| 1 | ; $Id: bs3-cmn-SwitchToRing0.asm 59949 2016-03-07 23:15:22Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - Bs3SwitchToRing0
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| 4 | ;
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| 5 |
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| 6 | ;
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| 7 | ; Copyright (C) 2007-2016 Oracle Corporation
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| 8 | ;
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| 9 | ; This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | ; available from http://www.virtualbox.org. This file is free software;
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| 11 | ; you can redistribute it and/or modify it under the terms of the GNU
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| 12 | ; General Public License (GPL) as published by the Free Software
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| 13 | ; Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | ; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | ; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | ;
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| 17 | ; The contents of this file may alternatively be used under the terms
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| 18 | ; of the Common Development and Distribution License Version 1.0
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| 19 | ; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | ; VirtualBox OSE distribution, in which case the provisions of the
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| 21 | ; CDDL are applicable instead of those of the GPL.
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| 22 | ;
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| 23 | ; You may elect to license modified versions of this file under the
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| 24 | ; terms and conditions of either the GPL or the CDDL or both.
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| 25 | ;
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| 26 |
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| 27 | %include "bs3kit-template-header.mac"
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| 28 |
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| 29 |
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| 30 | %if TMPL_BITS == 16
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| 31 | BS3_EXTERN_DATA16 g_bBs3CurrentMode
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| 32 | %endif
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| 33 | TMPL_BEGIN_TEXT
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| 34 |
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| 35 |
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| 36 | ;;
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| 37 | ; @cproto BS3_DECL(void) Bs3SwitchToRing0(void);
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| 38 | ;
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| 39 | ; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
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| 40 | ;
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| 41 | BS3_PROC_BEGIN_CMN Bs3SwitchToRing0
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| 42 | push xAX
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| 43 |
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| 44 | %if TMPL_BITS == 16
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| 45 | ; Check the current mode.
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| 46 | push ds
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| 47 | mov ax, seg g_bBs3CurrentMode
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| 48 | mov ds, ax
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| 49 | mov al, [BS3_DATA16_WRT(g_bBs3CurrentMode)]
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| 50 | pop ds
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| 51 |
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| 52 | ; If real mode: Nothing to do, it's considered ring-0 here.
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| 53 | cmp al, BS3_MODE_RM
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| 54 | je .return
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| 55 |
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| 56 | ; If V8086 mode: Have to make the system call (v8086 mode is ring-3).
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| 57 | and al, BS3_MODE_CODE_MASK
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| 58 | cmp al, BS3_MODE_CODE_V86
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| 59 | je .just_do_it
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| 60 | %endif
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| 61 |
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| 62 | ; In protected mode: Check the CPL we're currently at skip syscall if ring-0 already.
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| 63 | mov ax, cs
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| 64 | test ax, 3
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| 65 | jz .return
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| 66 |
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| 67 | .just_do_it:
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| 68 | mov xAX, BS3_SYSCALL_TO_RING0
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| 69 | int BS3_TRAP_SYSCALL
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| 70 |
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| 71 | .return:
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| 72 | pop xAX
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| 73 | ret
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| 74 | BS3_PROC_END_CMN Bs3SwitchToRing0
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| 75 |
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