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 // This program and the accompanying materials
   7 // are licensed and made available under the terms and conditions of the BSD License
   8 // which accompanies this distribution.  The full text of the license may be found at
   9 // http://opensource.org/licenses/bsd-license.php.
  10 //
  11 // THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 // WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 //
  14 //------------------------------------------------------------------------------
  15
  16 .text
  17 .align 5
  18
  19 GCC_ASM_EXPORT(InternalSwitchStackAsm)
  20 GCC_ASM_EXPORT(CpuPause)
  21
  22 /**
  23 //
  24 //  This allows the caller to switch the stack and goes to the new entry point
  25 //
  26 // @param      EntryPoint   The pointer to the location to enter
  27 // @param      Context      Parameter to pass in
  28 // @param      Context2     Parameter2 to pass in
  29 // @param      NewStack     New Location of the stack
  30 //
  31 // @return     Nothing. Goes to the Entry Point passing in the new parameters
  32 //
  33 VOID
  34 EFIAPI
  35 InternalSwitchStackAsm (
  36   SWITCH_STACK_ENTRY_POINT EntryPoint,
  37   VOID  *Context,
  38   VOID  *Context2,
  39   VOID  *NewStack
  40   );
  41 **/
  42 ASM_PFX(InternalSwitchStackAsm):
  43     MOV   LR, R0
  44     MOV   SP, R3
  45     MOV   R0, R1
  46     MOV   R1, R2
  47     BX    LR
  48
  49 /**
  50 //
  51 //  Requests CPU to pause for a short period of time.
  52 //
  53 //  Requests CPU to pause for a short period of time. Typically used in MP
  54 //  systems to prevent memory starvation while waiting for a spin lock.
  55 //
  56 VOID
  57 EFIAPI
  58 CpuPause (
  59   VOID
  60   )
  61 **/
  62 ASM_PFX(CpuPause):
  63     nop
  64     nop
  65     nop
  66     nop
  67     nop
  68     BX    LR