Merge branch 'core-urgent-for-linus' of git://

Pull core fixes from Thomas Gleixner:

 - A collection of objtool fixes which address recent fallout partially
   exposed by newer toolchains, clang, BPF and general code changes.

 - Force USER_DS for user stack traces

[ Note: the "objtool fixes" are not all to objtool itself, but for
  kernel code that triggers objtool warnings.

  Things like missing function size annotations, or code that confuses
  the unwinder etc.   - Linus]

* 'core-urgent-for-linus' of git:// (27 commits)
  objtool: Support conditional retpolines
  objtool: Convert insn type to enum
  objtool: Fix seg fault on bad switch table entry
  objtool: Support repeated uses of the same C jump table
  objtool: Refactor jump table code
  objtool: Refactor sibling call detection logic
  objtool: Do frame pointer check before dead end check
  objtool: Change dead_end_function() to return boolean
  objtool: Warn on zero-length functions
  objtool: Refactor function alias logic
  objtool: Track original function across branches
  objtool: Add mcsafe_handle_tail() to the uaccess safe list
  bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()
  x86/uaccess: Remove redundant CLACs in getuser/putuser error paths
  x86/uaccess: Don't leak AC flag into fentry from mcsafe_handle_tail()
  x86/uaccess: Remove ELF function annotation from copy_user_handle_tail()
  x86/head/64: Annotate start_cpu0() as non-callable
  x86/entry: Fix thunk function ELF sizes
  x86/kvm: Don't call kvm_spurious_fault() from .fixup
  x86/kvm: Replace vmx_vmenter()'s call to kvm_spurious_fault() with UD2