From patchwork Wed May 14 20:32:51 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kyle McMartin X-Patchwork-Id: 348968 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 8588E140083 for ; Thu, 15 May 2014 06:33:02 +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:subject:message-id:mime-version :content-type; q=dns; s=default; b=INmFN1ok1b1nXkToSyU+lRpiEDVTY /xKn+Por6WEjrmuvzc3fcPLRKkMnmbRRYNrsJtMe4sVJXFiBP6WZ5xAqLZlqawl8 GdI6QbOA+eA8pAPdtg3lmkU9HSQUIJy46nhmThp6MZ9pmurG6xvruiakfM4DcyRR vwASkqzDIRuby8= 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:subject:message-id:mime-version :content-type; s=default; bh=dAJIz/JeBAdwmPSVHZLYqjNrV+E=; b=Gak YAlnR5Pb6qLDpmJTdNyYL8JIGNq5NV+O1eqmjyFCW3Pm44DF5vCYJVWvHuIjWDyv M9nQE8fyAxQ0BL1a9RGrMyZR9VEoG/s4GtZPN9N1GpmTEA1dO6S3j3XzcD54NsJf 7Lc39sTturY4acgtDXOpwhuLWK/A0D4KPxFkzhfA= Received: (qmail 13992 invoked by alias); 14 May 2014 20:32:57 -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 13979 invoked by uid 89); 14 May 2014 20:32:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL, BAYES_00, RP_MATCHES_RCVD, SPF_HELO_PASS, SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Date: Wed, 14 May 2014 16:32:51 -0400 From: Kyle McMartin To: libc-alpha@sourceware.org Subject: [PATCH] fix static TLS consumption by TLS descriptors Message-ID: <20140514203250.GK26038@redacted.bos.redhat.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) AArch64 presently defaults to use TLS descriptors, as opposed to traditional dynamic TLS relocations, and has hit a bug in the copy-pasta used in elf_machine_rel{,a} for all TLS descriptor implementations. When a program calls dlopen() with R_AARCH64_TLSDESC relocs, we're consuming static TLS until it's exhausted (presumably as an optimisation.) However, this means that once our static TLS space is consumed, attempting to dlopen() any shared object which contain an R_AARCH64_TPREL reloc will fail, since we've exhausted all the space. Instead, always use dynamic TLS for TLS descriptors, which lets us load arbitrarily many proper dynamic TLS using shared objects, and allow the static TLS fallback only in the non-SHARED case. This issue is reproducible on x86_64, by specifying -ftls-dialect=gnu2 when building with gcc. I've written a test for this: https://github.com/jkkm/test-tls_desc.git Tweak DIALECT to be appropriate, and run ./test-tls_desc.sh, ./main and it should fail with: % ./test-tls_desc.sh; ./main ./tmp16.so: cannot allocate memory in static TLS block ./test-tls_desc.sh: line 18: 10141 Aborted (core dumped) ./main 2014-05-14 Kyle McMartin * sysdeps/aarch64/dl-machine.h (elf_machine_rela): always allocate dynamic TLS space for TLS descriptors. * sysdeps/x86_64/dl-machine.h (elf_machine_rela): ditto. * sysdeps/arm/dl-machine.h (elf_machine_rel): ditto. * sysdeps/i386/dl-machine.h (elf_machine_rel): ditto. --- a/sysdeps/aarch64/dl-machine.h +++ b/sysdeps/aarch64/dl-machine.h @@ -295,13 +295,12 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, # ifndef SHARED CHECK_STATIC_TLS (map, sym_map); # else - if (!TRY_STATIC_TLS (map, sym_map)) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + reloc->r_addend); td->entry = _dl_tlsdesc_dynamic; } - else + if (0) # endif #endif { diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h index 899b256..dcb2127 100644 --- a/sysdeps/arm/dl-machine.h +++ b/sysdeps/arm/dl-machine.h @@ -458,13 +458,12 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, # ifndef SHARED CHECK_STATIC_TLS (map, sym_map); # else - if (!TRY_STATIC_TLS (map, sym_map)) { td->argument.pointer = _dl_make_tlsdesc_dynamic (sym_map, value); td->entry = _dl_tlsdesc_dynamic; } - else + if (0) # endif # endif { diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index 368bee2..64cf74c 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -394,13 +394,12 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, # ifndef SHARED CHECK_STATIC_TLS (map, sym_map); # else - if (!TRY_STATIC_TLS (map, sym_map)) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + (ElfW(Word))td->arg); td->entry = _dl_tlsdesc_dynamic; } - else + if (0) # endif # endif { diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index 8df04a9..67e98d1 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -359,13 +359,12 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, # ifndef SHARED CHECK_STATIC_TLS (map, sym_map); # else - if (!TRY_STATIC_TLS (map, sym_map)) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + reloc->r_addend); td->entry = _dl_tlsdesc_dynamic; } - else + if (0) # endif # endif {