From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8768 invoked by alias); 30 Oct 2016 10:13:36 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 8756 invoked by uid 89); 30 Oct 2016 10:13:35 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=0.3 required=5.0 tests=AWL,BAYES_20,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=no version=3.3.2 spammy=commitdiff, pads, UD:glibc.git, glibcgit X-HELO: mail-wm0-f67.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version; bh=mPK7vv+optZO7zyONArsiWth7iY/KFWo+a/ANYrlx3g=; b=Gstbp41T4pUodqeTzarkl+mizP/VCQ18hlS2xg0qKXWHRl30RtpaJHWmnraBm9ar6U RhMXh1dhNH9TU5o3my3oOPa34FUUeVMbj9b1spndmaT73vot/zy5fgohLoduHvcHTNQk aYXURGHg5bOcq4BgjWIcYCVeypsC8VCNbSwb+cK9pYkqSkjEumJL30cixQBmhpuWtGLv F5+I0jzPIN+PG2vZJ2tgnf2OlLD2fvyepeHL+O+6jt1xQRspDnDTUQsW8bw1U8kAN/ZS 8S16pgCyA1bDdXqIM97J8F9yV/6tox+BAGP5UcQLJz3z3NCf/kZamuKCRFhLnB8FmeIf Jd1g== X-Gm-Message-State: ABUngvdsq3rYIPktr9VBgIN0zZEWkMzZZGlEXnt9FKMHmyVfZeOYOL8TPetqs9RioibDog== X-Received: by 10.28.191.142 with SMTP id o14mr5709633wmi.124.1477822403237; Sun, 30 Oct 2016 03:13:23 -0700 (PDT) Date: Sun, 30 Oct 2016 10:13:00 -0000 From: Sergei Trofimovich To: Andreas Schwab Cc: libc-alpha@sourceware.org, Sergei Trofimovich , Roland McGrath Subject: Re: [PATCH] m68k: restore handling of R_68K_NONE in elf_machine_lazy_rel() Message-ID: <20161030101318.6971a5f5@sf> In-Reply-To: <87lgx7nkr2.fsf@linux-m68k.org> References: <20161029134801.15082-1-slyich@gmail.com> <87pomjnp3v.fsf@linux-m68k.org> <20161029171527.423b573e@sf> <87lgx7nkr2.fsf@linux-m68k.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/otofoknu+=NTStA5S2f3qun"; protocol="application/pgp-signature" X-SW-Source: 2016-10/txt/msg00594.txt.bz2 --Sig_/otofoknu+=NTStA5S2f3qun Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Content-length: 2559 On Sat, 29 Oct 2016 19:11:13 +0200 Andreas Schwab wrote: > On Okt 29 2016, Sergei Trofimovich wrote: >=20 > > Commit https://sourceware.org/git/?p=3Dglibc.git;a=3Dcommitdiff;h=3D96e= 1bff2513873062233a13c7fd1eea57bb8db24 > > among other thing shows disappearance of 'case R_68K_NONE':=20=20 >=20 > The old history is mostly broken, you need to look at > . Same removal: http://repo.or.cz/glibc/history.git/commitdiff/60f0b5f25d09c1ee464141ee= 41995d9a31a604b7 binutils accidentally generates R_68K_NONE relocations around here https://sourceware.org/git/gitweb.cgi?p=3Dbinutils-gdb.git;a=3Dblob;f= =3Dbfd/elf32-m68k.c;h=3D7c2e0fcca3bfb35d71dc1431c69958c84f04de7b;hb=3D69003= 5b1471a58db62ec27d739f124f0f58f6af2#l3356 [bfd fails to properly estimate final relocation section size and pads with= zeros] 3356 /* Allocate memory for the section contents. */ 3357 /* FIXME: This should be a call to bfd_alloc not bfd_zalloc. 3358 Unused entries should be reclaimed before the section's c= ontents 3359 are written out, but at the moment this does not happen. = Thus in 3360 order to prevent writing out garbage, we initialise the s= ection's 3361 contents to zero. */ 3362 s->contents =3D (bfd_byte *) bfd_zalloc (dynobj, s->size); Curious can add "memset(s->contents, '\xFF', s->size);" to make sure it still happens. And indeed m68k-linux-gcc generates R_68K_NONE relocations even for minimal programs: $ echo 'int main(){}' > a.c $ m68k-unknown-linux-gnu-gcc a.c -o a $ readelf -a a | grep -C4 NONE 0x00000000 (NULL) 0x0 Relocation section '.rela.dyn' at offset 0x238 contains 3 entries: Offset Info Type Sym.Value Sym. Name + Addend 00000000 00000000 R_68K_NONE 0 00000000 00000000 R_68K_NONE 0 80004014 00000114 R_68K_GLOB_DAT 00000000 __gmon_start__ + 0 In general relocations happen to be non-lazy. I guess to trigger lazy case we need to build shared library with complex l= ibrary structure. At least GHC does that. Is there a reason to allow R_68K_NONE for non-lazy relocations in elf_machine_rela() + case R_68K_NONE: /* Alright, Wilbur. */ + break; but forbid R_68K_NONE for lazy relocations in elf_machine_lazy_rel() assuming mechanism to leak R_68K_NONE to both relocation types is the same? Thanks! --=20 Sergei --Sig_/otofoknu+=NTStA5S2f3qun Content-Type: application/pgp-signature Content-Description: Цифровая подпись OpenPGP Content-length: 163 -----BEGIN PGP SIGNATURE----- iEYEARECAAYFAlgVx74ACgkQcaHudmEf86r9OACcDc34P5a5ksL2CZH04u2P6abT 3EwAn1d4KdeM/mtfzZysPbsxarnwEzJs =W/ZN -----END PGP SIGNATURE----- --Sig_/otofoknu+=NTStA5S2f3qun--