On Fri, Feb 5, 2021 at 8:21 PM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 2/5/21 11:15 AM, Sedat Dilek wrote:
> > On Fri, Feb 5, 2021 at 8:10 PM Yonghong Song <yhs@xxxxxx> wrote:
> >>
> >>
> >>
> >> 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:
> >>>>
> >>>> On Fri, Feb 5, 2021 at 6:48 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >>>>>
> >>>>> On Fri, Feb 5, 2021 at 4:28 PM Arnaldo Carvalho de Melo
> >>>>> <arnaldo.melo@xxxxxxxxx> wrote:
> >>>>>>
> >>>>>> Em Fri, Feb 05, 2021 at 04:23:59PM +0100, Sedat Dilek escreveu:
> >>>>>>> On Fri, Feb 5, 2021 at 3:41 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >>>>>>>>
> >>>>>>>> On Fri, Feb 5, 2021 at 3:37 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >>>>>>>>>
> >>>>>>>>> Hi,
> >>>>>>>>>
> >>>>>>>>> when building with pahole v1.20 and binutils v2.35.2 plus Clang
> >>>>>>>>> v12.0.0-rc1 and DWARF-v5 I see:
> >>>>>>>>> ...
> >>>>>>>>> + info BTF .btf.vmlinux.bin.o
> >>>>>>>>> + [ != silent_ ]
> >>>>>>>>> + printf %-7s %s\n BTF .btf.vmlinux.bin.o
> >>>>>>>>> BTF .btf.vmlinux.bin.o
> >>>>>>>>> + 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.
> >>>>>>>>
> >>>>>>>> Grepping the pahole sources:
> >>>>>>>>
> >>>>>>>> $ git grep DW_ATE
> >>>>>>>> dwarf_loader.c: bt->is_bool = encoding == DW_ATE_boolean;
> >>>>>>>> dwarf_loader.c: bt->is_signed = encoding == DW_ATE_signed;
> >>>>>>>>
> >>>>>>>> Missing DW_ATE_unsigned encoding?
> >>>>>>>>
> >>>>>>>
> >>>>>>> Checked the LLVM sources:
> >>>>>>>
> >>>>>>> clang/lib/CodeGen/CGDebugInfo.cpp: Encoding =
> >>>>>>> llvm::dwarf::DW_ATE_unsigned_char;
> >>>>>>> clang/lib/CodeGen/CGDebugInfo.cpp: Encoding = llvm::dwarf::DW_ATE_unsigned;
> >>>>>>> clang/lib/CodeGen/CGDebugInfo.cpp: Encoding =
> >>>>>>> llvm::dwarf::DW_ATE_unsigned_fixed;
> >>>>>>> clang/lib/CodeGen/CGDebugInfo.cpp:
> >>>>>>> ? llvm::dwarf::DW_ATE_unsigned
> >>>>>>> ...
> >>>>>>> lld/test/wasm/debuginfo.test:CHECK-NEXT: DW_AT_encoding
> >>>>>>> (DW_ATE_unsigned)
> >>>>>>>
> >>>>>>> So, I will switch from GNU ld.bfd v2.35.2 to LLD-12.
> >>>>>>
> >>>>>> Thanks for the research, probably your conclusion is correct, can you go
> >>>>>> the next step and add that part and check if the end result is the
> >>>>>> expected one?
> >>>>>>
> >>>>>
> >>>>> Still building...
> >>>>>
> >>>>> Can you give me a hand on what has to be changed in dwarves/pahole?
> >>>>>
> >>>>> I guess switching from ld.bfd to ld.lld will show the same ERROR.
> >>>>>
> >>>>
> >>>> This builds successfully - untested:
> >>>>
> >>>> $ git diff
> >>>> diff --git a/btf_loader.c b/btf_loader.c
> >>>> index ec286f413f36..a39edd3362db 100644
> >>>> --- a/btf_loader.c
> >>>> +++ b/btf_loader.c
> >>>> @@ -107,6 +107,7 @@ static struct base_type *base_type__new(strings_t
> >>>> name, uint32_t attrs,
> >>>> bt->bit_size = size;
> >>>> bt->is_signed = attrs & BTF_INT_SIGNED;
> >>>> bt->is_bool = attrs & BTF_INT_BOOL;
> >>>> + bt->is_unsigned = attrs & BTF_INT_UNSIGNED;
> >>>> bt->name_has_encoding = false;
> >>>> bt->float_type = float_type;
> >>>> }
> >>>> diff --git a/ctf.h b/ctf.h
> >>>> index 25b79892bde3..9e47c3c74677 100644
> >>>> --- a/ctf.h
> >>>> +++ b/ctf.h
> >>>> @@ -100,6 +100,7 @@ struct ctf_full_type {
> >>>> #define CTF_TYPE_INT_CHAR 0x2
> >>>> #define CTF_TYPE_INT_BOOL 0x4
> >>>> #define CTF_TYPE_INT_VARARGS 0x8
> >>>> +#define CTF_TYPE_INT_UNSIGNED 0x16
> >>>>
> >>>> #define CTF_TYPE_FP_ATTRS(VAL) ((VAL) >> 24)
> >>>> #define CTF_TYPE_FP_OFFSET(VAL) (((VAL) >> 16) & 0xff)
> >>>> diff --git a/dwarf_loader.c b/dwarf_loader.c
> >>>> index b73d7867e1e6..79d40f183c24 100644
> >>>> --- a/dwarf_loader.c
> >>>> +++ b/dwarf_loader.c
> >>>> @@ -473,6 +473,7 @@ static struct base_type *base_type__new(Dwarf_Die
> >>>> *die, struct cu *cu)
> >>>> bt->is_bool = encoding == DW_ATE_boolean;
> >>>> bt->is_signed = encoding == DW_ATE_signed;
> >>>> bt->is_varargs = false;
> >>>> + bt->is_unsigned = encoding == DW_ATE_unsigned;
> >>>> bt->name_has_encoding = true;
> >>>> }
> >>>>
> >>>> diff --git a/dwarves.h b/dwarves.h
> >>>> index 98caf1abc54d..edf32d2e6f80 100644
> >>>> --- a/dwarves.h
> >>>> +++ b/dwarves.h
> >>>> @@ -1261,6 +1261,7 @@ struct base_type {
> >>>> uint8_t is_signed:1;
> >>>> uint8_t is_bool:1;
> >>>> uint8_t is_varargs:1;
> >>>> + uint8_t is_unsigned:1;
> >>>> uint8_t float_type:4;
> >>>> };
> >>>>
> >>>> diff --git a/lib/bpf b/lib/bpf
> >>>> --- a/lib/bpf
> >>>> +++ b/lib/bpf
> >>>> @@ -1 +1 @@
> >>>> -Subproject commit 5af3d86b5a2c5fecdc3ab83822d083edd32b4396
> >>>> +Subproject commit 5af3d86b5a2c5fecdc3ab83822d083edd32b4396-dirty
> >>>> diff --git a/libbtf.c b/libbtf.c
> >>>> index 9f7628304495..a0661a7bbed9 100644
> >>>> --- a/libbtf.c
> >>>> +++ b/libbtf.c
> >>>> @@ -247,6 +247,8 @@ static const char *
> >>>> btf_elf__int_encoding_str(uint8_t encoding)
> >>>> return "CHAR";
> >>>> else if (encoding == BTF_INT_BOOL)
> >>>> return "BOOL";
> >>>> + else if (encoding == BTF_INT_UNSIGNED)
> >>>> + return "UNSIGNED";
> >>>> else
> >>>> return "UNKN";
> >>>> }
> >>>> @@ -379,6 +381,8 @@ int32_t btf_elf__add_base_type(struct btf_elf
> >>>> *btfe, const struct base_type *bt,
> >>>> encoding = BTF_INT_SIGNED;
> >>>> } else if (bt->is_bool) {
> >>>> encoding = BTF_INT_BOOL;
> >>>> + } else if (bt->is_unsigned) {
> >>>> + encoding = BTF_INT_UNSIGNED;
> >>>> } else if (bt->float_type) {
> >>>> fprintf(stderr, "float_type is not supported\n");
> >>>> return -1;
> >>>>
> >>>> Additionally - I cannot see it with `git diff`:
> >>>>
> >>>> [ lib/bpf/include/uapi/linux/btf.h ]
> >>>>
> >>>> /* Attributes stored in the BTF_INT_ENCODING */
> >>>> #define BTF_INT_SIGNED (1 << 0)
> >>>> #define BTF_INT_CHAR (1 << 1)
> >>>> #define BTF_INT_BOOL (1 << 2)
> >>>> #define BTF_INT_UNSIGNED (1 << 3)
> >>>>
> >>>> Comments?
> >>>>
> >>>
> >>> Hmmm...
> >>>
> >>> + 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
> >>>
> >>> 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.
> >> Not sure whether this information will be useful or not
> >> for BTF. This needs to be discussed separately.
> >>
> >
> > [ CC Fangrui ]
> >
> > How can I teach pahole to ignore BTF_INT_UNSIGNED?
>
> i mean for the following:
>
> @@ -379,6 +381,8 @@ int32_t btf_elf__add_base_type(struct btf_elf
> *btfe, const struct base_type *bt,
> encoding = BTF_INT_SIGNED;
> } else if (bt->is_bool) {
> encoding = BTF_INT_BOOL;
> + } else if (bt->is_unsigned) {
> + encoding = BTF_INT_UNSIGNED;
> } else if (bt->float_type) {
> fprintf(stderr, "float_type is not supported\n");
> return -1;
>
> You can do
>
> @@ -379,6 +381,8 @@ int32_t btf_elf__add_base_type(struct btf_elf
> *btfe, const struct base_type *bt,
> encoding = BTF_INT_SIGNED;
> } else if (bt->is_bool) {
> encoding = BTF_INT_BOOL;
> + } else if (bt->is_unsigned) {
> + ; /* ignored for now */
> } else if (bt->float_type) {
> fprintf(stderr, "float_type is not supported\n");
> return -1;
>
> The default encoding is 0 which indicates an unsigned int.
>
So my diff looks good to you (I have no glue about BTF/pahole)?
I will try with that snippet you gave me.
Thanks.
- Sedat -
> >
> > Another tryout might be to use "-fbinutils-version=..." which is
> > available for LLVM-12 according to Fangrui?
> > Fangrui, which binutils versions can I pass and how?
>
> >
> > Thanks.
> >
> > - Sedat -
> >
