Messages in this thread | | | From | Doug Anderson <> | Date | Fri, 17 Jul 2020 15:39:58 -0700 | Subject | Re: [PATCH v2 3/3] kgdb: Add NOKPROBE labels on the trap handler functions |
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Hi,
On Thu, Jul 16, 2020 at 8:20 AM Daniel Thompson <daniel.thompson@linaro.org> wrote: > > Currently kgdb honours the kprobe blocklist but doesn't place its own > trap handling code on the list. Add labels to discourage attempting to > use kgdb to debug itself. > > These changes do not make it impossible to provoke recursive trapping > since they do not cover all the calls that can be made on kgdb's entry > logic. However going much further whilst we are sharing the kprobe > blocklist risks reducing the capabilities of kprobe and this would be a > bad trade off (especially so given kgdb's users are currently conditioned > to avoid recursive traps). > > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > --- > kernel/debug/debug_core.c | 8 ++++++++ > 1 file changed, 8 insertions(+)
I could just be missing something, but...
I understand not adding "NOKPROBE_SYMBOL" to generic kernel functions that kgdb happens to call, but I'm not quite sure I understand why all of the kdb / kgdb code itself shouldn't be in the blocklist. I certainly don't object to the functions you added to the blocklist, I guess I'm must trying to understand why it's a bad idea to add more or how you came up with the list of functions that you did.
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