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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 03:01:46 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 03:01:46 +0000
commitf8fe689a81f906d1b91bb3220acde2a4ecb14c5b (patch)
tree26484e9d7e2c67806c2d1760196ff01aaa858e8c /src/VBox/ValidationKit/bootsectors/bs3kit/bs3-mode-SwitchToPE32_16.asm
parentInitial commit. (diff)
downloadvirtualbox-f8fe689a81f906d1b91bb3220acde2a4ecb14c5b.tar.xz
virtualbox-f8fe689a81f906d1b91bb3220acde2a4ecb14c5b.zip
Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-mode-SwitchToPE32_16.asm')
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diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-mode-SwitchToPE32_16.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-mode-SwitchToPE32_16.asm
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+; $Id: bs3-mode-SwitchToPE32_16.asm $
+;; @file
+; BS3Kit - Bs3SwitchToPE32_16
+;
+
+;
+; Copyright (C) 2007-2019 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+%include "bs3kit-template-header.mac"
+
+
+;;
+; Switch to 16-bit code under 32-bit unpaged protected mode sys/tss from any other mode.
+;
+; @cproto BS3_DECL(void) Bs3SwitchToPE32_16(void);
+;
+; @uses Nothing (except high 32-bit register parts).
+;
+; @remarks Obviously returns to 16-bit mode, even if the caller was
+; in 32-bit or 64-bit mode.
+;
+; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
+;
+%if TMPL_BITS == 16
+BS3_GLOBAL_NAME_EX TMPL_NM(Bs3SwitchToPE32_16_Safe), function , 0
+%endif
+BS3_PROC_BEGIN_MODE Bs3SwitchToPE32_16, BS3_PBC_NEAR
+%if TMPL_MODE == BS3_MODE_PE32_16
+ ret
+
+%elif TMPL_MODE == BS3_MODE_PE32
+ extern BS3_CMN_NM(Bs3SwitchTo16Bit)
+ jmp BS3_CMN_NM(Bs3SwitchTo16Bit)
+
+%else
+ ;
+ ; Switch to PE32.
+ ;
+ extern TMPL_NM(Bs3SwitchToPE32)
+ call TMPL_NM(Bs3SwitchToPE32)
+ BS3_SET_BITS 32
+
+ ;
+ ; Make sure we're in the 16-bit segment and then do the switch to 16-bit.
+ ;
+ %if TMPL_BITS != 16
+ jmp .sixteen_bit_segment
+BS3_BEGIN_TEXT16
+ BS3_SET_BITS TMPL_BITS
+BS3_GLOBAL_LOCAL_LABEL .sixteen_bit_segment
+ %endif
+ extern _Bs3SwitchTo16Bit_c32
+ %if TMPL_BITS == 32
+ jmp _Bs3SwitchTo16Bit_c32
+ %else
+ call _Bs3SwitchTo16Bit_c32
+ BS3_SET_BITS 16
+ %if TMPL_BITS == 16
+ ret
+ %else
+ ret 6 ; Return and pop 6 bytes of "parameters" (unused return address).
+ %endif
+ %endif
+%endif
+BS3_PROC_END_MODE Bs3SwitchToPE32_16
+
+
+%if TMPL_BITS == 16
+;;
+; Custom far stub.
+BS3_BEGIN_TEXT16_FARSTUBS
+BS3_PROC_BEGIN_MODE Bs3SwitchToPE32_16, BS3_PBC_FAR
+ inc bp
+ push bp
+ mov bp, sp
+
+ ; Call the real thing.
+ call TMPL_NM(Bs3SwitchToPE32_16)
+
+ %if BS3_MODE_IS_RM_OR_V86(TMPL_MODE)
+ ; Jmp to common code for the tedious conversion.
+ BS3_EXTERN_CMN Bs3SwitchHlpConvRealModeRetfPopBpDecBpAndReturn
+ jmp Bs3SwitchHlpConvRealModeRetfPopBpDecBpAndReturn
+ %else
+ pop bp
+ dec bp
+ retf
+ %endif
+BS3_PROC_END_MODE Bs3SwitchToPE32_16
+
+%else
+;;
+; Safe far return to non-BS3TEXT16 code.
+BS3_EXTERN_CMN Bs3SwitchHlpConvFlatRetToRetfProtMode
+BS3_BEGIN_TEXT16
+BS3_SET_BITS TMPL_BITS
+BS3_PROC_BEGIN_MODE Bs3SwitchToPE32_16_Safe, BS3_PBC_NEAR
+ call Bs3SwitchHlpConvFlatRetToRetfProtMode ; Special internal function. Uses nothing, but modifies the stack.
+ call TMPL_NM(Bs3SwitchToPE32_16)
+ BS3_SET_BITS 16
+ retf
+BS3_PROC_END_MODE Bs3SwitchToPE32_16_Safe
+%endif
+