s390/ptrace: add function argument access API
Add regs_get_kernel_argument() which returns Nth argument of a
function call.
This enables ftrace kprobe events to access kernel function arguments
via $argN syntax.
This is the s390 variant of commit
a823c35ff2ed ("arm64: ptrace: Add
function argument access API").
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>