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(localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id DB6B5C0284; Fri, 7 Jan 2022 11:06:31 -0800 (PST) To: binutils@sourceware.org Subject: [PATCH 0/10] ld: Implement DT_RELR for x86 Date: Fri, 7 Jan 2022 11:06:21 -0800 Message-Id: <20220107190631.309790-1-hjl.tools@gmail.com> X-Mailer: git-send-email 2.33.1 MIME-Version: 1.0 X-Spam-Status: No, score=-3020.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, KAM_NUMSUBJECT, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Cc: libc-alpha@sourceware.org, Nick Clifton , Alan Modra Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Hi Nick, I'd like to enable DT_RELR for x86 in binutils 2.38. H.J. --- DT_RELR encodes consecutive R_*_RELATIVE relocations in GOT (the global offset table) and data sections in a compact format: https://groups.google.com/g/generic-abi/c/bX460iggiKg On some targets, R_*_RELATIVE relocations are counted and the GOT offsets are allocated when setting the dynamic section sizes after seeing all relocations. R_*_RELATIVE relocations are generated while relocating sections after section layout has been finalized. To prepare for DT_RELR implementation on these targets, extract _bfd_elf_link_iterate_on_relocs from _bfd_elf_link_check_relocs so that a backend can scan relocations in elf_backend_always_size_sections For x86 targets, the old check_relocs is renamed to scan_relocs and a new check_relocs is added to chek input sections and create dynamic relocation sections so that they will be mapped to output sections. scan_relocs is now called from elf_backend_always_size_sections. On some targets, the DT_RELR section size can be computed only after all symbols addresses can be determined: 1. Update ldelf_map_segments to pass need_layout to _bfd_elf_map_sections_to_segments which will size DT_RELR section and set need_layout to true if the DT_RELR section size is changed. 2. Set the preliminary DT_RELR section size before mapping sections to segments and set the final DT_RELR section size after regular symbol processing is done. On x86, DT_RELR is implemented with linker relaxation: 1. During linker relaxation, we scan input relocations with the same logic in relocate_section to determine if a relative relocation should be generated and save the relative relocation candidate information for sizing the DT_RELR section later after all symbols addresses can be determined. For these relative relocations which can't be placed in the DT_RELR section, they will be placed in the rela.dyn/rel.dyn section. 2. When DT_RELR is enabled, _bfd_elf_map_sections_to_segments calls a backend function to size the DT_RELR section which will compute the DT_RELR section size and tell ldelf_map_segments to layout sections again when the DT_RELR section size has been increased. 3. After regular symbol processing is finished, bfd_elf_final_link calls a backend function to finish the DT_RELR section. When DT_RELR is enabled, to avoid random run-time crash with older glibc binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version, which is provided by glibc with DT_RELR support, dependency on the shared C library if it provides a GLIBC_2.XX symbol version. It can build DT_RELR enabled glibc successfully on x86-64, x32 and i686. H.J. Lu (10): ld: Extract _bfd_elf_link_iterate_on_relocs elf: Add .relr.dyn to special_sections_r elf: Extract _bfd_elf_process_reverse_copy elf: Pass need_layout to _bfd_elf_map_sections_to_segments ld: Initial DT_RELR support elf: Add size_relative_relocs and finish_relative_relocs elf: Support DT_RELR in linker tests x86: Add DT_RELR support ld: Add simple DT_RELR tests ld: Add glibc dependency for DT_RELR bfd/elf-bfd.h | 19 +- bfd/elf.c | 22 +- bfd/elf32-i386.c | 112 +- bfd/elf64-x86-64.c | 118 +- bfd/elflink.c | 191 ++- bfd/elfxx-target.h | 8 + bfd/elfxx-x86.c | 1022 +++++++++++++++++ bfd/elfxx-x86.h | 197 +++- binutils/testsuite/lib/binutils-common.exp | 1 + include/bfdlink.h | 4 + ld/NEWS | 3 + ld/emulparams/dt-relr.sh | 21 + ld/emulparams/elf32_x86_64.sh | 1 + ld/emulparams/elf_i386.sh | 1 + ld/emulparams/elf_x86_64.sh | 1 + ld/emultempl/elf.em | 5 +- ld/ld.texi | 16 +- ld/ldelf.c | 13 + ld/ldelfgen.c | 3 +- ld/lexsup.c | 1 + ld/scripttempl/elf.sc | 4 + ld/testsuite/config/default.exp | 16 + ld/testsuite/ld-elf/dt-relr-1.s | 13 + ld/testsuite/ld-elf/dt-relr-1a.d | 10 + ld/testsuite/ld-elf/dt-relr-1b.d | 9 + ld/testsuite/ld-elf/dt-relr-1c.d | 9 + ld/testsuite/ld-elf/dt-relr-2.s | 20 + ld/testsuite/ld-elf/dt-relr-2a.d | 10 + ld/testsuite/ld-elf/dt-relr-2b.d | 17 + ld/testsuite/ld-elf/dt-relr-2c.d | 17 + ld/testsuite/ld-elf/dt-relr-2d.d | 9 + ld/testsuite/ld-elf/dt-relr-2e.d | 9 + ld/testsuite/ld-elf/dt-relr-2f.d | 8 + ld/testsuite/ld-elf/dt-relr-2g.d | 9 + ld/testsuite/ld-elf/dt-relr-2h.d | 9 + ld/testsuite/ld-elf/dt-relr-glibc-1.c | 11 + ld/testsuite/ld-elf/dt-relr-glibc-1a.rd | 4 + ld/testsuite/ld-elf/dt-relr-glibc-1b.rd | 7 + ld/testsuite/ld-elf/dt-relr.exp | 44 + ld/testsuite/ld-elf/shared.exp | 3 +- ld/testsuite/ld-i386/export-class.exp | 2 +- ld/testsuite/ld-i386/i386.exp | 20 +- ld/testsuite/ld-i386/ibt-plt-2a.d | 2 +- ld/testsuite/ld-i386/ibt-plt-3a.d | 2 +- ld/testsuite/ld-i386/ibt-plt-3c.d | 2 +- ld/testsuite/ld-i386/pr27491-1a.d | 4 +- ld/testsuite/ld-i386/report-reloc-1.d | 2 +- ld/testsuite/ld-ifunc/ifunc-2-i386-now.d | 2 +- .../ld-ifunc/ifunc-2-local-i386-now.d | 2 +- .../ld-ifunc/ifunc-2-local-x86-64-now.d | 2 +- ld/testsuite/ld-ifunc/ifunc-2-x86-64-now.d | 2 +- ld/testsuite/ld-ifunc/pr17154-x86-64-now.d | 2 +- ld/testsuite/ld-ifunc/pr17154-x86-64.d | 2 +- ld/testsuite/ld-x86-64/bnd-branch-1-now.d | 2 +- ld/testsuite/ld-x86-64/bnd-ifunc-1-now.d | 2 +- ld/testsuite/ld-x86-64/bnd-ifunc-2-now.d | 2 +- ld/testsuite/ld-x86-64/bnd-ifunc-2.d | 2 +- ld/testsuite/ld-x86-64/bnd-plt-1-now.d | 2 +- ld/testsuite/ld-x86-64/bnd-plt-1.d | 2 +- ld/testsuite/ld-x86-64/export-class.exp | 3 +- ld/testsuite/ld-x86-64/ibt-plt-2a-x32.d | 2 +- ld/testsuite/ld-x86-64/ibt-plt-2a.d | 2 +- ld/testsuite/ld-x86-64/ibt-plt-3a-x32.d | 2 +- ld/testsuite/ld-x86-64/ibt-plt-3a.d | 2 +- ld/testsuite/ld-x86-64/ilp32-4.d | 2 +- ld/testsuite/ld-x86-64/load1c.d | 2 +- ld/testsuite/ld-x86-64/load1d.d | 2 +- ld/testsuite/ld-x86-64/pr13082-2b.d | 2 +- ld/testsuite/ld-x86-64/pr14207.d | 2 +- ld/testsuite/ld-x86-64/pr18176.d | 2 +- ld/testsuite/ld-x86-64/pr19162.d | 2 +- ld/testsuite/ld-x86-64/pr19636-2d.d | 2 +- ld/testsuite/ld-x86-64/pr19636-2l.d | 2 +- ld/testsuite/ld-x86-64/pr20253-1d.d | 2 +- ld/testsuite/ld-x86-64/pr20253-1f.d | 2 +- ld/testsuite/ld-x86-64/pr20253-1j.d | 2 +- ld/testsuite/ld-x86-64/pr20253-1l.d | 2 +- ld/testsuite/ld-x86-64/pr27491-1a.d | 4 +- ld/testsuite/ld-x86-64/report-reloc-1-x32.d | 2 +- ld/testsuite/ld-x86-64/report-reloc-1.d | 2 +- ld/testsuite/ld-x86-64/x86-64.exp | 65 +- 81 files changed, 1931 insertions(+), 234 deletions(-) create mode 100644 ld/emulparams/dt-relr.sh create mode 100644 ld/testsuite/ld-elf/dt-relr-1.s create mode 100644 ld/testsuite/ld-elf/dt-relr-1a.d create mode 100644 ld/testsuite/ld-elf/dt-relr-1b.d create mode 100644 ld/testsuite/ld-elf/dt-relr-1c.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2.s create mode 100644 ld/testsuite/ld-elf/dt-relr-2a.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2b.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2c.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2d.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2e.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2f.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2g.d create mode 100644 ld/testsuite/ld-elf/dt-relr-2h.d create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd create mode 100644 ld/testsuite/ld-elf/dt-relr.exp