281
 282         /* Order update */
 283         asm volatile("sync":::"memory");
 284
 285         /* Set ASR */
 286         stabreal = get_paca()->stab_real | 0x1ul;
 287
 288 #ifdef CONFIG_PPC_ISERIES
 289         if (firmware_has_feature(FW_FEATURE_ISERIES)) {
 290                 HvCall1(HvCallBaseSetASR, stabreal);
 291                 return;
 292         }
 293 #endif /* CONFIG_PPC_ISERIES */
 294
 295         mtspr(SPRN_ASR, stabreal);
 296 }