From: Andi Kleen <andi@firstfloor.org>
To: "Ying Chu" <xjtuychu@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: sysenter cause a segmentation fault.
Date: 18 Mar 2007 16:51:21 +0100 [thread overview]
Message-ID: <p733b427dom.fsf@bingen.suse.de> (raw)
In-Reply-To: <b965e8580703180108t6bc50b0eg895c5464463ab09@mail.gmail.com>
"Ying Chu" <xjtuychu@gmail.com> writes:
> A simple code running on PIII 800,kernel 2.6.20 with SEP enabled
> causes a segmentation fault.
SYSENTER has a hardcoded return address, that is why you cannot be used
anywhere but in the vsyscall trampoline. In addition it doesn't work
on x86-64 for 32bit processes for AMD. The only system call method
supported without the vDSO is int 0x80. Better you just use the vDSO.
> More, when i enabled Kdb and set "bp sysenter_entry",it went with a
> catastrophic error errupted.
The stack and some other kernel state are not set up yet at this point.
-Andi
prev parent reply other threads:[~2007-03-18 14:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-18 8:08 sysenter cause a segmentation fault Ying Chu
2007-03-18 15:51 ` Andi Kleen [this message]
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