x86: Unify SYSENTER setup and add a 64-bit SYSENTER stack

These are boring patches. They're a cleanup, and something like them is mandatory if we want to wean the 64-bit #DB handler off IST.

The latter will be useful if we want to eliminate the IST reprogramming that we during NMIs unless we ban #DB outright inside NMIs. Even if we ban #DB inside NMI, it'll still be nice to get reduce IST usage to the bare minimum.

Andy Lutomirski (5):
x86/entry/32: Clean up enable_sep_cpu to prepare for 64-bit merge x86/entry/64, entry: Set up a valid sysenter stack and prepare for
32-bit merge
x86/entry: Merge 32-bit and 64-bit sysenter setup code x86/entry: Only allocate space for SYSENTER_stack if needed x86/entry: Replace SWAPGS_UNSAFE_STACK with SWAPGS in
entry_SYSENTER_compat

 arch/x86/entry/entry_64_compat.S |  2 +-
 arch/x86/include/asm/processor.h |  2 ++
 arch/x86/kernel/cpu/common.c     | 44 ++++++++++++++++++++++------------------
 3 files changed, 27 insertions(+), 21 deletions(-)

2.4.3