mirror of https://github.com/acidanthera/audk.git
83 lines
3.5 KiB
ArmAsm
83 lines
3.5 KiB
ArmAsm
#------------------------------------------------------------------------------
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#
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# Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
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# This program and the accompanying materials
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# are licensed and made available under the terms and conditions of the BSD License
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# which accompanies this distribution. The full text of the license may be found at
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# http://opensource.org/licenses/bsd-license.php.
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#
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# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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#
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# Module Name:
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#
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# DisablePaging64.S
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#
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# Abstract:
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#
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# AsmDisablePaging64 function
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#
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# Notes:
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#
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# VOID
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# EFIAPI
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# InternalX86DisablePaging64 (
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# IN UINT16 Cs,
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# IN UINT32 EntryPoint,
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# IN UINT32 Context1, OPTIONAL
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# IN UINT32 Context2, OPTIONAL
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# IN UINT32 NewStack
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# );
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#------------------------------------------------------------------------------
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ASM_GLOBAL ASM_PFX(InternalX86DisablePaging64)
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ASM_PFX(InternalX86DisablePaging64):
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cli
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lea L1(%rip), %rsi # rsi <- The start address of transition code
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mov 0x28(%rsp), %edi # rdi <- New stack
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lea _mTransitionEnd(%rip), %rax # rax <- end of transition code
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sub %rsi, %rax # rax <- The size of transition piece code
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add $4, %rax # round rax up to the next 4 byte boundary
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and $0xfc, %al
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sub %rax, %rdi # rdi <- use stack to hold transition code
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mov %edi, %r10d # r10 <- The start address of transicition code below 4G
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push %rcx # save rcx to stack
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mov %rax, %rcx # rcx <- The size of transition piece code
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rep
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movsb # copy transition code to (new stack - 64byte) below 4G
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pop %rcx # restore rcx
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mov %r8d, %esi
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mov %r9d, %edi
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mov %r10d, %eax
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sub $4, %eax
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push %rcx # push Cs to stack
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push %r10 # push address of transition code on stack
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.byte 0x48, 0xcb # retq: Use far return to load CS register from stack
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# (Use raw byte code since some GNU assemblers generates incorrect code for "retq")
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L1:
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mov %eax,%esp # set up new stack
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mov %cr0,%rax
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btr $0x1f,%eax # clear CR0.PG
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mov %rax,%cr0 # disable paging
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mov %edx,%ebx # save EntryPoint to ebx, for rdmsr will overwrite edx
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mov $0xc0000080,%ecx
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rdmsr
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and $0xfe,%ah # clear LME
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wrmsr
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mov %cr4,%rax
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and $0xdf,%al # clear PAE
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mov %rax,%cr4
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push %rdi # push Context2
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push %rsi # push Context1
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callq *%rbx # transfer control to EntryPoint
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jmp . # no one should get here
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_mTransitionEnd :
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