[PATCH] kprobes: bad manipulation of 2 byte opcode on x86_64

Problem:

If we put a probe onto a callq instruction and the probe is executed,
kernel panic of Bad RIP value occurs.

Root cause:

If resume_execution() found 0xff at first byte of p->ainsn.insn, it must
check the _second_ byte.  But current resume_execution check _first_ byte
again.

I changed it checks second byte of p->ainsn.insn.

Kprobes on i386 don't have this problem, because the implementation is a
little bit different from x86_64.

Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Satoshi Oshima <soshima@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>