arch/powerpc/mm/init_32.c

   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/prom.h>
  33 #include <asm/io.h>
  34 #include <asm/mmu.h>
  35 #include <asm/smp.h>
  36 #include <asm/machdep.h>
  37 #include <asm/btext.h>
  38 #include <asm/tlb.h>
  39 #include <asm/sections.h>
  40 #include <asm/hugetlb.h>
  41 #include <asm/kup.h>
  42 #include <asm/kasan.h>
  43
  44 #include <mm/mmu_decl.h>
  45
  46 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  47 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
  48 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
  49 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
  50 #endif
  51 #endif
  52 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  53
  54 phys_addr_t total_memory;
  55 phys_addr_t total_lowmem;
  56
  57 #ifdef CONFIG_RELOCATABLE
  58 /* Used in __va()/__pa() */
  59 long long virt_phys_offset;
  60 EXPORT_SYMBOL(virt_phys_offset);
  61 #endif
  62
  63 phys_addr_t lowmem_end_addr;
  64
  65 int boot_mapsize;
  66 #ifdef CONFIG_PPC_PMAC
  67 unsigned long agp_special_page;
  68 EXPORT_SYMBOL(agp_special_page);
  69 #endif
  70
  71 void MMU_init(void);
  72
  73 /*
  74  * this tells the system to map all of ram with the segregs
  75  * (i.e. page tables) instead of the bats.
  76  * -- Cort
  77  */
  78 int __map_without_bats;
  79 int __map_without_ltlbs;
  80
  81 /* max amount of low RAM to map in */
  82 unsigned long __max_low_memory = MAX_LOW_MEM;
  83
  84 /*
  85  * Check for command-line options that affect what MMU_init will do.
  86  */
  87 static void __init MMU_setup(void)
  88 {
  89         /* Check for nobats option (used in mapin_ram). */
  90         if (strstr(boot_command_line, "nobats")) {
  91                 __map_without_bats = 1;
  92         }
  93
  94         if (strstr(boot_command_line, "noltlbs")) {
  95                 __map_without_ltlbs = 1;
  96         }
  97         if (IS_ENABLED(CONFIG_PPC_8xx))
  98                 return;
  99
 100         if (debug_pagealloc_enabled())
 101                 __map_without_ltlbs = 1;
 102
 103         if (strict_kernel_rwx_enabled())
 104                 __map_without_ltlbs = 1;
 105 }
 106
 107 /*
 108  * MMU_init sets up the basic memory mappings for the kernel,
 109  * including both RAM and possibly some I/O regions,
 110  * and sets up the page tables and the MMU hardware ready to go.
 111  */
 112 void __init MMU_init(void)
 113 {
 114         if (ppc_md.progress)
 115                 ppc_md.progress("MMU:enter", 0x111);
 116
 117         /* parse args from command line */
 118         MMU_setup();
 119
 120         /*
 121          * Reserve gigantic pages for hugetlb.  This MUST occur before
 122          * lowmem_end_addr is initialized below.
 123          */
 124         if (memblock.memory.cnt > 1) {
 125 #ifndef CONFIG_WII
 126                 memblock_enforce_memory_limit(memblock.memory.regions[0].size);
 127                 pr_warn("Only using first contiguous memory region\n");
 128 #else
 129                 wii_memory_fixups();
 130 #endif
 131         }
 132
 133         total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
 134         lowmem_end_addr = memstart_addr + total_lowmem;
 135
 136 #ifdef CONFIG_FSL_BOOKE
 137         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 138          * entries, so we need to adjust lowmem to match the amount we can map
 139          * in the fixed entries */
 140         adjust_total_lowmem();
 141 #endif /* CONFIG_FSL_BOOKE */
 142
 143         if (total_lowmem > __max_low_memory) {
 144                 total_lowmem = __max_low_memory;
 145                 lowmem_end_addr = memstart_addr + total_lowmem;
 146 #ifndef CONFIG_HIGHMEM
 147                 total_memory = total_lowmem;
 148                 memblock_enforce_memory_limit(total_lowmem);
 149 #endif /* CONFIG_HIGHMEM */
 150         }
 151
 152         /* Initialize the MMU hardware */
 153         if (ppc_md.progress)
 154                 ppc_md.progress("MMU:hw init", 0x300);
 155         MMU_init_hw();
 156
 157         /* Map in all of RAM starting at KERNELBASE */
 158         if (ppc_md.progress)
 159                 ppc_md.progress("MMU:mapin", 0x301);
 160         mapin_ram();
 161
 162         /* Initialize early top-down ioremap allocator */
 163         ioremap_bot = IOREMAP_TOP;
 164
 165         if (ppc_md.progress)
 166                 ppc_md.progress("MMU:exit", 0x211);
 167
 168         /* From now on, btext is no longer BAT mapped if it was at all */
 169 #ifdef CONFIG_BOOTX_TEXT
 170         btext_unmap();
 171 #endif
 172
 173         kasan_mmu_init();
 174
 175         setup_kup();
 176
 177         /* Shortly after that, the entire linear mapping will be available */
 178         memblock_set_current_limit(lowmem_end_addr);
 179 }