Re: [PATCH v2 resend 6/6] arm64: switch to relative exception tables

From: Andrew Morton
Date: Wed Jan 27 2016 - 14:36:30 EST

On Wed, 27 Jan 2016 11:55:23 +0100 Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:

> Instead of using absolute addresses for both the exception location
> and the fixup, use offsets relative to the exception table entry values.
> Not only does this cut the size of the exception table in half, it is
> also a prerequisite for KASLR, since absolute exception table entries
> are subject to dynamic relocation, which is incompatible with the sorting
> of the exception table that occurs at build time.
> This patch also introduces the _ASM_EXTABLE preprocessor macro (which
> exists on x86 as well) and its _asm_extable assembly counterpart, as
> shorthands to emit exception table entries.

checkpatch speaketh truth:

ERROR: #define of 'ARCH_HAS_RELATIVE_EXTABLE' is wrong - use Kconfig variables or standard guards instead
#113: FILE: arch/arm64/include/asm/uaccess.h:56: