From: Will Deacon <will.deacon@arm.com>
Date: Wed, 1 Dec 2010 17:05:24 +0000 (+0000)
Subject: ARM: hw_breakpoint: disallow per-cpu breakpoints without overflow handler
X-Git-Tag: v2.6.38-rc1~471^2^2~6^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3ce70b2e24cd35cc9f2df8cf5205b8ab4e6178e1;p=pandora-kernel.git

ARM: hw_breakpoint: disallow per-cpu breakpoints without overflow handler

Single-stepping a breakpoint requires us to disable it temporarily so that
we don't get stuck in a recursive debug trap. With per-cpu breakpoints this
presents a problem where an interrupt can be taken before the single-step has
completed and a new task is eventually scheduled. This new task will not
hit the breakpoint because it will have been disabled during the previous
handling code.

This patch disallows per-cpu breakpoints on ARM when an overflow handler
is not present. A similar effect can be created by placing breakpoints on
a shell and then running applications there.

Signed-off-by: Will Deacon <will.deacon@arm.com>
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