Hi Andrew,
On Thu, May 30, 2019 at 10:09:44AM -0700, Andrew Pinski wrote:
> On Thu, May 30, 2019 at 10:01 AM Tycho Andersen <ty...@tycho.ws> wrote:
> >
> > Hi all,
> >
> > I've been trying to implement an idea Andy suggested recently for
> > preventing some kinds of ROP attacks. The discussion of the idea is
> > here:
> > https://lore.kernel.org/linux-mm/dfa69954-3f0f-4b79-a9b5-893d33d87...@amacapital.net/
> >
> > Right now I'm struggling to get my plugin to compile without crashing. The
> > basic idea is to insert some code before every "pop rbp" and "pop rsp"; I've
> > figured out how to find these instructions, and I'm inserting code using:
> >
> > emit_insn(gen_rtx_XOR(DImode, gen_rtx_REG(DImode,
> > HARD_FRAME_POINTER_REGNUM),
> > gen_rtx_MEM(DImode, gen_rtx_REG(DImode,
> > HARD_FRAME_POINTER_REGNUM))));
>
> Simplely this xor does not set anything.
> I think you want something like:
> emit_insn(gen_rtx_SET(gen_rtx_REG(DImode, HARD_FRAME_POINTER_REGNUM),
> gen_rtx_XOR(DImode, gen_rtx_REG(DImode, HARD_FRAME_POINTER_REGNUM),
> gen_rtx_MEM(DImode, gen_rtx_REG(DImode, HARD_FRAME_POINTER_REGNUM)))));
>
> But that might not work either, you might need some thing more.
Yes, thanks. You're also right that I still see the same problem:
kernel/seccomp.c: In function ‘seccomp_check_filter’:
kernel/seccomp.c:242:1: error: unrecognizable insn:
}
^
(insn 698 645 699 17 (set (reg:DI 6 bp)
(xor:DI (reg:DI 6 bp)
(mem:DI (reg:DI 6 bp) [0 S8 A8]))) "kernel/seccomp.c":242 -1
(nil))
during RTL pass: shorten
kernel/seccomp.c:242:1: internal compiler error: in insn_min_length, at
config/i386/i386.md:14714
Thanks,
Tycho
