arm64: mm: Allow forcing all userspace addresses to 52-bit
authorSteve Capper <steve.capper@arm.com>
Thu, 6 Dec 2018 22:50:42 +0000 (22:50 +0000)
committerWill Deacon <will.deacon@arm.com>
Mon, 10 Dec 2018 18:42:18 +0000 (18:42 +0000)
commitb9567720a1b8e739380e0241413606c056c57859
tree760f658f0fbb3ec46f0cbdaa0314245f6f094fb7
parent67e7fdfcc6824a4f768d76d89377b33baad58fad
arm64: mm: Allow forcing all userspace addresses to 52-bit

On arm64 52-bit VAs are provided to userspace when a hint is supplied to
mmap. This helps maintain compatibility with software that expects at
most 48-bit VAs to be returned.

In order to help identify software that has 48-bit VA assumptions, this
patch allows one to compile a kernel where 52-bit VAs are returned by
default on HW that supports it.

This feature is intended to be for development systems only.

Signed-off-by: Steve Capper <steve.capper@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm64/Kconfig
arch/arm64/include/asm/elf.h
arch/arm64/include/asm/processor.h