Return a string of hex addresses that are a backtrace of the stack of the current task. Output may be truncated as per maximum string length. Returns empty string when current probe point cannot determine user backtrace. See backtrace for kernel traceback.
To get (full) backtraces for user space applications and shared shared libraries not mentioned in the current script run stap with -d /path/to/exe-or-so and/or add --ldd to load all needed unwind data.