Re: ERROR: INT DW_ATE_unsigned_1 Error emitting BTF type

[Sedat Dilek]

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?

- Sedat -