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|
; $Id: bs3-cmn-SwitchTo32Bit.asm $
;; @file
; BS3Kit - Bs3SwitchTo32Bit
;
;
; Copyright (C) 2007-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox 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.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;
%include "bs3kit-template-header.mac"
%if TMPL_BITS == 16
BS3_EXTERN_CMN Bs3SelProtFar32ToFlat32
BS3_EXTERN_CMN Bs3Syscall
%endif
%if TMPL_BITS != 32
BS3_EXTERN_DATA16 g_bBs3CurrentMode
TMPL_BEGIN_TEXT
%endif
;;
; @cproto BS3_DECL(void) Bs3SwitchTo32Bit(void);
;
; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
;
BS3_PROC_BEGIN_CMN Bs3SwitchTo32Bit, BS3_PBC_NEAR
%if TMPL_BITS == 32
ret
%else
%if TMPL_BITS == 16
push ax ; Reserve space for larger return value (adjusted in 32-bit code).
push eax
pushfd
push edx
%else
pushfq
mov [rsp + 4], eax
%endif
cli
%if TMPL_BITS == 16
; Check for v8086 mode, we need to exit it to enter 32-bit mode.
mov ax, seg g_bBs3CurrentMode
mov ds, ax
mov al, [BS3_DATA16_WRT(g_bBs3CurrentMode)]
test al, BS3_MODE_CODE_V86
jz .not_v8086
; Calc flat stack into edx.
mov dx, ss
movzx edx, dx
shl edx, 4
add dx, sp
adc edx, 0 ; edx = flat stack address corresponding to ss:sp
; Switch to 16-bit ring0 and go on to do the far jump to 32-bit code.
mov ax, BS3_SYSCALL_TO_RING0
call Bs3Syscall
mov xAX, BS3_SEL_R0_CS32
jmp .do_far_jump
%endif
.not_v8086:
%if TMPL_BITS == 16
; Calc flat stack into edx.
movzx eax, sp
push ecx
push ebx
push ss
push eax
call Bs3SelProtFar32ToFlat32
add sp, 6
shl edx, 16
mov dx, ax ; edx = flat stack address corresponding to ss:sp
pop ebx
pop ecx
%endif
; Calc ring addend.
mov ax, cs
and xAX, 3
shl xAX, BS3_SEL_RING_SHIFT
add xAX, BS3_SEL_R0_CS32
; Create far return for switching to 32-bit mode.
.do_far_jump:
push sAX
%if TMPL_BITS == 16
push dword .thirty_two_bit wrt FLAT
o32 retf
%else
push .thirty_two_bit
o64 retf
%endif
BS3_SET_BITS 32
.thirty_two_bit:
; Load 32-bit segment registers.
add eax, BS3_SEL_R0_SS32 - BS3_SEL_R0_CS32
mov ss, ax
%if TMPL_BITS == 16
mov esp, edx ; Load flat stack address.
%endif
add eax, BS3_SEL_R0_DS32 - BS3_SEL_R0_SS32
mov ds, ax
mov es, ax
; Update globals.
and byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], ~BS3_MODE_CODE_MASK
or byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], BS3_MODE_CODE_32
%if TMPL_BITS == 16
; Adjust the return address.
movzx eax, word [esp + 4*3 + 2]
add eax, BS3_ADDR_BS3TEXT16
mov [esp + 4*3], eax
%endif
; Restore and return.
%if TMPL_BITS == 16
pop edx
%endif
popfd
pop eax
TONLY64 ret 4
TNOT64 ret
%endif
BS3_PROC_END_CMN Bs3SwitchTo32Bit
;; @todo far 16-bit variant.
|
