projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 9da59186 JY |
1 | #------------------------------------------------------------------------------\r |
| 2 | #\r | |
| 3 | # Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>\r | |
| 16a16ea6 | 4 | # SPDX-License-Identifier: BSD-2-Clause-Patent\r |
| 9da59186 JY |
5 | #\r |
| 6 | # Abstract:\r | |
| 7 | #\r | |
| 8 | # This is the code that goes from real-mode to protected mode.\r | |
| 9 | # It consumes the reset vector, configures the stack.\r | |
| 10 | #\r | |
| 11 | #------------------------------------------------------------------------------\r | |
| 12 | \r | |
| 13 | \r | |
| 14 | #\r | |
| 15 | # Contrary to the name, this file contains 16 bit code as well.\r | |
| 16 | #\r | |
| 17 | .text\r | |
| 18 | #----------------------------------------------------------------------------\r | |
| 19 | #\r | |
| 20 | # Procedure: _ModuleEntryPoint\r | |
| 21 | #\r | |
| 22 | # Input: None\r | |
| 23 | #\r | |
| 24 | # Output: None\r | |
| 25 | #\r | |
| 26 | # Destroys: Assume all registers\r | |
| 27 | #\r | |
| 28 | # Description:\r | |
| 29 | #\r | |
| 30 | # Transition to non-paged flat-model protected mode from a\r | |
| 31 | # hard-coded GDT that provides exactly two descriptors.\r | |
| 32 | # This is a bare bones transition to protected mode only\r | |
| 33 | # used for a while in PEI and possibly DXE.\r | |
| 34 | #\r | |
| 35 | # After enabling protected mode, a far jump is executed to\r | |
| 36 | # transfer to PEI using the newly loaded GDT.\r | |
| 37 | #\r | |
| 38 | # Return: None\r | |
| 39 | #\r | |
| 40 | #----------------------------------------------------------------------------\r | |
| 41 | ASM_GLOBAL ASM_PFX(_ModuleEntryPoint)\r | |
| 42 | ASM_PFX(_ModuleEntryPoint):\r | |
| 43 | \r | |
| 44 | #\r | |
| 45 | # Load the GDT table in GdtDesc\r | |
| 46 | #\r | |
| 47 | .byte 0x66,0xbe #movl $GdtDesc, %esi\r | |
| 48 | .long GdtDesc\r | |
| 49 | \r | |
| 50 | .byte 0x66,0x2e,0x0f,0x01,0x14 #lgdt %cs:(%si)\r | |
| 51 | \r | |
| 52 | #\r | |
| 53 | # Transition to 16 bit protected mode\r | |
| 54 | #\r | |
| 55 | .byte 0x0f,0x20,0xc0 #movl %cr0, %eax # Get control register 0\r | |
| 56 | .byte 0x66,0x83,0xc8,0x03 #orl $0x0000003, %eax # Set PE bit (bit #0) & MP bit (bit #1)\r | |
| 57 | .byte 0x0f,0x22,0xc0 #movl %eax, %cr0 # Activate protected mode\r | |
| 58 | \r | |
| 59 | #\r | |
| 60 | # Now we're in 16 bit protected mode\r | |
| 61 | # Set up the selectors for 32 bit protected mode entry\r | |
| 62 | # \r | |
| 63 | .byte 0xb8 #movw SYS_DATA_SEL, %ax\r | |
| 64 | .word SYS_DATA_SEL\r | |
| 65 | \r | |
| 66 | .byte 0x8e,0xd8 #movw %ax, %ds\r | |
| 67 | .byte 0x8e,0xc0 #movw %ax, %es\r | |
| 68 | .byte 0x8e,0xe0 #movw %ax, %fs\r | |
| 69 | .byte 0x8e,0xe8 #movw %ax, %gs\r | |
| 70 | .byte 0x8e,0xd0 #movw %ax, %ss\r | |
| 71 | \r | |
| 72 | #\r | |
| 73 | # Transition to Flat 32 bit protected mode\r | |
| 74 | # The jump to a far pointer causes the transition to 32 bit mode\r | |
| 75 | #\r | |
| 76 | .byte 0x66,0xbe #movl ProtectedModeEntryLinearAddress, %esi\r | |
| 77 | .long ProtectedModeEntryLinearAddress \r | |
| 78 | .byte 0x66,0x2e,0xff,0x2c #jmp %cs:(%esi)\r | |
| 79 | \r | |
| 80 | #\r | |
| 81 | # Protected mode portion initializes stack, configures cache, and calls C entry point\r | |
| 82 | #\r | |
| 83 | \r | |
| 84 | #----------------------------------------------------------------------------\r | |
| 85 | #\r | |
| 86 | # Procedure: ProtectedModeEntryPoint\r | |
| 87 | #\r | |
| 88 | # Input: Executing in 32 Bit Protected (flat) mode\r | |
| 89 | # cs: 0-4GB\r | |
| 90 | # ds: 0-4GB\r | |
| 91 | # es: 0-4GB\r | |
| 92 | # fs: 0-4GB\r | |
| 93 | # gs: 0-4GB\r | |
| 94 | # ss: 0-4GB\r | |
| 95 | #\r | |
| 96 | # Output: This function never returns\r | |
| 97 | #\r | |
| 98 | # Destroys:\r | |
| 99 | # ecx\r | |
| 100 | # edi\r | |
| 101 | # esi\r | |
| 102 | # esp\r | |
| 103 | #\r | |
| 104 | # Description:\r | |
| 105 | # Perform any essential early platform initilaisation\r | |
| 106 | # Setup a stack\r | |
| 107 | #\r | |
| 108 | #----------------------------------------------------------------------------\r | |
| 109 | ProtectedModeEntryPoint:\r | |
| 110 | #\r | |
| 111 | # Dummy function. Consume 2 API to make sure they can be linked.\r | |
| 112 | #\r | |
| 113 | movl ASM_PFX(TempRamInitApi), %eax\r | |
| 114 | movl ASM_PFX(FspInitApi), %eax\r | |
| 115 | #\r | |
| 116 | # Should never return\r | |
| 117 | #\r | |
| 118 | jmp . #'$'\r | |
| 119 | \r | |
| 120 | #\r | |
| 121 | # ROM-based Global-Descriptor Table for the PEI Phase\r | |
| 122 | #\r | |
| 123 | .align 16\r | |
| 124 | #\r | |
| 125 | # GDT[0]: 000h: Null entry, never used.\r | |
| 126 | #\r | |
| 127 | .equ NULL_SEL, . - GDT_BASE # Selector [0]\r | |
| 128 | GDT_BASE: \r | |
| 129 | BootGdtTable: \r | |
| 130 | .long 0\r | |
| 131 | .long 0\r | |
| 132 | #\r | |
| 133 | # Linear code segment descriptor\r | |
| 134 | #\r | |
| 135 | .equ LINEAR_CODE_SEL, . - GDT_BASE # Selector [08h]\r | |
| 136 | .word 0xFFFF # limit 0FFFFh\r | |
| 137 | .word 0 # base 0\r | |
| 138 | .byte 0\r | |
| 139 | .byte 0x9B # present, ring 0, data, expand-up, not-writable\r | |
| 140 | .byte 0xCF # page-granular, 32-bit\r | |
| 141 | .byte 0\r | |
| 142 | #\r | |
| 143 | # System data segment descriptor\r | |
| 144 | #\r | |
| 145 | .equ SYS_DATA_SEL, . - GDT_BASE # Selector [010h]\r | |
| 146 | .word 0xFFFF # limit 0FFFFh\r | |
| 147 | .word 0 # base 0\r | |
| 148 | .byte 0\r | |
| 149 | .byte 0x93 # present, ring 0, data, expand-up, not-writable\r | |
| 150 | .byte 0xCF # page-granular, 32-bit\r | |
| 151 | .byte 0\r | |
| 152 | \r | |
| 153 | .equ GDT_SIZE, . - BootGdtTable # Size, in bytes\r | |
| 154 | \r | |
| 155 | #\r | |
| 156 | # GDT Descriptor\r | |
| 157 | #\r | |
| 158 | GdtDesc: # GDT descriptor\r | |
| 159 | .word GDT_SIZE - 1 \r | |
| 160 | .long BootGdtTable \r | |
| 161 | \r | |
| 162 | ProtectedModeEntryLinearAddress:\r | |
| 163 | ProtectedModeEntryLinearOffset:\r | |
| 164 | .long ProtectedModeEntryPoint\r | |
| 165 | .word LINEAR_CODE_SEL\r |