On 9/21/21 3:02 PM, Andrii Nakryiko wrote:
On Sun, Sep 19, 2021 at 5:36 PM Yonghong Song <yhs@xxxxxx> 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@xxxxxx> --- 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
