Rust Linux kernel code ready for CPU security issue mitigation measures

The latest Linux kernel Rust effort, led by Miguel Ojeda, prepares various CPU security mitigations for Rust kernel code. Miguel today released the latest patch for implementing various CPU security mitigations in the Rust kernel code and enabling objtool support for Rust in it.

The point is to pass the relevant compiler flags to build Rust code based on the compiler's handling of Retpolines, Rethunk, and StraightLineSpeculation (SLS).

With these patches, appropriate flags will be passed to the Rust compiler to provide adequate protection in security mitigations that require compiler-side operations.

If you are interested in CPU mitigations for RustLinux kernel code, please see this patch series. Miguel hopes to get these patches applied soon to avoid the objtool warnings that currently appear when building the kernel's Rust code.