Re: die__process_unit: DW_TAG_label (0xa) @ <0x7b> not handled!

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Sep 27, 2022 at 12:59:03PM -0700, Nathan Chancellor escreveu:
> On Tue, Sep 27, 2022 at 04:08:02PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Tue, Sep 27, 2022 at 11:56:34AM -0700, Nathan Chancellor escreveu:
> > > Hi Arnaldo,
> > > 
> > > When building a kernel with LLVM and CONFIG_DEBUG_INFO_BTF after commit
> > > 32ef9e5054ec ("Makefile.debug: re-enable debug info for .S files") in
> > > the kernel, I see the following spew of warnings, which appear to come
> > > from pahole:
> > > 
> > > $ clang --version
> > > clang version 15.0.0 (Fedora 15.0.0-3.fc38)
> > > Target: x86_64-redhat-linux-gnu
> > > Thread model: posix
> > > InstalledDir: /usr/bin
> > > 
> > > $ pahole --version
> > > v1.24
> > > 
> > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig
> > > 
> > > $ scripts/config \
> > >     -d DEBUG_INFO_NONE \
> > >     -e BPF_SYSCALL \
> > >     -e DEBUG_INFO_BTF \
> > >     -e DEBUG_INFO_DWARF5
> > > 
> > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 olddefconfig all
> > > ...
> > > die__process_unit: DW_TAG_label (0xa) @ <0x7b> not handled!
> > > die__process_unit: tag not supported 0xa (label)!
> > > die__process_unit: DW_TAG_label (0xa) @ <0x97> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0xbd> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0xed> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0x109> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0x12a> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0x146> not handled!
> > > die__process_unit: DW_TAG_label (0xa) @ <0x16f> not handled!
> > > ...
> > > 
> > > Is this a problem with LLVM or pahole? I do not see this when building
> > > with GCC + GNU as but that could just be a red herring. I assume that
> > > there could be something missing for processing debug info from
> > > assembly, perhaps? If there is any further information I can provide or
> > > anything I can test, I am more than happy to do so.
> > 
> > I'll try to repro, but at first sight it looks like a label in a
> 
> If you need help reproducing this locally, feel free to reach out
> through this thread or #clangbuiltlinux on Libera.

Can you please provide the vmlinux file where this takes place?
 
> > DW_TAG_compile_unit/like level, I have to check what that means, but
> > seems to be just a warning, did the end result made sense?
> 
> Right, this appears to just be a warning, the build still completes
> successfully (I did not check much else). I only noticed this by
> scrolling back in my build logs.

Ok.

- Arnaldo