diff options
Diffstat (limited to 'src/VBox/Devices/EFI/Firmware/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm')
-rw-r--r-- | src/VBox/Devices/EFI/Firmware/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm b/src/VBox/Devices/EFI/Firmware/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm new file mode 100644 index 00000000..fefe2a41 --- /dev/null +++ b/src/VBox/Devices/EFI/Firmware/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm @@ -0,0 +1,142 @@ +;------------------------------------------------------------------------------ +; @file +; Transition from 16 bit real mode into 32 bit flat protected mode +; +; Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR> +; SPDX-License-Identifier: BSD-2-Clause-Patent +; +;------------------------------------------------------------------------------ + +%define SEC_DEFAULT_CR0 0x40000023 +%define SEC_DEFAULT_CR4 0x640 + +BITS 16 + +; +; Modified: EAX, EBX +; +; @param[out] DS Selector allowing flat access to all addresses +; @param[out] ES Selector allowing flat access to all addresses +; @param[out] FS Selector allowing flat access to all addresses +; @param[out] GS Selector allowing flat access to all addresses +; @param[out] SS Selector allowing flat access to all addresses +; +TransitionFromReal16To32BitFlat: + + debugShowPostCode POSTCODE_16BIT_MODE + + cli + + mov bx, 0xf000 + mov ds, bx + + mov bx, ADDR16_OF(gdtr) + +o32 lgdt [cs:bx] + + mov eax, SEC_DEFAULT_CR0 + mov cr0, eax + + jmp LINEAR_CODE_SEL:dword ADDR_OF(jumpTo32BitAndLandHere) +BITS 32 +jumpTo32BitAndLandHere: + + mov eax, SEC_DEFAULT_CR4 + mov cr4, eax + + debugShowPostCode POSTCODE_32BIT_MODE + + mov ax, LINEAR_SEL + mov ds, ax + mov es, ax + mov fs, ax + mov gs, ax + mov ss, ax + + OneTimeCallRet TransitionFromReal16To32BitFlat + +ALIGN 2 + +gdtr: + dw GDT_END - GDT_BASE - 1 ; GDT limit + dd ADDR_OF(GDT_BASE) + +ALIGN 16 + +; +; Macros for GDT entries +; + +%define PRESENT_FLAG(p) (p << 7) +%define DPL(dpl) (dpl << 5) +%define SYSTEM_FLAG(s) (s << 4) +%define DESC_TYPE(t) (t) + +; Type: data, expand-up, writable, accessed +%define DATA32_TYPE 3 + +; Type: execute, readable, expand-up, accessed +%define CODE32_TYPE 0xb + +; Type: execute, readable, expand-up, accessed +%define CODE64_TYPE 0xb + +%define GRANULARITY_FLAG(g) (g << 7) +%define DEFAULT_SIZE32(d) (d << 6) +%define CODE64_FLAG(l) (l << 5) +%define UPPER_LIMIT(l) (l) + +; +; The Global Descriptor Table (GDT) +; + +GDT_BASE: +; null descriptor +NULL_SEL equ $-GDT_BASE + DW 0 ; limit 15:0 + DW 0 ; base 15:0 + DB 0 ; base 23:16 + DB 0 ; sys flag, dpl, type + DB 0 ; limit 19:16, flags + DB 0 ; base 31:24 + +; linear data segment descriptor +LINEAR_SEL equ $-GDT_BASE + DW 0xffff ; limit 15:0 + DW 0 ; base 15:0 + DB 0 ; base 23:16 + DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(DATA32_TYPE) + DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf) + DB 0 ; base 31:24 + +; linear code segment descriptor +LINEAR_CODE_SEL equ $-GDT_BASE + DW 0xffff ; limit 15:0 + DW 0 ; base 15:0 + DB 0 ; base 23:16 + DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE32_TYPE) + DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf) + DB 0 ; base 31:24 + +%ifdef ARCH_X64 +; linear code (64-bit) segment descriptor +LINEAR_CODE64_SEL equ $-GDT_BASE + DW 0xffff ; limit 15:0 + DW 0 ; base 15:0 + DB 0 ; base 23:16 + DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE64_TYPE) + DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(0)|CODE64_FLAG(1)|UPPER_LIMIT(0xf) + DB 0 ; base 31:24 +%endif + +; linear code segment descriptor +LINEAR_CODE16_SEL equ $-GDT_BASE + DW 0xffff ; limit 15:0 + DW 0 ; base 15:0 + DB 0 ; base 23:16 + DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE32_TYPE) + DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(0)|CODE64_FLAG(0)|UPPER_LIMIT(0xf) + DB 0 ; base 31:24 + +GDT_END: + |