|author||Steve Capper <email@example.com>||2018-12-06 22:50:42 +0000|
|committer||Will Deacon <firstname.lastname@example.org>||2018-12-10 18:42:18 +0000|
|parent||arm64: mm: introduce 52-bit userspace support (diff)|
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 <email@example.com> Acked-by: Catalin Marinas <firstname.lastname@example.org> Signed-off-by: Will Deacon <email@example.com>
Diffstat (limited to '')
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 858e353b2f40..ca1f93233b22 100644
@@ -1186,6 +1186,19 @@ config ARM64_CNP
at runtime, and does not affect PEs that do not implement
+ bool "Force 52-bit virtual addresses for userspace"
+ depends on ARM64_52BIT_VA && EXPERT
+ For systems with 52-bit userspace VAs enabled, the kernel will attempt
+ to maintain compatibility with older software by providing 48-bit VAs
+ unless a hint is supplied to mmap.
+ This configuration option disables the 48-bit compatibility logic, and
+ forces all userspace addresses to be 52-bit on HW that supports it. One
+ should only enable this configuration option for stress testing userspace
+ memory management code. If unsure say N here.