diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2020-11-17 13:47:29 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-11-17 17:14:20 +0100 |
| commit | 7919385b9fb3cefe495310e5c44ca8a6d9c446e8 (patch) | |
| tree | 875d2aa41d96a4b68c68ed2b404791e636577c19 /arch/arm64/kernel/efi-header.S | |
| parent | arm64/head: avoid symbol names pointing into first 64 KB of kernel image (diff) | |
| download | linux-7919385b9fb3cefe495310e5c44ca8a6d9c446e8.tar.xz linux-7919385b9fb3cefe495310e5c44ca8a6d9c446e8.zip | |
arm64: head: tidy up the Image header definition
Even though support for EFI boot remains entirely optional for arm64,
it is unlikely that we will ever be able to repurpose the image header
fields that the EFI loader relies on, i.e., the magic NOP at offset
0x0 and the PE header address at offset 0x3c.
So let's factor out the differences into a 'efi_signature_nop' macro and
a local symbol representing the PE header address, and move the
conditional definitions into efi-header.S, taking into account whether
CONFIG_EFI is enabled or not. While at it, switch to a signature NOP
that behaves more like a NOP, i.e., one that only clobbers the
flags.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201117124729.12642-4-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/efi-header.S')
| -rw-r--r-- | arch/arm64/kernel/efi-header.S | 43 |
1 files changed, 33 insertions, 10 deletions
diff --git a/arch/arm64/kernel/efi-header.S b/arch/arm64/kernel/efi-header.S index ddaf57d825b5..28d8a5dca5f1 100644 --- a/arch/arm64/kernel/efi-header.S +++ b/arch/arm64/kernel/efi-header.S @@ -7,7 +7,27 @@ #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 @@ -26,8 +46,8 @@ .long __initdata_begin - .Lefi_header_end // SizeOfCode .long __pecoff_data_size // SizeOfInitializedData .long 0 // SizeOfUninitializedData - .long __efistub_efi_pe_entry - _head // AddressOfEntryPoint - .long .Lefi_header_end - _head // BaseOfCode + .long __efistub_efi_pe_entry - .L_head // AddressOfEntryPoint + .long .Lefi_header_end - .L_head // BaseOfCode .quad 0 // ImageBase .long SEGMENT_ALIGN // SectionAlignment @@ -40,10 +60,10 @@ .short 0 // MinorSubsystemVersion .long 0 // Win32VersionValue - .long _end - _head // SizeOfImage + .long _end - .L_head // SizeOfImage // Everything before the kernel image is considered part of the header - .long .Lefi_header_end - _head // SizeOfHeaders + .long .Lefi_header_end - .L_head // SizeOfHeaders .long 0 // CheckSum .short IMAGE_SUBSYSTEM_EFI_APPLICATION // Subsystem .short 0 // DllCharacteristics @@ -62,7 +82,7 @@ .quad 0 // BaseRelocationTable #ifdef CONFIG_DEBUG_EFI - .long .Lefi_debug_table - _head // DebugTable + .long .Lefi_debug_table - .L_head // DebugTable .long .Lefi_debug_table_size #endif @@ -70,9 +90,9 @@ .Lsection_table: .ascii ".text\0\0\0" .long __initdata_begin - .Lefi_header_end // VirtualSize - .long .Lefi_header_end - _head // VirtualAddress + .long .Lefi_header_end - .L_head // VirtualAddress .long __initdata_begin - .Lefi_header_end // SizeOfRawData - .long .Lefi_header_end - _head // PointerToRawData + .long .Lefi_header_end - .L_head // PointerToRawData .long 0 // PointerToRelocations .long 0 // PointerToLineNumbers @@ -84,9 +104,9 @@ .ascii ".data\0\0\0" .long __pecoff_data_size // VirtualSize - .long __initdata_begin - _head // VirtualAddress + .long __initdata_begin - .L_head // VirtualAddress .long __pecoff_data_rawsize // SizeOfRawData - .long __initdata_begin - _head // PointerToRawData + .long __initdata_begin - .L_head // PointerToRawData .long 0 // PointerToRelocations .long 0 // PointerToLineNumbers @@ -121,7 +141,7 @@ .long IMAGE_DEBUG_TYPE_CODEVIEW // Type .long .Lefi_debug_entry_size // SizeOfData .long 0 // RVA - .long .Lefi_debug_entry - _head // FileOffset + .long .Lefi_debug_entry - .L_head // FileOffset .set .Lefi_debug_table_size, . - .Lefi_debug_table .previous @@ -140,4 +160,7 @@ .balign SEGMENT_ALIGN .Lefi_header_end: +#else + .set .Lpe_header_offset, 0x0 +#endif .endm |