ArmPkg/Library/ArmSvcLib/Arm/ArmSvc.asm

   1 //
   2 //  Copyright (c) 2016 - 2017, ARM Limited. All rights reserved.
   3 //
   4 //  This program and the accompanying materials
   5 //  are licensed and made available under the terms and conditions of the BSD License
   6 //  which accompanies this distribution.  The full text of the license may be found at
   7 //  http://opensource.org/licenses/bsd-license.php
   8 //
   9 //  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 //  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 //
  12 //
  13
  14
  15     INCLUDE AsmMacroExport.inc
  16
  17  RVCT_ASM_EXPORT ArmCallSvc
  18     // r0 will be popped just after the SVC call
  19     push     {r0, r4-r8}
  20
  21     // Load the SVC arguments values into the appropriate registers
  22     ldm     r0, {r0-r7}
  23
  24     svc     #0
  25
  26     // Load the ARM_SVC_ARGS structure address from the stack into r8
  27     ldr     r8, [sp]
  28
  29     // Load the SVC returned values into the appropriate registers
  30     // A SVC call can return up to 4 values - we do not need to store back r4-r7.
  31     stm     r8, {r0-r3}
  32
  33     mov     r0, r8
  34
  35     // Restore the registers r4-r8
  36     pop     {r1, r4-r8}
  37     bx      lr
  38
  39     END