3 ms·

I've long wanted to have a way to see what actually happens inside a CPU when a set of instructions are executed. I'm pretty excited after skimming this paper a

by jf 2y ago

I've long wanted to have a way to see what actually happens inside a CPU when a set of instructions are executed. I'm pretty excited after skimming this paper as it looks like they developed a technique to automatically determine how the x86-64 instructions actually work by observing real world CPU behavior.

dzaima 2y ago
This is determining the directly observable behavior rather than anything about microarchitectural specifics.
- ddingus 2y ago
  And still quite a useful tool, particularly when exploring undocumented instructions.
fragmede 2y ago
blinkenlights might be up your alley, if you haven't seen it before. https://justine.lol/blinkenlights/ https://justine.lol/blinkenlights/
- rbanffy 2y ago
  Every computer deserves a blinking lights front panel.
westurner 2y ago
From https://news.ycombinator.com/item?id=33563857 https://news.ycombinator.com/item?id=33563857 : > Memory Debugger Valgrind > Memcheck, None: https://en.wikipedia.org/wiki/Valgrind https://en.wikipedia.org/wiki/Valgrind ; TIL Memcheck's `none` provides a traceback where the shell would normally just print "Segmentation fault" DynamoRio > Dr Memory: https://en.wikipedia.org/wiki/DynamoRIO#Dr._Memory https://en.wikipedia.org/wiki/DynamoRIO#Dr._Memory Intel Pin: https://en.wikipedia.org/wiki/Pin_(computer_program) https://en.wikipedia.org/wiki/Pin_(computer_program) https://news.ycombinator.com/item?id=22095435 https://news.ycombinator.com/item?id=22095435, : SoftICE, EPT, Hypervisor, HyperDbg, PulseDbg, BugChecker, pyvmidbg (libVMI + GDB), libVMI Python, volatilityfoundation/volatility, Google/rekall -> yara, winpmem, Microsoft/linpmem, AVML, rr, Ghidra Trace Format: https://github.com/NationalSecurityAgency/ghidra/discussions/4051 https://github.com/NationalSecurityAgency/ghidra/discussions... https://github.com/NationalSecurityAgency/ghidra/discussions/2730#discussioncomment-10424795 https://github.com/NationalSecurityAgency/ghidra/discussions... : appliepie, orange_slice, cannoli GDB can help with register introspection: https://web.stanford.edu/class/archive/cs/cs107/cs107.1202/lab7/ https://web.stanford.edu/class/archive/cs/cs107/cs107.1202/l... : > Auto-display and Printing Registers: The `info reg` command [and `info all-registers` (`i r a`)] emu86 implements X86 instructions in Python, optionally in Jupyter notebooks; still w/o X86S, SIMD, AVX-512, x86-84-v4
- westurner 2y ago
  > Valgrind `none` provides a traceback where the shell would normally just print "Segmentation fault" What would it take to get `bash` to print a --traceback after "Segmentation fault\n", and then possibly also --gdb like pytest --pdb? - [ ] ENH: bash: add valgrind `none`-style ~ --traceback after "Segmentation fault" given an env var or by default?

by jf 2y ago

dzaima 2y ago

This is determining the directly observable behavior rather than anything about microarchitectural specifics.

ddingus 2y ago
And still quite a useful tool, particularly when exploring undocumented instructions.

fragmede 2y ago

blinkenlights might be up your alley, if you haven't seen it before. https://justine.lol/blinkenlights/ https://justine.lol/blinkenlights/

rbanffy 2y ago
Every computer deserves a blinking lights front panel.

westurner 2y ago

From https://news.ycombinator.com/item?id=33563857 https://news.ycombinator.com/item?id=33563857 : > Memory Debugger Valgrind > Memcheck, None: https://en.wikipedia.org/wiki/Valgrind https://en.wikipedia.org/wiki/Valgrind ; TIL Memcheck's `none` provides a traceback where the shell would normally just print "Segmentation fault" DynamoRio > Dr Memory: https://en.wikipedia.org/wiki/DynamoRIO#Dr._Memory https://en.wikipedia.org/wiki/DynamoRIO#Dr._Memory Intel Pin: https://en.wikipedia.org/wiki/Pin_(computer_program) https://en.wikipedia.org/wiki/Pin_(computer_program) https://news.ycombinator.com/item?id=22095435 https://news.ycombinator.com/item?id=22095435, : SoftICE, EPT, Hypervisor, HyperDbg, PulseDbg, BugChecker, pyvmidbg (libVMI + GDB), libVMI Python, volatilityfoundation/volatility, Google/rekall -> yara, winpmem, Microsoft/linpmem, AVML, rr, Ghidra Trace Format: https://github.com/NationalSecurityAgency/ghidra/discussions/4051 https://github.com/NationalSecurityAgency/ghidra/discussions... https://github.com/NationalSecurityAgency/ghidra/discussions/2730#discussioncomment-10424795 https://github.com/NationalSecurityAgency/ghidra/discussions... : appliepie, orange_slice, cannoli GDB can help with register introspection: https://web.stanford.edu/class/archive/cs/cs107/cs107.1202/lab7/ https://web.stanford.edu/class/archive/cs/cs107/cs107.1202/l... : > Auto-display and Printing Registers: The `info reg` command [and `info all-registers` (`i r a`)] emu86 implements X86 instructions in Python, optionally in Jupyter notebooks; still w/o X86S, SIMD, AVX-512, x86-84-v4

westurner 2y ago
> Valgrind `none` provides a traceback where the shell would normally just print "Segmentation fault" What would it take to get `bash` to print a --traceback after "Segmentation fault\n", and then possibly also --gdb like pytest --pdb? - [ ] ENH: bash: add valgrind `none`-style ~ --traceback after "Segmentation fault" given an env var or by default?