public inbox for gcc@gcc.gnu.org
 help / color / mirror / Atom feed
From: Alexander Monakov <amonakov@ispras.ru>
To: "Martin Liška" <mliska@suse.cz>
Cc: Fangrui Song <i@maskray.me>,
	gcc@gcc.gnu.org, Jan Hubicka <hubicka@ucw.cz>
Subject: Re: -fpatchable-function-entry: leverage multi-byte NOP on x86
Date: Mon, 06 Jan 2020 09:40:00 -0000	[thread overview]
Message-ID: <alpine.LNX.2.20.13.2001061237520.31907@monopod.intra.ispras.ru> (raw)
In-Reply-To: <7884fb3e-f26a-46b9-321a-0a78d8c01df5@suse.cz>

[-- Attachment #1: Type: text/plain, Size: 595 bytes --]

On Mon, 6 Jan 2020, Martin Liška wrote:

> You are right, we do not leverage multi-byte NOPs. Note that the support
> depends
> on a CPU model (-march) and the similar code is quite complex in binutils:
> https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gas/config/tc-i386.c;h=d0b8f2624a1885d83d2595474bfd78ae844f48f2;hb=HEAD#l1441
> 
> I'm not sure how worthy would it be to implement that?

Huh? Surely the right move would be to ask Binutils to expose that via
a new pseudo-op, like .balign but requesting a specific space rather
than aligning up to a boundary.

Alexander

      reply	other threads:[~2020-01-06  9:40 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-04 20:48 Fangrui Song
2020-01-06  8:15 ` Fangrui Song
2020-01-06  9:34 ` Martin Liška
2020-01-06  9:40   ` Alexander Monakov [this message]

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=alpine.LNX.2.20.13.2001061237520.31907@monopod.intra.ispras.ru \
    --to=amonakov@ispras.ru \
    --cc=gcc@gcc.gnu.org \
    --cc=hubicka@ucw.cz \
    --cc=i@maskray.me \
    --cc=mliska@suse.cz \
    /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).