function::user_ulong_warn — Retrieves an unsigned long value stored in user space
user_ulong_warn:long(addr:long)
Returns the unsigned long value from a given user space address. Returns zero when user space data is not accessible and warns about the failure (but does not error). Note that the size of the unsigned long depends on the architecture of the current user space task (for those architectures that support both 64/32 bit compat tasks).