arch/x86/kernel/head32.c

   1 /*
   2  *  linux/arch/i386/kernel/head32.c -- prepare to run common code
   3  *
   4  *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
   5  *  Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/start_kernel.h>
  10 #include <linux/mm.h>
  11 #include <linux/memblock.h>
  12
  13 #include <asm/desc.h>
  14 #include <asm/setup.h>
  15 #include <asm/sections.h>
  16 #include <asm/e820/api.h>
  17 #include <asm/page.h>
  18 #include <asm/apic.h>
  19 #include <asm/io_apic.h>
  20 #include <asm/bios_ebda.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/bootparam_utils.h>
  23
  24 static void __init i386_default_early_setup(void)
  25 {
  26         /* Initialize 32bit specific setup functions */
  27         x86_init.resources.reserve_resources = i386_reserve_resources;
  28         x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
  29 }
  30
  31 asmlinkage __visible void __init i386_start_kernel(void)
  32 {
  33         /* Make sure IDT is set up before any exception happens */
  34         idt_setup_early_handler();
  35
  36         cr4_init_shadow();
  37
  38         sanitize_boot_params(&boot_params);
  39
  40         x86_early_init_platform_quirks();
  41
  42         /* Call the subarch specific early setup function */
  43         switch (boot_params.hdr.hardware_subarch) {
  44         case X86_SUBARCH_INTEL_MID:
  45                 x86_intel_mid_early_setup();
  46                 break;
  47         case X86_SUBARCH_CE4100:
  48                 x86_ce4100_early_setup();
  49                 break;
  50         default:
  51                 i386_default_early_setup();
  52                 break;
  53         }
  54
  55         start_kernel();
  56 }
  57
  58 /*
  59  * Initialize page tables.  This creates a PDE and a set of page
  60  * tables, which are located immediately beyond __brk_base.  The variable
  61  * _brk_end is set up to point to the first "safe" location.
  62  * Mappings are created both at virtual address 0 (identity mapping)
  63  * and PAGE_OFFSET for up to _end.
  64  *
  65  * In PAE mode initial_page_table is statically defined to contain
  66  * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
  67  * entries). The identity mapping is handled by pointing two PGD entries
  68  * to the first kernel PMD. Note the upper half of each PMD or PTE are
  69  * always zero at this stage.
  70  */
  71 void __init mk_early_pgtbl_32(void)
  72 {
  73 #ifdef __pa
  74 #undef __pa
  75 #endif
  76 #define __pa(x)  ((unsigned long)(x) - PAGE_OFFSET)
  77         pte_t pte, *ptep;
  78         int i;
  79         unsigned long *ptr;
  80         /* Enough space to fit pagetables for the low memory linear map */
  81         const unsigned long limit = __pa(_end) +
  82                 (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
  83 #ifdef CONFIG_X86_PAE
  84         pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);
  85 #define SET_PL2(pl2, val)    { (pl2).pmd = (val); }
  86 #else
  87         pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);
  88 #define SET_PL2(pl2, val)   { (pl2).pgd = (val); }
  89 #endif
  90
  91         ptep = (pte_t *)__pa(__brk_base);
  92         pte.pte = PTE_IDENT_ATTR;
  93
  94         while ((pte.pte & PTE_PFN_MASK) < limit) {
  95
  96                 SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
  97                 *pl2p = pl2;
  98 #ifndef CONFIG_X86_PAE
  99                 /* Kernel PDE entry */
 100                 *(pl2p +  ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
 101 #endif
 102                 for (i = 0; i < PTRS_PER_PTE; i++) {
 103                         *ptep = pte;
 104                         pte.pte += PAGE_SIZE;
 105                         ptep++;
 106                 }
 107
 108                 pl2p++;
 109         }
 110
 111         ptr = (unsigned long *)__pa(&max_pfn_mapped);
 112         /* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */
 113         *ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
 114
 115         ptr = (unsigned long *)__pa(&_brk_end);
 116         *ptr = (unsigned long)ptep + PAGE_OFFSET;
 117 }
 118