* [PATCH dwarves 0/2] btf: support typedef DW_TAG_LLVM_annotation
@ 2021-10-27 23:08 Yonghong Song
2021-10-27 23:08 ` [PATCH dwarves 1/2] dwarf_loader: " Yonghong Song
2021-10-27 23:08 ` [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes Yonghong Song
0 siblings, 2 replies; 5+ messages in thread
From: Yonghong Song @ 2021-10-27 23:08 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, dwarves
Cc: Alexei Starovoitov, Andrii Nakryiko, bpf, Daniel Borkmann, kernel-team
Latest llvm is able to generate DW_TAG_LLVM_annotation for typedef
declarations. Latest bpf-next supports BTF_KIND_DECL_TAG for
typedef declarations. This patch implemented dwarf DW_TAG_LLVM_annotation
to btf BTF_KIND_DECL_TAG conversion. Patch 1 is for dwarf_loader
to process DW_TAG_LLVM_annotation tags. Patch 2 is for the
dwarf->btf conversion.
Yonghong Song (2):
dwarf_loader: support typedef DW_TAG_LLVM_annotation
btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag
attributes
btf_encoder.c | 12 +++++++++---
dwarf_loader.c | 7 ++-----
2 files changed, 11 insertions(+), 8 deletions(-)
--
2.30.2
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH dwarves 1/2] dwarf_loader: support typedef DW_TAG_LLVM_annotation 2021-10-27 23:08 [PATCH dwarves 0/2] btf: support typedef DW_TAG_LLVM_annotation Yonghong Song @ 2021-10-27 23:08 ` Yonghong Song 2021-10-27 23:08 ` [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes Yonghong Song 1 sibling, 0 replies; 5+ messages in thread From: Yonghong Song @ 2021-10-27 23:08 UTC (permalink / raw) To: Arnaldo Carvalho de Melo, dwarves Cc: Alexei Starovoitov, Andrii Nakryiko, bpf, Daniel Borkmann, kernel-team llvm commit ([1]) added support for btf_decl_tag attribute with typedef declaration. Eventually, DW_TAG_LLVM_annotation tag may appear inside dwarf typedef declaration tag. kernel support for typedef BTF_KIND_DECL_TAG support is introduced in [2]. There is no additional libbpf change needed as the previous libbpf BTF_KIND_DECL_TAG support is generic enough to cover new typedef use cases. This patch added parsing of DW_TAG_LLVM_annotation for dwarf typedef decl. $ cat t.c $ clang -O2 -g -c t.c $ llvm-dwarfdump --debug-info t.o ...... 0x00000033: DW_TAG_typedef DW_AT_type (0x00000051 "structure ") DW_AT_name ("__t") DW_AT_decl_file ("/home/yhs/t.c") DW_AT_decl_line (3) 0x0000003e: DW_TAG_LLVM_annotation DW_AT_name ("btf_decl_tag") DW_AT_const_value ("tag1") 0x00000047: DW_TAG_LLVM_annotation DW_AT_name ("btf_decl_tag") DW_AT_const_value ("tag2") 0x00000050: NULL Previously, pahole will issue a warning if typedef tag contains any child tag. I removed this warning since it is not true any more. Note that dwarf standard doesn't prevent typedef decl tag from having nested tags. In the future if we need to process any tag inside typedef tag, we can just add code to process it. [1] https://reviews.llvm.org/D110127 [2] https://lore.kernel.org/bpf/20211021195628.4018847-1-yhs@fb.com Signed-off-by: Yonghong Song <yhs@fb.com> --- dwarf_loader.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/dwarf_loader.c b/dwarf_loader.c index c5bda81..f748bd7 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -1296,11 +1296,8 @@ static struct tag *die__create_new_typedef(Dwarf_Die *die, struct cu *cu, struct if (tdef == NULL) return NULL; - if (dwarf_haschildren(die)) { - struct dwarf_tag *dtag = tdef->namespace.tag.priv; - fprintf(stderr, "%s: DW_TAG_typedef %llx WITH children!\n", - __func__, (unsigned long long)dtag->id); - } + if (add_child_llvm_annotations(die, -1, conf, &tdef->namespace.annots)) + return NULL; return &tdef->namespace.tag; } -- 2.30.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes 2021-10-27 23:08 [PATCH dwarves 0/2] btf: support typedef DW_TAG_LLVM_annotation Yonghong Song 2021-10-27 23:08 ` [PATCH dwarves 1/2] dwarf_loader: " Yonghong Song @ 2021-10-27 23:08 ` Yonghong Song 2021-11-02 2:58 ` Andrii Nakryiko 1 sibling, 1 reply; 5+ messages in thread From: Yonghong Song @ 2021-10-27 23:08 UTC (permalink / raw) To: Arnaldo Carvalho de Melo, dwarves Cc: Alexei Starovoitov, Andrii Nakryiko, bpf, Daniel Borkmann, kernel-team 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> --- btf_encoder.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/btf_encoder.c b/btf_encoder.c index 40f6aa3..2f1f4ae 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -1437,19 +1437,25 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) } cu__for_each_type(cu, core_id, pos) { + const char *tag_name = "typedef"; struct namespace *ns; - if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type && + pos->tag != DW_TAG_typedef) continue; + if (pos->tag == DW_TAG_structure_type) + tag_name = "struct"; + else if (pos->tag == DW_TAG_union_type) + tag_name = "union"; + btf_type_id = type_id_off + core_id; ns = tag__namespace(pos); list_for_each_entry(annot, &ns->annots, node) { 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; } } -- 2.30.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes 2021-10-27 23:08 ` [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes Yonghong Song @ 2021-11-02 2:58 ` Andrii Nakryiko 2021-11-02 23:21 ` Yonghong Song 0 siblings, 1 reply; 5+ messages in thread From: Andrii Nakryiko @ 2021-11-02 2:58 UTC (permalink / raw) To: Yonghong Song Cc: Arnaldo Carvalho de Melo, dwarves, Alexei Starovoitov, Andrii Nakryiko, bpf, Daniel Borkmann, Kernel Team On Wed, Oct 27, 2021 at 4:08 PM Yonghong Song <yhs@fb.com> wrote: > > 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> > --- > btf_encoder.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/btf_encoder.c b/btf_encoder.c > index 40f6aa3..2f1f4ae 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -1437,19 +1437,25 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) > } > > cu__for_each_type(cu, core_id, pos) { > + const char *tag_name = "typedef"; > struct namespace *ns; > > - if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) > + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type && > + pos->tag != DW_TAG_typedef) > continue; > > + if (pos->tag == DW_TAG_structure_type) > + tag_name = "struct"; > + else if (pos->tag == DW_TAG_union_type) > + tag_name = "union"; nit: switch instead of these two related sets of if/else blocks would be cleaner > + > btf_type_id = type_id_off + core_id; > ns = tag__namespace(pos); > list_for_each_entry(annot, &ns->annots, node) { > 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; > } > } > -- > 2.30.2 > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes 2021-11-02 2:58 ` Andrii Nakryiko @ 2021-11-02 23:21 ` Yonghong Song 0 siblings, 0 replies; 5+ messages in thread From: Yonghong Song @ 2021-11-02 23:21 UTC (permalink / raw) To: Andrii Nakryiko Cc: Arnaldo Carvalho de Melo, dwarves, Alexei Starovoitov, Andrii Nakryiko, bpf, Daniel Borkmann, Kernel Team On 11/1/21 7:58 PM, Andrii Nakryiko wrote: > On Wed, Oct 27, 2021 at 4:08 PM Yonghong Song <yhs@fb.com> wrote: >> >> 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> >> --- >> btf_encoder.c | 12 +++++++++--- >> 1 file changed, 9 insertions(+), 3 deletions(-) >> >> diff --git a/btf_encoder.c b/btf_encoder.c >> index 40f6aa3..2f1f4ae 100644 >> --- a/btf_encoder.c >> +++ b/btf_encoder.c >> @@ -1437,19 +1437,25 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) >> } >> >> cu__for_each_type(cu, core_id, pos) { >> + const char *tag_name = "typedef"; >> struct namespace *ns; >> >> - if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) >> + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type && >> + pos->tag != DW_TAG_typedef) >> continue; >> >> + if (pos->tag == DW_TAG_structure_type) >> + tag_name = "struct"; >> + else if (pos->tag == DW_TAG_union_type) >> + tag_name = "union"; > > nit: switch instead of these two related sets of if/else blocks would be cleaner Sure. Will make the change in v2. > > >> + >> btf_type_id = type_id_off + core_id; >> ns = tag__namespace(pos); >> list_for_each_entry(annot, &ns->annots, node) { >> 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; >> } >> } >> -- >> 2.30.2 >> ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-11-02 23:21 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-10-27 23:08 [PATCH dwarves 0/2] btf: support typedef DW_TAG_LLVM_annotation Yonghong Song 2021-10-27 23:08 ` [PATCH dwarves 1/2] dwarf_loader: " Yonghong Song 2021-10-27 23:08 ` [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_DECL_TAGs for typedef btf_decl_tag attributes Yonghong Song 2021-11-02 2:58 ` Andrii Nakryiko 2021-11-02 23:21 ` Yonghong Song
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