From: Andi Kleen <ak@suse.de>
To: Jamie Lokier <jamie@shareable.org>
Cc: Andi Kleen <ak@suse.de>, Pavel Machek <pavel@suse.cz>,
Kevin Lawton <kevinlawton2001@yahoo.com>,
linux-kernel@vger.kernel.org
Subject: Re: Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)?
Date: Sun, 9 Feb 2003 01:56:19 +0100 [thread overview]
Message-ID: <20030209005618.GA12369@wotan.suse.de> (raw)
In-Reply-To: <20030208193149.GA9720@bjl1.jlokier.co.uk>
> - However, DR6 bit B0 is now set.
You cannot detect it. Linux offers no way to read DR6 from user space
as far as I can see. The only way to handle break points is to catch
the signals caused by the debug exceptions.
Yo access debug registers you need to use ptrace from another process.
ptrace only ever returns cached values in tsk->thread, but the register is
never stored in there.
So in fact __switch_to could drop the loaddebug(next, 6) because it is
useless.
-Andi
next prev parent reply other threads:[~2003-02-09 0:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20030203235140.10443.qmail@web80304.mail.yahoo.com.suse.lists.linux.kernel>
2003-02-04 0:39 ` Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)? Andi Kleen
2003-02-07 16:33 ` Pavel Machek
2003-02-08 17:22 ` Andi Kleen
2003-02-08 19:31 ` Jamie Lokier
2003-02-09 0:56 ` Andi Kleen [this message]
2003-02-09 6:15 ` [PATCH] Optimisation and CONFIG_PREEMPT fix of reloading of debug registers Jamie Lokier
2003-02-03 23:51 Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)? Kevin Lawton
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=20030209005618.GA12369@wotan.suse.de \
--to=ak@suse.de \
--cc=jamie@shareable.org \
--cc=kevinlawton2001@yahoo.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pavel@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 NNTP newsgroup(s).