From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x82a.google.com (mail-qt1-x82a.google.com [IPv6:2607:f8b0:4864:20::82a]) by sourceware.org (Postfix) with ESMTPS id E6A503857010 for ; Tue, 23 Feb 2021 13:24:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org E6A503857010 Received: by mail-qt1-x82a.google.com with SMTP id a2so6225408qtw.12 for ; Tue, 23 Feb 2021 05:24:55 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:references:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=5qr+wsYU+rN6/xfjS6I0N9shgEosSXNixUV69ba6ib8=; b=mcc6tSgsTTrAeS8R+Q31zL8CwwgHUWasuudkphylmbq5xfluQAIMc9Hw45PRJD79C6 3YqYbzrsp1z28E5tBivNzOpSR9VnB/UCMhWciVmkMgvJGEGXmLlD5VFxxwDWdQ5SMt8b zkEGJVGG5JMlLEtBI+ERSTGj+njbioiRC79Qk1RwUxHYeH+iOM/L+JQGcGNvkajKAY79 Xpnaq9mAywgS/QcahquyFVgS+xAQr9kJcY9nixrgiYZATvpJrlkYjzAo73rlatVBl/R5 q2srNtkI9yLzfwFP1l2i2QKHcM5kgSlHu/Amc7QE3C6r28nAKIxK6Q9zWJ/hM7YFSS+K nZOA== X-Gm-Message-State: AOAM533JIkgt58tYSCkMdOoK6OFKX/QwrL7e2FZPKiiMpvu18ywy0saz d/wXkusYQVVBPoLa7KIcTVGlAxD1UzztWw== X-Google-Smtp-Source: ABdhPJzR2akVxWDPTdA7sHn2A3Y+u+nZgivcsC87CjH453t/Svb8XE/MxRTaTc9A+Oh2TmgmBfHQ6Q== X-Received: by 2002:a05:622a:8a:: with SMTP id o10mr24954670qtw.9.1614086695394; Tue, 23 Feb 2021 05:24:55 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id p10sm14846434qke.92.2021.02.23.05.24.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Feb 2021 05:24:55 -0800 (PST) From: Adhemerval Zanella To: Vivek Das Mohapatra Cc: libc-alpha@sourceware.org, Alan Modra References: <20210209171839.7911-1-vivek@collabora.com> <20210209171839.7911-19-vivek@collabora.com> <3280e928-57d4-6d20-47a4-cf1c932a03b9@linaro.org> 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: [RFC][PATCH v8 18/20] Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE dynamic section+flag to glibc DSOs Message-ID: <167c83cf-6dd7-22a5-c3e7-e0c0f6f7f0d9@linaro.org> Date: Tue, 23 Feb 2021 10:24:52 -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: <3280e928-57d4-6d20-47a4-cf1c932a03b9@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.8 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, URIBL_BLACK 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, 23 Feb 2021 13:24:57 -0000 On 23/02/2021 09:02, Adhemerval Zanella wrote: > > > On 22/02/2021 21:17, Vivek Das Mohapatra wrote: >>> We have some options to fix it: >>> >>>  1. Bump the minimum supported binutils version to 2.36. It would be >>>     a large change, since we usually do incremental changes over releases >> >> It's a large bump: OTOH is it the case that people are going to be >> rolling out cutting edge glibc with old binutils? (Serious question, >> the answer might be yes in whic case we do need to think about this). >> >>>  2. Add a configure check and enable RTLD_SHARED iff ld supports >>>     -z unique.  It would require return EINVAL is RTLD_SHARED or >> >> Doable, but then we'd have glibc at the same version with different >> capabilities/behaviours in the linker: Asking for pain imo. >> >>>  3. Find a way to force add DF_GNU_1_UNIQUE on older binutils >>>     (since its support is just a dynamic section existence) >> >> I think this is doable, either with a linker script or by >> using the spare dynamic tags added by ld (cf --spare-dynamic-sections) >> and writing in the value we want in the first spare slot. > > In fact I now more inclined to use 3. now that I checked that Alan's > trick [1] does work. The assembly file should be architecture > independent, so it is a matter of building, changing the shlib.lds > generation to add the new object and adding the new note on each required > library. > > [1] https://sourceware.org/legacy-ml/binutils/2019-09/msg00287.html > This patch below based on your tree could get the dynamic note on libc.so. It has to explicit add the dynamic-note.os as an extra object (adding an extra object on libc.so build will add on libc_pic.{a,os} and linker script won't handle). The shlib.lds would require some work to get the previous '.dynamic' info dumped from compiler. Also it does not add the dynamic section on other libraries than libc.so. Alan pointed me out that _DYNAMIC can be in the script too, but I am not sure it would be simpler in our build process. And dynamic-notes.c could also be used to add other dynamic section when required. --- diff --git a/Makerules b/Makerules index 82adffdc27..fc6061e12d 100644 --- a/Makerules +++ b/Makerules @@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules PROVIDE(__start___libc_IO_vtables = .);\ __libc_IO_vtables : { *(__libc_IO_vtables) }\ PROVIDE(__stop___libc_IO_vtables = .);\ - /DISCARD/ : { *(.gnu.glibc-stub.*) }@' + /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \ + -e 's/^.*\*(\.dynamic).*$$/ .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/' test -s $@T mv -f $@T $@ common-generated += shlib.lds @@ -693,6 +694,7 @@ $(common-objpfx)linkobj/libc.so: link-libc-deps = # empty $(common-objpfx)libc.so: $(common-objpfx)libc_pic.os$(libc_pic_clean) \ $(elf-objpfx)sofini.os \ $(elf-objpfx)interp.os \ + $(elf-objpfx)dynamic-notes.os \ $(elf-objpfx)ld.so \ $(shlib-lds) $(build-shlib) diff --git a/elf/Makefile b/elf/Makefile index bccf31b1a9..e3c5937caf 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -105,7 +105,8 @@ ld-map = $(common-objpfx)ld.map endif ifeq (yes,$(build-shared)) -extra-objs = $(all-rtld-routines:%=%.os) sofini.os interp.os +extra-objs = $(all-rtld-routines:%=%.os) sofini.os interp.os \ + dynamic-notes.os generated += librtld.os dl-allobjs.os ld.so ldd install-others = $(inst_rtlddir)/$(rtld-installed-name) install-bin-script = ldd diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c new file mode 100644 index 0000000000..d0b487e970 --- /dev/null +++ b/elf/dynamic-notes.c @@ -0,0 +1,4 @@ +#include + +const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) = + { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };