head32.c 3.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * linux/arch/i386/kernel/head32.c -- prepare to run common code
  4. *
  5. * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
  6. * Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
  7. */
  8. #include <linux/init.h>
  9. #include <linux/start_kernel.h>
  10. #include <linux/mm.h>
  11. #include <linux/memblock.h>
  12. #include <asm/desc.h>
  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. static void __init i386_default_early_setup(void)
  23. {
  24. /* Initialize 32bit specific setup functions */
  25. x86_init.resources.reserve_resources = i386_reserve_resources;
  26. x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
  27. }
  28. asmlinkage __visible void __init i386_start_kernel(void)
  29. {
  30. /* Make sure IDT is set up before any exception happens */
  31. idt_setup_early_handler();
  32. cr4_init_shadow();
  33. sanitize_boot_params(&boot_params);
  34. x86_early_init_platform_quirks();
  35. /* Call the subarch specific early setup function */
  36. switch (boot_params.hdr.hardware_subarch) {
  37. case X86_SUBARCH_INTEL_MID:
  38. x86_intel_mid_early_setup();
  39. break;
  40. case X86_SUBARCH_CE4100:
  41. x86_ce4100_early_setup();
  42. break;
  43. default:
  44. i386_default_early_setup();
  45. break;
  46. }
  47. start_kernel();
  48. }
  49. /*
  50. * Initialize page tables. This creates a PDE and a set of page
  51. * tables, which are located immediately beyond __brk_base. The variable
  52. * _brk_end is set up to point to the first "safe" location.
  53. * Mappings are created both at virtual address 0 (identity mapping)
  54. * and PAGE_OFFSET for up to _end.
  55. *
  56. * In PAE mode initial_page_table is statically defined to contain
  57. * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
  58. * entries). The identity mapping is handled by pointing two PGD entries
  59. * to the first kernel PMD. Note the upper half of each PMD or PTE are
  60. * always zero at this stage.
  61. */
  62. void __init mk_early_pgtbl_32(void)
  63. {
  64. #ifdef __pa
  65. #undef __pa
  66. #endif
  67. #define __pa(x) ((unsigned long)(x) - PAGE_OFFSET)
  68. pte_t pte, *ptep;
  69. int i;
  70. unsigned long *ptr;
  71. /* Enough space to fit pagetables for the low memory linear map */
  72. const unsigned long limit = __pa(_end) +
  73. (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
  74. #ifdef CONFIG_X86_PAE
  75. pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);
  76. #define SET_PL2(pl2, val) { (pl2).pmd = (val); }
  77. #else
  78. pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);
  79. #define SET_PL2(pl2, val) { (pl2).pgd = (val); }
  80. #endif
  81. ptep = (pte_t *)__pa(__brk_base);
  82. pte.pte = PTE_IDENT_ATTR;
  83. while ((pte.pte & PTE_PFN_MASK) < limit) {
  84. SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
  85. *pl2p = pl2;
  86. #ifndef CONFIG_X86_PAE
  87. /* Kernel PDE entry */
  88. *(pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
  89. #endif
  90. for (i = 0; i < PTRS_PER_PTE; i++) {
  91. *ptep = pte;
  92. pte.pte += PAGE_SIZE;
  93. ptep++;
  94. }
  95. pl2p++;
  96. }
  97. ptr = (unsigned long *)__pa(&max_pfn_mapped);
  98. /* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */
  99. *ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
  100. ptr = (unsigned long *)__pa(&_brk_end);
  101. *ptr = (unsigned long)ptep + PAGE_OFFSET;
  102. }