Thread (4 messages) 4 messages, 2 authors, 2011-03-31

How to handle kprobe bugs?

From: Dave Martin <hidden>
Date: 2011-03-30 14:10:11

On Wed, Mar 30, 2011 at 02:53:33PM +0100, Tixy wrote:
Now that I'm writing some test code for kprobes I'm quickly finding
further bugs with the instruction emulation. E.g. ALU ops with an
immediate operand are broke. Shall I wait until I have completed writing
Good spot ... if so, this definitely needs fixing(!)
all test cases before submitting a single fix patch? (It could be a
couple of weeks.)
My view (others may differ):

If there are several independent fixes, that's probably best presented
as multiple patches; but it may be better to post them as a series when
you're done.

I expect this will be more digestible for people than a trickle of
patches over a longer period, unless the total changeset becomes
large.
I also find that instruction emulation for some (all?) ARMv6K and newer
instructions are missing. E.g. hint instructions like NOP and WFI. Shall
I produce a second patch to add these?
Sure.

Note that you should emulate all the hinted NOPs as actual NOPs,
since the event the hint waits for may happen in the meantime;
under some circumstances that would lead to stalls.
At some point I will also get around to doing my original task of adding
Thumb support to kprobes. I'm assuming that fixing ARM code is higher
priority than adding Thumb support?
I think that's reasonable, provided there is not too much work to do
to fix the ARM case -- it sounds like there isn't much to fix, but
please shout otherwise.

Cheers
---Dave
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