// // Copyright (c) 2011-2013, ARM Limited. All rights reserved. // Copyright (c) 2015-2016, Linaro 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 ASM_FUNC(_ModuleEntryPoint) // // We are built as a ET_DYN PIE executable, so we need to process all // relative relocations regardless of whether or not we are executing from // the same offset we were linked at. This is only possible if we are // running from RAM. // adr x8, __reloc_base adr x9, __reloc_start adr x10, __reloc_end .Lreloc_loop: cmp x9, x10 bhs .Lreloc_done // // AArch64 uses the ELF64 RELA format, which means each entry in the // relocation table consists of // // UINT64 offset : the relative offset of the value that needs to // be relocated // UINT64 info : relocation type and symbol index (the latter is // not used for R_AARCH64_RELATIVE relocations) // UINT64 addend : value to be added to the value being relocated // ldp x11, x12, [x9], #24 // read offset into x11 and info into x12 cmp x12, #0x403 // check info == R_AARCH64_RELATIVE? bne .Lreloc_loop // not a relative relocation? then skip ldr x12, [x9, #-8] // read addend into x12 add x12, x12, x8 // add reloc base to addend to get relocated value str x12, [x11, x8] // write relocated value at offset b .Lreloc_loop .Lreloc_done: 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 // 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 // VOID *ImageBase // passed by FDF trampoline in x1 // ); ASM_PFX(DiscoverDramFromDt): // // 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 x29, x30 // preserve LR mov x28, x0 // preserve DTB pointer mov x27, x1 // preserve base of image pointer // // The base of the runtime image has been preserved in x1. Check whether // the expected magic number can be found in the header. // ldr w8, .LArm64LinuxMagic ldr w9, [x1, #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, x1 str x1, [x8] str x7, [x9] // // 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. Since we are calling a C function, use the window at the // beginning of the FD image as a temp stack. // adr x1, PcdGet64 (PcdSystemMemoryBase) adr x2, PcdGet64 (PcdSystemMemorySize) mov sp, x7 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