MdePkg/Library/BaseLib/SwitchStack.c

   1 /** @file
   2   Switch Stack functions.
   3
   4   Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "BaseLibInternals.h"
  10
  11 /**
  12   Transfers control to a function starting with a new stack.
  13
  14   Transfers control to the function specified by EntryPoint using the
  15   new stack specified by NewStack and passing in the parameters specified
  16   by Context1 and Context2.  Context1 and Context2 are optional and may
  17   be NULL.  The function EntryPoint must never return.  This function
  18   supports a variable number of arguments following the NewStack parameter.
  19   These additional arguments are ignored on IA-32, x64, and EBC.
  20   IPF CPUs expect one additional parameter of type VOID * that specifies
  21   the new backing store pointer.
  22
  23   If EntryPoint is NULL, then ASSERT().
  24   If NewStack is NULL, then ASSERT().
  25
  26   @param  EntryPoint  A pointer to function to call with the new stack.
  27   @param  Context1    A pointer to the context to pass into the EntryPoint
  28                       function.
  29   @param  Context2    A pointer to the context to pass into the EntryPoint
  30                       function.
  31   @param  NewStack    A pointer to the new stack to use for the EntryPoint
  32                       function.
  33   @param  ...         This variable argument list is ignored for IA32, x64, and EBC.
  34                       For IPF, this variable argument list is expected to contain
  35                       a single parameter of type VOID * that specifies the new backing
  36                       store pointer.
  37
  38
  39 **/
  40 VOID
  41 EFIAPI
  42 SwitchStack (
  43   IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
  44   IN      VOID                      *Context1,  OPTIONAL
  45   IN      VOID                      *Context2,  OPTIONAL
  46   IN      VOID                      *NewStack,
  47   ...
  48   )
  49 {
  50   VA_LIST    Marker;
  51
  52   ASSERT (EntryPoint != NULL);
  53   ASSERT (NewStack != NULL);
  54
  55   //
  56   // New stack must be aligned with CPU_STACK_ALIGNMENT
  57   //
  58   ASSERT (((UINTN)NewStack & (CPU_STACK_ALIGNMENT - 1)) == 0);
  59
  60   VA_START (Marker, NewStack);
  61
  62   InternalSwitchStack (EntryPoint, Context1, Context2, NewStack, Marker);
  63
  64   VA_END (Marker);
  65
  66   //
  67   // InternalSwitchStack () will never return
  68   //
  69   ASSERT (FALSE);
  70 }