Can't add perf probe for C++ methods

c++, linux, perf

Solution

As a workaround you can get the method address with `objdump` and `perf probe` will accept it.

  $ perf probe -x /path/file '0x643f30'
Added new event:
  probe_libfile:abs_643f30 (on 0x643f30 in /path/file)

You can now use it in all perf tools, such as:

    perf record -e probe_libfile:abs_643f30 -aR sleep 1

Do note that `perf probe` expects an offset from the file, and `objdump` and `readelf` return the address after adjusting for the loading address. For `-pie` executable, where the loading address is 0, the addresses will be the same. For non `-pie` executables you can get the loading address by looking at the output of `readelf -l /path/file` and searching for the offset `0x000000` and looking at what `VirtAddr` it points to, then subtract that number from the symbol address that you get from `objdump --syms` or `readelf --syms`. It will usually be `0x400000`

Problem

I'm trying to add a `perf probe` for a C++ method in my library, but I keep getting the following: ``` $ perf probe --exec=/path/to/file --add='my::Own::Method' Semantic error :There is non-digit char in line number. ``` I've listed the available functions like so: ``` $ perf probe --funcs --exec=/path/to/file ``` And tried some C functions that are also included. A probe can be added for these just fine. So I tried the mangled name (e.g. `_ZN2my8Own16Method`) and `perf probe` says it doesn't exist. Is there a way around this issue?

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