arch/powerpc/mm/init_32.c

   1 /*
   2  *  PowerPC version
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   6  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   7  *    Copyright (C) 1996 Paul Mackerras
   8  *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
   9  *
  10  *  Derived from "arch/i386/mm/init.c"
  11  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  12  *
  13  *  This program is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU General Public License
  15  *  as published by the Free Software Foundation; either version
  16  *  2 of the License, or (at your option) any later version.
  17  *
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/sched.h>
  22 #include <linux/kernel.h>
  23 #include <linux/errno.h>
  24 #include <linux/string.h>
  25 #include <linux/types.h>
  26 #include <linux/mm.h>
  27 #include <linux/stddef.h>
  28 #include <linux/init.h>
  29 #include <linux/highmem.h>
  30 #include <linux/initrd.h>
  31 #include <linux/pagemap.h>
  32 #include <linux/memblock.h>
  33 #include <linux/gfp.h>
  34 #include <linux/slab.h>
  35 #include <linux/hugetlb.h>
  36
  37 #include <asm/pgalloc.h>
  38 #include <asm/prom.h>
  39 #include <asm/io.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/mmu.h>
  42 #include <asm/smp.h>
  43 #include <asm/machdep.h>
  44 #include <asm/btext.h>
  45 #include <asm/tlb.h>
  46 #include <asm/sections.h>
  47 #include <asm/hugetlb.h>
  48
  49 #include "mmu_decl.h"
  50
  51 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  52 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
  53 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
  54 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
  55 #endif
  56 #endif
  57 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  58
  59 phys_addr_t total_memory;
  60 phys_addr_t total_lowmem;
  61
  62 phys_addr_t memstart_addr = (phys_addr_t)~0ull;
  63 EXPORT_SYMBOL(memstart_addr);
  64 phys_addr_t kernstart_addr;
  65 EXPORT_SYMBOL(kernstart_addr);
  66
  67 #ifdef CONFIG_RELOCATABLE
  68 /* Used in __va()/__pa() */
  69 long long virt_phys_offset;
  70 EXPORT_SYMBOL(virt_phys_offset);
  71 #endif
  72
  73 phys_addr_t lowmem_end_addr;
  74
  75 int boot_mapsize;
  76 #ifdef CONFIG_PPC_PMAC
  77 unsigned long agp_special_page;
  78 EXPORT_SYMBOL(agp_special_page);
  79 #endif
  80
  81 void MMU_init(void);
  82
  83 /*
  84  * this tells the system to map all of ram with the segregs
  85  * (i.e. page tables) instead of the bats.
  86  * -- Cort
  87  */
  88 int __map_without_bats;
  89 int __map_without_ltlbs;
  90
  91 /*
  92  * This tells the system to allow ioremapping memory marked as reserved.
  93  */
  94 int __allow_ioremap_reserved;
  95
  96 /* max amount of low RAM to map in */
  97 unsigned long __max_low_memory = MAX_LOW_MEM;
  98
  99 /*
 100  * Check for command-line options that affect what MMU_init will do.
 101  */
 102 void __init MMU_setup(void)
 103 {
 104         /* Check for nobats option (used in mapin_ram). */
 105         if (strstr(boot_command_line, "nobats")) {
 106                 __map_without_bats = 1;
 107         }
 108
 109         if (strstr(boot_command_line, "noltlbs")) {
 110                 __map_without_ltlbs = 1;
 111         }
 112         if (debug_pagealloc_enabled()) {
 113                 __map_without_bats = 1;
 114                 __map_without_ltlbs = 1;
 115         }
 116 #ifdef CONFIG_STRICT_KERNEL_RWX
 117         if (rodata_enabled) {
 118                 __map_without_bats = 1;
 119                 __map_without_ltlbs = 1;
 120         }
 121 #endif
 122 }
 123
 124 /*
 125  * MMU_init sets up the basic memory mappings for the kernel,
 126  * including both RAM and possibly some I/O regions,
 127  * and sets up the page tables and the MMU hardware ready to go.
 128  */
 129 void __init MMU_init(void)
 130 {
 131         if (ppc_md.progress)
 132                 ppc_md.progress("MMU:enter", 0x111);
 133
 134         /* parse args from command line */
 135         MMU_setup();
 136
 137         /*
 138          * Reserve gigantic pages for hugetlb.  This MUST occur before
 139          * lowmem_end_addr is initialized below.
 140          */
 141         if (memblock.memory.cnt > 1) {
 142 #ifndef CONFIG_WII
 143                 memblock_enforce_memory_limit(memblock.memory.regions[0].size);
 144                 pr_warn("Only using first contiguous memory region\n");
 145 #else
 146                 wii_memory_fixups();
 147 #endif
 148         }
 149
 150         total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
 151         lowmem_end_addr = memstart_addr + total_lowmem;
 152
 153 #ifdef CONFIG_FSL_BOOKE
 154         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 155          * entries, so we need to adjust lowmem to match the amount we can map
 156          * in the fixed entries */
 157         adjust_total_lowmem();
 158 #endif /* CONFIG_FSL_BOOKE */
 159
 160         if (total_lowmem > __max_low_memory) {
 161                 total_lowmem = __max_low_memory;
 162                 lowmem_end_addr = memstart_addr + total_lowmem;
 163 #ifndef CONFIG_HIGHMEM
 164                 total_memory = total_lowmem;
 165                 memblock_enforce_memory_limit(total_lowmem);
 166 #endif /* CONFIG_HIGHMEM */
 167         }
 168
 169         /* Initialize the MMU hardware */
 170         if (ppc_md.progress)
 171                 ppc_md.progress("MMU:hw init", 0x300);
 172         MMU_init_hw();
 173
 174         /* Map in all of RAM starting at KERNELBASE */
 175         if (ppc_md.progress)
 176                 ppc_md.progress("MMU:mapin", 0x301);
 177         mapin_ram();
 178
 179         /* Initialize early top-down ioremap allocator */
 180         ioremap_bot = IOREMAP_TOP;
 181
 182         if (ppc_md.progress)
 183                 ppc_md.progress("MMU:exit", 0x211);
 184
 185         /* From now on, btext is no longer BAT mapped if it was at all */
 186 #ifdef CONFIG_BOOTX_TEXT
 187         btext_unmap();
 188 #endif
 189
 190         /* Shortly after that, the entire linear mapping will be available */
 191         memblock_set_current_limit(lowmem_end_addr);
 192 }