MdePkg/Library/BaseLib/Arm/SwitchStack.S

   1 //------------------------------------------------------------------------------
   2 //
   3 // Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   4 // Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   5 // Portions copyright (c) 2011, ARM Limited. All rights reserved.<BR>
   6 // SPDX-License-Identifier: BSD-2-Clause-Patent
   7 //
   8 //------------------------------------------------------------------------------
   9
  10 .text
  11 .align 5
  12
  13 GCC_ASM_EXPORT(InternalSwitchStackAsm)
  14 GCC_ASM_EXPORT(CpuPause)
  15
  16 /**
  17 //
  18 //  This allows the caller to switch the stack and goes to the new entry point
  19 //
  20 // @param      EntryPoint   The pointer to the location to enter
  21 // @param      Context      Parameter to pass in
  22 // @param      Context2     Parameter2 to pass in
  23 // @param      NewStack     New Location of the stack
  24 //
  25 // @return     Nothing. Goes to the Entry Point passing in the new parameters
  26 //
  27 VOID
  28 EFIAPI
  29 InternalSwitchStackAsm (
  30   SWITCH_STACK_ENTRY_POINT EntryPoint,
  31   VOID  *Context,
  32   VOID  *Context2,
  33   VOID  *NewStack
  34   );
  35 **/
  36 ASM_PFX(InternalSwitchStackAsm):
  37     MOV   LR, R0
  38     MOV   SP, R3
  39     MOV   R0, R1
  40     MOV   R1, R2
  41     BX    LR
  42
  43 /**
  44 //
  45 //  Requests CPU to pause for a short period of time.
  46 //
  47 //  Requests CPU to pause for a short period of time. Typically used in MP
  48 //  systems to prevent memory starvation while waiting for a spin lock.
  49 //
  50 VOID
  51 EFIAPI
  52 CpuPause (
  53   VOID
  54   )
  55 **/
  56 ASM_PFX(CpuPause):
  57     nop
  58     nop
  59     nop
  60     nop
  61     nop
  62     BX    LR