On Wed, May 18, 2022 at 06:34:18PM +0000, Song Liu wrote: > > > > On May 18, 2022, at 10:09 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > On Sun, May 15, 2022 at 10:40:48PM -0700, Song Liu wrote: > >> Introduce a memset like API for text_poke. This will be used to fill the > >> unused RX memory with illegal instructions. > > > > FWIW, you're going to use it to set INT3 (0xCC), that's not an illegal > > instruction. INTO (0xCE) would be an illegal instruction (in 64bit > > mode). > > Hmm… we have been using INT3 as illegal/invalid/special instructions in > the JIT. I guess they are equally good for this job? INT3 is right, it's just not illegal. Terminology is everything :-) INT3 is the breakpoint instruction, it raises #BP, an illegal instruction would raise #UD. Different exception vectors and such.
