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|
; $Id$
;; @file
; BS3Kit - Bs3SwitchToPP16
;
;
; Copyright (C) 2007-2016 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"
%ifndef TMPL_PP16
extern NAME(Bs3EnteredMode_pp16)
%ifdef TMPL_PP32
BS3_EXTERN_CMN Bs3SwitchTo16Bit
%else
%endif
%endif
;;
; Switch to 16-bit paged protected mode from any other mode.
;
; @cproto BS3_DECL(void) Bs3SwitchToPP16(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(Bs3SwitchToPP16_Safe), function , 0
%endif
BS3_PROC_BEGIN_MODE Bs3SwitchToPP16, BS3_PBC_NEAR
%ifdef TMPL_PP16
extern BS3_CMN_NM(Bs3SwitchToRing0)
call BS3_CMN_NM(Bs3SwitchToRing0)
push ax
mov ax, BS3_SEL_R0_DS16
mov ds, ax
mov es, ax
pop ax
ret
%elif BS3_MODE_IS_V86(TMPL_MODE)
;
; V8086 - Switch to 16-bit ring-0 and call worker for that mode.
;
extern BS3_CMN_NM(Bs3SwitchToRing0)
call BS3_CMN_NM(Bs3SwitchToRing0)
extern %[BS3_MODE_R0_NM_ %+ TMPL_MODE](Bs3SwitchToPP16)
jmp %[BS3_MODE_R0_NM_ %+ TMPL_MODE](Bs3SwitchToPP16)
%else
;
; Switch to 16-bit text segment and prepare for returning in 16-bit mode.
;
%if TMPL_BITS != 16
shl xPRE [xSP + xCB], TMPL_BITS - 16 ; Adjust the return address.
add xSP, xCB - 2
; Must be in 16-bit segment when calling Bs3SwitchToRM and Bs3SwitchTo16Bit.
jmp .sixteen_bit_segment
BS3_BEGIN_TEXT16
BS3_SET_BITS TMPL_BITS
.sixteen_bit_segment:
%endif
%ifdef TMPL_PP32
;
; No need to go to real-mode here, we use the same CR3 and stuff.
; Just switch to 32-bit mode and call the Bs3EnteredMode routine to
; load the right descriptor tables.
;
call Bs3SwitchTo16Bit
BS3_SET_BITS 16
call NAME(Bs3EnteredMode_pp16)
ret
%else
;
; Switch to real mode.
;
extern TMPL_NM(Bs3SwitchToRM)
call TMPL_NM(Bs3SwitchToRM)
BS3_SET_BITS 16
push eax
push ecx
pushfd
%ifdef BS3_STRICT
mov ax, ds
cmp ax, BS3_ADDR_BS3DATA16 >> 4
je .real_mode_ds_ok
hlt
.real_mode_ds_ok:
%endif
;
; Get the page directory (returned in eax).
; Will lazy init page tables (in 16-bit prot mode).
;
extern NAME(Bs3PagingGetRootForPP16_rm)
call NAME(Bs3PagingGetRootForPP16_rm)
cli
mov cr3, eax
;
; Make sure PAE is really off and that PSE is enabled when supported.
;
BS3_EXTERN_DATA16 g_uBs3CpuDetected
BS3_BEGIN_TEXT16
test byte [1 + BS3_DATA16_WRT(g_uBs3CpuDetected)], (BS3CPU_F_CPUID >> 8)
jz .cr4_is_fine
mov eax, cr4
mov ecx, eax
and eax, ~(X86_CR4_PAE | X86_CR4_PSE)
test byte [1 + BS3_DATA16_WRT(g_uBs3CpuDetected)], (BS3CPU_F_PSE >> 8)
jz .no_pse
or eax, X86_CR4_PSE
.no_pse:
cmp eax, ecx
je .cr4_is_fine
mov cr4, eax
.cr4_is_fine:
;
; Load the GDT and enable PP16.
;
BS3_EXTERN_SYSTEM16 Bs3Lgdt_Gdt
BS3_BEGIN_TEXT16
mov ax, BS3SYSTEM16
mov ds, ax
lgdt [Bs3Lgdt_Gdt]
mov eax, cr0
or eax, X86_CR0_PE | X86_CR0_PG
mov cr0, eax
jmp BS3_SEL_R0_CS16:.reload_cs_and_stuff
.reload_cs_and_stuff:
;
; Convert the (now) real mode stack to 16-bit.
;
mov ax, .stack_fix_return
extern NAME(Bs3ConvertRMStackToP16UsingCxReturnToAx_c16)
jmp NAME(Bs3ConvertRMStackToP16UsingCxReturnToAx_c16)
.stack_fix_return:
;
; Call rountine for doing mode specific setups.
;
call NAME(Bs3EnteredMode_pp16)
popfd
pop ecx
pop eax
ret
%endif ; !TMPL_PP32
%if TMPL_BITS != 16
TMPL_BEGIN_TEXT
%endif
%endif
BS3_PROC_END_MODE Bs3SwitchToPP16
%if TMPL_BITS == 16
;;
; Custom far stub.
BS3_BEGIN_TEXT16_FARSTUBS
BS3_PROC_BEGIN_MODE Bs3SwitchToPP16, BS3_PBC_FAR
inc bp
push bp
mov bp, sp
; Call the real thing.
call TMPL_NM(Bs3SwitchToPP16)
%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 Bs3SwitchToPP16
%else
;;
; Safe far return to non-BS3TEXT16 code.
BS3_EXTERN_CMN Bs3SwitchHlpConvFlatRetToRetfProtMode
BS3_BEGIN_TEXT16
BS3_SET_BITS TMPL_BITS
BS3_PROC_BEGIN_MODE Bs3SwitchToPP16_Safe, BS3_PBC_NEAR
call Bs3SwitchHlpConvFlatRetToRetfProtMode ; Special internal function. Uses nothing, but modifies the stack.
call TMPL_NM(Bs3SwitchToPP16)
BS3_SET_BITS 16
retf
BS3_PROC_END_MODE Bs3SwitchToPP16_Safe
%endif
|
