x86/unwind: Show function name+offset in ORC error messages

Improve the warning messages to show the relevant function name+offset.
This makes it much easier to diagnose problems with the ORC metadata.

Before:

  WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b

After:

  WARNING: can't dereference iret registers at ffff880178f5ffe0 for ip int3+0x5b/0x60

Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: ee9f8fce ("x86/unwind: Add the ORC unwinder")
Link: http://lkml.kernel.org/r/6bada6b9eac86017e16bd79e1e77877935cb50bb.1508516398.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>