[RFC PATCH 2/5] livepatch: ftrace: add ftrace_function_stub_ip function

The function of ftrace_function_stub_ip is to convert the function address to the ftrace stub calling instruction address. This is needed for the platform that the complier does not support "profile before prologue" feature and the profile calling instruction is not at begin of the function.

[RFC PATCH 2/5] livepatch: ftrace: add ftrace_function_stub_ip function

The function of ftrace_function_stub_ip is to convert the function address to the ftrace stub calling instruction address. This is needed for the platform that the complier does not support profile before prologue feature and the profile calling instruction is not at begin of the function.