Re: sysenter cause a segmentation fault.
From: Andi Kleen
Date: Sun Mar 18 2007 - 10:52:45 EST
"Ying Chu" <xjtuychu@xxxxxxxxx> 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
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