Re: ERROR: INT DW_ATE_unsigned_1 Error emitting BTF type

[Sedat Dilek]

On Fri, Feb 5, 2021 at 10:54 PM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 2/5/21 12:31 PM, Sedat Dilek wrote:
> > On Fri, Feb 5, 2021 at 9:03 PM Yonghong Song <yhs@xxxxxx> wrote:
> >>
> >>
> >>
> >> On 2/5/21 11:24 AM, Arnaldo Carvalho de Melo wrote:
> >>> Em Fri, Feb 05, 2021 at 11:10:08AM -0800, Yonghong Song escreveu:
> >>>> On 2/5/21 11:06 AM, Sedat Dilek wrote:
> >>>>> On Fri, Feb 5, 2021 at 7:53 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >>>>> Grepping through linux.git/tools I guess some BTF tools/libs need to
> >>>>> know what BTF_INT_UNSIGNED is?
> >>>
> >>>> BTF_INT_UNSIGNED needs kernel support. Maybe to teach pahole to
> >>>> ignore this for now until kernel infrastructure is ready.
> >>>
> >>> Yeah, I thought about doing that.
> >>>
> >>>> Not sure whether this information will be useful or not
> >>>> for BTF. This needs to be discussed separately.
> >>>
> >>> Maybe search for the rationale for its introduction in DWARF.
> >>
> >> In LLVM, we have:
> >>     uint8_t BTFEncoding;
> >>     switch (Encoding) {
> >>     case dwarf::DW_ATE_boolean:
> >>       BTFEncoding = BTF::INT_BOOL;
> >>       break;
> >>     case dwarf::DW_ATE_signed:
> >>     case dwarf::DW_ATE_signed_char:
> >>       BTFEncoding = BTF::INT_SIGNED;
> >>       break;
> >>     case dwarf::DW_ATE_unsigned:
> >>     case dwarf::DW_ATE_unsigned_char:
> >>       BTFEncoding = 0;
> >>       break;
> >>
> >> I think DW_ATE_unsigned can be ignored in pahole since
> >> the default encoding = 0. A simple comment is enough.
> >>
> >
> > Yonghong Son, do you have a patch/diff for me?
>
> Looking at error message from log:
>
>   LLVM_OBJCOPY=/opt/binutils/bin/objcopy /opt/pahole/bin/pahole -J
> .tmp_vmlinux.btf
> [115] INT DW_ATE_unsigned_1 Error emitting BTF type
> Encountered error while encoding BTF.
>
> Not exactly what is the root cause. Maybe bt->bit_size is not
> encoded correctly. Could you put vmlinux (in the above it is
> .tmp_vmlinux.btf) somewhere, I or somebody else can investigate
> and provide a proper fix.
>

[ TO: Masahiro ]

Thanks for taking care Yonghong - hope this is your first name, if not
I am sorry.
In case of mixing my first and last name you will make me female -
Dilek is a Turkish female first name :-).
So, in some cultures you need to be careful.

Anyway... back to business and facts.

Out of frustration I killed my last build via `make distclean`.
The whole day I tested diverse combination of GCC-10 and LLVM-12
together with BTF Kconfigs, selfmade pahole, etc.

I will do ne run with some little changes:

#1: Pass LLVM_IAS=1 to make (means use Clang's Integrated ASsembler -
as per Nick this leads to the same error - should be unrelated)
#2: I did: DEBUG_INFO_COMPRESSED y -> n

#2 I did in case you need vmlinux and I have to upload - I will
compress the resulting vmlinux with ZSTD.
You need vmlinux or .tmp_vmlinux.btf file?
Nick was not allowed from his company to download from a Dropbox link.
So, as an alternative I can offer GoogleDrive...
...or bomb into your INBOX :-).

Now, why I CCed Masahiro:

In case of ERRORs when running `scripts/link-vmlinux.sh` above files
will be removed.

Last, I found a hack to bypass this - means to keep these files (I
need to check old emails).

Masahiro, you see a possibility to have a way to keep these files in
case of ERRORs without doing hackery?

>From a previous post in this thread:

+ info BTF .btf.vmlinux.bin.o
+ [  != silent_ ]
+ printf   %-7s %s\n BTF .btf.vmlinux.bin.o
 BTF     .btf.vmlinux.bin.o
+ LLVM_OBJCOPY=llvm-objcopy /opt/pahole/bin/pahole -J .tmp_vmlinux.btf
[2] INT long unsigned int Error emitting BTF type
Encountered error while encoding BTF.
+ llvm-objcopy --only-section=.BTF --set-section-flags
.BTF=alloc,readonly --strip-all .tmp_vmlinux.btf .btf.vmlinux.bin.o
...
+ info BTFIDS vmlinux
+ [  != silent_ ]
+ printf   %-7s %s\n BTFIDS vmlinux
 BTFIDS  vmlinux
+ ./tools/bpf/resolve_btfids/resolve_btfids vmlinux
FAILED: load BTF from vmlinux: Invalid argument
+ on_exit
+ [ 255 -ne 0 ]
+ cleanup
+ rm -f .btf.vmlinux.bin.o
+ rm -f .tmp_System.map
+ rm -f .tmp_vmlinux.btf .tmp_vmlinux.kallsyms1
.tmp_vmlinux.kallsyms1.S .tmp_vmlinux.kallsyms1.o
.tmp_vmlinux.kallsyms2 .tmp_vmlinux.kallsyms2.S .tmp_vmlinux.kallsyms
2.o
+ rm -f System.map
+ rm -f vmlinux
+ rm -f vmlinux.o
make[3]: *** [Makefile:1166: vmlinux] Error 255

^^^ Look here.

Thanks.

Regards,
- Sedat -