[PATCH v2 0/6] x86/cfi: Fix FineIBT

[Peter Zijlstra]

Hi!

Alyssa reported a FineIBT issue (patch 6) which led to the discovery of
a kCFI issue (patch 5) and a bunch of cleanups and enhancements (the
rest).

Backports can probably suffice with just the last two.

Much thanks to Brian for the better ret_from_fork() cleanup.

Tested using llvm-16 on an Alderlake with both FineIBT and kCFI.

Also available at:

  git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/urgent

(I'm aiming for the merge window, not this cycle)

v1: https://lkml.kernel.org/r/20230615193546.949657149@xxxxxxxxxxxxx

---
 arch/um/kernel/um_arch.c             |  2 +-
 arch/x86/entry/entry_32.S            | 54 +++++++---------------------
 arch/x86/entry/entry_64.S            | 35 ++++++------------
 arch/x86/include/asm/alternative.h   |  2 +-
 arch/x86/include/asm/ibt.h           |  2 +-
 arch/x86/include/asm/nospec-branch.h |  4 +++
 arch/x86/include/asm/switch_to.h     |  4 ++-
 arch/x86/kernel/alternative.c        | 69 +++++++++++++++++++++++++++++++++---
 arch/x86/kernel/module.c             |  2 +-
 arch/x86/kernel/process.c            | 22 +++++++++++-
 10 files changed, 120 insertions(+), 76 deletions(-)