Add support for C++ mangled symbols in uprobe names #687

[caringi]

Allow to specify uprobe names using demangled C++ format (this is done
with the help of abi::__cxa_demangle() function).

Example:

$ nm -g a.out |grep foo
0000000000401151 T _Z3fooi
0000000000401146 T _Z3foov

$ nm -g --demangle a.out |grep foo
0000000000401151 T foo(int)
0000000000401146 T foo()

$ bpftrace -e 'uprobe:./a.out:foo {printf("ok\n");}'
Attaching 2 probes...
^C

$ bpftrace -e 'uprobe:./a.out:"foo()" {printf("ok\n");}'
Attaching 1 probe...
^C

[danobi]

Haven't looked too closely at the code yet, but I like this feature.

One thought: should we make bpftrace -l uprobe:/path/to/bin print demanged names as well? Sometimes it can be tricky to guess what the demangled name will be.

[caringi]

One thought: should we make bpftrace -l uprobe:/path/to/bin print demanged names as well? Sometimes it can be tricky to guess what the demangled name will be.

I think that's a good idea...

Maybe bpftrace -l uprobe:/path/to/bin could print mangled and demangled names side by side...

Something like:

uprobe:./a.out:foo() [_Z3foov]
uprobe:./a.out:foo(int) [_Z3fooi]

Another option would be to use -lv to print demangled names, and leave -l printing the symbols without demangling.

[dalehamel]

One thought: should we make bpftrace -l uprobe:/path/to/bin print demanged names as well? Sometimes it can be tricky to guess what the demangled name will be.

I think the default behavior should be that listing uprobes this way should print demangled by default, as we also want to be able to have the list and attach syntax be consistent. (echoing what I said on #687 )

Thanks for doing this @caringi

[ajor]

Nice approach! This will be very useful

[ajor]

Looks good to me. Is it still a RFC or ok to merge?

[caringi]

Looks good to me. Is it still a RFC or ok to merge?

I've added the RFC prefix to emphasize I needed feedback...

I think it's ok to merge it...

[dalehamel]

this is awesome @caringi i think this is ok to merge!