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Reply-To: sedat.dilek@gmail.com
From:   Sedat Dilek <sedat.dilek@gmail.com>
Date:   Sat, 6 Feb 2021 06:53:49 +0100
Message-ID: <CA+icZUUj1P_PAj=E8iF=C4m6gYm9zqb+WWbOdoTqemTeGnZbww@mail.gmail.com>
Subject: Re: ERROR: INT DW_ATE_unsigned_1 Error emitting BTF type
To:     Yonghong Song <yhs@fb.com>, Masahiro Yamada <masahiroy@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        dwarves@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        bpf@vger.kernel.org, Jiri Olsa <jolsa@kernel.org>,
        Jan Engelhardt <jengelh@inai.de>,
        Domenico Andreoli <cavok@debian.org>,
        Matthias Schwarzott <zzam@gentoo.org>,
        Andrii Nakryiko <andriin@fb.com>,
        Mark Wieelard <mjw@redhat.com>,
        Paul Moore <paul@paul-moore.com>,
        Ondrej Mosnacek <omosnace@redhat.com>,
        =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= <berrange@redhat.com>,
        Tom Stellard <tstellar@redhat.com>
Content-Type: text/plain; charset="UTF-8"
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On Sat, Feb 6, 2021 at 6:44 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Sat, Feb 6, 2021 at 4:34 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Fri, Feb 5, 2021 at 10:54 PM Yonghong Song <yhs@fb.com> wrote:
> > >
> > >
> > >
> > > On 2/5/21 12:31 PM, Sedat Dilek wrote:
> > > > On Fri, Feb 5, 2021 at 9:03 PM Yonghong Song <yhs@fb.com> 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@gmail.com> 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.
> >
>
> With this diff:
>
> $ git diff scripts/link-vmlinux.sh
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index eef40fa9485d..40f1b6aae553 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -330,7 +330,7 @@ vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
> # fill in BTF IDs
> if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
>        info BTFIDS vmlinux
> -       ${RESOLVE_BTFIDS} vmlinux
> +       ##${RESOLVE_BTFIDS} vmlinux
> fi
>
> if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
>
> This files are kept - not removed:
>
> $ LC_ALL=C ll .*btf* vmlinux vmlinux.o
> -rwxr-xr-x 1 dileks dileks  31M Feb  6 06:37 .btf.vmlinux.bin.o
> -rwxr-xr-x 1 dileks dileks 348M Feb  6 06:37 .tmp_vmlinux.btf
> -rwxr-xr-x 1 dileks dileks 348M Feb  6 06:37 vmlinux
> -rw-r--r-- 1 dileks dileks 344M Feb  6 06:37 vmlinux.o
>
> Pleas let me know where to upload - Dropbox or GoogleDrive or
> elsewhere and give me a link.
>


WOW, ZSTD is great :-).

$ zstd -19 -T0 -v vmlinux
*** zstd command line interface 64-bits v1.4.8, by Yann Collet ***
Note: 2 physical core(s) detected
vmlinux              : 22.71%   (364466016 => 82784801 bytes, vmlinux.zst)

$ du -m vmlinux*
348     vmlinux
79      vmlinux.zst

- Sedat -