diff options
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchTo32Bit.asm')
| -rw-r--r-- | src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchTo32Bit.asm | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchTo32Bit.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchTo32Bit.asm new file mode 100644 index 00000000..5b3cf18b --- /dev/null +++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchTo32Bit.asm @@ -0,0 +1,162 @@ +; $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. + |