1 files changed, 68 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchHlpConvFlatRetToRetfProtMode.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchHlpConvFlatRetToRetfProtMode.asm
new file mode 100644
index 00000000..ed88bc3b
--- /dev/null
+++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchHlpConvFlatRetToRetfProtMode.asm
@@ -0,0 +1,68 @@
+; $Id: bs3-cmn-SwitchHlpConvFlatRetToRetfProtMode.asm $
+;; @file
+; BS3Kit - SwitchHlpConvFlatRetToRetfProtMode
+;
+
+;
+; 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"
+
+%if TMPL_BITS != 16
+BS3_EXTERN_CMN Bs3SelFlatCodeToProtFar16
+
+;;
+; SwitchToXxx helper that converts a 32-bit or 64-bit flat return address
+; into a 16-bit protected mode far return.
+;
+;
+; The caller calls this routine before switching modes. The flat return
+; to be converted is immediately after our own return address on the stack.
+;
+; @uses     Nothing.
+; @remarks  No 16-bit version.
+;
+BS3_PROC_BEGIN_CMN Bs3SwitchHlpConvFlatRetToRetfProtMode, BS3_PBC_NEAR
+ %if TMPL_BITS == 64
+        push        xAX
+        push        xCX
+        sub         xSP, 20h
+
+        mov         xCX, [xSP + xCB*3 + 20h]
+        call        Bs3SelFlatCodeToProtFar16 ; well behaved assembly function, only clobbers ecx
+        mov         [xSP + xCB*3 + 20h + 4], eax
+
+        add         xSP, 20h
+        pop         xCX
+        pop         xAX
+        ret         4
+ %else
+        xchg        eax, [xSP + xCB]
+        push        xAX
+        call        Bs3SelFlatCodeToProtFar16 ; well behaved assembly function, only clobbers eax
+        add         xSP, 4
+        xchg        [xSP + xCB], eax
+        ret
+ %endif
+BS3_PROC_END_CMN   Bs3SwitchHlpConvFlatRetToRetfProtMode
+
+%endif ; 32 || 64
+