Debugging hardfault handlers

In my thread 1, which is HardFault_Handler when i backtrace it. Its Innermost function call @ #14 0x08011402 in _port_thread_start () not showing any file location and line number.
Why is it so, how can I examine that from where is this function being called?
I am Using GDB+Openocd+cygwin
on examining the memory I am getting this, but not getting any thoughts on where is the function _port_thread_start()