On Thu, 22 Jun 2017 00:20:28 +0530
"Naveen N. Rao" <naveen.n....@linux.vnet.ibm.com> wrote:
> KPROBES_ON_FTRACE is only available on powerpc64le. Update comment to
> clarify this.
>
> Also, we should use an offset of 8 to ensure that the probe does not
> fall on ftrace location. The current offset of 4 will fall before the
> function local entry point and won't fire, while an offset of 12 or 16
> will fall on ftrace location. Offset 8 is currently guaranteed to not be
> the ftrace location.
OK, these part seems good to me.
>
> Finally, do not filter out symbols with a dot. Powerpc Elfv1 uses dot
> prefix for all functions and this prevents us from testing some of those
> symbols. Furthermore, with the patch to derive event names properly in
> the presence of ':' and '.', such names are accepted by kprobe_events
> and constitutes a good test for those symbols.
Hmm, the reason why I added such filter was to avoid symbols including
gcc-generated suffixes like as .constprop or .isra etc.
So if the Powerpc Elfv1 use dot prefix, that is OK, in that case,
could you update the filter as "^.*\\..*" ?
Thank you,
>
> Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> ---
> tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> 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 f4d1ff785d67..d209c071b2c0 100644
> --- a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
> @@ -2,16 +2,16 @@
> # description: Register/unregister many kprobe events
>
> # ftrace fentry skip size depends on the machine architecture.
> -# Currently HAVE_KPROBES_ON_FTRACE defined on x86 and powerpc
> +# Currently HAVE_KPROBES_ON_FTRACE defined on x86 and powerpc64le
> case `uname -m` in
> x86_64|i[3456]86) OFFS=5;;
> - ppc*) OFFS=4;;
> + ppc64le) OFFS=8;;
> *) OFFS=0;;
> esac
>
> echo "Setup up to 256 kprobes"
> -grep t /proc/kallsyms | cut -f3 -d" " | grep -v .*\\..* | \
> -head -n 256 | while read i; do echo p ${i}+${OFFS} ; done > kprobe_events ||:
> +grep t /proc/kallsyms | cut -f3 -d" " | head -n 256 | \
> +while read i; do echo p ${i}+${OFFS} ; done > kprobe_events ||:
>
> echo 1 > events/kprobes/enable
> echo 0 > events/kprobes/enable
> --
> 2.13.1
>
--
Masami Hiramatsu <mhira...@kernel.org>
