From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x82e.google.com (mail-qt1-x82e.google.com [IPv6:2607:f8b0:4864:20::82e]) by sourceware.org (Postfix) with ESMTPS id 17EB2386F465 for ; Thu, 21 Jan 2021 14:10:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 17EB2386F465 Received: by mail-qt1-x82e.google.com with SMTP id v3so1564983qtw.4 for ; Thu, 21 Jan 2021 06:10:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:autocrypt:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=LKz0tb+/PoeHLNf2RC17tJ6a8OWRgpUoKpnLwJRhfEM=; b=EtlHAzVkWO793XqPj76iHKT4AlgLFrNTn5fEgas82F4BfLKrs1NJuZ3NKq7hnP40G5 lDdIpNWQ15E3cZIPLOyTOKm9je2/I0oIRk6E12mhl7A5VRXdiquAWZjSaYQJ6gJiZ6Mv Zujmn2v+rnOYNInV1SJIfFt/Vld8dIMs+ywJfNVu6nR5tB+cWKY4MLi/fh3LpMlOqYTY U7z1svauF3U18lyZUcwOyjZ4u//efr1f7pS52Zy37THBIfCkVOfW/ia4anczyi9lPjOY ncN/dLH0vkqWOW4sqM53e5yYV5u4rpjaQmatlekvgGJMOIF8T5UYc4C1uZMEOUTToF23 xJ1A== X-Gm-Message-State: AOAM533fPOUVMalpLCpV2O6qNlbgo6mMOIF6Gk8zujvczMkIgqexDHGE fvUcaMjGgCeR4aQeL3PM+bXGHXi4QVVeWQ== X-Google-Smtp-Source: ABdhPJzgAinvX8HDDYidcJpTX3HZE94jQJiV6+J2qQcSd/cVejfKnnSG+rmZAe516kJyeuRJZ0TN9Q== X-Received: by 2002:ac8:505:: with SMTP id u5mr13728487qtg.25.1611238206342; Thu, 21 Jan 2021 06:10:06 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id v145sm3912735qka.27.2021.01.21.06.10.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Jan 2021 06:10:05 -0800 (PST) Subject: Re: [PATCH v5 7/7] Make libc symbols hidden in static PIE To: Szabolcs Nagy , libc-alpha@sourceware.org References: 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 Message-ID: <12d40524-2c44-68b3-0a06-6bfe28a3b041@linaro.org> Date: Thu, 21 Jan 2021 11:10:03 -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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-13.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, 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: Thu, 21 Jan 2021 14:10:10 -0000 On 20/01/2021 12:31, Szabolcs Nagy via Libc-alpha wrote: > Hidden visibility can avoid indirections and RELATIVE relocs in > static PIE libc. > > The check should use IS_IN_LIB instead of IS_IN(libc) since all > symbols are defined locally in static PIE and the optimization is > useful in all libraries not just libc. However the test system > links objects from libcrypt.a into dynamic linked test binaries > where hidden visibility does not work. I think mixing static and > shared libc components in the same binary should not be supported > usage, but to be safe only use hidden in libc.a. Why do we need this linkage for testing? Could we fix it so this change could be used in all static libraries? > > On some targets (i386) this optimization cannot be applied because > hidden visibility PIE ifunc functions don't work, so it is gated by > NO_HIDDEN_EXTERN_FUNC_IN_PIE. > > From -static-pie linked 'int main(){}' this shaves off 71 relative > relocs on aarch64 and reduces code size by about 2k. Nice. LGTM, thanks. Reviewed-by: Adhemerval Zanella > --- > include/libc-symbols.h | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index ea126ae70c..f4dd735555 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -434,13 +434,18 @@ for linking") > strong_alias(real, name) > #endif > > -#if defined SHARED || defined LIBC_NONSHARED \ > - || (BUILD_PIE_DEFAULT && IS_IN (libc)) > +#if defined SHARED || defined LIBC_NONSHARED > # define attribute_hidden __attribute__ ((visibility ("hidden"))) > #else > # define attribute_hidden > #endif > > +/* Mark all symbols hidden in static PIE libc to avoid GOT indirections. */ > +#if BUILD_PIE_DEFAULT && !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE \ > + && IS_IN (libc) && !defined LIBC_NONSHARED > +# pragma GCC visibility push(hidden) > +#endif > + > #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec"))) > > #define attribute_relro __attribute__ ((section (".data.rel.ro"))) > Ok.