[ Please quote correctly. I fixed this up a bit. ] On Mon, Aug 24, 2020 at 02:47:22PM +0000, Rodriguez Bahena, Victor wrote: > > The call-clobbered regs are the only ones you *can* touch. That does > > not mean you should clear them all (it doesn't help much at all in some > > cases). Only the backend knows. > > I think that for ROP mitigation purpose, we only need to clear the call-used > (i.e, call-clobbered) registers that are used in the current routine and > can pass parameters.
Which is more than you *can* do as well (consider return value registers for example; there are more cases, in general; only the backend code can know what is safe to do). Segher
