In this blog post, we will get into the details of the implementation of Spectre, the exploit that targets the vulnerbilities found in CPUs built by AMD, ARM, and Intel. We assume you are familiar with the concept of the attack, and you can inspect the Proof of Concept source code provided in the Appendix of the paper linked above. You might also find it easier to read this blog post with the source code side by side.
Article Link: https://blog.fortinet.com/2018/01/17/into-the-implementation-of-spectre