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[176.36.0.241]) by smtp.gmail.com with ESMTPSA id vk8-20020a170907cbc800b00a36f9e61664sm20269ejc.107.2024.02.05.08.54.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Feb 2024 08:54:36 -0800 (PST) Message-ID: <39f3d8a2163678cb5306caab338e9f3c6b7c003e.camel@gmail.com> Subject: Re: [PATCH dwarves v4 2/2] pahole: Inject kfunc decl tags into BTF From: Eduard Zingerman To: Daniel Xu , acme@kernel.org, jolsa@kernel.org, quentin@isovalent.com, alan.maguire@oracle.com Cc: andrii.nakryiko@gmail.com, ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org Date: Mon, 05 Feb 2024 18:54:34 +0200 In-Reply-To: <28e81ccf28d6dd33f6db50af6526dc1770502b8d.1707071969.git.dxu@dxuuu.xyz> References: <28e81ccf28d6dd33f6db50af6526dc1770502b8d.1707071969.git.dxu@dxuuu.xyz> Autocrypt: addr=eddyz87@gmail.com; prefer-encrypt=mutual; keydata=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 nYzhLWGcczc6J71q1Dje0l5vIPaSFOgwmWD4DA+WvuxM/shH4rtWeodbv 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 t1iq+gsfnXbPz5AnS598ScZI1oP7OrPSFJkt/z4acEbOQDQs8aUqrd46PV jsdqGvKnXZxzylux29UTNby4jTlz9pNJM+wPrDRmGfchLDUmf6CffaUYCbu4FiId+9+dcTCDvxbABRy1C3OJ8QY7cxfJ+pEZW18fRJ0XCl/fiV/ecAOfB3HsqgTzAn555h0rkFgay0hAvMU/mAW/CFNSIxV397zm749ZNLA0L2dMy1AKuOqH+/B+/ImBfJMDjmdyJQ8WU/OFRuGLdqOd2oZrA1iuPIa+yUYyZkaZfz/emQwpIL1+Q4p1R/OplA4yc301AqruXXUcVDbEB+joHW3hy5FwK5t5OwTKatrSJBkydSF9zdXy98fYzGniRyRA65P0Ix/8J3BYB4edY2/w0Ip/mdYsYQljBY0A== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sun, 2024-02-04 at 11:40 -0700, Daniel Xu wrote: [...] > +static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) > +{ > + const char *filename =3D encoder->filename; > + struct gobuffer btf_kfunc_ranges =3D {}; > + struct gobuffer btf_funcs =3D {}; > + Elf_Scn *symscn =3D NULL; > + int symbols_shndx =3D -1; > + int fd =3D -1, err =3D -1; > + int idlist_shndx =3D -1; > + Elf_Scn *scn =3D NULL; > + size_t idlist_addr; > + Elf_Data *symbols; > + Elf_Data *idlist; > + size_t strtabidx; > + Elf *elf =3D NULL; > + GElf_Shdr shdr; > + size_t strndx; > + char *secname; > + int nr_syms; > + int i =3D 0; Note: when compiled in Release mode (e.g. using buildcmd.sh from the repo) there is a number of false-positive warnings reported by GCC 13.2.1: $ ./buildcmd.sh ... In function =E2=80=98is_sym_kfunc_set=E2=80=99, inlined from =E2=80=98btf_encoder__tag_kfuncs=E2=80=99 at /home/eddy/wo= rk/dwarves-fork/btf_encoder.c:1639:8, inlined from =E2=80=98btf_encoder__encode=E2=80=99 at /home/eddy/work/d= warves-fork/btf_encoder.c:1724:29: /home/eddy/work/dwarves-fork/btf_encoder.c:1395:29: warning: =E2=80=98idlis= t_addr=E2=80=99 may be used uninitialized [-Wmaybe-uninitialized] 1395 | off =3D sym->st_value - idlist_addr; | ~~~~~~~~~~~~~~^~~~~~~~~~~~~ /home/eddy/work/dwarves-fork/btf_encoder.c: In function =E2=80=98btf_encode= r__encode=E2=80=99: /home/eddy/work/dwarves-fork/btf_encoder.c:1538:16: note: =E2=80=98idlist_a= ddr=E2=80=99 was declared here 1538 | size_t idlist_addr; | ^~~~~~~~~~~ In function =E2=80=98btf_encoder__tag_kfuncs=E2=80=99, inlined from =E2=80=98btf_encoder__encode=E2=80=99 at /home/eddy/work/d= warves-fork/btf_encoder.c:1724:29: Same thing is reported for: - btf_encoder.c:1630:22: warning: =E2=80=98symbols=E2=80=99 may be used uni= nitialized - btf_encoder.c:1385:15: warning: =E2=80=98idlist=E2=80=99 may be used unin= itialized - btf_encoder.c:1638:24: warning: =E2=80=98strtabidx=E2=80=99 may be used u= ninitialized GCC does not figure out that the variables above are guarded by -1 checks b= elow. [...] > + while ((scn =3D elf_nextscn(elf, scn)) !=3D NULL) { [...] > + if (shdr.sh_type =3D=3D SHT_SYMTAB) { > + symbols_shndx =3D i; > + symscn =3D scn; > + symbols =3D data; > + strtabidx =3D shdr.sh_link; > + } else if (!strcmp(secname, BTF_IDS_SECTION)) { > + idlist_shndx =3D i; > + idlist_addr =3D shdr.sh_addr; > + idlist =3D data; > + } > + } > + > + /* Cannot resolve symbol or .BTF_ids sections. Nothing to do. */ > + if (symbols_shndx =3D=3D -1 || idlist_shndx =3D=3D -1) { > + err =3D 0; > + goto out; > + } [...]