Files
system76-edk2/ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S
Ard Biesheuvel 0bcf71c13c ArmPlatformPkg: clear frame pointer in startup code
When setting up the stack in the startup code and jumping into C code
for the first time, ensure that the frame pointer register is cleared
so that backtraces terminate correctly. Otherwise, output like the
below is shown when encountering an exception on a DEBUG build:

  Synchronous Exception at 0x0000000078A14780
  PC 0x000078A14780 (0x000078A00000+0x00014780) [ 0] ArmVeNorFlashDxe.dll
  PC 0x000078A10634 (0x000078A00000+0x00010634) [ 0] ArmVeNorFlashDxe.dll
  PC 0x000078A11CF0 (0x000078A00000+0x00011CF0) [ 0] ArmVeNorFlashDxe.dll
  PC 0x000078A11DD0 (0x000078A00000+0x00011DD0) [ 0] ArmVeNorFlashDxe.dll
  PC 0x00007BC9D87C (0x00007BC98000+0x0000587C) [ 1] PartitionDxe.dll
  PC 0x00007BC99B3C (0x00007BC98000+0x00001B3C) [ 1] PartitionDxe.dll
  PC 0x00007F362F50 (0x00007F359000+0x00009F50) [ 2] DxeCore.dll
  PC 0x00007BD63BB0 (0x00007BD5B000+0x00008BB0) [ 3] BdsDxe.dll
  PC 0x00007BD6EE00 (0x00007BD5B000+0x00013E00) [ 3] BdsDxe.dll
  PC 0x00007BD67C70 (0x00007BD5B000+0x0000CC70) [ 3] BdsDxe.dll
  PC 0x00007F3724F0 (0x00007F359000+0x000194F0) [ 4] DxeCore.dll
  PC 0x00004008FC30
  PC 0x000040090130
  PC 0x5800F6025800F5E1

  Recursive exception occurred while dumping the CPU state

which is rather unhelpful, given that this prevent the remaining debug
output from being printed (register dump, stack dump, fault related
system registers etc)

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
2018-11-19 11:10:09 -08:00

97 lines
3.2 KiB
ArmAsm

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