Keeping Memory Contents Secret

Re:Keeping Memory Contents Secret by PeterisP on Monday November 25, 2019 @07:46AM (#21627636)

This seems weird - the hardware has no notion of processes, that's a construct implemented by the kernel. It can enforce a separation of privileges between kernel and non-kernel, but that's about it.

Hardware gets a flag that says "am I in privileged mode now?" and it does not (and fundamentally can not) know to whether the currently running code belongs to process A or something else, or to whom a particular memory region belongs - as far as hardware is concerned, there's no "whom" at all, that's an abstract construct arbitrarily introduced and maintained by the OS.

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Re:Keeping Memory Contents Secret by hvidgaard on Wednesday November 27, 2019 @02:52AM (#21646078)

While the current crop of mainstream CPUs does not support anything like it, the idea is old. Basically the CPU need to have hardware support for a PCB and be solely responsible for context switching, and the already complex MMU needs to be context aware.

I'm pretty sure we've seen specialized CPUs in the past that did exactly that.

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Re:Keeping Memory Contents Secret by Dylan16807 on Tuesday November 26, 2019 @03:37AM (#21636530)

That's how it works right now on x86.

There's no reason hardware can't be given a notion of processes, and used to set boundaries between each other and the kernel. It's not an untested idea.

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