From: Tycho Andersen <tycho@tycho.ws>
To: Andrew Pinski <pinskia@gmail.com>
Cc: GCC Mailing List <gcc@gcc.gnu.org>, kernel-hardening@lists.openwall.com
Subject: Re: unrecognizable insn generated in plugin?
Date: Thu, 30 May 2019 19:26:00 -0000 [thread overview]
Message-ID: <20190530192606.GB5739@cisco> (raw)
In-Reply-To: <CA+=Sn1kSg-Y8SseUWPTTJi5HRgYYxVtcDGUJvCcCYQQzKeiUQw@mail.gmail.com>
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 <tycho@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-A9B5-893D33D87E51@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 âseccomp_check_filterâ:
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
next prev parent reply other threads:[~2019-05-30 19:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 17:00 Tycho Andersen
2019-05-30 17:10 ` Andrew Pinski
2019-05-30 19:26 ` Tycho Andersen [this message]
2019-05-31 15:44 ` Mark Brand via gcc
2019-05-31 17:06 ` Tycho Andersen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190530192606.GB5739@cisco \
--to=tycho@tycho.ws \
--cc=gcc@gcc.gnu.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=pinskia@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).