ArmPkg/Library/ArmHvcLib/Arm/ArmHvc.S

   1 //
   2 //  Copyright (c) 2012-2014, ARM Limited. All rights reserved.
   3 //  Copyright (c) 2014, Linaro Limited. All rights reserved.
   4 //
   5 //  This program and the accompanying materials
   6 //  are licensed and made available under the terms and conditions of the BSD License
   7 //  which accompanies this distribution.  The full text of the license may be found at
   8 //  http://opensource.org/licenses/bsd-license.php
   9 //
  10 //  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 //  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12 //
  13 //
  14
  15 .text
  16 .align 3
  17 .arch_extension virt
  18
  19 GCC_ASM_EXPORT(ArmCallHvc)
  20
  21 ASM_PFX(ArmCallHvc):
  22     push    {r4-r8}
  23     // r0 will be popped just after the HVC call
  24     push    {r0}
  25
  26     // Load the HVC arguments values into the appropriate registers
  27     ldr     r7, [r0, #28]
  28     ldr     r6, [r0, #24]
  29     ldr     r5, [r0, #20]
  30     ldr     r4, [r0, #16]
  31     ldr     r3, [r0, #12]
  32     ldr     r2, [r0, #8]
  33     ldr     r1, [r0, #4]
  34     ldr     r0, [r0, #0]
  35
  36     hvc     #0
  37
  38     // Pop the ARM_HVC_ARGS structure address from the stack into r8
  39     pop     {r8}
  40
  41     // Load the HVC returned values into the appropriate registers
  42     // A HVC call can return up to 4 values - we do not need to store back r4-r7.
  43     str     r3, [r8, #12]
  44     str     r2, [r8, #8]
  45     str     r1, [r8, #4]
  46     str     r0, [r8, #0]
  47
  48     mov     r0, r8
  49
  50     // Restore the registers r4-r8
  51     pop     {r4-r8}
  52
  53     bx      lr