__cxa_get_globals returns a value of 0x1001, due to __tls_get_addr caching without the required __tls_get_addr_opt plt call stub.
Created attachment 12858 [details] patch under test
The master branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=294338867c268b6da43327b6cbe70e746bff1a04 commit 294338867c268b6da43327b6cbe70e746bff1a04 Author: Alan Modra <amodra@gmail.com> Date: Tue Sep 22 22:51:42 2020 +0930 PR26656, power10 libstdc++.so segfault in __cxxabiv1::__cxa_throw This adds missing support for a power10 version of the __tls_get_addr call stub implementing DT_PPC64_OPT PPC64_OPT_TLS. Without this, power10 code using __tls_get_addr fails miserably at runtime unless the --no-tls-get-addr-optimize option is given. PR 26656 * elf64-ppc.c (plt_stub_size): Add "odd" param. Use it with size_power10_offset rather than calculating from start of stub. Add size for notoc tls_get_addr_opt stub. (plt_stub_pad): Add "odd" param, pass to plt_stub_size. (build_tls_get_addr_head, build_tls_get_addr_tail): New functions. (build_tls_get_addr_stub): Delete. (ppc_build_one_stub): Use a temp for htab->params->stub_bfd. Emit notoc tls_get_addr_opt stub. Move eh_frame code to suit. Adjust code to use bfd_tls_get_addr_head/tail in place of build_tls_get_addr_stub. (ppc_size_one_stub): Size notoc tls_get_addr_opt stub. Adjust plt_stub_size and plt_stub_pad calls. Correct "odd" when padding stub. Size eh_frame for notoc stub too. Correct lr_restore value. (ppc64_elf_relocate_section): Don't skip over first insn of notoc tls_get_addr_opt stub.
The binutils-2_35-branch branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6f9a6c28850f6839ff61af22c277b2abbf7895da commit 6f9a6c28850f6839ff61af22c277b2abbf7895da Author: Alan Modra <amodra@gmail.com> Date: Tue Sep 22 22:51:42 2020 +0930 PR26656, power10 libstdc++.so segfault in __cxxabiv1::__cxa_throw This adds missing support for a power10 version of the __tls_get_addr call stub implementing DT_PPC64_OPT PPC64_OPT_TLS. Without this, power10 code using __tls_get_addr fails miserably at runtime unless the --no-tls-get-addr-optimize option is given. PR 26656 * elf64-ppc.c (plt_stub_size): Add "odd" param. Use it with size_power10_offset rather than calculating from start of stub. Add size for notoc tls_get_addr_opt stub. (plt_stub_pad): Add "odd" param, pass to plt_stub_size. (build_tls_get_addr_head, build_tls_get_addr_tail): New functions. (build_tls_get_addr_stub): Delete. (ppc_build_one_stub): Use a temp for htab->params->stub_bfd. Emit notoc tls_get_addr_opt stub. Move eh_frame code to suit. Adjust code to use bfd_tls_get_addr_head/tail in place of build_tls_get_addr_stub. (ppc_size_one_stub): Size notoc tls_get_addr_opt stub. Adjust plt_stub_size and plt_stub_pad calls. Correct "odd" when padding stub. Size eh_frame for notoc stub too. Correct lr_restore value. (ppc64_elf_relocate_section): Don't skip over first insn of notoc tls_get_addr_opt stub. (cherry picked from commit 294338867c268b6da43327b6cbe70e746bff1a04)
Fixed
The master branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=12cf8b93da0ae155643d262235486fde5af72a80 commit 12cf8b93da0ae155643d262235486fde5af72a80 Author: Alan Modra <amodra@gmail.com> Date: Mon Sep 28 09:30:19 2020 +0930 Re: PR26656, power10 libstdc++.so segfault in __cxxabiv1::__cxa_throw Some missing NULL checks meant a stub for a local symbol used a stub looking like the __tls_get_addr_opt stub. PR 26656 * elf64-ppc.c (ppc_build_one_stub, ppc_size_one_stub): Check for NULL stub_entry->h before calling is_tls_get_addr.
The binutils-2_35-branch branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=39f2c1f7b80a30297e93f04c885b444e5a874372 commit 39f2c1f7b80a30297e93f04c885b444e5a874372 Author: Alan Modra <amodra@gmail.com> Date: Mon Sep 28 09:30:19 2020 +0930 Re: PR26656, power10 libstdc++.so segfault in __cxxabiv1::__cxa_throw Some missing NULL checks meant a stub for a local symbol used a stub looking like the __tls_get_addr_opt stub. PR 26656 * elf64-ppc.c (ppc_build_one_stub, ppc_size_one_stub): Check for NULL stub_entry->h before calling is_tls_get_addr. (cherry picked from commit 12cf8b93da0ae155643d262235486fde5af72a80)