Apparently the binutils 2.20 assembler can't handle the '&&' operator in
the UNWIND_HINT_REGS macro.  Rearrange the macro to do without it.

This fixes the following error:

  arch/x86/entry/entry_64.S: Assembler messages:
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 39358a03 ("objtool, x86: Add facility for asm code to provide unwind hints")
Link: http://lkml.kernel.org/r/e2ad97c1ae49a484644b4aaa4dd3faa4d6d969b2.1502116651.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Some asm (and inline asm) code does special things to the stack which
objtool can't understand.  (Nor can GCC or GNU assembler, for that
matter.)  In such cases we need a facility for the code to provide
annotations, so the unwinder can unwind through it.

This provides such a facility, in the form of unwind hints.  They're
similar to the GNU assembler .cfi* directives, but they give more
information, and are needed in far fewer places, because objtool can
fill in the blanks by following branches and adjusting the stack pointer
for pushes and pops.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/0f5f3c9104fca559ff4088bece1d14ae3bca52d5.1499786555.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>