mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-12-01 12:53:27 +01:00
69 lines
1.5 KiB
NASM
69 lines
1.5 KiB
NASM
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;------------------------------------------------------------------------------
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; @file
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; Transition from 32 bit flat protected mode into 64 bit flat protected mode
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;
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; Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR>
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; Copyright (c) 2019, Citrix Systems, Inc.
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;
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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;
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;------------------------------------------------------------------------------
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BITS 32
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;
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; Modified: EAX, EBX, ECX, EDX, ESP
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;
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Transition32FlatTo64Flat:
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OneTimeCall SetCr3ForPageTables64
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mov eax, cr4
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bts eax, 5 ; enable PAE
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mov cr4, eax
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mov ecx, 0xc0000080
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rdmsr
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bts eax, 8 ; set LME
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wrmsr
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mov eax, cr0
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bts eax, 31 ; set PG
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mov cr0, eax ; enable paging
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;
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; backup ESP
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;
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mov ebx, esp
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;
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; recalculate delta
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;
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mov esp, PVH_SPACE(16)
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call .delta
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.delta:
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pop edx
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sub edx, ADDR_OF(.delta)
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;
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; push return addr and seg to the stack, then return far
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;
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push dword LINEAR_CODE64_SEL
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mov eax, ADDR_OF(jumpTo64BitAndLandHere)
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add eax, edx ; add delta
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push eax
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retf
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BITS 64
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jumpTo64BitAndLandHere:
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;
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; restore ESP
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;
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mov esp, ebx
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debugShowPostCode POSTCODE_64BIT_MODE
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OneTimeCallRet Transition32FlatTo64Flat
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