If jump target is outside of function range, perf is not handling it
correctly. Especially when target address is lesser than function start
address, target offset will be negative. But, target address declared to
be unsigned, converts negative number into 2's complement. See below
example. Here target of 'jumpq' instruction at 34cf8 is 34ac0 which is
lesser than function start address(34cf0).

        34ac0 - 34cf0 = -0x230 = 0xfffffffffffffdd0

Objdump output:

  0000000000034cf0 <__sigaction>:
  __GI___sigaction():
    34cf0: lea    -0x20(%rdi),%eax
    34cf3: cmp    -bashx1,%eax
    34cf6: jbe    34d00 <__sigaction+0x10>
    34cf8: jmpq   34ac0 <__GI___libc_sigaction>
    34cfd: nopl   (%rax)
    34d00: mov    0x386161(%rip),%rax        # 3bae68 <_DYNAMIC+0x2e8>
    34d07: movl   -bashx16,%fs:(%rax)
    34d0e: mov    -bashxffffffff,%eax
    34d13: retq

perf annotate before applying patch:

  __GI___sigaction  /usr/lib64/libc-2.22.so
           lea    -0x20(%rdi),%eax
           cmp    -bashx1,%eax
        v  jbe    10
        v  jmpq   fffffffffffffdd0
           nop
    10:    mov    _DYNAMIC+0x2e8,%rax
           movl   -bashx16,%fs:(%rax)
           mov    -bashxffffffff,%eax
           retq

perf annotate after applying patch:

  __GI___sigaction  /usr/lib64/libc-2.22.so
           lea    -0x20(%rdi),%eax
           cmp    -bashx1,%eax
        v  jbe    10
        ^  jmpq   34ac0 <__GI___libc_sigaction>
           nop
    10:    mov    _DYNAMIC+0x2e8,%rax
           movl   -bashx16,%fs:(%rax)
           mov    -bashxffffffff,%eax
           retq

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Chris Riyder <chris.ryder@arm.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Taeung Song <treeze.taeung@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1480953407-7605-3-git-send-email-ravi.bangoria@linux.vnet.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>