93314ae597
As described in the Xen PVH documentation [1], "ebx: contains the physical memory address where the loader has placed the boot start info structure". To have this pointer saved to be able to use it later in the PEI phase, we allocate some space in the MEMFD for it. We use 'XPVH' as a signature (for "Xen PVH"). [1] https://xenbits.xenproject.org/docs/unstable/misc/pvh.html Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689 Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> Acked-by: Laszlo Ersek <lersek@redhat.com> Message-Id: <20190813113119.14804-8-anthony.perard@citrix.com>
56 lines
1.3 KiB
NASM
56 lines
1.3 KiB
NASM
;------------------------------------------------------------------------------
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; @file
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; An entry point use by Xen when a guest is started in PVH mode.
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;
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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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xenPVHMain:
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;
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; 'BP' to indicate boot-strap processor
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;
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mov di, 'BP'
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;
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; ESP will be used as initial value of the EAX register
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; in Main.asm
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;
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xor esp, esp
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;
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; Store "Start of day" struct pointer for later use
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;
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mov dword[PVH_SPACE (0)], ebx
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mov dword[PVH_SPACE (4)], 'XPVH'
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mov ebx, ADDR_OF(gdtr)
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lgdt [ebx]
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mov eax, SEC_DEFAULT_CR0
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mov cr0, eax
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jmp LINEAR_CODE_SEL:ADDR_OF(.jmpToNewCodeSeg)
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.jmpToNewCodeSeg:
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mov eax, SEC_DEFAULT_CR4
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mov cr4, eax
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mov ax, LINEAR_SEL
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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;
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; Jump to the main routine of the pre-SEC code
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; skiping the 16-bit part of the routine and
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; into the 32-bit flat mode part
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;
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OneTimeCallRet TransitionFromReal16To32BitFlat
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