From: Will Deacon <will.deacon@arm.com>
Date: Mon, 23 Jul 2012 13:18:13 +0000 (+0100)
Subject: ARM: 7479/1: mm: avoid NULL dereference when flushing gate_vma with VIVT caches
X-Git-Tag: v3.6-rc1~15^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b74253f78400f9a4b42da84bb1de7540b88ce7c4;p=pandora-kernel.git

ARM: 7479/1: mm: avoid NULL dereference when flushing gate_vma with VIVT caches

The vivt_flush_cache_{range,page} functions check that the mm_struct
of the VMA being flushed has been active on the current CPU before
performing the cache maintenance.

The gate_vma has a NULL mm_struct pointer and, as such, will cause a
kernel fault if we try to flush it with the above operations. This
happens during ELF core dumps, which include the gate_vma as it may be
useful for debugging purposes.

This patch adds checks to the VIVT cache flushing functions so that VMAs
with a NULL mm_struct are flushed unconditionally (the vectors page may
be dirty if we use it to store the current TLS pointer).

Cc: <stable@vger.kernel.org> # 3.4+
Reported-by: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Tested-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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