LinuxCon + CloudOpen + ELC-E Europe 2014

The function hook facility of ftrace is what makes ftrace stand out from other kernel tracers. The ability of live modification of the kernel to convert a nop into a ftrace callback has revolutionized tracing inside the kernel. Because it is dynamic, ftrace gives you the ability to chose what functions are to be traced, as well as tracing all functions within the kernel. This talk is not about tracing though, it is about what is coming in the future and the hurdles that needs to overcome and how it will be done. The ftrace function hooks allows for "hijacking" of a function. That is, when the function is called, the hook can intercept the call and divert it to call another function. Live patching such as kgraft and kpatch were built on this facility. To use these new features of ftrace, more must be done. This talk will go over how the hooks work and what more needs to be done.