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

To:	Zachary Amsden <zach@xxxxxxxxxx>
Subject:	[Xen-devel] Re: [RFC, PATCH 7/24] i386 Vmi memory hole
From:	Chris Wright <chrisw@xxxxxxxxxxxx>
Date:	Wed, 15 Mar 2006 01:41:49 -0800
Cc:	Andrew Morton <akpm@xxxxxxxx>, Joshua LeVasseur <jtl@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Pratap Subrahmanyam <pratap@xxxxxxxxxx>, Wim Coekaerts <wim.coekaerts@xxxxxxxxxx>, Jack Lo <jlo@xxxxxxxxxx>, Dan Hecht <dhecht@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>, Christopher Li <chrisl@xxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxxxxxx>, Virtualization Mailing List <virtualization@xxxxxxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxx>, Anne Holler <anne@xxxxxxxxxx>, Jyothy Reddy <jreddy@xxxxxxxxxx>, Kip Macy <kmacy@xxxxxxxxxxx>, Gerd Hoffmann <kraxel@xxxxxxx>, Leendert van Doorn <leendert@xxxxxxxxxxxxxx>, Ky Srinivasan <ksrinivasan@xxxxxxxxxx>, Dan Arai <arai@xxxxxxxxxx>
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* 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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[Xen-devel] Re: [RFC, PATCH 7/24] i386 Vmi memory hole