From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by sourceware.org (Postfix) with ESMTPS id 5BE32386F036 for ; Tue, 12 Jan 2021 17:52:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 5BE32386F036 Received: by mail-qk1-x732.google.com with SMTP id b64so2593032qkc.12 for ; Tue, 12 Jan 2021 09:52:29 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:references:from:autocrypt:subject:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=JDrCiAnGaIzHvKiIX5lyQQtHUOb1caKPIIeaK6hpgF4=; b=jtiNnV6TnxvCPTMkdQ7Ehf8OwDB1qwF756fZ5bBSQwPBOarT2wFKMj++lY2LTQK7c1 cZu0zyi0dpP5zC559945AAWYq69ByXwXXfT61IM396dwINiayJ9gieidi3OW6N2iDMCC w2Ha0syt6Ly5mlQnIOoKPT0DM+BE97PXxIpWiiEUU9HfyqEZtLBHKEjCTA4j2fsmirJl KdAd6cuW0gQGu/3HA1TkX+62j5KD/XgW5+1vMCidMMShect3aAj0duHt+NFrJicapTYz k1uvTV2/stYpAECqWaY1Fgh0bKQCY4ck/SWebuvBMD1X2KNv/SWCAkU1uJYRdJBUt5as lttQ== X-Gm-Message-State: AOAM533bEZ1recQ5f6rHeMvbmCeDqr3gOV+qBJc5XbPMevrQpMeqMs9f iKH2ohK/cwWSVXcQ+GkweSzLraN5JZcdbw== X-Google-Smtp-Source: ABdhPJzyNApaW0KftxobLCUGyPwzWJsCersHzeVCfnCLGNawMl0I1U545KRgkNXeWqQwHsmYkG80gQ== X-Received: by 2002:a05:620a:3cf:: with SMTP id r15mr497593qkm.292.1610473948492; Tue, 12 Jan 2021 09:52:28 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id o201sm1722027qke.60.2021.01.12.09.52.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jan 2021 09:52:27 -0800 (PST) To: Szabolcs Nagy , libc-alpha@sourceware.org References: <20210111151146.27850-1-szabolcs.nagy@arm.com> From: Adhemerval Zanella Autocrypt: addr=adhemerval.zanella@linaro.org; prefer-encrypt=mutual; keydata= mQINBFcVGkoBEADiQU2x/cBBmAVf5C2d1xgz6zCnlCefbqaflUBw4hB/bEME40QsrVzWZ5Nq 8kxkEczZzAOKkkvv4pRVLlLn/zDtFXhlcvQRJ3yFMGqzBjofucOrmdYkOGo0uCaoJKPT186L NWp53SACXguFJpnw4ODI64ziInzXQs/rUJqrFoVIlrPDmNv/LUv1OVPKz20ETjgfpg8MNwG6 iMizMefCl+RbtXbIEZ3TE/IaDT/jcOirjv96lBKrc/pAL0h/O71Kwbbp43fimW80GhjiaN2y WGByepnkAVP7FyNarhdDpJhoDmUk9yfwNuIuESaCQtfd3vgKKuo6grcKZ8bHy7IXX1XJj2X/ BgRVhVgMHAnDPFIkXtP+SiarkUaLjGzCz7XkUn4XAGDskBNfbizFqYUQCaL2FdbW3DeZqNIa nSzKAZK7Dm9+0VVSRZXP89w71Y7JUV56xL/PlOE+YKKFdEw+gQjQi0e+DZILAtFjJLoCrkEX w4LluMhYX/X8XP6/C3xW0yOZhvHYyn72sV4yJ1uyc/qz3OY32CRy+bwPzAMAkhdwcORA3JPb kPTlimhQqVgvca8m+MQ/JFZ6D+K7QPyvEv7bQ7M+IzFmTkOCwCJ3xqOD6GjX3aphk8Sr0dq3 4Awlf5xFDAG8dn8Uuutb7naGBd/fEv6t8dfkNyzj6yvc4jpVxwARAQABtElBZGhlbWVydmFs IFphbmVsbGEgTmV0dG8gKExpbmFybyBWUE4gS2V5KSA8YWRoZW1lcnZhbC56YW5lbGxhQGxp bmFyby5vcmc+iQI3BBMBCAAhBQJXFRpKAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJ EKqx7BSnlIjv0e8P/1YOYoNkvJ+AJcNUaM5a2SA9oAKjSJ/M/EN4Id5Ow41ZJS4lUA0apSXW NjQg3VeVc2RiHab2LIB4MxdJhaWTuzfLkYnBeoy4u6njYcaoSwf3g9dSsvsl3mhtuzm6aXFH /Qsauav77enJh99tI4T+58rp0EuLhDsQbnBic/ukYNv7sQV8dy9KxA54yLnYUFqH6pfH8Lly sTVAMyi5Fg5O5/hVV+Z0Kpr+ZocC1YFJkTsNLAW5EIYSP9ftniqaVsim7MNmodv/zqK0IyDB GLLH1kjhvb5+6ySGlWbMTomt/or/uvMgulz0bRS+LUyOmlfXDdT+t38VPKBBVwFMarNuREU2 69M3a3jdTfScboDd2ck1u7l+QbaGoHZQ8ZNUrzgObltjohiIsazqkgYDQzXIMrD9H19E+8fw kCNUlXxjEgH/Kg8DlpoYJXSJCX0fjMWfXywL6ZXc2xyG/hbl5hvsLNmqDpLpc1CfKcA0BkK+ k8R57fr91mTCppSwwKJYO9T+8J+o4ho/CJnK/jBy1pWKMYJPvvrpdBCWq3MfzVpXYdahRKHI ypk8m4QlRlbOXWJ3TDd/SKNfSSrWgwRSg7XCjSlR7PNzNFXTULLB34sZhjrN6Q8NQZsZnMNs TX8nlGOVrKolnQPjKCLwCyu8PhllU8OwbSMKskcD1PSkG6h3r0AquQINBFcVGkoBEACgAdbR Ck+fsfOVwT8zowMiL3l9a2DP3Eeak23ifdZG+8Avb/SImpv0UMSbRfnw/N81IWwlbjkjbGTu oT37iZHLRwYUFmA8fZX0wNDNKQUUTjN6XalJmvhdz9l71H3WnE0wneEM5ahu5V1L1utUWTyh VUwzX1lwJeV3vyrNgI1kYOaeuNVvq7npNR6t6XxEpqPsNc6O77I12XELic2+36YibyqlTJIQ V1SZEbIy26AbC2zH9WqaKyGyQnr/IPbTJ2Lv0dM3RaXoVf+CeK7gB2B+w1hZummD21c1Laua +VIMPCUQ+EM8W9EtX+0iJXxI+wsztLT6vltQcm+5Q7tY+HFUucizJkAOAz98YFucwKefbkTp eKvCfCwiM1bGatZEFFKIlvJ2QNMQNiUrqJBlW9nZp/k7pbG3oStOjvawD9ZbP9e0fnlWJIsj 6c7pX354Yi7kxIk/6gREidHLLqEb/otuwt1aoMPg97iUgDV5mlNef77lWE8vxmlY0FBWIXuZ yv0XYxf1WF6dRizwFFbxvUZzIJp3spAao7jLsQj1DbD2s5+S1BW09A0mI/1DjB6EhNN+4bDB SJCOv/ReK3tFJXuj/HbyDrOdoMt8aIFbe7YFLEExHpSk+HgN05Lg5TyTro8oW7TSMTk+8a5M kzaH4UGXTTBDP/g5cfL3RFPl79ubXwARAQABiQIfBBgBCAAJBQJXFRpKAhsMAAoJEKqx7BSn lIjvI/8P/jg0jl4Tbvg3B5kT6PxJOXHYu9OoyaHLcay6Cd+ZrOd1VQQCbOcgLFbf4Yr+rE9l mYsY67AUgq2QKmVVbn9pjvGsEaz8UmfDnz5epUhDxC6yRRvY4hreMXZhPZ1pbMa6A0a/WOSt AgFj5V6Z4dXGTM/lNManr0HjXxbUYv2WfbNt3/07Db9T+GZkpUotC6iknsTA4rJi6u2ls0W9 1UIvW4o01vb4nZRCj4rni0g6eWoQCGoVDk/xFfy7ZliR5B+3Z3EWRJcQskip/QAHjbLa3pml xAZ484fVxgeESOoaeC9TiBIp0NfH8akWOI0HpBCiBD5xaCTvR7ujUWMvhsX2n881r/hNlR9g fcE6q00qHSPAEgGr1bnFv74/1vbKtjeXLCcRKk3Ulw0bY1OoDxWQr86T2fZGJ/HIZuVVBf3+ gaYJF92GXFynHnea14nFFuFgOni0Mi1zDxYH/8yGGBXvo14KWd8JOW0NJPaCDFJkdS5hu0VY 7vJwKcyHJGxsCLU+Et0mryX8qZwqibJIzu7kUJQdQDljbRPDFd/xmGUFCQiQAncSilYOcxNU EMVCXPAQTteqkvA+gNqSaK1NM9tY0eQ4iJpo+aoX8HAcn4sZzt2pfUB9vQMTBJ2d4+m/qO6+ cFTAceXmIoFsN8+gFN3i8Is3u12u8xGudcBPvpoy4OoG Subject: Re: [PATCH] elf: work around a gcc bug in elf_get_dynamic_info Message-ID: <60f29111-84e2-a085-8acf-8b6d30552536@linaro.org> Date: Tue, 12 Jan 2021 14:52:25 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210111151146.27850-1-szabolcs.nagy@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jan 2021 17:52:31 -0000 On 11/01/2021 12:11, Szabolcs Nagy via Libc-alpha wrote: > Since commit 2f056e8a5dd4dc0f075413f931e82cede37d1057 > "aarch64: define PI_STATIC_AND_HIDDEN", > building glibc with gcc-8 on aarch64 fails with > > /BLD/elf/librtld.os: in function `elf_get_dynamic_info': > /SRC/elf/get-dynamic-info.h:70:(.text+0xad8): relocation truncated to > fit: R_AARCH64_ADR_PREL_PG_HI21 against symbol `_rtld_local' defined > in .data section in /BLD/elf/librtld.os > > This is a gcc bug: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98618 > > Rewriting the affected code in elf_get_dynamic_info > seems to make this issue go away on old gcc. > > The change makes the logic a bit clearer too (by > separating the index computation and array update) > and drops an older gcc workaround (since gcc 4.6 > is no longer supported). So if I understood correctly this bug affects only gcc-8? Or does it affect older version as well? From comment #3, Wilco stated it was fixed by on gcc-10, so I take it was backported to gcc-9 already (since you didn't see it on gcc-9). I did a sniff build tests with different gcc (8 and 9 mostly) on different architectures and it seems ok. LGTM with the just nit below about VERSYMIDX. Reviewed-by: Adhemerval Zanella > --- > note: with new gcc the code generation only changes > slightly on aarch64 (the code becomes a bit smaller), > with old gcc the change is not a robust fix for the > issue but it seems to be be sufficient in my testing. > > the change only expected to have minor effect on > other targets, since it's mostly cosmetic. > > elf/get-dynamic-info.h | 41 ++++++++++++++++++----------------------- > 1 file changed, 18 insertions(+), 23 deletions(-) > > diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h > index 4f9aac63de..d8b071dff5 100644 > --- a/elf/get-dynamic-info.h > +++ b/elf/get-dynamic-info.h > @@ -28,52 +28,47 @@ static > auto > #endif > inline void __attribute__ ((unused, always_inline)) > elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp) > { > - ElfW(Dyn) *dyn = l->l_ld; > - ElfW(Dyn) **info; > #if __ELF_NATIVE_CLASS == 32 > typedef Elf32_Word d_tag_utype; > #elif __ELF_NATIVE_CLASS == 64 > typedef Elf64_Xword d_tag_utype; > #endif > > #if !defined RTLD_BOOTSTRAP && !defined STATIC_PIE_BOOTSTRAP > - if (dyn == NULL) > + if (l->l_ld == NULL) > return; > #endif > > - info = l->l_info; > + ElfW(Dyn) **info = l->l_info; > Ok. > - while (dyn->d_tag != DT_NULL) > + for (ElfW(Dyn) *dyn = l->l_ld; dyn->d_tag != DT_NULL; dyn++) > { > + d_tag_utype i; > + > if ((d_tag_utype) dyn->d_tag < DT_NUM) > - info[dyn->d_tag] = dyn; > + i = dyn->d_tag; > else if (dyn->d_tag >= DT_LOPROC > && dyn->d_tag < DT_LOPROC + DT_THISPROCNUM) > - { > - /* This does not violate the array bounds of l->l_info, but > - gcc 4.6 on sparc somehow does not see this. */ > - DIAG_PUSH_NEEDS_COMMENT; > - DIAG_IGNORE_NEEDS_COMMENT (4.6, > - "-Warray-bounds"); > - info[dyn->d_tag - DT_LOPROC + DT_NUM] = dyn; > - DIAG_POP_NEEDS_COMMENT; > - } > + i = dyn->d_tag - DT_LOPROC + DT_NUM; Ok. > else if ((d_tag_utype) DT_VERSIONTAGIDX (dyn->d_tag) < DT_VERSIONTAGNUM) > - info[VERSYMIDX (dyn->d_tag)] = dyn; > + i = DT_VERSIONTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM; Why expand VERSYMIDX macro here? > else if ((d_tag_utype) DT_EXTRATAGIDX (dyn->d_tag) < DT_EXTRANUM) > - info[DT_EXTRATAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > - + DT_VERSIONTAGNUM] = dyn; > + i = DT_EXTRATAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > + + DT_VERSIONTAGNUM; Ok. > else if ((d_tag_utype) DT_VALTAGIDX (dyn->d_tag) < DT_VALNUM) > - info[DT_VALTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > - + DT_VERSIONTAGNUM + DT_EXTRANUM] = dyn; > + i = DT_VALTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > + + DT_VERSIONTAGNUM + DT_EXTRANUM; Ok. > else if ((d_tag_utype) DT_ADDRTAGIDX (dyn->d_tag) < DT_ADDRNUM) > - info[DT_ADDRTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > - + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM] = dyn; > - ++dyn; > + i = DT_ADDRTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM > + + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM; > + else > + continue; > + > + info[i] = dyn; > } > > #define DL_RO_DYN_TEMP_CNT 8 > > #ifndef DL_RO_DYN_SECTION > Ok.