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SubjectRe: [PATCH] selftests/ftrace: Extend multiple_kprobes.tc to add multiple consecutive probes in a function
Akanksha J N wrote:
> Commit 97f88a3d723162 ("powerpc/kprobes: Fix null pointer reference in
> arch_prepare_kprobe()") fixed a recent kernel oops that was caused as
> ftrace-based kprobe does not generate kprobe::ainsn::insn and it gets
> set to NULL.
> Extend multiple kprobes test to add kprobes on first 256 bytes within a
> function, to be able to test potential issues with kprobes on
> successive instructions.
> The '|| true' is added with the echo statement to ignore errors that are
> caused by trying to add kprobes to non probeable lines and continue with
> the test.
>
> Signed-off-by: Akanksha J N <akanksha@linux.ibm.com>
> ---
> .../selftests/ftrace/test.d/kprobe/multiple_kprobes.tc | 4 ++++
> 1 file changed, 4 insertions(+)

Thanks for adding this test!

>
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
> index be754f5bcf79..f005c2542baa 100644
> --- a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
> @@ -25,6 +25,10 @@ if [ $L -ne 256 ]; then
> exit_fail
> fi
>
> +for i in `seq 0 255`; do
> + echo p $FUNCTION_FORK+${i} >> kprobe_events || true
> +done
> +
> cat kprobe_events >> $testlog
>
> echo 1 > events/kprobes/enable

Thinking about this more, I wonder if we should add an explicit fork
after enabling the events, similar to kprobe_args.tc:
( echo "forked" )

That will ensure we hit all the probes we added. With that change:
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>


- Naveen

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