x86: Support compiling out userspace IO (iopl and ioperm)

This patch series makes it possible to compile out the userspace IO system calls, iopl and ioperm.

The first patch does some 32/64 unification in copy_thread to make subsequent changes easier. The second patch simplifies the complex calculation of the TSS segment limit, which also makes it easier to change in the last patch. Patches 3-9 introduce helpers to make it easier to compile out IO. The last patch adds and uses the new CONFIG_X86_IOPORT to support compiling out userspace IO.

v3 had patches 3-10 as a single patch; v4 splits out the various helpers and macros into separate patches, as requested by Thomas Gleixner.

I've verified that this compiles after each patch.

Josh Triplett (10):
x86: process: Unify 32-bit and 64-bit copy_thread I/O bitmap handling
x86: tss: Eliminate fragile calculation of TSS segment limit
x86: processor.h: Introduce macros to initialize IO fields of thread
and TSS
x86: paravirt: Wrap initialization of set_iopl_mask in a macro
x86: cpu: Add helper function unifying 32-bit and 64-bit IO init in
cpu_init
x86: process: Introduce helper to clear a thread's IO bitmap
x86: process: Introduce helper to switch iopl mask
x86: process: Introduce helper for IO-related bits of exit_thread
x86: process: Introduce helper to switch IO bitmap
x86: Support compiling out userspace IO (iopl and ioperm)

 arch/x86/Kconfig                      | 10 ++++
 arch/x86/include/asm/desc.h           | 11 +----
 arch/x86/include/asm/paravirt.h       |  2 +
 arch/x86/include/asm/paravirt_types.h |  5 ++
 arch/x86/include/asm/processor.h      | 55 +++++++++++++++++----
 arch/x86/include/asm/syscalls.h       |  3 ++
 arch/x86/kernel/Makefile              |  3 +-
 arch/x86/kernel/cpu/common.c          | 12 +----
 arch/x86/kernel/entry_64.S            |  9 ++--
 arch/x86/kernel/paravirt.c            |  2 +-
 arch/x86/kernel/process-io.h          | 93 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/process.c             | 34 ++-----------
 arch/x86/kernel/process_32.c          | 41 +++++----------
 arch/x86/kernel/process_64.c          | 27 +++-------
 arch/x86/kernel/ptrace.c              |  8 +++
 arch/x86/xen/enlighten.c              |  4 +-
 drivers/tty/vt/vt_ioctl.c             |  2 +-
 kernel/sys_ni.c                       |  5 ++
 18 files changed, 208 insertions(+), 118 deletions(-)
 create mode 100644 arch/x86/kernel/process-io.h

2.1.1