Analyzing Core I9-9900K performance with Spectre and Meltdown mitigations

Re:Analyzing Core I9-9900K performance with Spectre and Melt... by roadkillon101 on Wednesday January 02, 2019 @11:22AM (#18807268)

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?

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Re:Analyzing Core I9-9900K performance with Spectre and Melt... by sigi45 on Wednesday January 02, 2019 @11:45AM (#18807506)

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.

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Re:Analyzing Core I9-9900K performance with Spectre and Melt... by __bjoernd on Wednesday January 02, 2019 @11:35AM (#18807395)

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

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Re:Analyzing Core I9-9900K performance with Spectre and Melt... by saagarjha on Wednesday January 02, 2019 @01:08PM (#18808409)

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.

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