3 ms·
What does systems mean here? There is a dirty trick with a NOP and self rewriting code that's quite cheap when not triggered. I think java does it that way.
by wbl 7y ago
What does systems mean here? There is a dirty trick with a NOP and self rewriting code that's quite cheap when not triggered. I think java does it that way.
- sansnomme 7y agoElaborate?
- wbl 7y agoSo you put in a NOP before each backward jump. To preempt you overwrite it with a jump to a handler that saves the state of the thread.
- jedisct1 7y agoHow multitasking used to work on Atari :) But this requires code pages to be writable. Which, from a security perspective is awful.
- heavenlyblue 7y agoHow does that resolve syscall question?
- wbl 7y agoSyscall you have to do with a signal
- nine_k 7y agoThis presumes writable code segments, which many OSes shun.
- hyperman1 7y agoIt's java. Dynamic code generated by a jit.
- adwn 7y agoWhich NOP do you overwrite? Do you have to do this for all backward-jump-NOPs in all loaded executable code, or do you have to determine, which loop the thread in question is executing right now?