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A comment on A Complete Formal Semantics of x86-64 User-Level Instruction Set Architecture. Parent comment

Re:A Complete Formal Semantics of x86-64 User-Level Instruct... by schoen on Tuesday April 23, 2019 @06:49PM (#19733776)
I was going to ask if you could then fuzz a physical CPU to find CPU bugs, but sure enough, the paper authors have already been doing that!
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Re:A Complete Formal Semantics of x86-64 User-Level Instruct... by jchw on Tuesday April 23, 2019 @07:10PM (#19733933)
There was a really good Blackhat talk a year or two ago in a sort of similar vein: they developed an approach to iterate and find undocumented opcodes.

https://youtu.be/KrksBdWcZgQ

The software they developed is called Sandsifter.

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Re:A Complete Formal Semantics of x86-64 User-Level Instruct... by xelxebar on Tuesday April 23, 2019 @08:31PM (#19734444)
Oh yeah. That's Christopher Domas, the same guy that built a functioning compiler that only emits MOV instructions [0] [1].

His other talks are quite interesting, as well!

[0]:https://github.com/xoreaxeaxeax/movfuscator [1]:https://www.youtube.com/watch?v=2VF_wPkiBJY

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