arch/powerpc/mm/ppc_mmu_32.c

   1 /*
   2  * This file contains the routines for handling the MMU on those
   3  * PowerPC implementations where the MMU substantially follows the
   4  * architecture specification.  This includes the 6xx, 7xx, 7xxx,
   5  * 8260, and POWER3 implementations but excludes the 8xx and 4xx.
   6  *  -- paulus
   7  *
   8  *  Derived from arch/ppc/mm/init.c:
   9  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  10  *
  11  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  12  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  13  *    Copyright (C) 1996 Paul Mackerras
  14  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
  15  *
  16  *  Derived from "arch/i386/mm/init.c"
  17  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  18  *
  19  *  This program is free software; you can redistribute it and/or
  20  *  modify it under the terms of the GNU General Public License
  21  *  as published by the Free Software Foundation; either version
  22  *  2 of the License, or (at your option) any later version.
  23  *
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/mm.h>
  28 #include <linux/init.h>
  29 #include <linux/highmem.h>
  30
  31 #include <asm/prom.h>
  32 #include <asm/mmu.h>
  33 #include <asm/machdep.h>
  34 #include <asm/lmb.h>
  35
  36 #include "mmu_decl.h"
  37
  38 PTE *Hash, *Hash_end;
  39 unsigned long Hash_size, Hash_mask;
  40 unsigned long _SDR1;
  41
  42 union ubat {                    /* BAT register values to be loaded */
  43         BAT     bat;
  44         u32     word[2];
  45 } BATS[8][2];                   /* 8 pairs of IBAT, DBAT */
  46
  47 struct batrange {               /* stores address ranges mapped by BATs */
  48         unsigned long start;
  49         unsigned long limit;
  50         unsigned long phys;
  51 } bat_addrs[8];
  52
  53 /*
  54  * Return PA for this VA if it is mapped by a BAT, or 0
  55  */
  56 unsigned long v_mapped_by_bats(unsigned long va)
  57 {
  58         int b;
  59         for (b = 0; b < 4; ++b)
  60                 if (va >= bat_addrs[b].start && va < bat_addrs[b].limit)
  61                         return bat_addrs[b].phys + (va - bat_addrs[b].start);
  62         return 0;
  63 }
  64
  65 /*
  66  * Return VA for a given PA or 0 if not mapped
  67  */
  68 unsigned long p_mapped_by_bats(unsigned long pa)
  69 {
  70         int b;
  71         for (b = 0; b < 4; ++b)
  72                 if (pa >= bat_addrs[b].phys
  73                     && pa < (bat_addrs[b].limit-bat_addrs[b].start)
  74                               +bat_addrs[b].phys)
  75                         return bat_addrs[b].start+(pa-bat_addrs[b].phys);
  76         return 0;
  77 }
  78
  79 unsigned long __init mmu_mapin_ram(void)
  80 {
  81 #ifdef CONFIG_POWER4
  82         return 0;
  83 #else
  84         unsigned long tot, bl, done;
  85         unsigned long max_size = (256<<20);
  86         unsigned long align;
  87
  88         if (__map_without_bats)
  89                 return 0;
  90
  91         /* Set up BAT2 and if necessary BAT3 to cover RAM. */
  92
  93         /* Make sure we don't map a block larger than the
  94            smallest alignment of the physical address. */
  95         /* alignment of PPC_MEMSTART */
  96         align = ~(PPC_MEMSTART-1) & PPC_MEMSTART;
  97         /* set BAT block size to MIN(max_size, align) */
  98         if (align && align < max_size)
  99                 max_size = align;
 100
 101         tot = total_lowmem;
 102         for (bl = 128<<10; bl < max_size; bl <<= 1) {
 103                 if (bl * 2 > tot)
 104                         break;
 105         }
 106
 107         setbat(2, KERNELBASE, PPC_MEMSTART, bl, _PAGE_RAM);
 108         done = (unsigned long)bat_addrs[2].limit - KERNELBASE + 1;
 109         if ((done < tot) && !bat_addrs[3].limit) {
 110                 /* use BAT3 to cover a bit more */
 111                 tot -= done;
 112                 for (bl = 128<<10; bl < max_size; bl <<= 1)
 113                         if (bl * 2 > tot)
 114                                 break;
 115                 setbat(3, KERNELBASE+done, PPC_MEMSTART+done, bl, _PAGE_RAM);
 116                 done = (unsigned long)bat_addrs[3].limit - KERNELBASE + 1;
 117         }
 118
 119         return done;
 120 #endif
 121 }
 122
 123 /*
 124  * Set up one of the I/D BAT (block address translation) register pairs.
 125  * The parameters are not checked; in particular size must be a power
 126  * of 2 between 128k and 256M.
 127  */
 128 void __init setbat(int index, unsigned long virt, unsigned long phys,
 129                    unsigned int size, int flags)
 130 {
 131         unsigned int bl;
 132         int wimgxpp;
 133         union ubat *bat = BATS[index];
 134
 135         if (((flags & _PAGE_NO_CACHE) == 0) &&
 136             cpu_has_feature(CPU_FTR_NEED_COHERENT))
 137                 flags |= _PAGE_COHERENT;
 138
 139         bl = (size >> 17) - 1;
 140         if (PVR_VER(mfspr(SPRN_PVR)) != 1) {
 141                 /* 603, 604, etc. */
 142                 /* Do DBAT first */
 143                 wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
 144                                    | _PAGE_COHERENT | _PAGE_GUARDED);
 145                 wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX;
 146                 bat[1].word[0] = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
 147                 bat[1].word[1] = phys | wimgxpp;
 148 #ifndef CONFIG_KGDB /* want user access for breakpoints */
 149                 if (flags & _PAGE_USER)
 150 #endif
 151                         bat[1].bat.batu.vp = 1;
 152                 if (flags & _PAGE_GUARDED) {
 153                         /* G bit must be zero in IBATs */
 154                         bat[0].word[0] = bat[0].word[1] = 0;
 155                 } else {
 156                         /* make IBAT same as DBAT */
 157                         bat[0] = bat[1];
 158                 }
 159         } else {
 160                 /* 601 cpu */
 161                 if (bl > BL_8M)
 162                         bl = BL_8M;
 163                 wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
 164                                    | _PAGE_COHERENT);
 165                 wimgxpp |= (flags & _PAGE_RW)?
 166                         ((flags & _PAGE_USER)? PP_RWRW: PP_RWXX): PP_RXRX;
 167                 bat->word[0] = virt | wimgxpp | 4;      /* Ks=0, Ku=1 */
 168                 bat->word[1] = phys | bl | 0x40;        /* V=1 */
 169         }
 170
 171         bat_addrs[index].start = virt;
 172         bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
 173         bat_addrs[index].phys = phys;
 174 }
 175
 176 /*
 177  * Preload a translation in the hash table
 178  */
 179 void hash_preload(struct mm_struct *mm, unsigned long ea,
 180                   unsigned long access, unsigned long trap)
 181 {
 182         pmd_t *pmd;
 183
 184         if (Hash == 0)
 185                 return;
 186         pmd = pmd_offset(pgd_offset(mm, ea), ea);
 187         if (!pmd_none(*pmd))
 188                 add_hash_page(mm->context.id, ea, pmd_val(*pmd));
 189 }
 190
 191 /*
 192  * Initialize the hash table and patch the instructions in hashtable.S.
 193  */
 194 void __init MMU_init_hw(void)
 195 {
 196         unsigned int hmask, mb, mb2;
 197         unsigned int n_hpteg, lg_n_hpteg;
 198
 199         extern unsigned int hash_page_patch_A[];
 200         extern unsigned int hash_page_patch_B[], hash_page_patch_C[];
 201         extern unsigned int hash_page[];
 202         extern unsigned int flush_hash_patch_A[], flush_hash_patch_B[];
 203
 204         if (!cpu_has_feature(CPU_FTR_HPTE_TABLE)) {
 205                 /*
 206                  * Put a blr (procedure return) instruction at the
 207                  * start of hash_page, since we can still get DSI
 208                  * exceptions on a 603.
 209                  */
 210                 hash_page[0] = 0x4e800020;
 211                 flush_icache_range((unsigned long) &hash_page[0],
 212                                    (unsigned long) &hash_page[1]);
 213                 return;
 214         }
 215
 216         if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);
 217
 218 #define LG_HPTEG_SIZE   6               /* 64 bytes per HPTEG */
 219 #define SDR1_LOW_BITS   ((n_hpteg - 1) >> 10)
 220 #define MIN_N_HPTEG     1024            /* min 64kB hash table */
 221
 222         /*
 223          * Allow 1 HPTE (1/8 HPTEG) for each page of memory.
 224          * This is less than the recommended amount, but then
 225          * Linux ain't AIX.
 226          */
 227         n_hpteg = total_memory / (PAGE_SIZE * 8);
 228         if (n_hpteg < MIN_N_HPTEG)
 229                 n_hpteg = MIN_N_HPTEG;
 230         lg_n_hpteg = __ilog2(n_hpteg);
 231         if (n_hpteg & (n_hpteg - 1)) {
 232                 ++lg_n_hpteg;           /* round up if not power of 2 */
 233                 n_hpteg = 1 << lg_n_hpteg;
 234         }
 235         Hash_size = n_hpteg << LG_HPTEG_SIZE;
 236
 237         /*
 238          * Find some memory for the hash table.
 239          */
 240         if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
 241         Hash = __va(lmb_alloc_base(Hash_size, Hash_size,
 242                                    __initial_memory_limit));
 243         cacheable_memzero(Hash, Hash_size);
 244         _SDR1 = __pa(Hash) | SDR1_LOW_BITS;
 245
 246         Hash_end = (PTE *) ((unsigned long)Hash + Hash_size);
 247
 248         printk("Total memory = %ldMB; using %ldkB for hash table (at %p)\n",
 249                total_memory >> 20, Hash_size >> 10, Hash);
 250
 251
 252         /*
 253          * Patch up the instructions in hashtable.S:create_hpte
 254          */
 255         if ( ppc_md.progress ) ppc_md.progress("hash:patch", 0x345);
 256         Hash_mask = n_hpteg - 1;
 257         hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
 258         mb2 = mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
 259         if (lg_n_hpteg > 16)
 260                 mb2 = 16 - LG_HPTEG_SIZE;
 261
 262         hash_page_patch_A[0] = (hash_page_patch_A[0] & ~0xffff)
 263                 | ((unsigned int)(Hash) >> 16);
 264         hash_page_patch_A[1] = (hash_page_patch_A[1] & ~0x7c0) | (mb << 6);
 265         hash_page_patch_A[2] = (hash_page_patch_A[2] & ~0x7c0) | (mb2 << 6);
 266         hash_page_patch_B[0] = (hash_page_patch_B[0] & ~0xffff) | hmask;
 267         hash_page_patch_C[0] = (hash_page_patch_C[0] & ~0xffff) | hmask;
 268
 269         /*
 270          * Ensure that the locations we've patched have been written
 271          * out from the data cache and invalidated in the instruction
 272          * cache, on those machines with split caches.
 273          */
 274         flush_icache_range((unsigned long) &hash_page_patch_A[0],
 275                            (unsigned long) &hash_page_patch_C[1]);
 276
 277         /*
 278          * Patch up the instructions in hashtable.S:flush_hash_page
 279          */
 280         flush_hash_patch_A[0] = (flush_hash_patch_A[0] & ~0xffff)
 281                 | ((unsigned int)(Hash) >> 16);
 282         flush_hash_patch_A[1] = (flush_hash_patch_A[1] & ~0x7c0) | (mb << 6);
 283         flush_hash_patch_A[2] = (flush_hash_patch_A[2] & ~0x7c0) | (mb2 << 6);
 284         flush_hash_patch_B[0] = (flush_hash_patch_B[0] & ~0xffff) | hmask;
 285         flush_icache_range((unsigned long) &flush_hash_patch_A[0],
 286                            (unsigned long) &flush_hash_patch_B[1]);
 287
 288         if ( ppc_md.progress ) ppc_md.progress("hash:done", 0x205);
 289 }