ArmPkg/Library/ArmSvcLib/AArch64/ArmSvc.S

   1 //
   2 //  Copyright (c) 2012 - 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 .text
  15 .align 3
  16
  17 GCC_ASM_EXPORT(ArmCallSvc)
  18
  19 ASM_PFX(ArmCallSvc):
  20   // Push frame pointer and return address on the stack
  21   stp   x29, x30, [sp, #-32]!
  22   mov   x29, sp
  23
  24   // Push x0 on the stack - The stack must always be quad-word aligned
  25   str   x0, [sp, #16]
  26
  27   // Load the SVC arguments values into the appropriate registers
  28   ldp   x6, x7, [x0, #48]
  29   ldp   x4, x5, [x0, #32]
  30   ldp   x2, x3, [x0, #16]
  31   ldp   x0, x1, [x0, #0]
  32
  33   svc   #0
  34
  35   // Pop the ARM_SVC_ARGS structure address from the stack into x9
  36   ldr   x9, [sp, #16]
  37
  38   // Store the SVC returned values into the ARM_SVC_ARGS structure.
  39   // A SVC call can return up to 4 values - we do not need to store back x4-x7.
  40   stp   x0, x1, [x9, #0]
  41   stp   x2, x3, [x9, #16]
  42
  43   mov   x0, x9
  44
  45   ldp   x29, x30, [sp], #32
  46   ret