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