From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>, Josh Triplett <josh@joshtriplett.org>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>,
Jeremy Fitzhardinge <jeremy@goop.org>,
"x86@kernel.org" <x86@kernel.org>,
Len Brown <len.brown@intel.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
David Herrmann <dh.herrmann@gmail.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Seiji Aguchi <seiji.aguchi@hds.com>, Jiri Slaby <jslaby@suse.cz>,
Alok Kataria <akataria@vmware.com>,
Jesper Nilsson <jesper.nilsson@axis.com>,
Andi Kleen <ak@linux.intel.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Ingo Molnar <mingo@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
xen-devel@lists.xenproject.org, Borislav Petkov <bp@suse.de>,
Fenghua Yu <fenghua.yu@intel.com>,
Konrad
Subject: Re: [PATCH 2/3] x86: tss: Eliminate fragile calculation of TSS segment limit
Date: Wed, 30 Oct 2013 15:53:11 -0700 [thread overview]
Message-ID: <52718DD7.7040905@zytor.com> (raw)
In-Reply-To: <CAGXu5jLNhzrQHtgkW8rAm3em=aEHsTXy+DndEqLJCMH0H8n_Sg@mail.gmail.com>
On 10/30/2013 03:22 PM, Kees Cook wrote:
>>
>> - /*
>> - * sizeof(unsigned long) coming from an extra "long" at the end
>> - * of the iobitmap. See tss_struct definition in processor.h
>> - *
>> - * -1? seg base+limit should be pointing to the address of the
>> - * last valid byte
>
> I think it might be better to keep at least a minimal comment near the
> TSS_LIMIT declaration, just to explain the "-1" part, which is not
> entirely obvious from just reading the code.
>
Agreed, although it doesn't need to be an unsigned long at all... the
CPU will only ever access one extra byte past the end.
-hpa
next prev parent reply other threads:[~2013-10-30 22:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-22 2:33 [PATCH 0/3] x86: Support compiling out userspace I/O (iopl and ioperm) Josh Triplett
2013-10-22 2:34 ` [PATCH 1/3] x86: process: Unify 32-bit and 64-bit copy_thread I/O bitmap handling Josh Triplett
2013-10-30 22:21 ` Kees Cook
2013-10-31 20:01 ` Alexander van Heukelum
2013-11-01 16:33 ` Josh Triplett
2013-10-22 2:34 ` [PATCH 2/3] x86: tss: Eliminate fragile calculation of TSS segment limit Josh Triplett
2013-10-30 22:22 ` Kees Cook
2013-10-30 22:53 ` H. Peter Anvin [this message]
2013-10-31 11:17 ` Josh Triplett
2013-10-31 11:12 ` Josh Triplett
2013-10-31 20:02 ` Alexander van Heukelum
2013-11-01 16:40 ` Josh Triplett
2013-10-22 2:35 ` [PATCH 3/3] x86: Support compiling out userspace I/O (iopl and ioperm) Josh Triplett
2013-10-26 3:17 ` Stephen Hemminger
2013-10-26 4:30 ` Kees Cook
2013-10-31 20:04 ` Alexander van Heukelum
2013-11-01 17:19 ` Josh Triplett
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=52718DD7.7040905@zytor.com \
--to=hpa@zytor.com \
--cc=ak@linux.intel.com \
--cc=akataria@vmware.com \
--cc=bp@suse.de \
--cc=daniel.lezcano@linaro.org \
--cc=dh.herrmann@gmail.com \
--cc=fenghua.yu@intel.com \
--cc=fweisbec@gmail.com \
--cc=heukelum@fastmail.fm \
--cc=jeremy@goop.org \
--cc=jesper.nilsson@axis.com \
--cc=josh@joshtriplett.org \
--cc=jslaby@suse.cz \
--cc=keescook@chromium.org \
--cc=len.brown@intel.com \
--cc=masami.hiramatsu.pt@hitachi.com \
--cc=mingo@redhat.com \
--cc=paul.gortmaker@windriver.com \
--cc=raghavendra.kt@linux.vnet.ibm.com \
--cc=rostedt@goodmis.org \
--cc=seiji.aguchi@hds.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.