Commit 52982d2b authored Oct 10, 2014 by Ard Biesheuvel Committed by Kees Cook Oct 07, 2015

UPSTREAM: arm64/efi: set PE/COFF section alignment to 4 KB



Position independent AArch64 code needs to be linked and loaded at the
same relative offset from a 4 KB boundary, or adrp/add and adrp/ldr
pairs will not work correctly. (This is how PC relative symbol
references with a 4 GB reach are emitted)

We need to declare this in the PE/COFF header, otherwise the PE/COFF
loader may load the Image and invoke the stub at an offset which
violates this rule.

Reviewed-by: Roy Franz <roy.franz@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

(cherry picked from commit ea6bc80d1819f307d98c6562c8ebb2c6c1297d47)
Signed-off-by: Tomasz Figa <tfiga@chromium.org>

Bug: 24475017

Change-Id: Iae24c73314b680bf3be1dd04bd38bfa1c3209dd2
Signed-off-by: Kees Cook <keescook@google.com>

parent 7564cb65

arch/arm64/kernel/head.S

+10 −2

Original line number	Diff line number	Diff line
		@@ -161,7 +161,7 @@ optional_header:

		extra_header_fields:
		.quad 0 // ImageBase
		.long 0x20 // SectionAlignment
		.long 0x1000 // SectionAlignment
		.long 0x8 // FileAlignment
		.short 0 // MajorOperatingSystemVersion
		.short 0 // MinorOperatingSystemVersion
		@@ -228,7 +228,15 @@ section_table:
		.short 0 // NumberOfRelocations (0 for executables)
		.short 0 // NumberOfLineNumbers (0 for executables)
		.long 0xe0500020 // Characteristics (section flags)
		.align 5

		/*
		* EFI will load stext onwards at the 4k section alignment
		* described in the PE/COFF header. To ensure that instruction
		* sequences using an adrp and a :lo12: immediate will function
		* correctly at this alignment, we must ensure that stext is
		* placed at a 4k boundary in the Image to begin with.
		*/
		.align 12
		#endif

		ENTRY(stext)