From 6e32a714438f3938e1fb64cb380e7fa8b0c8789a Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Thu, 24 Aug 2017 16:54:18 -0400

Subject: [PATCH] arm64: efi: remove pointless dummy .reloc section

The kernel's EFI PE/COFF header contains a dummy .reloc section, and

an explanatory comment that claims that this is required for the EFI

application loader to accept the Image as a relocatable image (i.e.,

one that can be loaded at any offset and fixed up in place)

This was inherited from the x86 implementation, which has elaborate host

tooling to mangle the PE/COFF header post-link time, and which populates

the .reloc section with a single dummy base relocation. On ARM, no such

tooling exists, and the .reloc section remains empty, and is never even

exposed via the BaseRelocationTable directory entry, which is where the

PE/COFF loader looks for it.

The PE/COFF spec is unclear about relocatable images that do not require

any fixups, but the EDK2 implementation, which is the de facto reference

for PE/COFF in the UEFI space, clearly does not care, and explicitly

mentions (in a comment) that relocatable images with no base relocations

are perfectly fine, as long as they don't have the RELOCS_STRIPPED

attribute set (which is not the case for our PE/COFF image)

So simply remove the .reloc section altogether.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Acked-by: Mark Rutland <mark.rutland@arm.com>

Acked-by: Peter Jones <pjones@redhat.com>

---

 gnuefi/crt0-efi-aarch64.S | 22 +---------------------

 1 file changed, 1 insertion(+), 21 deletions(-)

diff --git a/gnuefi/crt0-efi-aarch64.S b/gnuefi/crt0-efi-aarch64.S

index 7a9e5c2..fef997b 100644

--- a/gnuefi/crt0-efi-aarch64.S

+++ b/gnuefi/crt0-efi-aarch64.S

@@ -31,7 +31,7 @@ pe_header:

 	.short 	0

 coff_header:

 	.short	0xaa64				// AArch64

-	.short	2				// nr_sections

+	.short	1				// nr_sections

 	.long	0 				// TimeDateStamp

 	.long	0				// PointerToSymbolTable

 	.long	1				// NumberOfSymbols

@@ -85,26 +85,6 @@ extra_header_fields:

 	// 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

-- 

2.13.5