ARM64 Patches For Linux 4.18 Roll Out With Spectre V4 Mitigation
Written by Michael Larabel in Arm on 8 June 2018 at 01:31 PM EDT. Add A Comment
ARM --
The ARM64 (64-bit ARM / AArch64) architecture updates have been submitted today for the Linux 4.18 kernel.

Arguably the most notable addition for ARM64 in Linux 4.18 is now having Spectre Variant Four mitigation after the ARM patches had been floating around in recent weeks. The ARM64 mitigation follows the x86 approach in Speculative Store Bypass Disable (SSBD) for addressing this recent CPU vulnerability. The ARM64 SSBD support relies upon an SMC firmware call to set a hardware chicken bit.

The ARM64 pull also includes ACPI Processor Properties Topology Table (PPTT) support, which exposes processor and cache topology as part of the ACPI 6.2 specification. The ACPI PPTT ARM64 patches have been floating around since last year while now are merged.

There are also updates to its perf subsystem integration, some optimizations to remove spurious wakeups, turning LSE atomics on by default, and various other cleanups and code improvements. The Large System Extensions Atomics support being enabled by default allows these LSE instructions to be used for in-kernel atomic routines and scale up to very large ARM systems.

The complete list of ARM64 patches for Linux 4.18 can be found via this pull request.
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