This patch set cleans up the tests done to determine if a fast syscall
return instruction can be used to return to userspace.  It converts the
code to C, and refactors existing code to be more readable.

v3:
 - Remove patches already applied to -tip.
 - Keep Xen alternatives on the asm side to skip testing the return
   value.
 - Add patch to simplify canonical-RIP test.

v2:
 - Fix shift value for canonical RIP test and use
   __is_canonical_address()

Brian Gerst (3):
  x86/entry/64: Convert SYSRET validation tests to C
  x86/entry/64: Use TASK_SIZE_MAX for canonical RIP test
  x86/entry/32: Clean up syscall fast exit tests

 arch/x86/entry/common.c        | 91 ++++++++++++++++++++++++----------
 arch/x86/entry/entry_64.S      | 53 +-------------------
 arch/x86/include/asm/syscall.h |  2 +-
 3 files changed, 67 insertions(+), 79 deletions(-)

-- 
2.41.0