1// 2// Copyright (c) 2011-2013, ARM Limited. All rights reserved. 3// Copyright (c) 2015-2016, Linaro Limited. All rights reserved. 4// 5// SPDX-License-Identifier: BSD-2-Clause-Patent 6// 7// 8 9#include <AsmMacroIoLibV8.h> 10 11ASM_FUNC(_ModuleEntryPoint) 12 bl ASM_PFX(DiscoverDramFromDt) 13 14 // Get ID of this CPU in Multicore system 15 bl ASM_PFX(ArmReadMpidr) 16 // Keep a copy of the MpId register value 17 mov x20, x0 18 19// Check if we can install the stack at the top of the System Memory or if we need 20// to install the stacks at the bottom of the Firmware Device (case the FD is located 21// at the top of the DRAM) 22_SetupStackPosition: 23 // Compute Top of System Memory 24 ldr x1, PcdGet64 (PcdSystemMemoryBase) 25 ldr x2, PcdGet64 (PcdSystemMemorySize) 26 sub x2, x2, #1 27 add x1, x1, x2 // x1 = SystemMemoryTop = PcdSystemMemoryBase + PcdSystemMemorySize 28 29 // Calculate Top of the Firmware Device 30 ldr x2, PcdGet64 (PcdFdBaseAddress) 31 MOV32 (w3, FixedPcdGet32 (PcdFdSize) - 1) 32 add x3, x3, x2 // x3 = FdTop = PcdFdBaseAddress + PcdFdSize 33 34 // UEFI Memory Size (stacks are allocated in this region) 35 MOV32 (x4, FixedPcdGet32(PcdSystemMemoryUefiRegionSize)) 36 37 // 38 // Reserve the memory for the UEFI region (contain stacks on its top) 39 // 40 41 // Calculate how much space there is between the top of the Firmware and the Top of the System Memory 42 subs x0, x1, x3 // x0 = SystemMemoryTop - FdTop 43 b.mi _SetupStack // Jump if negative (FdTop > SystemMemoryTop). Case when the PrePi is in XIP memory outside of the DRAM 44 cmp x0, x4 45 b.ge _SetupStack 46 47 // Case the top of stacks is the FdBaseAddress 48 mov x1, x2 49 50_SetupStack: 51 // x1 contains the top of the stack (and the UEFI Memory) 52 53 // Because the 'push' instruction is equivalent to 'stmdb' (decrement before), we need to increment 54 // one to the top of the stack. We check if incrementing one does not overflow (case of DRAM at the 55 // top of the memory space) 56 adds x21, x1, #1 57 b.cs _SetupOverflowStack 58 59_SetupAlignedStack: 60 mov x1, x21 61 b _GetBaseUefiMemory 62 63_SetupOverflowStack: 64 // Case memory at the top of the address space. Ensure the top of the stack is EFI_PAGE_SIZE 65 // aligned (4KB) 66 and x1, x1, ~EFI_PAGE_MASK 67 68_GetBaseUefiMemory: 69 // Calculate the Base of the UEFI Memory 70 sub x21, x1, x4 71 72_GetStackBase: 73 // r1 = The top of the Mpcore Stacks 74 mov sp, x1 75 76 // Stack for the primary core = PrimaryCoreStack 77 MOV32 (x2, FixedPcdGet32(PcdCPUCorePrimaryStackSize)) 78 sub x22, x1, x2 79 80 mov x0, x20 81 mov x1, x21 82 mov x2, x22 83 84 // Set the frame pointer to NULL so any backtraces terminate here 85 mov x29, xzr 86 87 // Jump to PrePiCore C code 88 // x0 = MpId 89 // x1 = UefiMemoryBase 90 // x2 = StacksBase 91 bl ASM_PFX(CEntryPoint) 92 93_NeverReturn: 94 b _NeverReturn 95 96// VOID 97// DiscoverDramFromDt ( 98// VOID *DeviceTreeBaseAddress, // passed by loader in x0 99// VOID *ImageBase // passed by FDF trampoline in x1 100// ); 101ASM_PFX(DiscoverDramFromDt): 102 // 103 // If we are booting from RAM using the Linux kernel boot protocol, x0 will 104 // point to the DTB image in memory. Otherwise, use the default value defined 105 // by the platform. 106 // 107 cbnz x0, 0f 108 ldr x0, PcdGet64 (PcdDeviceTreeInitialBaseAddress) 109 1100:mov x29, x30 // preserve LR 111 mov x28, x0 // preserve DTB pointer 112 mov x27, x1 // preserve base of image pointer 113 114 // 115 // The base of the runtime image has been preserved in x1. Check whether 116 // the expected magic number can be found in the header. 117 // 118 ldr w8, .LArm64LinuxMagic 119 ldr w9, [x1, #0x38] 120 cmp w8, w9 121 bne .Lout 122 123 // 124 // 125 // OK, so far so good. We have confirmed that we likely have a DTB and are 126 // booting via the arm64 Linux boot protocol. Update the base-of-image PCD 127 // to the actual relocated value, and add the shift of PcdFdBaseAddress to 128 // PcdFvBaseAddress as well 129 // 130 adr x8, PcdGet64 (PcdFdBaseAddress) 131 adr x9, PcdGet64 (PcdFvBaseAddress) 132 ldr x6, [x8] 133 ldr x7, [x9] 134 sub x7, x7, x6 135 add x7, x7, x1 136 str x1, [x8] 137 str x7, [x9] 138 139 // 140 // The runtime address may be different from the link time address so fix 141 // up the PE/COFF relocations. Since we are calling a C function, use the 142 // window at the beginning of the FD image as a temp stack. 143 // 144 mov x0, x7 145 adr x1, PeCoffLoaderImageReadFromMemory 146 mov sp, x7 147 bl RelocatePeCoffImage 148 149 // 150 // Discover the memory size and offset from the DTB, and record in the 151 // respective PCDs. This will also return false if a corrupt DTB is 152 // encountered. 153 // 154 mov x0, x28 155 adr x1, PcdGet64 (PcdSystemMemoryBase) 156 adr x2, PcdGet64 (PcdSystemMemorySize) 157 bl FindMemnode 158 cbz x0, .Lout 159 160 // 161 // Copy the DTB to the slack space right after the 64 byte arm64/Linux style 162 // image header at the base of this image (defined in the FDF), and record the 163 // pointer in PcdDeviceTreeInitialBaseAddress. 164 // 165 adr x8, PcdGet64 (PcdDeviceTreeInitialBaseAddress) 166 add x27, x27, #0x40 167 str x27, [x8] 168 169 mov x0, x27 170 mov x1, x28 171 bl CopyFdt 172 173.Lout: 174 ret x29 175 176.LArm64LinuxMagic: 177 .byte 0x41, 0x52, 0x4d, 0x64 178