From: James Bottomley <James.Bottomley@SteelEye.com>
To: "Carlos O'Donell" <carlos@baldric.uwo.ca>
Cc: PARISC list <parisc-linux@lists.parisc-linux.org>,
Randolph Chung <tausq@debian.org>
Subject: Re: [parisc-linux] syscall restart block.
Date: 12 Sep 2004 17:36:00 -0400 [thread overview]
Message-ID: <1095024967.1990.23.camel@mulgrave> (raw)
In-Reply-To: <20040912184553.GT1854@baldric.uwo.ca>
On Sun, 2004-09-12 at 14:45, Carlos O'Donell wrote:
> The problem is that we should in general disable restartable syscalls as
> we walk the userspace return trampoline. If the user took a signal
> during the trampoline walk, the signal handler could execute a
> restartable syscall, and if that syscall was interrupted, the restorer
> function would be changed (there is only one entry for a restorer, they
> aren't chained). This means that you technically call the wrong syscall
> when you unwind from the signal that you took on the stack trampoline.
If I read this scenario correctly it can only be triggered on an SMP
system (where another user process executing on a different CPU sends a
singnal to this process) or if the process is unlucky enough to take an
interrupt while executing the trampoline ... still, the window exists
and should be plugged
> I only just realized we still had this hole and it might manifest itself
> under heavy signal load.
Precisely, because heavy load usually implies higher disc or network
interrupt load.
James
_______________________________________________
parisc-linux mailing list
parisc-linux@lists.parisc-linux.org
http://lists.parisc-linux.org/mailman/listinfo/parisc-linux
next prev parent reply other threads:[~2004-09-12 21:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-12 18:45 [parisc-linux] syscall restart block Carlos O'Donell
2004-09-12 21:36 ` James Bottomley [this message]
2004-09-13 0:05 ` [parisc-linux] " Randolph Chung
2004-09-13 16:03 ` [parisc-linux] [RFC] hppa needs a vDSO? Solves signal trampolines and opens up new possibilities 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=1095024967.1990.23.camel@mulgrave \
--to=james.bottomley@steeleye.com \
--cc=carlos@baldric.uwo.ca \
--cc=parisc-linux@lists.parisc-linux.org \
--cc=tausq@debian.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