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//
// Copyright (c) 2011-2013, ARM Limited. All rights reserved.
// Copyright (c) 2015-2016, Linaro Limited. All rights reserved.
//
// SPDX-License-Identifier: BSD-2-Clause-Patent
//
//
#include <AsmMacroIoLibV8.h>
ASM_FUNC(_ModuleEntryPoint)
//
// If we are booting from RAM using the Linux kernel boot protocol, x0 will
// point to the DTB image in memory. Otherwise, use the default value defined
// by the platform.
//
cbnz x0, 0f
ldr x0, PcdGet64 (PcdDeviceTreeInitialBaseAddress)
0:mov x28, x0 // preserve DTB pointer
mov x27, x1 // preserve base of image pointer
#if (FixedPcdGet32 (PcdVFPEnabled))
// Enable Floating Point. This needs to be done before entering C code, which
// may use FP/SIMD registers.
bl ArmEnableVFP
#endif
bl ASM_PFX(DiscoverDramFromDt)
// Get ID of this CPU in Multicore system
bl ASM_PFX(ArmReadMpidr)
// Keep a copy of the MpId register value
mov x20, x0
// Check if we can install the stack at the top of the System Memory or if we need
// to install the stacks at the bottom of the Firmware Device (case the FD is located
// at the top of the DRAM)
_SetupStackPosition:
// Compute Top of System Memory
ldr x1, PcdGet64 (PcdSystemMemoryBase)
ldr x2, PcdGet64 (PcdSystemMemorySize)
sub x2, x2, #1
add x1, x1, x2 // x1 = SystemMemoryTop = PcdSystemMemoryBase + PcdSystemMemorySize
// Calculate Top of the Firmware Device
ldr x2, PcdGet64 (PcdFdBaseAddress)
MOV32 (w3, FixedPcdGet32 (PcdFdSize) - 1)
add x3, x3, x2 // x3 = FdTop = PcdFdBaseAddress + PcdFdSize
// UEFI Memory Size (stacks are allocated in this region)
MOV32 (x4, FixedPcdGet32(PcdSystemMemoryUefiRegionSize))
//
// Reserve the memory for the UEFI region (contain stacks on its top)
//
// Calculate how much space there is between the top of the Firmware and the Top of the System Memory
subs x0, x1, x3 // x0 = SystemMemoryTop - FdTop
b.mi _SetupStack // Jump if negative (FdTop > SystemMemoryTop). Case when the PrePi is in XIP memory outside of the DRAM
cmp x0, x4
b.ge _SetupStack
// Case the top of stacks is the FdBaseAddress
mov x1, x2
_SetupStack:
// x1 contains the top of the stack (and the UEFI Memory)
// Because the 'push' instruction is equivalent to 'stmdb' (decrement before), we need to increment
// one to the top of the stack. We check if incrementing one does not overflow (case of DRAM at the
// top of the memory space)
adds x21, x1, #1
b.cs _SetupOverflowStack
_SetupAlignedStack:
mov x1, x21
b _GetBaseUefiMemory
_SetupOverflowStack:
// Case memory at the top of the address space. Ensure the top of the stack is EFI_PAGE_SIZE
// aligned (4KB)
and x1, x1, ~EFI_PAGE_MASK
_GetBaseUefiMemory:
// Calculate the Base of the UEFI Memory
sub x21, x1, x4
_GetStackBase:
// r1 = The top of the Mpcore Stacks
mov sp, x1
// Stack for the primary core = PrimaryCoreStack
MOV32 (x2, FixedPcdGet32(PcdCPUCorePrimaryStackSize))
sub x22, x1, x2
mov x0, x20
mov x1, x21
mov x2, x22
// Set the frame pointer to NULL so any backtraces terminate here
mov x29, xzr
// Jump to PrePiCore C code
// x0 = MpId
// x1 = UefiMemoryBase
// x2 = StacksBase
bl ASM_PFX(CEntryPoint)
_NeverReturn:
b _NeverReturn
// VOID
// DiscoverDramFromDt (
// VOID *DeviceTreeBaseAddress, // passed by loader in x0, preserved in x28
// VOID *ImageBase // passed by FDF trampoline in x1, preserved in x27
// );
ASM_PFX(DiscoverDramFromDt):
mov x29, x30 // preserve LR
//
// The base of the runtime image has been preserved in x27. Check whether
// the expected magic number can be found in the header.
//
ldr w8, .LArm64LinuxMagic
ldr w9, [x27, #0x38]
cmp w8, w9
bne .Lout
//
//
// OK, so far so good. We have confirmed that we likely have a DTB and are
// booting via the arm64 Linux boot protocol. Update the base-of-image PCD
// to the actual relocated value, and add the shift of PcdFdBaseAddress to
// PcdFvBaseAddress as well
//
adr x8, PcdGet64 (PcdFdBaseAddress)
adr x9, PcdGet64 (PcdFvBaseAddress)
ldr x6, [x8]
ldr x7, [x9]
sub x7, x7, x6
add x7, x7, x27
str x27, [x8]
str x7, [x9]
//
// The runtime address may be different from the link time address so fix
// up the PE/COFF relocations. Since we are calling a C function, use the
// window at the beginning of the FD image as a temp stack.
//
mov x0, x7
adr x1, PeCoffLoaderImageReadFromMemory
mov sp, x7
bl RelocatePeCoffImage
//
// Discover the memory size and offset from the DTB, and record in the
// respective PCDs. This will also return false if a corrupt DTB is
// encountered.
//
mov x0, x28
adr x1, PcdGet64 (PcdSystemMemoryBase)
adr x2, PcdGet64 (PcdSystemMemorySize)
bl FindMemnode
cbz x0, .Lout
//
// Copy the DTB to the slack space right after the 64 byte arm64/Linux style
// image header at the base of this image (defined in the FDF), and record the
// pointer in PcdDeviceTreeInitialBaseAddress.
//
adr x8, PcdGet64 (PcdDeviceTreeInitialBaseAddress)
add x27, x27, #0x40
str x27, [x8]
mov x0, x27
mov x1, x28
bl CopyFdt
.Lout:
ret x29
.LArm64LinuxMagic:
.byte 0x41, 0x52, 0x4d, 0x64
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