| Message ID | 20210920003555.3525533-1-yhs@fb.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | generate BTF_KIND_TAG types from DW_TAG_LLVM_annotation dwarf tags | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
| bpf/vmtest-bpf-PR | fail | merge-conflict |
| bpf/vmtest-bpf-next-PR | fail | merge-conflict |
On Sun, Sep 19, 2021 at 5:36 PM Yonghong Song <yhs@fb.com> wrote: > > The following is an example with latest upstream clang: > $ cat t.c > #define __tag1 __attribute__((btf_tag("tag1"))) > #define __tag2 __attribute__((btf_tag("tag2"))) > > struct t { > int a:1 __tag1; > int b __tag2; > } __tag1 __tag2; > > int g __tag1 __attribute__((section(".data..percpu"))); > > int __tag1 foo(struct t *a1, int a2 __tag2) { > return a1->b + a2 + g; > } > > $ clang -O2 -g -c t.c > $ pahole -JV t.o > Found per-CPU symbol 'g' at address 0x0 > Found 1 per-CPU variables! > Found 1 functions! > File t.o: > [1] INT int size=4 nr_bits=32 encoding=SIGNED > [2] PTR (anon) type_id=3 > [3] STRUCT t size=8 > a type_id=1 bitfield_size=1 bits_offset=0 > b type_id=1 bitfield_size=0 bits_offset=32 > [4] TAG tag1 type_id=3 component_idx=0 > [5] TAG tag2 type_id=3 component_idx=1 > [6] TAG tag1 type_id=3 component_idx=-1 > [7] TAG tag2 type_id=3 component_idx=-1 > [8] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) > [9] FUNC foo type_id=8 > [10] TAG tag2 type_id=9 component_idx=1 > [11] TAG tag1 type_id=9 component_idx=-1 > search cu 't.c' for percpu global variables. > Variable 'g' from CU 't.c' at address 0x0 encoded > [12] VAR g type=1 linkage=1 > [13] TAG tag1 type_id=12 component_idx=-1 > [14] DATASEC .data..percpu size=4 vlen=1 > type=12 offset=0 size=4 > $ ... > > With additional option --skip_encoding_btf_tag, pahole doesn't > generate BTF_KIND_TAGs any more. > $ pahole -JV --skip_encoding_btf_tag t.o > Found per-CPU symbol 'g' at address 0x0 > Found 1 per-CPU variables! > Found 1 functions! > File t.o: > [1] INT int size=4 nr_bits=32 encoding=SIGNED > [2] PTR (anon) type_id=3 > [3] STRUCT t size=8 > a type_id=1 bitfield_size=1 bits_offset=0 > b type_id=1 bitfield_size=0 bits_offset=32 > [4] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) > [5] FUNC foo type_id=4 > search cu 't.c' for percpu global variables. > Variable 'g' from CU 't.c' at address 0x0 encoded > [6] VAR g type=1 linkage=1 > [7] DATASEC .data..percpu size=4 vlen=1 > type=6 offset=0 size=4 > $ ... > > Signed-off-by: Yonghong Song <yhs@fb.com> > --- > btf_encoder.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > [...] > @@ -1244,6 +1266,10 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder, struct > goto out; > } > > + list_for_each_entry(annot, &var->annots, node) { > + btf_encoder__add_tag(encoder, annot->value, id, annot->component_idx); check errors? > + } > + > /* > * add a BTF_VAR_SECINFO in encoder->percpu_secinfo, which will be added into > * encoder->types later when we add BTF_VAR_DATASEC. > @@ -1359,6 +1385,7 @@ void btf_encoder__delete(struct btf_encoder *encoder) > int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) > { > uint32_t type_id_off = btf__get_nr_types(encoder->btf); > + struct llvm_annotation *annot; > uint32_t core_id; > struct function *fn; > struct tag *pos; > @@ -1396,6 +1423,20 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) > encoder->has_index_type = true; > } > > + cu__for_each_type(cu, core_id, pos) { > + struct namespace *ns; > + int btf_type_id; > + > + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) > + continue; > + > + btf_type_id = type_id_off + core_id; > + ns = tag__namespace(pos); > + list_for_each_entry(annot, &ns->annots, node) { > + btf_encoder__add_tag(encoder, annot->value, btf_type_id, annot->component_idx); same, this can fail > + } > + } > + > cu__for_each_function(cu, core_id, fn) { > int btf_fnproto_id, btf_fn_id; > const char *name; > @@ -1436,6 +1477,10 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) > printf("error: failed to encode function '%s'\n", function__name(fn)); > goto out; > } > + > + list_for_each_entry(annot, &fn->annots, node) { > + btf_encoder__add_tag(encoder, annot->value, btf_fn_id, annot->component_idx); and here as well > + } > } > > if (!encoder->skip_encoding_vars) > -- > 2.30.2 >
On 9/21/21 3:02 PM, Andrii Nakryiko wrote: > On Sun, Sep 19, 2021 at 5:36 PM Yonghong Song <yhs@fb.com> wrote: >> >> The following is an example with latest upstream clang: >> $ cat t.c >> #define __tag1 __attribute__((btf_tag("tag1"))) >> #define __tag2 __attribute__((btf_tag("tag2"))) >> >> struct t { >> int a:1 __tag1; >> int b __tag2; >> } __tag1 __tag2; >> >> int g __tag1 __attribute__((section(".data..percpu"))); >> >> int __tag1 foo(struct t *a1, int a2 __tag2) { >> return a1->b + a2 + g; >> } >> >> $ clang -O2 -g -c t.c >> $ pahole -JV t.o >> Found per-CPU symbol 'g' at address 0x0 >> Found 1 per-CPU variables! >> Found 1 functions! >> File t.o: >> [1] INT int size=4 nr_bits=32 encoding=SIGNED >> [2] PTR (anon) type_id=3 >> [3] STRUCT t size=8 >> a type_id=1 bitfield_size=1 bits_offset=0 >> b type_id=1 bitfield_size=0 bits_offset=32 >> [4] TAG tag1 type_id=3 component_idx=0 >> [5] TAG tag2 type_id=3 component_idx=1 >> [6] TAG tag1 type_id=3 component_idx=-1 >> [7] TAG tag2 type_id=3 component_idx=-1 >> [8] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) >> [9] FUNC foo type_id=8 >> [10] TAG tag2 type_id=9 component_idx=1 >> [11] TAG tag1 type_id=9 component_idx=-1 >> search cu 't.c' for percpu global variables. >> Variable 'g' from CU 't.c' at address 0x0 encoded >> [12] VAR g type=1 linkage=1 >> [13] TAG tag1 type_id=12 component_idx=-1 >> [14] DATASEC .data..percpu size=4 vlen=1 >> type=12 offset=0 size=4 >> $ ... >> >> With additional option --skip_encoding_btf_tag, pahole doesn't >> generate BTF_KIND_TAGs any more. >> $ pahole -JV --skip_encoding_btf_tag t.o >> Found per-CPU symbol 'g' at address 0x0 >> Found 1 per-CPU variables! >> Found 1 functions! >> File t.o: >> [1] INT int size=4 nr_bits=32 encoding=SIGNED >> [2] PTR (anon) type_id=3 >> [3] STRUCT t size=8 >> a type_id=1 bitfield_size=1 bits_offset=0 >> b type_id=1 bitfield_size=0 bits_offset=32 >> [4] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) >> [5] FUNC foo type_id=4 >> search cu 't.c' for percpu global variables. >> Variable 'g' from CU 't.c' at address 0x0 encoded >> [6] VAR g type=1 linkage=1 >> [7] DATASEC .data..percpu size=4 vlen=1 >> type=6 offset=0 size=4 >> $ ... >> >> Signed-off-by: Yonghong Song <yhs@fb.com> >> --- >> btf_encoder.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 45 insertions(+) >> > > [...] > >> @@ -1244,6 +1266,10 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder, struct >> goto out; >> } >> >> + list_for_each_entry(annot, &var->annots, node) { >> + btf_encoder__add_tag(encoder, annot->value, id, annot->component_idx); > > check errors? Yes, I missed it. Will fix this and the following two other instances and send v2. > >> + } >> + >> /* >> * add a BTF_VAR_SECINFO in encoder->percpu_secinfo, which will be added into >> * encoder->types later when we add BTF_VAR_DATASEC. >> @@ -1359,6 +1385,7 @@ void btf_encoder__delete(struct btf_encoder *encoder) >> int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) >> { >> uint32_t type_id_off = btf__get_nr_types(encoder->btf); >> + struct llvm_annotation *annot; >> uint32_t core_id; >> struct function *fn; >> struct tag *pos; >> @@ -1396,6 +1423,20 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) >> encoder->has_index_type = true; >> } >> >> + cu__for_each_type(cu, core_id, pos) { >> + struct namespace *ns; >> + int btf_type_id; >> + >> + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) >> + continue; >> + >> + btf_type_id = type_id_off + core_id; >> + ns = tag__namespace(pos); >> + list_for_each_entry(annot, &ns->annots, node) { >> + btf_encoder__add_tag(encoder, annot->value, btf_type_id, annot->component_idx); > > same, this can fail > >> + } >> + } >> + >> cu__for_each_function(cu, core_id, fn) { >> int btf_fnproto_id, btf_fn_id; >> const char *name; >> @@ -1436,6 +1477,10 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) >> printf("error: failed to encode function '%s'\n", function__name(fn)); >> goto out; >> } >> + >> + list_for_each_entry(annot, &fn->annots, node) { >> + btf_encoder__add_tag(encoder, annot->value, btf_fn_id, annot->component_idx); > > and here as well > >> + } >> } >> >> if (!encoder->skip_encoding_vars) >> -- >> 2.30.2 >>
diff --git a/btf_encoder.c b/btf_encoder.c index 1b4e83d..e983750 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -141,6 +141,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = { [BTF_KIND_VAR] = "VAR", [BTF_KIND_DATASEC] = "DATASEC", [BTF_KIND_FLOAT] = "FLOAT", + [BTF_KIND_TAG] = "TAG", }; static const char *btf__printable_name(const struct btf *btf, uint32_t offset) @@ -644,6 +645,26 @@ static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char return id; } +static int32_t btf_encoder__add_tag(struct btf_encoder *encoder, const char *value, uint32_t type, + int component_idx) +{ + struct btf *btf = encoder->btf; + const struct btf_type *t; + int32_t id; + + id = btf__add_tag(btf, value, type, component_idx); + if (id > 0) { + t = btf__type_by_id(btf, id); + btf_encoder__log_type(encoder, t, false, true, "type_id=%u component_idx=%d", + t->type, component_idx); + } else { + btf__log_err(btf, BTF_KIND_TAG, value, true, "component_idx=%d Error emitting BTF type", + component_idx); + } + + return id; +} + /* * This corresponds to the same macro defined in * include/linux/kallsyms.h @@ -1158,6 +1179,7 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder, struct struct variable *var = tag__variable(pos); uint32_t size, type, linkage; const char *name, *dwarf_name; + struct llvm_annotation *annot; const struct tag *tag; uint64_t addr; int id; @@ -1244,6 +1266,10 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder, struct goto out; } + list_for_each_entry(annot, &var->annots, node) { + btf_encoder__add_tag(encoder, annot->value, id, annot->component_idx); + } + /* * add a BTF_VAR_SECINFO in encoder->percpu_secinfo, which will be added into * encoder->types later when we add BTF_VAR_DATASEC. @@ -1359,6 +1385,7 @@ void btf_encoder__delete(struct btf_encoder *encoder) int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) { uint32_t type_id_off = btf__get_nr_types(encoder->btf); + struct llvm_annotation *annot; uint32_t core_id; struct function *fn; struct tag *pos; @@ -1396,6 +1423,20 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) encoder->has_index_type = true; } + cu__for_each_type(cu, core_id, pos) { + struct namespace *ns; + int btf_type_id; + + if (pos->tag != DW_TAG_structure_type && pos->tag != DW_TAG_union_type) + continue; + + btf_type_id = type_id_off + core_id; + ns = tag__namespace(pos); + list_for_each_entry(annot, &ns->annots, node) { + btf_encoder__add_tag(encoder, annot->value, btf_type_id, annot->component_idx); + } + } + cu__for_each_function(cu, core_id, fn) { int btf_fnproto_id, btf_fn_id; const char *name; @@ -1436,6 +1477,10 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) printf("error: failed to encode function '%s'\n", function__name(fn)); goto out; } + + list_for_each_entry(annot, &fn->annots, node) { + btf_encoder__add_tag(encoder, annot->value, btf_fn_id, annot->component_idx); + } } if (!encoder->skip_encoding_vars)
The following is an example with latest upstream clang: $ cat t.c #define __tag1 __attribute__((btf_tag("tag1"))) #define __tag2 __attribute__((btf_tag("tag2"))) struct t { int a:1 __tag1; int b __tag2; } __tag1 __tag2; int g __tag1 __attribute__((section(".data..percpu"))); int __tag1 foo(struct t *a1, int a2 __tag2) { return a1->b + a2 + g; } $ clang -O2 -g -c t.c $ pahole -JV t.o Found per-CPU symbol 'g' at address 0x0 Found 1 per-CPU variables! Found 1 functions! File t.o: [1] INT int size=4 nr_bits=32 encoding=SIGNED [2] PTR (anon) type_id=3 [3] STRUCT t size=8 a type_id=1 bitfield_size=1 bits_offset=0 b type_id=1 bitfield_size=0 bits_offset=32 [4] TAG tag1 type_id=3 component_idx=0 [5] TAG tag2 type_id=3 component_idx=1 [6] TAG tag1 type_id=3 component_idx=-1 [7] TAG tag2 type_id=3 component_idx=-1 [8] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) [9] FUNC foo type_id=8 [10] TAG tag2 type_id=9 component_idx=1 [11] TAG tag1 type_id=9 component_idx=-1 search cu 't.c' for percpu global variables. Variable 'g' from CU 't.c' at address 0x0 encoded [12] VAR g type=1 linkage=1 [13] TAG tag1 type_id=12 component_idx=-1 [14] DATASEC .data..percpu size=4 vlen=1 type=12 offset=0 size=4 $ ... With additional option --skip_encoding_btf_tag, pahole doesn't generate BTF_KIND_TAGs any more. $ pahole -JV --skip_encoding_btf_tag t.o Found per-CPU symbol 'g' at address 0x0 Found 1 per-CPU variables! Found 1 functions! File t.o: [1] INT int size=4 nr_bits=32 encoding=SIGNED [2] PTR (anon) type_id=3 [3] STRUCT t size=8 a type_id=1 bitfield_size=1 bits_offset=0 b type_id=1 bitfield_size=0 bits_offset=32 [4] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2) [5] FUNC foo type_id=4 search cu 't.c' for percpu global variables. Variable 'g' from CU 't.c' at address 0x0 encoded [6] VAR g type=1 linkage=1 [7] DATASEC .data..percpu size=4 vlen=1 type=6 offset=0 size=4 $ ... Signed-off-by: Yonghong Song <yhs@fb.com> --- btf_encoder.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+)