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

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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>
This commit is contained in:
Ard Biesheuvel 2014-10-10 11:25:24 +02:00
parent 95b395963f
commit ea6bc80d18
1 changed files with 10 additions and 2 deletions
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12
arch/arm64/kernel/head.S
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@ -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)