1 ;; @file 2 ; This is the code that goes from real-mode to protected mode. 3 ; It consumes the reset vector, configures the stack. 4 ; 5 ; Copyright (c) 2015 - 2016, 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 assembler characteristics 17 ; 18 19 extern ASM_PFX(TempRamInitApi) 20 21 SECTION .text 22 23 %macro RET_ESI 0 24 25 movd esi, mm7 ; restore ESP from MM7 26 jmp esi 27 28 %endmacro 29 30 ; 31 ; Perform early platform initialization 32 ; 33 global ASM_PFX(SecPlatformInit) 34 ASM_PFX(SecPlatformInit): 35 36 RET_ESI 37 38 ; 39 ; Protected mode portion initializes stack, configures cache, and calls C entry point 40 ; 41 42 ;---------------------------------------------------------------------------- 43 ; 44 ; Procedure: ProtectedModeEntryPoint 45 ; 46 ; Input: Executing in 32 Bit Protected (flat) mode 47 ; cs: 0-4GB 48 ; ds: 0-4GB 49 ; es: 0-4GB 50 ; fs: 0-4GB 51 ; gs: 0-4GB 52 ; ss: 0-4GB 53 ; 54 ; Output: This function never returns 55 ; 56 ; Destroys: 57 ; ecx 58 ; edi 59 ; esi 60 ; esp 61 ; 62 ; Description: 63 ; Perform any essential early platform initilaisation 64 ; Setup a stack 65 ; 66 ;---------------------------------------------------------------------------- 67 global ASM_PFX(ProtectedModeEntryPoint) 68 ASM_PFX(ProtectedModeEntryPoint): 69 ; 70 ; Dummy function. Consume 2 API to make sure they can be linked. 71 ; 72 mov eax, ASM_PFX(TempRamInitApi) 73 74 ; Should never return 75 jmp $ 76 77 ; 78 ; ROM-based Global-Descriptor Table for the PEI Phase 79 ; 80 align 16 81 global ASM_PFX(BootGdtTable) 82 83 ; 84 ; GDT[0]: 0x00: Null entry, never used. 85 ; 86 NULL_SEL equ $ - GDT_BASE ; Selector [0] 87 GDT_BASE: 88 ASM_PFX(BootGdtTable): DD 0 89 DD 0 90 ; 91 ; Linear code segment descriptor 92 ; 93 LINEAR_CODE_SEL equ $ - GDT_BASE ; Selector [0x8] 94 DW 0FFFFh ; limit 0xFFFF 95 DW 0 ; base 0 96 DB 0 97 DB 09Bh ; present, ring 0, data, expand-up, not-writable 98 DB 0CFh ; page-granular, 32-bit 99 DB 0 100 ; 101 ; System data segment descriptor 102 ; 103 SYS_DATA_SEL equ $ - GDT_BASE ; Selector [0x10] 104 DW 0FFFFh ; limit 0xFFFF 105 DW 0 ; base 0 106 DB 0 107 DB 093h ; present, ring 0, data, expand-up, not-writable 108 DB 0CFh ; page-granular, 32-bit 109 DB 0 110 111 GDT_SIZE EQU $ - GDT_BASE ; Size, in bytes 112 113 ; 114 ; GDT Descriptor 115 ; 116 GdtDesc: ; GDT descriptor 117 DW GDT_SIZE - 1 ; GDT limit 118 DD GDT_BASE ; GDT base address 119 120 global ASM_PFX(ProtectedModeEntryLinearAddress) 121 global ASM_PFX(ProtectedModeEntryLinearOffset) 122 123 ASM_PFX(ProtectedModeEntryLinearAddress): 124 ASM_PFX(ProtectedModeEntryLinearOffset): 125 DD ASM_PFX(ProtectedModeEntryPoint) ; Offset of our 32 bit code 126 DW LINEAR_CODE_SEL 127 128
