11.6.2 pid Probe Arguments

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.

A return probe fires when the traced function returns or makes a tail call to another function. The arg1 probe argument holds the function return value.

An offset probe fires whenever execution reaches the instruction at the specified offset in the function. For example, to trace the instruction at the address 4 bytes into function main, you can use pid123:a.out:main:4. The arguments for offset probes are undefined. The uregs[] array will help you when examining the process state at these probe sites. See Section 12.5, “uregs[] Array”.