From: Chuck Ebbert <76306.1226@compuserve.com>
To: Gabriel Paubert <paubert@iram.es>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: desc v0.61 found a 2.5 kernel bug
Date: Sat, 10 May 2003 23:50:07 -0400 [thread overview]
Message-ID: <200305102353_MC3-1-385A-BC35@compuserve.com> (raw)
Gabriel Paubert wrote:
> The devil is in the details: you have to edit the TSS, clear the busy bit
> of the previous TSS, LTR, clear the busy bit of the debug TSS, restore
> many registers from the previous TSS image, switch to the kernel stack of
> the interrupted process, push a lot of stuff on the stack to be used by iret.
> (depending on whether you return to kernel/user/v86 modes). All of this in the
> right order, of course (and after having cleared your own NT flag).
And this is the way to do it right, but...
> Doable I believe but not simple, and there is still the TS issue.
I finally realized the TS problem is basically unsolvable. There is no
way to know what the value was before a switch happened.
(BTW some other Free kernel has interesting things in its descriptor
tables: DPL 1 execute-only code segments, conforming code, expand-down
data, multiple LDTs etc... It uncovered a bug in my code, too.)
next reply other threads:[~2003-05-11 3:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-11 3:50 Chuck Ebbert [this message]
2003-05-11 17:22 ` desc v0.61 found a 2.5 kernel bug paubert
-- strict thread matches above, loose matches on Subject: below --
2003-05-09 8:58 Chuck Ebbert
2003-04-30 20:08 Chuck Ebbert
2003-05-08 22:54 ` paubert
2003-04-30 2:33 Chuck Ebbert
2003-04-30 17:10 ` Gabriel Paubert
2003-04-27 21:09 Chuck Ebbert
2003-04-28 10:34 ` Gabriel Paubert
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