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[61.245.154.180]) by smtp.googlemail.com with ESMTPSA id f19sm3566643pgn.42.2020.03.09.06.45.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Mar 2020 06:45:31 -0700 (PDT) Subject: Re: RFC: [PATCH] ELF: Don't require section header on ELF objects References: <20200308175947.GA911529@gmail.com> <87y2sac5er.fsf@mid.deneb.enyo.de> <79bc289f-9202-9aff-61c3-92c7190d2f7d@gmail.com> <875zfdad9j.fsf@mid.deneb.enyo.de> <36183da0-ed0c-13bf-2cb3-bd004e8d46f9@gmail.com> <87y2s98y94.fsf@mid.deneb.enyo.de> <87tv2x8xmy.fsf@mid.deneb.enyo.de> To: binutils@sourceware.org From: Kaylee Blake Openpgp: preference=signencrypt Autocrypt: addr=klkblake@gmail.com; prefer-encrypt=mutual; keydata= xsBNBFEjQLEBCADjjSJEqGgOWM+dK6wvOi5B/i1LFM00hy9x1bZZCj34Z7/6H60KhI00yRaj bJzPzmlAO402Ac69NZMXV+mmFFBAabIg70R0VyJKPxX7QyZ4GM9K9w2+LZM+9OgKhOzoypMa S0O93f4EdJ9R7GbsbnWf4SOhv7tKAnJr3jZwp55YkQDnZBHvLw4r8vHykTd6E198CGy4zOYj z2T09rVBmuuklUOea+zj3M6N6zVOcl3JPYM1t2a53x1tuuNtRW1uJNkw37vOuv27jE4UCFBh WA+0NGMqmst40sf033fJMAGT5lUsHhLJy52SSWZMIlPEtFNI04re0k7YG/W1/yr3qJC/ABEB AAHNH0t5bGUgQmxha2UgPGtsa2JsYWtlQGdtYWlsLmNvbT7CwJYEEwECAEACGyMHCwkIBwMC AQYVCAIJCgsEFgIDAQIeAQIXgBYhBKOwrUWr3Qf9tbRhWQjfzoNJjQmjBQJeKmIcBQkO6FTm AAoJEAjfzoNJjQmjvOgH/jcoYAOeqZt/7QR4KIfmbs7r1KeZBU34l3vVNDiycc59abbsW9cC OjUxurgRbOMBd86pVsXaBDwt4F7lAmvONCxJAmpdiweXqvNZ843VP7vCzBWPnBOksneKrvXi w0UgtQqnrI46T5hzRrpmVQVUjKPcYyuGAdt9zv6Kxk6iwri7/s0/bmIvm3p8zfA5rv2A7OH+ lx/PWRSN8IEwNJq9vEKPiVCSawF9xzLC6Q5M2gCxFuX87ewCgrdyCz9BZvlDg4+YvU5pcCb5 Bl0W9L97zi8ZsfNtd+Y2XO8FGiLP08UHcYPCZ/ZctQeyLTxbIwh6RALHGVEJJcnpyqYxrqJB 7NHOwE0EUSNAsQEIAN9XABpQz0Z29d7/0+6tPmdp40RNzpc/UhOEi0qfdzn9EeSDBC5hZDxl PxgtTHSuOUpmofwvS3g2HOmE3keh+gyhgKJtS+o6b+DZfTXJgXYNDPoXnlL0zfu6GebqIicN 4KWTkhu23w+7RWxwWxTiuYn3Aj2M/2p+Y7tOkzjB0RDjuV/M4lWUVXPpb8TWyVkgwQA42Zz/ mlnDi43BFu9Qy3DRP28aJ8bNTGGQ6CLubEt9WBxBhXD4W57gJq8TVCc/uvUJbt/+VfoD7MJV vFzN4lagN1y8uLR00I9bRjoCZ+ZvlAUBPCAcC3t4TmQLA5eajkmBQ2BOijKH7nFf29oV6IMA EQEAAcLAZQQYAQIADwUCUSNAsQIbDAUJCWYBgAAKCRAI386DSY0JozmEB/9k0s1wDQagXUMw 1HAX0R86QtrIChHINkaD1xhquuNpCD1vkIqbZSfw50jR+unBpqNOTcJcuBsi6dWI6maHw1Xd 27T6Jgm/5C2sgUD6dYFFATGlotID2jNRhYe7PfzL38RDIkx9qi5o7b3/zh20Tm+CLZm1bX7T X7D2TANhpl1S2IusNJUBk2ZMXft3ADeIThYd4xEWiT27zYdV1dBOQLiS4qYW1v+EojnnmoIP xoHvXdSGfLyJTTwqLw1yXxL9yMVfNEl/AGPhMHtwbtWTMofGbLCTrHp03pqCTNaF2VHE0HuO eUz1vhRCYch06svzICIRcrn7NyJvcGhil4f5SF/dwsB8BBgBAgAmAhsMFiEEo7CtRavdB/21 tGFZCN/Og0mNCaMFAl4qYhwFCQ7oVOsACgkQCN/Og0mNCaMiZgf+IZZV5fg1mNscH90Py/k2 I5zznzXqdnCd5DmocX3t9Z26/mcTI0hQhiY8UZFkDxI3E0LFu8hDaRB+ioXNidVNdWZAhpr2 zDMjjwVmlx/Jt3+MI/RygsidIRuYYGy94RLvYTQh6qfuHy/5GDIwgsq+S0MfjdcPCO5NLpPH 8pYowlZiehA0QT5hwNzFR1S2YvxHr+nN99jxhOnQZ2TUt5+mQfXwfCQVHoSiJKrwU6z8Q85o ClHHtbUpOY+W6S2I9lRgeaF/fiDo6nZeKRaF5enwxLHuz6tXkdv04vDx5lJevqjtvUUCglQ1 EdpFPEpbpgoe5SmlCrB+cO0ATaAAA06SxQ== Message-ID: Date: Tue, 10 Mar 2020 00:15:27 +1030 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <87tv2x8xmy.fsf@mid.deneb.enyo.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, HK_RANDOM_ENVFROM, HK_RANDOM_FROM, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: binutils@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Binutils mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Mar 2020 13:45:33 -0000 On 9/3/20 11:59 pm, Florian Weimer wrote: > * Kaylee Blake: > >>> I think that's conceptually the wrong thing to do for ELF, sorry. If >>> there is no section header, the object should be unlinkable. The >>> linker should not use the dynamic segment to locate the symbol >>> information, only the dynamic section (in case the link ABI and >>> run-time ABI are different). >> >> I'm confused by your comment about link and run-time ABIs differing; >> surely if the ABI at runtime differs from the ABI at link time, you are >> just going to crash at runtime? > > No, the typical application are fewer symbols in the DSO at link time > than at load time, for example for linking against an older version of > glibc than is installed on the system. How is that being done? On my machine, the symbols in glibc found through the section header are identical to the ones found through the dynamic array, except that some of the latter are missing symbol versions, which I think is due to this patch not looking them up? (I'm not actually sure if this patch does that or not). -- Kaylee Blake C is the worst language, except for all the others.