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A comment on Undocumented x86 instructions in Intel CPUs that can modify microcode. Parent comment

Re:Undocumented x86 instructions in Intel CPUs that can modi... by dooglius on Friday March 19, 2021 @10:11PM (#26520180)
This would still break SGX/remote attestation, no? The chip can correctly say it's running some piece of assembly but if "ret" has been redefined to do whatever I want...
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by strstr on Friday March 19, 2021 @11:13PM (#26520526)
The keys are stripped out if you put it into the required unlock mode.
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by userbinator on Friday March 19, 2021 @10:40PM (#26520340)
That would be a good thing, given what those features are usually used for (DRM and other user-hostility).
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by tkinom on Saturday March 20, 2021 @10:40AM (#26523523)
I would love ability to redefine call/ret to profile an app without compiler generate diff code.
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by vlovich123 on Saturday March 20, 2021 @12:51PM (#26524344)
Can’t you do that through ebpf?
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by tkinom on Saturday March 20, 2021 @01:56PM (#26524764)
My understand of ebpf can hook into the function calls in linux kernel.

Can one do that on user space app?

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Re:Undocumented x86 instructions in Intel CPUs that can modi... by vlovich123 on Saturday March 20, 2021 @02:06PM (#26524818)
Yes, that is my understanding.
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Re:Undocumented x86 instructions in Intel CPUs that can modi... by sodality2 on Friday March 19, 2021 @10:41PM (#26520345)
This is what I'm interested in since they pushed that so heavily.
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