linux-stable/arch/arm64/kernel/efi-header.S
Ard Biesheuvel e0169d62ef arm64: efi: Set NX compat flag in PE/COFF header
[ Upstream commit 3c66bb1918 ]

The PE/COFF header has a NX compat flag which informs the firmware that
the application does not rely on memory regions being mapped with both
executable and writable permissions at the same time.

This is typically used by the firmware to decide whether it can set the
NX attribute on all allocations it returns, but going forward, it may be
used to enforce a policy that only permits applications with the NX flag
set to be loaded to begin wiht in some configurations, e.g., when Secure
Boot is in effect.

Even though the arm64 version of the EFI stub may relocate the kernel
before executing it, it always did so after disabling the MMU, and so we
were always in line with what the NX compat flag conveys, we just never
bothered to set it.

So let's set the flag now.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-04-06 12:10:37 +02:00

166 lines
5 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2013 - 2017 Linaro, Ltd.
* Copyright (C) 2013, 2014 Red Hat, Inc.
*/
#include <linux/pe.h>
#include <linux/sizes.h>
.macro efi_signature_nop
#ifdef CONFIG_EFI
.L_head:
/*
* This ccmp instruction has no meaningful effect except that
* its opcode forms the magic "MZ" signature required by UEFI.
*/
ccmp x18, #0, #0xd, pl
#else
/*
* Bootloaders may inspect the opcode at the start of the kernel
* image to decide if the kernel is capable of booting via UEFI.
* So put an ordinary NOP here, not the "MZ.." pseudo-nop above.
*/
nop
#endif
.endm
.macro __EFI_PE_HEADER
#ifdef CONFIG_EFI
.set .Lpe_header_offset, . - .L_head
.long PE_MAGIC
.short IMAGE_FILE_MACHINE_ARM64 // Machine
.short .Lsection_count // NumberOfSections
.long 0 // TimeDateStamp
.long 0 // PointerToSymbolTable
.long 0 // NumberOfSymbols
.short .Lsection_table - .Loptional_header // SizeOfOptionalHeader
.short IMAGE_FILE_DEBUG_STRIPPED | \
IMAGE_FILE_EXECUTABLE_IMAGE | \
IMAGE_FILE_LINE_NUMS_STRIPPED // Characteristics
.Loptional_header:
.short PE_OPT_MAGIC_PE32PLUS // PE32+ format
.byte 0x02 // MajorLinkerVersion
.byte 0x14 // MinorLinkerVersion
.long __initdata_begin - .Lefi_header_end // SizeOfCode
.long __pecoff_data_size // SizeOfInitializedData
.long 0 // SizeOfUninitializedData
.long __efistub_efi_pe_entry - .L_head // AddressOfEntryPoint
.long .Lefi_header_end - .L_head // BaseOfCode
.quad 0 // ImageBase
.long SEGMENT_ALIGN // SectionAlignment
.long PECOFF_FILE_ALIGNMENT // FileAlignment
.short 0 // MajorOperatingSystemVersion
.short 0 // MinorOperatingSystemVersion
.short LINUX_EFISTUB_MAJOR_VERSION // MajorImageVersion
.short LINUX_EFISTUB_MINOR_VERSION // MinorImageVersion
.short 0 // MajorSubsystemVersion
.short 0 // MinorSubsystemVersion
.long 0 // Win32VersionValue
.long _end - .L_head // SizeOfImage
// Everything before the kernel image is considered part of the header
.long .Lefi_header_end - .L_head // SizeOfHeaders
.long 0 // CheckSum
.short IMAGE_SUBSYSTEM_EFI_APPLICATION // Subsystem
.short IMAGE_DLL_CHARACTERISTICS_NX_COMPAT // DllCharacteristics
.quad 0 // SizeOfStackReserve
.quad 0 // SizeOfStackCommit
.quad 0 // SizeOfHeapReserve
.quad 0 // SizeOfHeapCommit
.long 0 // LoaderFlags
.long (.Lsection_table - .) / 8 // NumberOfRvaAndSizes
.quad 0 // ExportTable
.quad 0 // ImportTable
.quad 0 // ResourceTable
.quad 0 // ExceptionTable
.quad 0 // CertificationTable
.quad 0 // BaseRelocationTable
#ifdef CONFIG_DEBUG_EFI
.long .Lefi_debug_table - .L_head // DebugTable
.long .Lefi_debug_table_size
#endif
// Section table
.Lsection_table:
.ascii ".text\0\0\0"
.long __initdata_begin - .Lefi_header_end // VirtualSize
.long .Lefi_header_end - .L_head // VirtualAddress
.long __initdata_begin - .Lefi_header_end // SizeOfRawData
.long .Lefi_header_end - .L_head // PointerToRawData
.long 0 // PointerToRelocations
.long 0 // PointerToLineNumbers
.short 0 // NumberOfRelocations
.short 0 // NumberOfLineNumbers
.long IMAGE_SCN_CNT_CODE | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_EXECUTE // Characteristics
.ascii ".data\0\0\0"
.long __pecoff_data_size // VirtualSize
.long __initdata_begin - .L_head // VirtualAddress
.long __pecoff_data_rawsize // SizeOfRawData
.long __initdata_begin - .L_head // PointerToRawData
.long 0 // PointerToRelocations
.long 0 // PointerToLineNumbers
.short 0 // NumberOfRelocations
.short 0 // NumberOfLineNumbers
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_WRITE // Characteristics
.set .Lsection_count, (. - .Lsection_table) / 40
#ifdef CONFIG_DEBUG_EFI
/*
* The debug table is referenced via its Relative Virtual Address (RVA),
* which is only defined for those parts of the image that are covered
* by a section declaration. Since this header is not covered by any
* section, the debug table must be emitted elsewhere. So stick it in
* the .init.rodata section instead.
*
* Note that the EFI debug entry itself may legally have a zero RVA,
* which means we can simply put it right after the section headers.
*/
__INITRODATA
.align 2
.Lefi_debug_table:
// EFI_IMAGE_DEBUG_DIRECTORY_ENTRY
.long 0 // Characteristics
.long 0 // TimeDateStamp
.short 0 // MajorVersion
.short 0 // MinorVersion
.long IMAGE_DEBUG_TYPE_CODEVIEW // Type
.long .Lefi_debug_entry_size // SizeOfData
.long 0 // RVA
.long .Lefi_debug_entry - .L_head // FileOffset
.set .Lefi_debug_table_size, . - .Lefi_debug_table
.previous
.Lefi_debug_entry:
// EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY
.ascii "NB10" // Signature
.long 0 // Unknown
.long 0 // Unknown2
.long 0 // Unknown3
.asciz VMLINUX_PATH
.set .Lefi_debug_entry_size, . - .Lefi_debug_entry
#endif
.balign SEGMENT_ALIGN
.Lefi_header_end:
#else
.set .Lpe_header_offset, 0x0
#endif
.endm