[PATCHv9 0/4] x86: 5-level related changes into decompression code

[Kirill A. Shutemov]

These patcheset is a preparation for boot-time switching between paging
modes. Please apply.

The first patch is pure cosmetic change: it gives file with KASLR helpers
a proper name.

The last three patches bring support of booting into 5-level paging mode if
a bootloader put the kernel above 4G.

Patch 2/4 Renames l5_paging_required() into paging_prepare() and change
interface of the function.
Patch 3/4 Handles allocation of space for trampoline and gets it prepared.
Patch 4/4 Gets trampoline used.

v9:
 - Patch 3 now saves and restores lowmem used for trampoline.

   There was report the patch causes issue on a machine. I suspect it's
   BIOS issue that doesn't report proper bounds of usable lowmem.

   Restoring memory back to oringinal state makes problem go away.
v8:
 - Support switching from 5- to 4-level paging.
v7:
 - Fix booting when 5-level paging is enabled before handing off boot to
   the kernel, like in kexec() case.

Kirill A. Shutemov (4):
  x86/boot/compressed/64: Rename pagetable.c to kaslr_64.c
  x86/boot/compressed/64: Introduce paging_prepare()
  x86/boot/compressed/64: Prepare trampoline memory
  x86/boot/compressed/64: Handle 5-level paging boot if kernel is above
    4G

 arch/x86/boot/compressed/Makefile                  |   2 +-
 arch/x86/boot/compressed/head_64.S                 | 178 ++++++++++++++-------
 .../boot/compressed/{pagetable.c => kaslr_64.c}    |   0
 arch/x86/boot/compressed/pgtable.h                 |  18 +++
 arch/x86/boot/compressed/pgtable_64.c              | 100 ++++++++++--
 5 files changed, 232 insertions(+), 66 deletions(-)
 rename arch/x86/boot/compressed/{pagetable.c => kaslr_64.c} (100%)
 create mode 100644 arch/x86/boot/compressed/pgtable.h

-- 
2.15.1