From: Chris Zankel <chris@zankel.net>
Date: Wed, 24 Oct 2012 20:15:21 +0000 (-0700)
Subject: xtensa: reset windowbase/windowstart when cloning the VM
X-Git-Tag: v3.7-rc4~13^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6ebe7da25b7879194fdb5c43ea67b383dd9014d6;p=pandora-kernel.git

xtensa: reset windowbase/windowstart when cloning the VM

When we copy a user thread with CLONE_VM, we also have to reset
windowbase and windowstart to start a pristine stack frame. Otherwise,
overflows can happen using the address 0 as the stack pointer.
Also add a special case for vfork, which continues on the
parent stack until it calls execve. Because this could be a call8, we
need to spill the stack pointer of the previus frame (if still 'live' in
the register file).

Signed-off-by: Chris Zankel <chris@zankel.net>
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