x86: Implement simple stack memory protection

[zephyrbot]

Reported by Andrew Boie:

Implement a simple stack protection scheme on x86.
General policy:

1. Writes to any stacks not owned by the currently running thread should pagefault
2. Writes to any memory immediately preceding the current stack should immediately pagefault

To implement #2, stacks may need to be positioned between rodata and data, such that the first byte before the first stack is read-only and will trigger a pagefault if written to.

Depends on GH-3623, GH-3531

(Imported from Jira ZEP-2188)

[zephyrbot]

by Andrew Boie:

I have a naive POC but when the stack overflows the CPU just resets.
On retrospect, this makes perfect sense since when the page fault exception hits, the x86 CPU is still trying to use the stack that overflowed, and we end up faulting infinitely.
Need to look at the best way to do an automatic stack switch when the exception hits, I think we need to set up a special TSS for exception handling or something.

[zephyrbot]

by Andrew Boie:

Moving this out to v1.10.0. Looking like we will need to implement user vs supervisor mode first, GH-3627 first. Continuing to research this.

[zephyrbot]

by Andrew Boie:

Mark Linkmeyer I think I can get this one for 1.9, a lot of progress was made this week

[zephyrbot]

by Andrew Boie:

I have this working end-to-end, but the QEMU in the SDK is broken, see GH-3827

[zephyrbot]

by Andrew Boie:

#810

[zephyrbot]

by Andrew Boie:

enabled by default for x86 QEMU targets