[PATCH v2 00/18] Entry stack switching

[Andy Lutomirski <luto@kernel.org>]

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

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.

Ingo, patch 1 may be tip/urgent material.  It fixes what I think is
a bug in Xen.  I'm having a hard time testing because it's being
masked by a bigger unrelated bug that's keeping Xen from booting
when configured to hit the bug I'm fixing.  (The latter bug goes at
least back to v4.13, I think I know roughtly what's wrong, and I've
reported it to the maintainers.)

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 (18):
  x86/entry/64: Fix entry_SYSCALL_64_after_hwframe IRQ tracing
  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  x86/irq: Remove an old outdated comment about context tracking races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

 arch/x86/entry/entry_32.S          |   6 +-
 arch/x86/entry/entry_64.S          | 168 +++++++++++++++++++++++++++++++++----
 arch/x86/entry/entry_64_compat.S   |   6 +-
 arch/x86/include/asm/desc.h        |  11 +--
 arch/x86/include/asm/fixmap.h      |  55 +++++++++++-
 arch/x86/include/asm/processor.h   |  46 +++++-----
 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      |   9 ++
 arch/x86/kernel/asm-offsets_32.c   |   5 --
 arch/x86/kernel/asm-offsets_64.c   |   1 +
 arch/x86/kernel/cpu/common.c       | 136 +++++++++++++++++++++++-------
 arch/x86/kernel/doublefault.c      |  36 ++++----
 arch/x86/kernel/dumpstack.c        |  46 +++++++---
 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          |  12 ++-
 arch/x86/kernel/process_64.c       |   1 +
 arch/x86/kernel/traps.c            |  23 ++---
 arch/x86/kernel/vmlinux.lds.S      |  10 +++
 arch/x86/mm/kasan_init_64.c        |   9 +-
 arch/x86/power/cpu.c               |  16 ++--
 arch/x86/xen/mmu_pv.c              |   2 +-
 27 files changed, 480 insertions(+), 154 deletions(-)

-- 
2.13.6