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SUSE:ALP:Source:Standard:0.1
dwarves
0006-btf_encoder-Encode-DW_TAG_unspecified_type...
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File 0006-btf_encoder-Encode-DW_TAG_unspecified_type-returning.patch of Package dwarves
From b55a35326c9ea1cd9287a7ce87193443bb523c9b Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo <acme@redhat.com> Date: Mon, 10 Oct 2022 11:20:07 -0300 Subject: [PATCH 6/7] btf_encoder: Encode DW_TAG_unspecified_type returning routines as void MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since we don´t have how to encode this info in BTF, and from what we saw, at least in this case: Built binutils from git://sourceware.org/git/binutils-gdb.git, then used gcc's -B option to point to the directory with the new as, that is built as as-new, so make a symlink, ending up with: 15e20ce2324a:~/git/linux # readelf -wi ./arch/x86/entry/entry.o Contents of the .debug_info section: Compilation Unit @ offset 0: Length: 0x35 (32-bit) Version: 5 Unit Type: DW_UT_compile (1) Abbrev Offset: 0 Pointer Size: 8 <0><c>: Abbrev Number: 1 (DW_TAG_compile_unit) <d> DW_AT_stmt_list : 0 <11> DW_AT_low_pc : 0 <19> DW_AT_high_pc : 19 <1a> DW_AT_name : (indirect string, offset: 0): arch/x86/entry/entry.S <1e> DW_AT_comp_dir : (indirect string, offset: 0x17): /root/git/linux <22> DW_AT_producer : (indirect string, offset: 0x27): GNU AS 2.39.50 <26> DW_AT_language : 32769 (MIPS assembler) <1><28>: Abbrev Number: 2 (DW_TAG_subprogram) <29> DW_AT_name : (indirect string, offset: 0x36): entry_ibpb <2d> DW_AT_external : 1 <2d> DW_AT_type : <0x37> <2e> DW_AT_low_pc : 0 <36> DW_AT_high_pc : 19 <1><37>: Abbrev Number: 3 (DW_TAG_unspecified_type) <1><38>: Abbrev Number: 0 So we have that asm label encoded by GNU AS 2.39.50 as a DW_TAG_subprogram that has as its DW_AT_type the DW_TAG_unspecified_type 0x37 that we convert to 0 (void): 15e20ce2324a:~/git/linux # pahole -J ./arch/x86/entry/entry.o 15e20ce2324a:~/git/linux # pahole -JV ./arch/x86/entry/entry.o btf_encoder__new: 'entry.o' doesn't have '.data..percpu' section Found 0 per-CPU variables! Found 1 functions! File entry.o: [1] FUNC_PROTO (anon) return=0 args=(void) [2] FUNC entry_ibpb type_id=1 15e20ce2324a:~/git/linux # pfunct -F btf ./arch/x86/entry/entry.o entry_ibpb 15e20ce2324a:~/git/linux # pfunct --proto -F btf ./arch/x86/entry/entry.o void entry_ibpb(void); 15e20ce2324a:~/git/linux # 15e20ce2324a:~/git/linux # tools/bpf/bpftool/bpftool btf dump file ./arch/x86/entry/entry.o format raw [1] FUNC_PROTO '(anon)' ret_type_id=0 vlen=0 [2] FUNC 'entry_ibpb' type_id=1 linkage=static 15e20ce2324a:~/git/linux # I think this is what can be done to avoid having to skip ASM DWARF when gets widely used, i.e. binutils gets updated. Acked-by: Yonghong Song <yhs@fb.com> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>, Cc: Martin Liška <mliska@suse.cz> Link: https://lore.kernel.org/all/Y0R7uu3s%2FimnvPzM@kernel.org/ Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- btf_encoder.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/btf_encoder.c b/btf_encoder.c index e74862cfc0a3a802..eee55a0ade5e74ee 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -570,6 +570,19 @@ static int32_t btf_encoder__add_func_param(struct btf_encoder *encoder, const ch } } +static int32_t btf_encoder__tag_type(struct btf_encoder *encoder, uint32_t type_id_off, uint32_t tag_type) +{ + if (tag_type == 0) + return 0; + + if (encoder->cu->unspecified_type.tag && tag_type == encoder->cu->unspecified_type.type) { + // No provision for encoding this, turn it into void. + return 0; + } + + return type_id_off + tag_type; +} + static int32_t btf_encoder__add_func_proto(struct btf_encoder *encoder, struct ftype *ftype, uint32_t type_id_off) { struct btf *btf = encoder->btf; @@ -580,7 +593,7 @@ static int32_t btf_encoder__add_func_proto(struct btf_encoder *encoder, struct f /* add btf_type for func_proto */ nr_params = ftype->nr_parms + (ftype->unspec_parms ? 1 : 0); - type_id = ftype->tag.type == 0 ? 0 : type_id_off + ftype->tag.type; + type_id = btf_encoder__tag_type(encoder, type_id_off, ftype->tag.type); id = btf__add_func_proto(btf, type_id); if (id > 0) { @@ -943,6 +956,15 @@ static int btf_encoder__encode_tag(struct btf_encoder *encoder, struct tag *tag, return btf_encoder__add_enum_type(encoder, tag, conf_load); case DW_TAG_subroutine_type: return btf_encoder__add_func_proto(encoder, tag__ftype(tag), type_id_off); + case DW_TAG_unspecified_type: + /* Just don't encode this for now, converting anything with this type to void (0) instead. + * + * If we end up needing to encode this, one possible hack is to do as follows, as "const void". + * + * Returning zero means we skipped encoding a DWARF type. + */ + // btf_encoder__add_ref_type(encoder, BTF_KIND_CONST, 0, NULL, false); + return 0; default: fprintf(stderr, "Unsupported DW_TAG_%s(0x%x): type: 0x%x\n", dwarf_tag_name(tag->tag), tag->tag, ref_type_id); @@ -1464,7 +1486,7 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu, struct co { uint32_t type_id_off = btf__type_cnt(encoder->btf) - 1; struct llvm_annotation *annot; - int btf_type_id, tag_type_id; + int btf_type_id, tag_type_id, skipped_types = 0; uint32_t core_id; struct function *fn; struct tag *pos; @@ -1487,8 +1509,13 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu, struct co cu__for_each_type(cu, core_id, pos) { btf_type_id = btf_encoder__encode_tag(encoder, pos, type_id_off, conf_load); + if (btf_type_id == 0) { + ++skipped_types; + continue; + } + if (btf_type_id < 0 || - tag__check_id_drift(pos, core_id, btf_type_id, type_id_off)) { + tag__check_id_drift(pos, core_id, btf_type_id + skipped_types, type_id_off)) { err = -1; goto out; } -- 2.39.1
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