ply

ply is a light-weight dynamic tracer for Linux that leverages the kernel’s BPF VM in concert with kprobes and tracepoints to attach probes to arbitrary points in the kernel. Most tracers that generate BPF bytecode are based on the LLVM based BCC toolchain. ply on the other hand has no required external dependencies except for libc. In addition to x86_64, ply also runs on aarch64, arm, and powerpc. Adding support for more ISAs is easy.

ply follows the Little Language approach of yore, compiling ply scripts into Linux BPF programs that are attached to kprobes and tracepoints in the kernel. The scripts have a C-like syntax, heavily inspired by dtrace(1) and, by extension, awk(1).

The primary goals of ply are:

• Expose most of the BPF tracing feature-set in such a way that new scripts can be whipped up very quickly to test different hypotheses.
• Keep dependencies to a minimum. Right now Flex and Bison are required at build-time, leaving libc as the only runtime dependency. Thus, ply is well suited for embedded targets.

If you need more fine-grained control over the kernel/userspace interaction in your tracing, checkout the bcc project which compiles C programs to BPF using LLVM in combination with a python userspace recipient to give you the full six degrees of freedom.

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