[roadkillon101]

How would you write a program to use these exploit? Unless I'm mistaken, I'm under the impression you have to talk directly to the processor through the kernel in order to do any of these exploit. You would have to write the code in assembler or use a special library to do predictive branching?

[sigi45]

Your code always talks directly to the cpu. Your program 'just' runs in a env where it is not allowed to do a few things the kernel is allowed to.

Probing the cpu for timings of memory access you don't have access to, or forcing it to something somewhere where you do have access to, you don't need the kernel for that. Thats the problem.

[__bjoernd]

Yes, you'd write some assembly or C. Or your start from existing demos: https://samsclass.info/123/proj14/spectre.htm

[saagarjha]

You don't need to write assembly or C; it is possible to perform an exploit by utilizing any high-resolution clock, like the one JavaScript on most browsers provided until recently.