64-bit ARM Changes For Linux 4.19 Has "A Bunch Of Good Stuff"

Written by Michael Larabel in Arm on 15 August 2018 at 07:49 AM EDT. Add A Comment
ARM
Will Deacon submitted the 64-bit ARM (ARM64/AArch64) changes on Tuesday for the Linux 4.19 kernel merge window.

The 64-bit ARM space on Linux remains as busy as ever. For this next kernel cycle, Deacon characterized the changes as "a bunch of good stuff in here." That good 64-bit ARM stuff for Linux 4.19 includes:

- ARM64 support for the new GCC STACKLEAK plug-in that was merged into gcc-plugins for Linux 4.19. The STACKLEAK compiler plug-in is able to fend off possible flaws/attacks pertaining to uninitialized stack usage, stack content leaking, and stack exhaustion/guard-page skipping. This mainline kernel STACKLEAK was ported from old GrSecurity/PaX code.

- Support for the Restartable Sequences system call. This new system call was originally added in Linux 4.18 and "RSEQ" allows for faster user-space operations on per-CPU data by providing a shared data structure ABI between each user-space thread and the kernel.

- A rewrite of their syscall entry code in C in order to zero out the GPR registers on entry from user-space.

- Kexec and Kdump now work on systems started without ACPI support.

- Qspinlock to replace their old ticket lock code.

- Support for chained PMU counters.

- Re-enabled support for huge vmalloc/IO mappings.

The complete list of patches can be found via the kernel mailing list.
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