Solana!

eBPF instruction set architecture

• https://github.com/iovisor/bpf-docs/blob/master/eBPF.md

rust BPF (user space, usually kernel) VM

• https://github.com/solana-labs/rbpf
  • interpreter,
  • an x86_64 JIT-compiler for eBPF programs,
  • assembler,
  • disassembler*
  • verifier.
    • problems: https://github.com/solana-labs/rbpf/pull/212
    • JVM verifier: https://docs.oracle.com/javase/specs/jvms/se6/html/ClassFile.doc.html#88597
  • fuzzing
    • https://medium.com/wasmer/fuzz-testing-in-webassembly-vms-3a301f982e5a “//! This “verifier” performs simple checks when the eBPF program is loaded into the VM (before it is //! interpreted or JIT-compiled). It has nothing to do with the much more elaborated verifier inside //! Linux kernel. There is no verification regarding the program flow control (should be a Direct //! Acyclic Graph) or the consistency for registers usage (the verifier of the kernel assigns types //! to the registers and is much stricter). //! //! On the other hand, rbpf is not expected to run in kernel space. //! //! Improving the verifier would be nice, but this is not trivial (and Linux kernel is under GPL //! license, so we cannot copy it). //! //! Contrary to the verifier of the Linux kernel, this one does not modify the bytecode at all.”

Understand all this

• https://github.com/solana-labs/solana/tree/7ddf10e602d2ed87a9e3737aa8c32f1db9f909d8/sdk/program/src -https://docs.solana.com/developing/on-chain-programs/overview

examples: https://github.com/solana-labs/rbpf/tree/main/examples

• https://github.com/solana-labs/rbpf/blob/886ed9d9ac45a483a1ce64fa3eb08ed9bf556681/src/vm.rs#L424

linux kernel verifier?

• https://github.com/torvalds/linux/blob/master/kernel/bpf/verifier.c

Rust fork that can build bpf modules

• https://github.com/solana-labs/rust

LLVM fork https://github.com/solana-labs/llvm-project

JVM

• instruction verifier, type verifier (part of linking?)
• bytecode verifier
  • branches valid (static in load time)
  • data initialized and type-safe (static in load time)
  • access violations (runtime dynamic)
• verification: https://docs.oracle.com/javase/specs/jvms/se6/html/ClassFile.doc.html#88597

Links

• Upstream issue
• https://github.com/solana-labs/solana/issues/21483
• learn more OS and systems! study some distrib systems