[PATCH v3 00/19] Entry stack switching

[Andy Lutomirski]

This sets up stack switching, including for SYSCALL.  I think it's
in decent shape.

I'm fiddling with a patch to make the TSS remap read-only on 64-bit.

Known issues:
 - I think we're going to want a way to turn the stack switching on and
   off either at boot time or at runtime.  It should be fairly straightforward
   to make it work.

 - I think the ORC unwinder isn't so good at dealing with stack overflows.
   It bails too early (I think), resulting in lots of ? entries.  This
   isn't a regression with this series -- it's just something that could
   be improved.

Changes from v2:
 - Tons of review comments
 - The IDT entry stack switching code is less messy
 - The last patch is new

Changes from v1:
 - Fixed KASAN for real (as far as I can tell).
 - Compiler errors due to my old hackish KASAN fix are gone.
 - Context tracking lockdep errors are fixed (and maybe 

Changes from farther back:
 - This is quite massively changed from last time.
 - 32-bit seems to build and mostly work
 - KASAN is less broken now

Andy Lutomirski (19):
  x86/asm/64: Allocate and enable the SYSENTER stack
  x86/dumpstack: Add get_stack_info() support for the SYSENTER stack
  x86/gdt: Put per-cpu GDT remaps in ascending order
  x86/fixmap: Generalize the GDT fixmap mechanism
  x86/kasan/64: Teach KASAN about the cpu_entry_area
  x86/asm: Fix assumptions that the HW TSS is at the beginning of
    cpu_tss
  x86/dumpstack: Handle stack overflow on all stacks
  x86/asm: Move SYSENTER_stack to the beginning of struct tss_struct
  x86/asm: Remap the TSS into the cpu entry area
  x86/asm/64: Separate cpu_current_top_of_stack from TSS.sp0
  x86/espfix/64: Stop assuming that pt_regs is on the entry stack
  x86/asm/64: Use a percpu trampoline stack for IDT entries
  x86/asm/64: Return to userspace from the trampoline stack
  x86/entry/64: Create a percpu SYSCALL entry trampoline
  x86/irq: Remove an old outdated comment about context tracking races
  x86/irq/64: In the stack overflow warning, print the offending IP
  x86/entry/64: Move the IST stacks into cpu_entry_area
  x86/entry/64: Remove the SYSENTER stack canary
  x86/entry: Clean up SYSENTER_stack code

 arch/x86/entry/entry_32.S          |   6 +-
 arch/x86/entry/entry_64.S          | 170 ++++++++++++++++++++++++++++++++-----
 arch/x86/entry/entry_64_compat.S   |   7 +-
 arch/x86/include/asm/desc.h        |  11 +--
 arch/x86/include/asm/fixmap.h      |  58 ++++++++++++-
 arch/x86/include/asm/processor.h   |  49 ++++++-----
 arch/x86/include/asm/stacktrace.h  |   3 +
 arch/x86/include/asm/switch_to.h   |   2 +-
 arch/x86/include/asm/thread_info.h |   2 +-
 arch/x86/include/asm/traps.h       |   1 -
 arch/x86/kernel/asm-offsets.c      |   7 ++
 arch/x86/kernel/asm-offsets_32.c   |   5 --
 arch/x86/kernel/asm-offsets_64.c   |   1 +
 arch/x86/kernel/cpu/common.c       | 133 +++++++++++++++++++++--------
 arch/x86/kernel/doublefault.c      |  36 ++++----
 arch/x86/kernel/dumpstack.c        |  42 ++++++---
 arch/x86/kernel/dumpstack_32.c     |   6 ++
 arch/x86/kernel/dumpstack_64.c     |   6 ++
 arch/x86/kernel/irq.c              |  12 ---
 arch/x86/kernel/irq_64.c           |   4 +-
 arch/x86/kernel/process.c          |  13 ++-
 arch/x86/kernel/process_64.c       |   1 +
 arch/x86/kernel/traps.c            |  27 +++---
 arch/x86/kernel/vmlinux.lds.S      |  10 +++
 arch/x86/mm/kasan_init_64.c        |  13 ++-
 arch/x86/power/cpu.c               |  16 ++--
 arch/x86/xen/mmu_pv.c              |   2 +-
 27 files changed, 473 insertions(+), 170 deletions(-)

-- 
2.13.6