Automatically download user space debug symbols using a debuginfod service

[ema]

Debugging symbols need to be installed in order to probe user space programs with bpftrace:

$ sudo bpftrace -e 'uprobe:/bin/ls:format_user_or_group { print(pid); exit() }'
No probes to attach

After installing the right package - in this case with apt install coreutils-dbgsym given that I am on a Debian system:

$ sudo bpftrace -e 'uprobe:/bin/ls:format_user_or_group { print(pid); exit() }'
Attaching 1 probe...
377901

GDB and SystemTap support using a debuginfod service in order to automatically fetch the appropriate debuginfo symbols from the network without any user intervention. It would be great if this feature could be added to bpftrace as well.

[rupran]

As the code dealing with debug information resides in iovisor/bcc, I implemented the debuginfod integration there, happy to take comments and suggestions!

[yump]

Any ideas on how to make this work on Fedora 38?

> sudo bpftrace -e 'uprobe:/bin/ls:format_user_or_group { print(pid); exit() }'
No probes to attach
> sudo debuginfo-install /usr/bin/ls
*SNIP*
> sudo bpftrace -e 'uprobe:/bin/ls:format_user_or_group { print(pid); exit() }'
Attaching 1 probe...
574429
> sudo dnf history undo last
*SNIP*
> ldd /usr/bin/bpftrace | grep debug
        libdebuginfod.so.1 => /lib64/libdebuginfod.so.1 (0x00007f6613626000)
> env | grep -i debug
DEBUGINFOD_URLS=https://debuginfod.fedoraproject.org/
> gdb ls
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Reading symbols from ls...

This GDB supports auto-downloading debuginfo from the following URLs:
  <https://debuginfod.fedoraproject.org/>
Enable debuginfod for this session? (y or [n]) y
Debuginfod has been enabled.
To make this setting permanent, add 'set debuginfod enabled on' to .gdbinit.
Reading symbols from /home/rhaley/.cache/debuginfod_client/a146002a40b622e4d8420c5b96513f0784c8eb7b/debuginfo...

What am I missing?

Edit: Aha! DEBUGINFOD_URLS is an env variable, but bpftrace requires sudo, and sudo drops env variables.

Solution:

sudo --preserve-env=DEBUGINFOD_URLS bpftrace -e 'uprobe:/bin/ls:format_user_or_group { print(pid); exit() }'