From patchwork Tue Jun 3 17:50:42 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kyle McMartin X-Patchwork-Id: 1271 Received: (qmail 10720 invoked by alias); 3 Jun 2014 17:50:47 -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 10709 invoked by uid 89); 3 Jun 2014 17:50:46 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 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: Tue, 3 Jun 2014 13:50:42 -0400 From: Kyle McMartin To: libc-alpha@sourceware.org Subject: [PATCHv2] Fix static TLS exhaustion by TLS descriptors Message-ID: <20140603175042.GH15355@redacted.bos.redhat.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) 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 -mtls-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 2014-06-03 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 @@ -295,7 +295,7 @@ 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)) + if (1) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + reloc->r_addend); diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h index 899b256..f55a991 100644 --- a/sysdeps/arm/dl-machine.h +++ b/sysdeps/arm/dl-machine.h @@ -458,7 +458,7 @@ 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)) + if (1) { td->argument.pointer = _dl_make_tlsdesc_dynamic (sym_map, value); diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index 368bee2..b6b5802 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -394,7 +394,7 @@ 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)) + if (1) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + (ElfW(Word))td->arg); diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index 8df04a9..4ec4340 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -359,7 +359,7 @@ 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)) + if (1) { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + reloc->r_addend);