1 ;------------------------------------------------------------------------------ 2 ; @file 3 ; Transition from 16 bit real mode into 32 bit flat protected mode 4 ; 5 ; Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR> 6 ; This program and the accompanying materials 7 ; are licensed and made available under the terms and conditions of the BSD License 8 ; which accompanies this distribution. The full text of the license may be found at 9 ; http://opensource.org/licenses/bsd-license.php 10 ; 11 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 12 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 13 ; 14 ;------------------------------------------------------------------------------ 15 16 %define SEC_DEFAULT_CR0 0x40000023 17 %define SEC_DEFAULT_CR4 0x640 18 19 BITS 16 20 21 ; 22 ; Modified: EAX, EBX 23 ; 24 TransitionFromReal16To32BitFlat: 25 26 debugShowPostCode POSTCODE_16BIT_MODE 27 28 cli 29 30 mov bx, 0xf000 31 mov ds, bx 32 33 mov bx, ADDR16_OF(gdtr) 34 35 o32 lgdt [cs:bx] 36 37 mov eax, SEC_DEFAULT_CR0 38 mov cr0, eax 39 40 jmp LINEAR_CODE_SEL:dword ADDR_OF(jumpTo32BitAndLandHere) 41 BITS 32 42 jumpTo32BitAndLandHere: 43 44 mov eax, SEC_DEFAULT_CR4 45 mov cr4, eax 46 47 debugShowPostCode POSTCODE_32BIT_MODE 48 49 mov ax, LINEAR_SEL 50 mov ds, ax 51 mov es, ax 52 mov fs, ax 53 mov gs, ax 54 mov ss, ax 55 56 OneTimeCallRet TransitionFromReal16To32BitFlat 57 58 ALIGN 2 59 60 gdtr: 61 dw GDT_END - GDT_BASE - 1 ; GDT limit 62 dd ADDR_OF(GDT_BASE) 63 64 ALIGN 16 65 66 ; 67 ; Macros for GDT entries 68 ; 69 70 %define PRESENT_FLAG(p) (p << 7) 71 %define DPL(dpl) (dpl << 5) 72 %define SYSTEM_FLAG(s) (s << 4) 73 %define DESC_TYPE(t) (t) 74 75 ; Type: data, expand-up, writable, accessed 76 %define DATA32_TYPE 3 77 78 ; Type: execute, readable, expand-up, accessed 79 %define CODE32_TYPE 0xb 80 81 ; Type: execute, readable, expand-up, accessed 82 %define CODE64_TYPE 0xb 83 84 %define GRANULARITY_FLAG(g) (g << 7) 85 %define DEFAULT_SIZE32(d) (d << 6) 86 %define CODE64_FLAG(l) (l << 5) 87 %define UPPER_LIMIT(l) (l) 88 89 ; 90 ; The Global Descriptor Table (GDT) 91 ; 92 93 GDT_BASE: 94 ; null descriptor 95 NULL_SEL equ $-GDT_BASE 96 DW 0 ; limit 15:0 97 DW 0 ; base 15:0 98 DB 0 ; base 23:16 99 DB 0 ; sys flag, dpl, type 100 DB 0 ; limit 19:16, flags 101 DB 0 ; base 31:24 102 103 ; linear data segment descriptor 104 LINEAR_SEL equ $-GDT_BASE 105 DW 0xffff ; limit 15:0 106 DW 0 ; base 15:0 107 DB 0 ; base 23:16 108 DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(DATA32_TYPE) 109 DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf) 110 DB 0 ; base 31:24 111 112 ; linear code segment descriptor 113 LINEAR_CODE_SEL equ $-GDT_BASE 114 DW 0xffff ; limit 15:0 115 DW 0 ; base 15:0 116 DB 0 ; base 23:16 117 DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE32_TYPE) 118 DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf) 119 DB 0 ; base 31:24 120 121 %ifdef ARCH_X64 122 ; linear code (64-bit) segment descriptor 123 LINEAR_CODE64_SEL equ $-GDT_BASE 124 DW 0xffff ; limit 15:0 125 DW 0 ; base 15:0 126 DB 0 ; base 23:16 127 DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE64_TYPE) 128 DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(0)|CODE64_FLAG(1)|UPPER_LIMIT(0xf) 129 DB 0 ; base 31:24 130 %endif 131 132 GDT_END: 133 134
