Direct, unsafe Rust bindings for Linux's perf_event_open system call

This crate exports unsafe Rust wrappers for Linux system calls for accessing performance monitoring counters and tracing facilities. This includes:

• the processor's own performance monitoring registers
• kernel counters for things like context switches and page faults
• kernel tracepoints, kprobe, and uprobes
• processor tracing facilities like Intel's Branch Trace Store (BTS)
• hardware breakpoints

This crate provides:

• a Rust wrapper the Linux perf_event_open system call
• Rust wrappers for the ioctls you can apply to a file descriptor returned by perf_event_open
• bindings for perf_event_open's associated header files, automatically generated by bindgen

All functions are direct, unsafe wrappers for the underlying calls. They operate on raw pointers and raw file descriptors.

For a type-safe API for basic functionality, see the [perf-event] crate.

Updating the System Call Bindings

The bindings module defines Rust equivalents for the types and constants used by the Linux perf_event_open system call and its related ioctls. These are generated automatically using [bindgen] from the kernel's C header files. Both the interface and the underlying functionality are quite complex, and new features are added at a steady pace. As explained in the module documentation, regenerating the bindings as needed should not break downstream crates if they are written properly.

To update the generated bindings, run the regenerate.sh script, found in the same directory as this README.md file. This runs bindgen and splices its output in the bindings module's source code, preserving the documentation.

Please also fix the comments in src/lib.rs explaining exactly which version of the kernel headers you generated the bindings from.