From: Jeff Dike <jdike@addtoit.com>
To: "Stroesser, Bodo" <Bodo.Stroesser@fujitsu-siemens.com>
Cc: user-mode-linux-devel@lists.sourceforge.net,
BlaisorBlade <blaisorblade_spam@yahoo.it>
Subject: Re: [uml-devel] Signal handling: use the kernels restorer
Date: Thu, 30 Sep 2004 21:59:13 -0400 [thread overview]
Message-ID: <200410010159.i911xDqR004636@ccure.user-mode-linux.org> (raw)
In-Reply-To: Your message of "Thu, 30 Sep 2004 21:59:08 +0200." <8B6FF516CBA0194AB0996705076B02520F7C40@ABGEX01E.abg.fsc.net>
Can you fix your mailer so that it doesn't wrap patches?
I mostly applied that (by hand since it was corrupt :-).
> But if a user directly calls sys_sigaction() without glibc being
> involved (e.g. via "int 0x80"), he can reset SA_RESTORER. Now the
> kernel should use it's own restorer-stub. On i386 it's located in the
> vsyscall-page. UML must use the old method of putting it onto the
> stack. The patch modifies the signal-stack-setup to get the restorer
> on the stack working.
This is the part I didn't apply. As the comment says, gdb uses that as
a signature, and I don't want to change it for that reason. Let's just
leave it the same as as x86, even if that's wrong.
> While testing that stuff, I could crash UML by using the wrong
> systemcall-number in the restorer-stub (has been wrong for
> sys_sigreturn). I think, there is no check in sys_(rt_)sigreturn(),
> whether the contents of the stack is wrong.
If the syscall number is wrong, then it'll never hit sys_sigreturn. It
sounds like there's some other sanity-checking that's missing.
> Unfortunately at the moment I can't see, what UML prints out, because
> messages to console are not displayed (don't know why, yet). If the
> system runs, I can use dmesg, but when it is crashed ...
At gdb, printf "%s", log_buf
Jeff
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next prev parent reply other threads:[~2004-10-01 0:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-30 19:59 [uml-devel] Signal handling: use the kernels restorer Stroesser, Bodo
2004-10-01 1:59 ` Jeff Dike [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-10-01 8:57 Stroesser, Bodo
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