IBM S/390 Linux 4.19 Kernel Code Sees More Spectre Updates, Boot Code Rework

The IBM System/390 "s390" architecture code has seen a number of improvements for Linux 4.19.

Highlights of the s390 code updates sent in today for the just-opened Linux 4.19 kernel merge window include:

- Continued mitigation around the Spectre speculative execution vulnerabilities for s390. This latest batch of updates include adding Expolines to a few more indirect branches among other work.

- Large page support for KVM guests.

- A large rework to the s390 early boot code to improve the integration around the Kernel Address Sanitizer "KASAN" and address space layout randomization "KASLR".

- The Linux kernel GCC plug-ins support is re-enabled for s390.

- Some cleanups of warnings generated when compiling the s390 Linux kernel under GCC 8.

- Various bug fixes and other code improvements.

Those interested in IBM s390 can find the complete list of patches for the 4.19 kernel via this pull request.