From patchwork Fri Jun 20 17:21:29 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 362306 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 9783914008F for ; Sat, 21 Jun 2014 03:21:58 +1000 (EST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:message-id :mime-version:content-type; q=dns; s=default; b=HfMX/aDi2eU1DjoB JuqolWHvn3gELEG6IJR80rnExYh/DyYFwZvERD//i5C41M+mlfr8qUkFb+kA7iW9 eNqEUmU0Xr3ish88bA+GYuSlzqPRr0YEW1dEv5Uo7Lq0bHdcjXKEiEXdxT6LU1vQ B8QarlbJyIWx/HVum0PT7JAYxS4= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:message-id :mime-version:content-type; s=default; bh=WqceMzyEwFZIr81J+8DBhU IQkhc=; b=vCOd87TR9SFsYtxkh7311wGKFH9Kdq+zNXegJ19EyvoWXcUxeMB2pw pd1xVg01U91zS51p5Ee3DBObOye5xTSlJOA7D7u+LltBV3sJPMv0iZcH+mFZ6gC7 JvWBNdvMtKJoXK/xiOw4xC5c/O/5GOCnPOgyDUSvnkLXBGlOwtJkk= Received: (qmail 30849 invoked by alias); 20 Jun 2014 17:21:52 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 30834 invoked by uid 89); 20 Jun 2014 17:21:50 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.0 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Date: Fri, 20 Jun 2014 18:21:29 +0100 From: "Maciej W. Rozycki" To: CC: "Joseph S. Myers" , Rich Felker Subject: [PATCH v2][BZ #17075] ARM: Fix immediate calculation of R_ARM_TLS_DESC Message-ID: User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Hello, I've noticed external symbol value calculation made in the dynamic linker is broken while processing the R_ARM_TLS_DESC reloc in the global immediately-bound case, where code has been originally linked for lazy binding. To figure out the final value of the symbol the calculation makes use of the descriptor's argument that in this case is set to the symbol's table index in the symbol table ORed with 0x80000000 and adds it to the actual value of the symbol resolved by the linker. Such calculated value is then used if the static specialisation is selected and the typical result is a segfault. This is easily reproduced by trying any program that has (or whose link-time dependency has) R_ARM_TLS_DESC relocs against external symbols and has been linked with `-Wl,-z,lazy' in effect (no DT_BIND_NOW dynamic tag present), and running it with $LD_BIND_NOW set to 1 in the environment. Such calculation is plain wrong and in the case of a lazily-bound external symbol the value of the descriptor's argument provided by the static linker can be simply discarded as it's only needed by the lazy specialisation to resolve the symbol (that in this case already has been). This is addressed with the patch below. Three test cases are included, to cover the local, global lazy and global immediate references. It has been verified across a number multilibs, all failing the global lazy test case before and passing after the fix has been applied. No regressions, but one'd expect that for such a localised change. The test case required extra `configure' scriptery, because older versions of GCC do not support TLS descriptors or the `-mtls-dialect=' option. Additionally GCC does not validate binutils' support for TLS decriptors at the build time, so modern GCC built with the effective configuration of `--with-tls=gnu' will still work with older binutils and accept the `-mtls-dialect=gnu2' option, but the assembler will then choke on the lack of support for the syntax used to produce TLS descriptor relocations if any code is produced that requests them. Therefore the `configure' test uses a piece of inline assembly that explicitly requests a TLS descriptor relocation on a symbol and is guaranteed to break with older binutils. Consequently both GCC and binutils support is verified with a single `configure' test. There is no need to verify binutils' support for the `-z lazy' linker option as all the versions that support TLS descriptors also support the said option (it has been present since 2000). This is an updated version, changes from version 1: 1. Joseph's note about using LIBC_CONFIG_VAR taken into account, no more changes outside sysdeps/arm/. 2. The global immediate case taken into account and the regression introduced by the previous revision of this change fixed. Test cases added to handle all the three kinds of references: local, global lazy and global immediate. The latter test case covers the regression with the previous revision of this change. OK to apply? 2014-06-19 Maciej W. Rozycki [BZ #17075] * sysdeps/arm/dl-machine.h (elf_machine_rel) : Fix calculation of the symbol's value. * sysdeps/arm/tst-armtlsdescloc.c: New file. * sysdeps/arm/tst-armtlsdesclocmod.c: New file. * sysdeps/arm/tst-armtlsdescextnow.c: New file. * sysdeps/arm/tst-armtlsdescextlazymod.c: New file. * sysdeps/arm/tst-armtlsdescextlazy.c: New file. * sysdeps/arm/tst-armtlsdescextnowmod.c: New file. * sysdeps/arm/Makefile (tests): Add `tst-armtlsdesc', `tst-armtlsdescextnow' and `tst-armtlsdescextlazy'. (modules-names): Add `tst-armtlsdescmod', `tst-armtlsdescextlazymod' and `tst-armtlsdescextnowmod'. (CPPFLAGS-tst-armtlsdescextnowmod.c): New variable. (CPPFLAGS-tst-armtlsdescextlazymod.c): Likewise. (CFLAGS-tst-armtlsdesclocmod.c): Likewise. (CFLAGS-tst-armtlsdescextnowmod.c): Likewise. (CFLAGS-tst-armtlsdescextlazymod.c): Likewise. (LDFLAGS-tst-armtlsdescextnowmod.so): Likewise. ($(objpfx)tst-armtlsdescloc): New dependency. ($(objpfx)tst-armtlsdescextnow): Likewise. ($(objpfx)tst-armtlsdescextlazy): Likewise. * sysdeps/arm/configure.ac: Add a check for tools' GNU descriptor TLS scheme support. * sysdeps/arm/configure: Regenerate. Maciej glibc-arm-tls-desc-imm.diff Index: glibc-fsf-trunk-quilt/sysdeps/arm/Makefile =================================================================== --- glibc-fsf-trunk-quilt.orig/sysdeps/arm/Makefile 2014-06-20 05:46:45.000000000 +0100 +++ glibc-fsf-trunk-quilt/sysdeps/arm/Makefile 2014-06-20 06:53:01.661995040 +0100 @@ -11,6 +11,26 @@ $(objpfx)libgcc-stubs.a: $(objpfx)aeabi_ $(build-extra-lib) lib-noranlib: $(objpfx)libgcc-stubs.a + +ifeq ($(build-shared),yes) +ifeq ($(have-arm-tls-desc),yes) +tests += tst-armtlsdescloc tst-armtlsdescextnow tst-armtlsdescextlazy +modules-names += tst-armtlsdesclocmod +modules-names += tst-armtlsdescextlazymod tst-armtlsdescextnowmod +CPPFLAGS-tst-armtlsdescextnowmod.c += -Dstatic= +CPPFLAGS-tst-armtlsdescextlazymod.c += -Dstatic= +CFLAGS-tst-armtlsdesclocmod.c += -mtls-dialect=gnu2 +CFLAGS-tst-armtlsdescextnowmod.c += -mtls-dialect=gnu2 +CFLAGS-tst-armtlsdescextlazymod.c += -mtls-dialect=gnu2 +LDFLAGS-tst-armtlsdescextnowmod.so += -Wl,-z,now +tst-armtlsdescloc-ENV = LD_BIND_NOW=1 +tst-armtlsdescextnow-ENV = LD_BIND_NOW=1 +tst-armtlsdescextlazy-ENV = LD_BIND_NOW=1 +$(objpfx)tst-armtlsdescloc: $(objpfx)tst-armtlsdesclocmod.so +$(objpfx)tst-armtlsdescextnow: $(objpfx)tst-armtlsdescextnowmod.so +$(objpfx)tst-armtlsdescextlazy: $(objpfx)tst-armtlsdescextlazymod.so +endif +endif endif ifeq ($(subdir),csu) Index: glibc-fsf-trunk-quilt/sysdeps/arm/configure =================================================================== --- glibc-fsf-trunk-quilt.orig/sysdeps/arm/configure 2014-06-20 05:46:45.000000000 +0100 +++ glibc-fsf-trunk-quilt/sysdeps/arm/configure 2014-06-20 05:52:38.571931573 +0100 @@ -203,3 +203,39 @@ else config_vars="$config_vars default-abi = soft" fi + +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the build tools support the GNU descriptor TLS scheme" >&5 +$as_echo_n "checking whether the build tools support the GNU descriptor TLS scheme... " >&6; } +if ${libc_cv_arm_tls_desc+:} false; then : + $as_echo_n "(cached) " >&6 +else + old_CFLAGS="$CFLAGS" + CFLAGS="$CFLAGS -mtls-dialect=gnu2" + cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +asm (".word\tfoo(tlsdesc)"); +int +main () +{ + + ; + return 0; +} +_ACEOF +if ac_fn_c_try_compile "$LINENO"; then : + libc_cv_arm_tls_desc=yes +else + libc_cv_arm_tls_desc=no +fi +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext + CFLAGS="$old_CFLAGS" +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_arm_tls_desc" >&5 +$as_echo "$libc_cv_arm_tls_desc" >&6; } +if test $libc_cv_arm_tls_desc = yes; then + config_vars="$config_vars +have-arm-tls-desc = yes" +else + config_vars="$config_vars +have-arm-tls-desc = no" +fi Index: glibc-fsf-trunk-quilt/sysdeps/arm/configure.ac =================================================================== --- glibc-fsf-trunk-quilt.orig/sysdeps/arm/configure.ac 2014-06-20 05:46:45.000000000 +0100 +++ glibc-fsf-trunk-quilt/sysdeps/arm/configure.ac 2014-06-20 05:52:38.571931573 +0100 @@ -44,3 +44,16 @@ if test $libc_cv_arm_pcs_vfp = yes; then else LIBC_CONFIG_VAR([default-abi], [soft]) fi + +AC_CACHE_CHECK([whether the build tools support the GNU descriptor TLS scheme], + [libc_cv_arm_tls_desc], + [old_CFLAGS="$CFLAGS" + CFLAGS="$CFLAGS -mtls-dialect=gnu2" + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([asm (".word\tfoo(tlsdesc)");], [])], + [libc_cv_arm_tls_desc=yes], [libc_cv_arm_tls_desc=no]) + CFLAGS="$old_CFLAGS"]) +if test $libc_cv_arm_tls_desc = yes; then + LIBC_CONFIG_VAR([have-arm-tls-desc], [yes]) +else + LIBC_CONFIG_VAR([have-arm-tls-desc], [no]) +fi Index: glibc-fsf-trunk-quilt/sysdeps/arm/dl-machine.h =================================================================== --- glibc-fsf-trunk-quilt.orig/sysdeps/arm/dl-machine.h 2014-06-20 05:46:45.000000000 +0100 +++ glibc-fsf-trunk-quilt/sysdeps/arm/dl-machine.h 2014-06-20 07:08:08.301787149 +0100 @@ -452,7 +452,10 @@ elf_machine_rel (struct link_map *map, c else # endif { - value = sym->st_value + td->argument.value; + if (ELF32_R_SYM (reloc->r_info) == STN_UNDEF) + value = td->argument.value; + else + value = sym->st_value; # ifndef RTLD_BOOTSTRAP # ifndef SHARED Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextlazy.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextlazy.c 2014-06-20 05:59:57.641975761 +0100 @@ -0,0 +1 @@ +#include "tst-armtlsdescloc.c" Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextlazymod.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextlazymod.c 2014-06-20 06:51:44.141980570 +0100 @@ -0,0 +1 @@ +#include "tst-armtlsdesclocmod.c" Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextnow.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextnow.c 2014-06-20 06:01:07.151978683 +0100 @@ -0,0 +1 @@ +#include "tst-armtlsdescloc.c" Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextnowmod.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescextnowmod.c 2014-06-20 06:51:34.141867198 +0100 @@ -0,0 +1 @@ +#include "tst-armtlsdesclocmod.c" Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescloc.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdescloc.c 2014-06-20 05:52:38.571931573 +0100 @@ -0,0 +1,28 @@ +/* ARM immediate binding GNU TLS descriptor relocation test. + Copyright (C) 2013-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +int getfoo (void); + +int +do_test (void) +{ + return getfoo (); +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" Index: glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdesclocmod.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ glibc-fsf-trunk-quilt/sysdeps/arm/tst-armtlsdesclocmod.c 2014-06-20 06:51:07.641787978 +0100 @@ -0,0 +1,44 @@ +/* DSO used for ARM immediate binding GNU TLS descriptor relocation test. + Copyright (C) 2013-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +static int __thread bar = 1; +static int __thread foo; + +int +getfoo (void) +{ + return foo; +} + +void +setfoo (int i) +{ + foo = 1; +} + +int +getbar (void) +{ + return bar; +} + +void +setbar (int i) +{ + bar = 1; +}