PING [Patch][Middle-end]Add -fzero-call-used-regs=[skip|used-gpr|all-gpr|used|all]

[Segher Boessenkool]

On Mon, Sep 14, 2020 at 10:07:31PM -0500, Qing Zhao wrote:
> > On Sep 14, 2020, at 6:09 PM, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> >> Gadget 1:
> >> 
> >> mov  rax,  value
> >> syscall
> >> ret
> > 
> > No, just
> > 
> > mov rax,59
> > syscall
> > 
> > (no ret necessary!)
> 
> But for ROP, a typical gadget should be ended with a “ret” (or indirect branch), right?

Not the last one :-)  (Especially if it is exec!)


Segher