Uprobes is the user-space counterpart to kprobes: they
enable instrumentation applications (such as 'perf probe')
to establish unintrusive probes in user-space binaries and
libraries, by executing handler functions when the probes
are hit by user-space applications.

( These probes come in the form of single-byte breakpoints,
managed by the kernel and kept transparent to the probed
application. )

source code:

arch/x86/kernel/uprobes.c