ArmPlatformPkg: clear frame pointer in startup code

[mirror_edk2.git] / ArmPlatformPkg / PrePeiCore / AArch64 / PrePeiCoreEntryPoint.S

//\r
//  Copyright (c) 2011-2014, ARM Limited. All rights reserved.\r
//\r
//  This program and the accompanying materials\r
//  are licensed and made available under the terms and conditions of the BSD License\r
//  which accompanies this distribution.  The full text of the license may be found at\r
//  http://opensource.org/licenses/bsd-license.php\r
//\r
//  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
//  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
//\r
//\r
\r
#include <AsmMacroIoLibV8.h>\r
\r
ASM_FUNC(_ModuleEntryPoint)\r
  // Do early platform specific actions\r
  bl    ASM_PFX(ArmPlatformPeiBootAction)\r
\r
// NOTE: We could be booting from EL3, EL2 or EL1. Need to correctly detect\r
//       and configure the system accordingly. EL2 is default if possible.\r
// If we started in EL3 we need to switch and run at EL2.\r
// If we are running at EL2 stay in EL2\r
// If we are starting at EL1 stay in EL1.\r
\r
// If started at EL3 Sec is run and switches to EL2 before jumping to PEI.\r
// If started at EL1 or EL2 Sec jumps directly to PEI without making any\r
// changes.\r
\r
// Which EL are we running at? Every EL needs some level of setup...\r
// We should not run this code in EL3\r
  EL1_OR_EL2(x0)\r
1:bl    ASM_PFX(SetupExceptionLevel1)\r
  b     ASM_PFX(MainEntryPoint)\r
2:bl    ASM_PFX(SetupExceptionLevel2)\r
  b     ASM_PFX(MainEntryPoint)\r
\r
ASM_PFX(MainEntryPoint):\r
  // Identify CPU ID\r
  bl    ASM_PFX(ArmReadMpidr)\r
  // Keep a copy of the MpId register value\r
  mov   x5, x0\r
\r
  // Is it the Primary Core ?\r
  bl    ASM_PFX(ArmPlatformIsPrimaryCore)\r
\r
  // Get the top of the primary stacks (and the base of the secondary stacks)\r
  MOV64 (x1, FixedPcdGet64(PcdCPUCoresStackBase) + FixedPcdGet32(PcdCPUCorePrimaryStackSize))\r
\r
  // x0 is equal to 1 if I am the primary core\r
  cmp   x0, #1\r
  b.eq   _SetupPrimaryCoreStack\r
\r
_SetupSecondaryCoreStack:\r
  // x1 contains the base of the secondary stacks\r
\r
  // Get the Core Position\r
  mov   x6, x1      // Save base of the secondary stacks\r
  mov   x0, x5\r
  bl    ASM_PFX(ArmPlatformGetCorePosition)\r
  // The stack starts at the top of the stack region. Add '1' to the Core Position to get the top of the stack\r
  add   x0, x0, #1\r
\r
  // StackOffset = CorePos * StackSize\r
  MOV32 (x2, FixedPcdGet32(PcdCPUCoreSecondaryStackSize))\r
  mul   x0, x0, x2\r
  // SP = StackBase + StackOffset\r
  add   sp, x6, x0\r
\r
_PrepareArguments:\r
  // The PEI Core Entry Point has been computed by GenFV and stored in the second entry of the Reset Vector\r
  MOV64 (x2, FixedPcdGet64(PcdFvBaseAddress))\r
  ldr   x1, [x2, #8]\r
\r
  // Move sec startup address into a data register\r
  // Ensure we're jumping to FV version of the code (not boot remapped alias)\r
  ldr   x3, =ASM_PFX(CEntryPoint)\r
\r
  // Set the frame pointer to NULL so any backtraces terminate here\r
  mov   x29, xzr\r
\r
  // Jump to PrePeiCore C code\r
  //    x0 = mp_id\r
  //    x1 = pei_core_address\r
  mov   x0, x5\r
  blr   x3\r
\r
_SetupPrimaryCoreStack:\r
  mov   sp, x1\r
  MOV64 (x8, FixedPcdGet64 (PcdCPUCoresStackBase))\r
  MOV64 (x9, FixedPcdGet32 (PcdInitValueInTempStack) |\\r
             FixedPcdGet32 (PcdInitValueInTempStack) << 32)\r
0:stp   x9, x9, [x8], #16\r
  cmp   x8, x1\r
  b.lt  0b\r
  b     _PrepareArguments\r