Messages in this thread | | | Date | Fri, 18 Sep 2009 20:44:03 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] arm: Make kprobes unregistration SMP safe |
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On Thu, Sep 17, 2009 at 08:40:10PM -0400, Nicolas Pitre wrote: > On Wed, 16 Sep 2009, Frédéric RISS wrote: > > > ARM kprobes use an illegal instruction to trigger kprobes. In the > > current implementation, there's a race between the unregistration of a > > kprobe and the illegal instruction exception handler if they run at the > > same time on different cores. > > > > When reading the value of the undefined instruction, the exception > > handler might get the original legal instruction as just patched > > concurrently by arch_disarm_kprobe(). When this happen the kprobe > > handler won't run, and thus the exception handler will oops because it > > believe it just hit an undefined instruction in kernel space. > > > > The following patch synchronizes the code patching in the kprobes > > unregistration using stop_machine and thus avoids the above race. > > > > Signed-off-by: Frederic RISS <frederic.riss@gmail.com> > > Acked-by: Nicolas Pitre <nico@fluxnic.net>
Frédéric, please submit to the patch system, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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