Messages in this thread | | | Date | Thu, 10 Jun 2021 19:29:26 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] tools/perf probe: Print a hint if adding a probe fails |
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Hi Naveen,
On Thu, 10 Jun 2021 15:14:42 +0530 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> Adding a probe can fail in a few scenarios. perf already checks for the > address in the kprobe blacklist. However, the address could still be a > jump label, or have a BUG_ON(). In such cases, it isn't always evident > why adding the probe failed. Add a hint so that the user knows how to > proceed. >
Thanks for the report.
Since now there is <tracefs>/error_log, if you see any errors in registering probe-events, perf probe should dump the error_log for the hint message. Also, kprobes should return the correct different error code for each errors.
Thank you,
> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > --- > tools/perf/builtin-probe.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c > index 6b150756677014..ff9f3fdce600dd 100644 > --- a/tools/perf/builtin-probe.c > +++ b/tools/perf/builtin-probe.c > @@ -352,8 +352,11 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs) > } > > ret = apply_perf_probe_events(pevs, npevs); > - if (ret < 0) > + if (ret < 0) { > + pr_info("Hint: Check dmesg to understand reason for probe failure.\n" > + " Consider probing at the next/previous instruction.\n"); > goto out_cleanup; > + } > > for (i = k = 0; i < npevs; i++) > k += pevs[i].ntevs; > > base-commit: 0808b3d5b7514dc856178dbc509929329bbf301d > -- > 2.31.1 >
-- Masami Hiramatsu <mhiramat@kernel.org>
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