root/arch/powerpc/mm/init_32.c

DEFINITIONS

1. MMU_setup
2. MMU_init

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  PowerPC version
   4  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   5  *
   6  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   7  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   8  *    Copyright (C) 1996 Paul Mackerras
   9  *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
  10  *
  11  *  Derived from "arch/i386/mm/init.c"
  12  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  13  */
  14 
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/errno.h>
  19 #include <linux/string.h>
  20 #include <linux/types.h>
  21 #include <linux/mm.h>
  22 #include <linux/stddef.h>
  23 #include <linux/init.h>
  24 #include <linux/highmem.h>
  25 #include <linux/initrd.h>
  26 #include <linux/pagemap.h>
  27 #include <linux/memblock.h>
  28 #include <linux/gfp.h>
  29 #include <linux/slab.h>
  30 #include <linux/hugetlb.h>
  31 
  32 #include <asm/pgalloc.h>
  33 #include <asm/prom.h>
  34 #include <asm/io.h>
  35 #include <asm/pgtable.h>
  36 #include <asm/mmu.h>
  37 #include <asm/smp.h>
  38 #include <asm/machdep.h>
  39 #include <asm/btext.h>
  40 #include <asm/tlb.h>
  41 #include <asm/sections.h>
  42 #include <asm/hugetlb.h>
  43 #include <asm/kup.h>
  44 #include <asm/kasan.h>
  45 
  46 #include <mm/mmu_decl.h>
  47 
  48 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  49 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
  50 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
  51 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
  52 #endif
  53 #endif
  54 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  55 
  56 phys_addr_t total_memory;
  57 phys_addr_t total_lowmem;
  58 
  59 phys_addr_t memstart_addr = (phys_addr_t)~0ull;
  60 EXPORT_SYMBOL(memstart_addr);
  61 phys_addr_t kernstart_addr;
  62 EXPORT_SYMBOL(kernstart_addr);
  63 
  64 #ifdef CONFIG_RELOCATABLE
  65 /* Used in __va()/__pa() */
  66 long long virt_phys_offset;
  67 EXPORT_SYMBOL(virt_phys_offset);
  68 #endif
  69 
  70 phys_addr_t lowmem_end_addr;
  71 
  72 int boot_mapsize;
  73 #ifdef CONFIG_PPC_PMAC
  74 unsigned long agp_special_page;
  75 EXPORT_SYMBOL(agp_special_page);
  76 #endif
  77 
  78 void MMU_init(void);
  79 
  80 /*
  81  * this tells the system to map all of ram with the segregs
  82  * (i.e. page tables) instead of the bats.
  83  * -- Cort
  84  */
  85 int __map_without_bats;
  86 int __map_without_ltlbs;
  87 
  88 /* max amount of low RAM to map in */
  89 unsigned long __max_low_memory = MAX_LOW_MEM;
  90 
  91 /*
  92  * Check for command-line options that affect what MMU_init will do.
  93  */
  94 static void __init MMU_setup(void)
  95 {
  96         /* Check for nobats option (used in mapin_ram). */
  97         if (strstr(boot_command_line, "nobats")) {
  98                 __map_without_bats = 1;
  99         }
 100 
 101         if (strstr(boot_command_line, "noltlbs")) {
 102                 __map_without_ltlbs = 1;
 103         }
 104         if (debug_pagealloc_enabled()) {
 105                 __map_without_bats = 1;
 106                 __map_without_ltlbs = 1;
 107         }
 108         if (strict_kernel_rwx_enabled() && !IS_ENABLED(CONFIG_PPC_8xx))
 109                 __map_without_ltlbs = 1;
 110 }
 111 
 112 /*
 113  * MMU_init sets up the basic memory mappings for the kernel,
 114  * including both RAM and possibly some I/O regions,
 115  * and sets up the page tables and the MMU hardware ready to go.
 116  */
 117 void __init MMU_init(void)
 118 {
 119         if (ppc_md.progress)
 120                 ppc_md.progress("MMU:enter", 0x111);
 121 
 122         /* parse args from command line */
 123         MMU_setup();
 124 
 125         /*
 126          * Reserve gigantic pages for hugetlb.  This MUST occur before
 127          * lowmem_end_addr is initialized below.
 128          */
 129         if (memblock.memory.cnt > 1) {
 130 #ifndef CONFIG_WII
 131                 memblock_enforce_memory_limit(memblock.memory.regions[0].size);
 132                 pr_warn("Only using first contiguous memory region\n");
 133 #else
 134                 wii_memory_fixups();
 135 #endif
 136         }
 137 
 138         total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
 139         lowmem_end_addr = memstart_addr + total_lowmem;
 140 
 141 #ifdef CONFIG_FSL_BOOKE
 142         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 143          * entries, so we need to adjust lowmem to match the amount we can map
 144          * in the fixed entries */
 145         adjust_total_lowmem();
 146 #endif /* CONFIG_FSL_BOOKE */
 147 
 148         if (total_lowmem > __max_low_memory) {
 149                 total_lowmem = __max_low_memory;
 150                 lowmem_end_addr = memstart_addr + total_lowmem;
 151 #ifndef CONFIG_HIGHMEM
 152                 total_memory = total_lowmem;
 153                 memblock_enforce_memory_limit(total_lowmem);
 154 #endif /* CONFIG_HIGHMEM */
 155         }
 156 
 157         /* Initialize the MMU hardware */
 158         if (ppc_md.progress)
 159                 ppc_md.progress("MMU:hw init", 0x300);
 160         MMU_init_hw();
 161 
 162         /* Map in all of RAM starting at KERNELBASE */
 163         if (ppc_md.progress)
 164                 ppc_md.progress("MMU:mapin", 0x301);
 165         mapin_ram();
 166 
 167         /* Initialize early top-down ioremap allocator */
 168         ioremap_bot = IOREMAP_TOP;
 169 
 170         if (ppc_md.progress)
 171                 ppc_md.progress("MMU:exit", 0x211);
 172 
 173         /* From now on, btext is no longer BAT mapped if it was at all */
 174 #ifdef CONFIG_BOOTX_TEXT
 175         btext_unmap();
 176 #endif
 177 
 178         kasan_mmu_init();
 179 
 180         setup_kup();
 181 
 182         /* Shortly after that, the entire linear mapping will be available */
 183         memblock_set_current_limit(lowmem_end_addr);
 184 }