linux-kernel - Re: failed to add c++ probe

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Message-ID: <alpine.DEB.2.20.1609200129550.5524@nanos>
Date:   Tue, 20 Sep 2016 01:32:04 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Masami Hiramatsu <mhiramat@...nel.org>
cc:     Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>
Subject: Re: failed to add c++ probe

Masami,

On Tue, 20 Sep 2016, Masami Hiramatsu wrote:
> Hmm, could you try to find mangled symbol from the library as below?
> 
> ./perf probe -x /usr/lib64/libstdc++.so.6 -F \*
> 
> And also try to do adding probe with -v option again?
> 
> In my case, I could find the mangled symbol, but failed to setup the probe...

./perf probe -x /usr/lib/x86_64-linux-gnu/libstdc++.so.6 -v _X_ZNKSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv
probe-definition(0): _X_ZNKSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv 
symbol:_X_ZNKSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv file:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
symbol:catch file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:throw file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:rethrow file:(null) line:0 offset:0 return:0 lazy:(null)
Open Debuginfo file: /usr/lib/debug/usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22
Try to find probe point from debuginfo.
Symbol _X_ZNKSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv address found : 8c620
Matched function: is_open
found inline addr: 0x8cad0
Probe point found: is_open+0
found inline addr: 0x8cac0
Probe point found: is_open+0
found inline addr: 0x8cab0
Probe point found: is_open+0
Matched function: is_open
An error occurred in debuginfo analysis (-2).
Trying to use symbols.
Opening /sys/kernel/tracing//uprobe_events write=1
Writing event: p:probe_libstdc++/_X_ZNKSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22:0x8c620
Failed to write event: Invalid argument
  Error: Failed to add events. Reason: Invalid argument (Code: -22)

[16568.176464] Failed to allocate trace_uprobe.(-22)
[16568.176468] Failed to parse address or file.

Aside of that mangled symbols with a @plt suffix do not work at all.

Thanks,

	tglx