ArmPkg/Drivers/ArmPsciMpServicesDxe/MpFuncs.S

#===============================================================================
#  Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
#
#  SPDX-License-Identifier: BSD-2-Clause-Patent
#===============================================================================

.text
.align 3

#include <AsmMacroIoLibV8.h>
#include <IndustryStandard/ArmStdSmc.h>
#include <Library/ArmLib.h>

#include "MpServicesInternal.h"

GCC_ASM_IMPORT (gApStacksBase)
GCC_ASM_IMPORT (gProcessorIDs)
GCC_ASM_IMPORT (ApProcedure)
GCC_ASM_IMPORT (gApStackSize)
GCC_ASM_IMPORT (gTcr)
GCC_ASM_IMPORT (gTtbr0)
GCC_ASM_IMPORT (gMair)

GCC_ASM_EXPORT (ApEntryPoint)

// Entry-point for the AP
// VOID
// ApEntryPoint (
//   VOID
//   );
ASM_PFX(ApEntryPoint):
  // Configure the MMU and caches
  ldr x0, gTcr
  bl ArmSetTCR
  ldr x0, gTtbr0
  bl ArmSetTTBR0
  ldr x0, gMair
  bl ArmSetMAIR
  bl ArmDisableAlignmentCheck
  bl ArmEnableStackAlignmentCheck
  bl ArmEnableInstructionCache
  bl ArmEnableDataCache
  bl ArmEnableMmu

  mrs x0, mpidr_el1
  // Mask the non-affinity bits
  bic x0, x0, 0x00ff000000
  and x0, x0, 0xffffffffff
  ldr x1, gProcessorIDs
  mov x2, 0                   // x2 = processor index

// Find index in gProcessorIDs for current processor
1:
  ldr x3, [x1, x2, lsl #3]    // x4 = gProcessorIDs + x2 * 8
  cmp x3, #-1                 // check if we've reached the end of gProcessorIDs
  beq ProcessorNotFound
  add x2, x2, 1               // x2++
  cmp x0, x3                  // if mpidr_el1 != gProcessorIDs[x] then loop
  bne 1b

// Calculate stack address
  // x2 contains the index for the current processor plus 1
  ldr x0, gApStacksBase
  ldr x1, gApStackSize
  mul x3, x2, x1              // x3 = (ProcessorIndex + 1) * gApStackSize
  add sp, x0, x3              // sp = gApStacksBase + x3
  mov x29, xzr
  bl ApProcedure              // doesn't return

ProcessorNotFound:
// Turn off the processor
  MOV32 (w0, ARM_SMC_ID_PSCI_CPU_OFF)
  smc #0
  b .