From patchwork Tue Sep 26 21:08:42 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Myers X-Patchwork-Id: 23166 Received: (qmail 21910 invoked by alias); 26 Sep 2017 21:08:54 -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 21891 invoked by uid 89); 26 Sep 2017 21:08:54 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-24.5 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS, URIBL_RED autolearn=ham version=3.3.2 spammy=28016, sk:inhibit X-HELO: relay1.mentorg.com Date: Tue, 26 Sep 2017 21:08:42 +0000 From: Joseph Myers To: CC: Subject: Fix make-syscalls.sh VDSO support for GCC 8 Message-ID: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) sysdeps/unix/make-syscalls.sh has support, used only by x32, for generating IFUNCs for kernel VDSO symbols. This support creates IFUNCs by setting symbol types manually, which is bad for debug info and does not work with current GCC mainline because it results in errors from the checks on types of function aliases. This patch fixes it to use the common __ifunc macro, which uses the ifunc attribute when available and so works with GCC mainline. Note however that the original error resulted from an indirect inclusion of a header declaring __gettimeofday from the generated sources, and using __ifunc now relies on such an indirect inclusion remaining as it means use of __typeof to determine the correct types. If glibc's headers change in such a way as to remove that indirect inclusion, it will become necessary to change the syscalls.list syntax for VDSO syscalls so the name of the header to include can be specified. Tested (compilation only) with build-many-glibcs.py that this fixes the build for x32 with GCC mainline. 2017-09-26 Joseph Myers * sysdeps/unix/make-syscalls.sh: Use __ifunc to define symbols using VDSO. Reviewed-by: Carlos O'Donell diff --git a/sysdeps/unix/make-syscalls.sh b/sysdeps/unix/make-syscalls.sh index 042cfac..874ad69 100644 --- a/sysdeps/unix/make-syscalls.sh +++ b/sysdeps/unix/make-syscalls.sh @@ -280,16 +280,14 @@ while read file srcfile caller syscall args strong weak; do \$(foreach p,\$(sysd-rules-targets),\$(objpfx)\$(patsubst %,\$p,$file).os): \\ \$(..)sysdeps/unix/make-syscalls.sh \$(make-target-directory) - (echo '#include '; \\ - echo 'extern void *${strong}_ifunc (void) __asm ("${strong}");'; \\ - echo 'void *'; \\ - echo 'inhibit_stack_protector'; \\ - echo '${strong}_ifunc (void)'; \\ - echo '{'; \\ - echo ' PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\ - echo ' return _dl_vdso_vsym ("${vdso_symbol}", &symver);'; \\ - echo '}'; \\ - echo 'asm (".type ${strong}, %gnu_indirect_function");'; \\ + (echo '#define ${strong} __redirect_${strong}'; \\ + echo '#include '; \\ + echo '#undef ${strong}'; \\ + echo '#define vdso_ifunc_init() \\'; \\ + echo ' PREPARE_VERSION_KNOWN (symver, ${vdso_symver})'; \\ + echo '__ifunc (__redirect_${strong}, ${strong},'; \\ + echo ' _dl_vdso_vsym ("${vdso_symbol}", &symver), void,'; \\ + echo ' vdso_ifunc_init)'; \\ EOF # This is doing "hidden_def (${strong})", but the compiler # doesn't know that we've defined ${strong} in the same file, so