Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy

From: Ingo Molnar
Date: Mon Dec 14 2015 - 03:09:23 EST



A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

* Jeff Merkey <linux.mdb@xxxxxxxxx> wrote:

> I trigger it by writing to the dr7 and dr1, 2, 3 or four register and
> set an execute breakpoint without going through
> arch_install_hw_breakpoint. When the breakpoint fires, the system
> crashes and hangs on the processor stuck in an endless loop inside the
> int1 handler in hw_breakpoint.c --

What is still not clear to me, can you trigger the hang not via some special
kernel driver that goes outside regular APIs and messes with the state of the
debug registers, but via the proper access methods, i.e. various user-space ABIs?

Thanks,

Ingo
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