Function Boundary Probes

The pid provider enables you to trace function entry and return in user programs just as the FBT provider provides that capability for the kernel. Most of the examples in this manual that use the FBT provider to trace kernel function calls can be modified slightly to apply to user processes.

entry Probes

An entry probe fires when the traced function is invoked. The arguments to entry probes are the values of the arguments to the traced function.

return Probes

A return probes fires when the traced function returns or makes a tail call to another function. The value for arg0 is the offset in the function of the return instruction; arg1 holds the return value.

Note - Using argN returns the raw unfiltered values as type int64_t. The pid provider does not support the args[N] format.