1 files changed, 41 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.nasm b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.nasm
new file mode 100644
index 00000000..e81d4b4f
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.nasm
@@ -0,0 +1,41 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+; Portions copyright (c) 2011, Apple Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   InternalSwitchStack.nasm
+;
+; Abstract:
+;
+;   Implementation of a stack switch on IA-32.
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; InternalSwitchStack (
+;   IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
+;   IN      VOID                      *Context1,   OPTIONAL
+;   IN      VOID                      *Context2,   OPTIONAL
+;   IN      VOID                      *NewStack
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalSwitchStack)
+ASM_PFX(InternalSwitchStack):
+  push  ebp
+  mov   ebp, esp
+
+  mov   esp, [ebp + 20]    ; switch stack
+  sub   esp, 8
+  mov   eax, [ebp + 16]
+  mov   [esp + 4], eax
+  mov   eax, [ebp + 12]
+  mov   [esp], eax
+  push  0                  ; keeps gdb from unwinding stack
+  jmp   dword [ebp + 8]    ; call and never return