Bug#1010849: DWARF support disabled during build / no symbolic stack traces or argument types

[Harald Welte]

Package: bpftrace
Version: 0.14.1-3
Severity: normal

It seems the Debian bpftrace is built without libdw support. This means no stack
traces can be provided with uprobes, and one cannot dereference structs or other
type information from the DWARF information.

# bpftrace -lv 'uprobe:/usr/local/lib/libosmocore.so.18.0.0:osmo_timer_schedule'
WARNING: Cannot parse DWARF: libdw not available

# bpftrace --info
System
OS: Linux 5.16.0-5-amd64 #1 SMP PREEMPT Debian 5.16.14-1 (2022-03-15)
Arch: x86_64

Build
version: v0.14.1
LLVM: 13.0.1
ORC: v2
foreach_sym: yes
unsafe uprobe: no
bfd: no
bpf_attach_kfunc: yes
bcc_usdt_addsem: yes
bcc bpf_attach_uprobe refcount: yes
bcc library path resolution: yes
libbpf: yes
libbpf btf dump: yes
libbpf btf dump type decl: yes
libdw (DWARF support): no
^^^^^^^^^^^^^^^^^^^^^^^^^

I'm wondering what is the rationale of not including DWARF support? Is this
intentional? It renders large portions of uprobe use cases useless.

-- System Information:
Debian Release: bookworm/sid
APT prefers unstable-debug
APT policy: (500, 'unstable-debug'), (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.16.0-5-amd64 (SMP w/4 CPU threads; PREEMPT)
Kernel taint flags: TAINT_DIE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages bpftrace depends on:
ii libbpf0 1:0.7.0-2
ii libbpfcc 0.24.0+ds-1
ii libc6 2.33-7
ii libclang1-13 1:13.0.1-3+b2
ii libgcc-s1 12.1.0-1
ii libllvm13 1:13.0.1-3+b2
ii libstdc++6 12.1.0-1

bpftrace recommends no packages.

bpftrace suggests no packages.

-- no debconf information

[Vincent Bernat]

❦ 11 May 2022 16:00 +02, Harald Welte:

> It seems the Debian bpftrace is built without libdw support. This means no stack
> traces can be provided with uprobes, and one cannot dereference structs or other
> type information from the DWARF information.
>
> # bpftrace -lv 'uprobe:/usr/local/lib/libosmocore.so.18.0.0:osmo_timer_schedule'
> WARNING: Cannot parse DWARF: libdw not available

No particular reason. I have added it to as a build-dep and it works
just fine. Well, it took me two tries!
--
There is a great discovery still to be made in Literature: that of
paying literary men by the quantity they do NOT write.