Re: [RFC, PATCH 7/24] i386 Vmi memory hole

From: Chris Wright
Date: Wed Mar 15 2006 - 04:34:38 EST


* Zachary Amsden (zach@xxxxxxxxxx) wrote:
> >+ DEFINE(VSYSCALL_BASE, (PAGE_OFFSET - 2*PAGE_SIZE));
>
> Ok, I'm confused. What fixed math?

Sorry, bad choice of words. From above, the VYSYCALL_BASE is known
at compile time (in asm-offsets.h). So the SYSENTER_RETURN is still
fixed addr. For execshield it's truly dynamic, so you get something
like this instead of the constant SYSENTER_RETURN:

- pushl $SYSENTER_RETURN
+ pushl (TI_sysenter_return-THREAD_SIZE+8+4*4)(%esp)

thanks,
-chris
-
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