Ptrace, utrace, uprobes: Lightweight, dynamic tracing of user apps. Linux Symposium

The ptrace system-call API, though useful for many tools such as gdb and strace, generally proves unsat-isfactory when tracing multithreaded or multi-process applications, especially in timing-dependent debugging scenarios. With the utrace kernel API, a kernel-side instrumentation module can track interesting events in traced processes. The uprobes kernel API exploits and extends utrace to provide kprobes-like, breakpoint-based probing of user applications. We describe how utrace, uprobes, and kprobes together provide an instrumentation facility that overcomes some limitations of ptrace. For attendees, familiarity with a tracing API such as ptrace or kprobes will be helpful but not essential.