KAISER: Kernel Address Isolation

KAISER: Kernel Address Isolation

This patch introduces our implementation of KAISER (Kernel Address
Isolation to have Side-channels Efficiently Removed), a kernel isolation
technique to close hardware side channels on kernel address information.

More information about the original patch can be found at:
https://github.com/IAIK/KAISER
http://marc.info/?l=linux-kernel&m=149390087310405&w=2

Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Richard Fellner <richard.fellner@student.tugraz.at>
Michael Schwarz <michael.schwarz@iaik.tugraz.at>
<clementine.maurice@iaik.tugraz.at>
<moritz.lipp@iaik.tugraz.at>

That original was then developed further by
Dave Hansen <dave.hansen@intel.com>
Hugh Dickins <hughd@google.com>
then others after this snapshot.

This combined patch for 3.2.96 was derived from hughd's patches below
for 3.18.72, in 2017-12-04's kaiser-3.18.72.tar; except for the last,
which was sent in 2017-12-09's nokaiser-3.18.72.tar.  They have been
combined in order to minimize the effort of rebasing: most of the
patches in the 3.18.72 series were small fixes and cleanups and
enhancements to three large patches.  About the only new work in this
backport is a simple reimplementation of kaiser_remove_mapping():
since mm/pageattr.c changed a lot between 3.2 and 3.18, and the
mods there for Kaiser never seemed necessary.

KAISER: Kernel Address Isolation
kaiser: merged update
kaiser: do not set _PAGE_NX on pgd_none
kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE
kaiser: fix build and FIXME in alloc_ldt_struct()
kaiser: KAISER depends on SMP
kaiser: fix regs to do_nmi() ifndef CONFIG_KAISER
kaiser: fix perf crashes
kaiser: ENOMEM if kaiser_pagetable_walk() NULL
kaiser: tidied up asm/kaiser.h somewhat
kaiser: tidied up kaiser_add/remove_mapping slightly
kaiser: kaiser_remove_mapping() move along the pgd
kaiser: align addition to x86/mm/Makefile
kaiser: cleanups while trying for gold link
kaiser: name that 0x1000 KAISER_SHADOW_PGD_OFFSET
kaiser: delete KAISER_REAL_SWITCH option
kaiser: vmstat show NR_KAISERTABLE as nr_overhead
kaiser: enhanced by kernel and user PCIDs
kaiser: load_new_mm_cr3() let SWITCH_USER_CR3 flush user
kaiser: PCID 0 for kernel and 128 for user
kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user
kaiser: paranoid_entry pass cr3 need to paranoid_exit
kaiser: _pgd_alloc() without __GFP_REPEAT to avoid stalls
kaiser: fix unlikely error in alloc_ldt_struct()
kaiser: drop is_atomic arg to kaiser_pagetable_walk()

Signed-off-by: Hugh Dickins <hughd@google.com>
[bwh:
 - Fixed the #undef in arch/x86/boot/compressed/misc.h
 - Add missing #include in arch/x86/mm/kaiser.c]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>