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btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes 

Emit BTF BTF_KIND_DECL_TAGs for btf_decl_tag attributes attached to
typedef declarations. The following is a simple example:
  $ cat t.c
    #define __tag1 __attribute__((btf_decl_tag("tag1")))
    #define __tag2 __attribute__((btf_decl_tag("tag2")))
    typedef struct { int a; int b; } __t __tag1 __tag2;
    __t g;
  $ clang -O2 -g -c t.c
  $ pahole -JV t.o
    btf_encoder__new: 't.o' doesn't have '.data..percpu' section
    Found 0 per-CPU variables!
    File t.o:
    [1] TYPEDEF __t type_id=2
    [2] STRUCT (anon) size=8
            a type_id=3 bits_offset=0
            b type_id=3 bits_offset=32
    [3] INT int size=4 nr_bits=32 encoding=SIGNED
    [4] DECL_TAG tag1 type_id=1 component_idx=-1
    [5] DECL_TAG tag2 type_id=1 component_idx=-1

Signed-off-by: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Yonghong Song 2021-11-02 16:35:10 -07:00 committed by Arnaldo Carvalho de Melo
parent 468b4196f6
commit ec62499774
1 changed files with 14 additions and 3 deletions
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17
btf_encoder.c
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@ -1438,9 +1438,21 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu)
cu__for_each_type(cu, core_id, pos) {
struct namespace *ns;
const char *tag_name;
if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type)
switch (pos->tag) {
case DW_TAG_structure_type:
tag_name = "struct";
break;
case DW_TAG_union_type:
tag_name = "union";
break;
case DW_TAG_typedef:
tag_name = "typedef";
break;
default:
continue;
}
btf_type_id = type_id_off + core_id;
ns = tag__namespace(pos);
@ -1448,8 +1460,7 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu)
tag_type_id = btf_encoder__add_decl_tag(encoder, annot->value, btf_type_id, annot->component_idx);
if (tag_type_id < 0) {
fprintf(stderr, "error: failed to encode tag '%s' to %s '%s' with component_idx %d\n",
annot->value, pos->tag == DW_TAG_structure_type ? "struct" : "union",
namespace__name(ns), annot->component_idx);
annot->value, tag_name, namespace__name(ns), annot->component_idx);
goto out;
}
}