arm64: efi: add EFI stub

This patch adds PE/COFF header fields to the start of the kernel
Image so that it appears as an EFI application to UEFI firmware.
An EFI stub is included to allow direct booting of the kernel
Image.

Signed-off-by: Mark Salter <msalter@redhat.com>
[Add support in PE/COFF header for signed images]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 0fd565000772..738291b5be29 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -108,8 +108,18 @@
         /*
          * DO NOT MODIFY. Image header expected by Linux boot-loaders.
          */
+#ifdef CONFIG_EFI
+efi_head:
+        /*
+         * This add instruction has no meaningful effect except that
+         * its opcode forms the magic "MZ" signature required by UEFI.
+         */
+        add     x13, x18, #0x16
+        b       stext
+#else
         b       stext                           // branch to kernel start, magic
         .long   0                               // reserved
+#endif
         .quad   TEXT_OFFSET                     // Image load offset from start of RAM
         .quad   0                               // reserved
         .quad   0                               // reserved
@@ -120,7 +130,109 @@
         .byte   0x52
         .byte   0x4d
         .byte   0x64
+#ifdef CONFIG_EFI
+        .long   pe_header - efi_head            // Offset to the PE header.
+#else
         .word   0                               // reserved
+#endif
+
+#ifdef CONFIG_EFI
+        .align 3
+pe_header:
+        .ascii  "PE"
+        .short  0
+coff_header:
+        .short  0xaa64                          // AArch64
+        .short  2                               // nr_sections
+        .long   0                               // TimeDateStamp
+        .long   0                               // PointerToSymbolTable
+        .long   1                               // NumberOfSymbols
+        .short  section_table - optional_header // SizeOfOptionalHeader
+        .short  0x206                           // Characteristics.
+                                                // IMAGE_FILE_DEBUG_STRIPPED |
+                                                // IMAGE_FILE_EXECUTABLE_IMAGE |
+                                                // IMAGE_FILE_LINE_NUMS_STRIPPED
+optional_header:
+        .short  0x20b                           // PE32+ format
+        .byte   0x02                            // MajorLinkerVersion
+        .byte   0x14                            // MinorLinkerVersion
+        .long   _edata - stext                  // SizeOfCode
+        .long   0                               // SizeOfInitializedData
+        .long   0                               // SizeOfUninitializedData
+        .long   efi_stub_entry - efi_head       // AddressOfEntryPoint
+        .long   stext - efi_head                // BaseOfCode
+
+extra_header_fields:
+        .quad   0                               // ImageBase
+        .long   0x20                            // SectionAlignment
+        .long   0x8                             // FileAlignment
+        .short  0                               // MajorOperatingSystemVersion
+        .short  0                               // MinorOperatingSystemVersion
+        .short  0                               // MajorImageVersion
+        .short  0                               // MinorImageVersion
+        .short  0                               // MajorSubsystemVersion
+        .short  0                               // MinorSubsystemVersion
+        .long   0                               // Win32VersionValue
+
+        .long   _edata - efi_head               // SizeOfImage
+
+        // Everything before the kernel image is considered part of the header
+        .long   stext - efi_head                // SizeOfHeaders
+        .long   0                               // CheckSum
+        .short  0xa                             // Subsystem (EFI application)
+        .short  0                               // DllCharacteristics
+        .quad   0                               // SizeOfStackReserve
+        .quad   0                               // SizeOfStackCommit
+        .quad   0                               // SizeOfHeapReserve
+        .quad   0                               // SizeOfHeapCommit
+        .long   0                               // LoaderFlags
+        .long   0x6                             // NumberOfRvaAndSizes
+
+        .quad   0                               // ExportTable
+        .quad   0                               // ImportTable
+        .quad   0                               // ResourceTable
+        .quad   0                               // ExceptionTable
+        .quad   0                               // CertificationTable
+        .quad   0                               // BaseRelocationTable
+
+        // Section table
+section_table:
+
+        /*
+         * The EFI application loader requires a relocation section
+         * because EFI applications must be relocatable.  This is a
+         * dummy section as far as we are concerned.
+         */
+        .ascii  ".reloc"
+        .byte   0
+        .byte   0                       // end of 0 padding of section name
+        .long   0
+        .long   0
+        .long   0                       // SizeOfRawData
+        .long   0                       // PointerToRawData
+        .long   0                       // PointerToRelocations
+        .long   0                       // PointerToLineNumbers
+        .short  0                       // NumberOfRelocations
+        .short  0                       // NumberOfLineNumbers
+        .long   0x42100040              // Characteristics (section flags)
+
+
+        .ascii  ".text"
+        .byte   0
+        .byte   0
+        .byte   0                       // end of 0 padding of section name
+        .long   _edata - stext          // VirtualSize
+        .long   stext - efi_head        // VirtualAddress
+        .long   _edata - stext          // SizeOfRawData
+        .long   stext - efi_head        // PointerToRawData
+
+        .long   0               // PointerToRelocations (0 for executables)
+        .long   0               // PointerToLineNumbers (0 for executables)
+        .short  0               // NumberOfRelocations  (0 for executables)
+        .short  0               // NumberOfLineNumbers  (0 for executables)
+        .long   0xe0500020      // Characteristics (section flags)
+        .align 5
+#endif
 
 ENTRY(stext)
         mov     x21, x0                         // x21=FDT