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SubjectRe: [PATCH] perf-probe: Failback to symbol-base probe for probes on module
Please ignore this. I will send a better fix.

Thanks,

On Tue, 23 Feb 2021 10:48:30 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> If an error occurs on post processing (this converts probe point to
> _text relative address for identifying non-unique symbols) for the
> probes on module, failback to symbol-base probe.
>
> There are many non-unique name symbols (local static functions can
> be in the different name spaces) in the kernel. If perf-probe uses
> a symbol-based probe definition, it can be put on an unintended
> symbol. To avoid such mistake, perf-probe tries to convert the
> address to the _text relative address expression.
>
> However, such symbol duplication is rare for only one module. Thus
> even if the conversion fails, perf probe can failback to the symbol
> based probe.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> tools/perf/util/probe-event.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index a9cff3a50ddf..af946f68e32e 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -779,16 +779,16 @@ post_process_module_probe_trace_events(struct probe_trace_event *tevs,
>
> map = get_target_map(module, NULL, false);
> if (!map || debuginfo__get_text_offset(dinfo, &text_offs, true) < 0) {
> - pr_warning("Failed to get ELF symbols for %s\n", module);
> - return -EINVAL;
> + pr_info("NOTE: Failed to get ELF symbols for %s. Use symbol based probe.\n", module);
> + return 0;
> }
>
> mod_name = find_module_name(module);
> for (i = 0; i < ntevs; i++) {
> - ret = post_process_probe_trace_point(&tevs[i].point,
> - map, (unsigned long)text_offs);
> - if (ret < 0)
> - break;
> + if (post_process_probe_trace_point(&tevs[i].point,
> + map, (unsigned long)text_offs) < 0)
> + pr_info("NOTE: %s is not in the symbol map. Use symbol based probe.\n",
> + tevs[i].point.symbol);
> tevs[i].point.module =
> strdup(mod_name ? mod_name : module);
> if (!tevs[i].point.module) {
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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