PTI support for x32

Hi,

here is an updated version of my PTI enablement patches for
the x86-32 architecture. I worked in the review comments for
v3 and updated the patches here and there. The patch that
re-organized RESTORE_REGS to load segments first is dropped
now.

A notable addition in this version is the last
patch which adds debug-checks to the kernel entry/exit
points that will cause a BUG if they find a wrong CR3. The
checks can be enabled with a config-option and are for
debugging only. I used them for testing this series, the
checks did not trigger during my tests. I included the patch
because I am not sure whether it is wanted upstream, if not,
just tell me and I'll drop it.

While at testing: I tested the patches again on a real
machine (4C/8T, 16GB RAM) and ran 'perf top' for the NMI
load, the x86 self-tests in a loop, and a -j16 kernel
compile loop in parallel for a couple of hours. This didn't
trigger any problems. I also boot-tested various
combinations of PAE/non-PAE and HIGHMEM/no-HIGHMEM, also
without any issues.

In particular, the changes to v3 are:

	* Dropped the RESTORE_REGS splitting

	* Changed the cpu_current_top_of_stack to just point
	  to tss.sp1, like it does on x86-64.

	* Simplified SAVE_ALL_NMI to just use
	  SWITCH_TO_KERNEL_CR3 now that this macro returns
	  the old cr3

	* Added a debug Kconfig option which adds checks to
	  the kernel entry/exit paths if the cpu is on the
	  expected cr3 and which will BUG if not.

	* Explicitly clear the high word of the CS slot in
	  pt_regs for hardware that doesn't do it for us.

There is also a again branch with these patches on git.kernel.org:

	  git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git pti-x32-v4

The previous version of this patch-set can be found at:

	* For v3:
	  Post : https://marc.info/?l=linux-kernel&m=152024559419876&...
	  Git  : git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git pti-x32-v3

	* For v2:
	  Post : https://marc.info/?l=linux-kernel&m=151816914932088&...
	  Git  : git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git pti-x32-v2

Please review.

Thanks,

	Joerg

Joerg Roedel (35):
  x86/asm-offsets: Move TSS_sp0 and TSS_sp1 to asm-offsets.c
  x86/entry/32: Rename TSS_sysenter_sp0 to TSS_entry_stack
  x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler
  x86/entry/32: Put ESPFIX code into a macro
  x86/entry/32: Unshare NMI return path
  x86/entry/32: Split off return-to-kernel path
  x86/entry/32: Enter the kernel via trampoline stack
  x86/entry/32: Leave the kernel via trampoline stack
  x86/entry/32: Introduce SAVE_ALL_NMI and RESTORE_ALL_NMI
  x86/entry/32: Handle Entry from Kernel-Mode on Entry-Stack
  x86/entry/32: Simplify debug entry point
  x86/32: Use tss.sp1 as cpu_current_top_of_stack
  x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points
  x86/entry/32: Add PTI cr3 switches to NMI handler code
  x86/pgtable: Rename pti_set_user_pgd to pti_set_user_pgtbl
  x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled
  x86/pgtable/32: Allocate 8k page-tables when PTI is enabled
  x86/pgtable: Move pgdp kernel/user conversion functions to pgtable.h
  x86/pgtable: Move pti_set_user_pgtbl() to pgtable.h
  x86/pgtable: Move two more functions from pgtable_64.h to pgtable.h
  x86/mm/pae: Populate valid user PGD entries
  x86/mm/pae: Populate the user page-table with user pgd's
  x86/mm/legacy: Populate the user page-table with user pgd's
  x86/mm/pti: Add an overflow check to pti_clone_pmds()
  x86/mm/pti: Define X86_CR3_PTI_PCID_USER_BIT on x86_32
  x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32
  x86/mm/dump_pagetables: Define INIT_PGD
  x86/pgtable/pae: Use separate kernel PMDs for user page-table
  x86/ldt: Reserve address-space range on 32 bit for the LDT
  x86/ldt: Define LDT_END_ADDR
  x86/ldt: Split out sanity check in map_ldt_struct()
  x86/ldt: Enable LDT user-mapping for PAE
  x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32
  x86/mm/pti: Add Warning when booting on a PCID capable CPU
  x86/entry/32: Add debug code to check entry/exit cr3

 arch/x86/Kconfig.debug                      |  12 +
 arch/x86/entry/entry_32.S                   | 640 +++++++++++++++++++++++-----
 arch/x86/include/asm/mmu_context.h          |   4 -
 arch/x86/include/asm/pgtable-2level.h       |   9 +
 arch/x86/include/asm/pgtable-2level_types.h |   3 +
 arch/x86/include/asm/pgtable-3level.h       |   7 +
 arch/x86/include/asm/pgtable-3level_types.h |   6 +-
 arch/x86/include/asm/pgtable.h              |  88 ++++
 arch/x86/include/asm/pgtable_32_types.h     |   9 +-
 arch/x86/include/asm/pgtable_64.h           |  89 +---
 arch/x86/include/asm/pgtable_64_types.h     |   4 +
 arch/x86/include/asm/pgtable_types.h        |  28 +-
 arch/x86/include/asm/processor-flags.h      |   8 +-
 arch/x86/include/asm/processor.h            |   4 -
 arch/x86/include/asm/switch_to.h            |   6 +-
 arch/x86/include/asm/thread_info.h          |   2 -
 arch/x86/kernel/asm-offsets.c               |   5 +
 arch/x86/kernel/asm-offsets_32.c            |   2 +-
 arch/x86/kernel/asm-offsets_64.c            |   2 -
 arch/x86/kernel/cpu/common.c                |   9 +-
 arch/x86/kernel/head_32.S                   |  20 +-
 arch/x86/kernel/ldt.c                       | 137 ++++--
 arch/x86/kernel/process.c                   |   2 -
 arch/x86/kernel/process_32.c                |   4 +-
 arch/x86/mm/dump_pagetables.c               |  21 +-
 arch/x86/mm/pgtable.c                       | 105 ++++-
 arch/x86/mm/pti.c                           |  42 +-
 security/Kconfig                            |   2 +-
 28 files changed, 969 insertions(+), 301 deletions(-)

-- 
2.7.4