From: David S. Miller <davem@davemloft.net>
Date: Tue, 21 Sep 2010 06:24:52 +0000 (-0700)
Subject: sparc64: Fix race in signal instruction flushing.
X-Git-Tag: v2.6.36-rc6~77^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05c5e7698bdc54b3079a3517d86077f49ebcc788;p=pandora-kernel.git

sparc64: Fix race in signal instruction flushing.

If another cpu does a very wide munmap() on the signal frame area,
it can tear down the page table hierarchy from underneath us.

Borrow an idea from the 64-bit fault path's get_user_insn(), and
disable cross call interrupts during the page table traversal
to lock them in place while we operate.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
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