public inbox for libc-ports@sourceware.org
 help / color / mirror / Atom feed
From: "Carlos O'Donell" <carlos@redhat.com>
To: Will Newton <will.newton@linaro.org>
Cc: libc-ports@sourceware.org, patches@linaro.org
Subject: Re: [PATCH] ARM: Add pointer guard support.
Date: Wed, 25 Sep 2013 16:09:00 -0000	[thread overview]
Message-ID: <52430AA4.70703@redhat.com> (raw)
In-Reply-To: <5242A79D.1030709@linaro.org>

On 09/25/2013 05:06 AM, Will Newton wrote:
> 
> Add support for pointer mangling in glibc internal structures in C
> and assembler code.
> 
> Tested on armv7 with hard and soft thread pointers.

Have you measured the performance versus using the existing
global variable? 

TLS access on ARM is quite slow and it looks to me like it 
may be faster to use the global variable. Keep in mind that
the pointer guard and stack guard do not vary by thread.

32-bit ARM is currently using a global variable e.g.
__pointer_chk_guard, all you need to do to make it work
is adjust the definitions of PTR_MANGLE and PTR_DEMANGLE
to reference the global symbol.

This is the second proposal for ARM (first was [1] for
AArch64) to support storing the a guard in the TCB, but
nobody has responded yet to my question about performance.

Cheers,
Carlos.

[1] https://sourceware.org/ml/libc-ports/2013-08/msg00052.html

  reply	other threads:[~2013-09-25 16:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-25  9:06 Will Newton
2013-09-25 16:09 ` Carlos O'Donell [this message]
2013-09-25 16:20   ` pinskia
2013-09-25 16:23   ` Will Newton
2013-09-25 16:25     ` Carlos O'Donell
2013-09-25 16:59     ` Andrew Haley
2013-09-25 19:32       ` Will Newton
2013-09-26 15:02 ` Carlos O'Donell

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=52430AA4.70703@redhat.com \
    --to=carlos@redhat.com \
    --cc=libc-ports@sourceware.org \
    --cc=patches@linaro.org \
    --cc=will.newton@linaro.org \
    /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).