From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Cc: Fangrui Song <maskray@google.com>,
Joseph Myers <joseph@codesourcery.com>
Subject: [PATCH v6 0/5] Support DT_RELR relative relocation format
Date: Thu, 10 Mar 2022 12:03:24 -0800 [thread overview]
Message-ID: <20220310200329.1935466-1-hjl.tools@gmail.com> (raw)
Changes in v6:
1. Move ELF_DYNAMIC_DO_RELR before ELF_DYNAMIC_DO_REL.
Changes in v5:
1. Update NEWS entry with the linker option, -z pack-relative-relocs.
2. Remove elf/libc-abi-version.exp and use $(READELF) to check
GLIBC_ABI_DT_RELR.
Changes in v4:
1. Always enable GLIBC_ABI_DT_RELR check.
2. Use $(OBJDUMP) instead of $(NM) for GLIBC_ABI_DT_RELR check.
Changes in v3:
1. Don't define SUPPORT_DT_RELR.
2. Enable DT_RELR in glibc shared libraries and position independent
executables (PIE) automatically if linker supports -z pack-relative-relocs.
Changes in v2:
1. Enable DT_RELR for all targets.
2. Issue an error if there is a DT_RELR entry without GLIBC_ABI_DT_RELR
dependency nor GLIBC_PRIVATE definition.
---
PIE and shared objects usually have many relative relocations. In
2017/2018, SHT_RELR/DT_RELR was proposed on
https://groups.google.com/g/generic-abi/c/bX460iggiKg/m/GxjM0L-PBAAJ
("Proposal for a new section type SHT_RELR") and is a pre-standard. RELR
usually takes 3% or smaller space than R_*_RELATIVE relocations. The
virtual memory size of a mostly statically linked PIE is typically 5~10%
smaller.
Binutils 2.38 supports DT_RELR on x86 with the -z report-relative-reloc
option. When DT_RELR is enabled, ld adds a GLIBC_ABI_DT_RELR symbol
version dependency on libc.so to outputs. Issue an error if there is a
DT_RELR entry without GLIBC_ABI_DT_RELR dependency nor GLIBC_PRIVATE
definition.
DT_RELR is enabled in glibc shared libraries and position independent
executables (PIE) automatically if linker supports -z pack-relative-relocs.
The DT_RELR usage in glibc can be disabled with --disable-default-dt-relr.
Tested with binutils 2.38 on i686, x86-64 and x32.
Fangrui Song (1):
elf: Support DT_RELR relative relocation format [BZ #27924]
H.J. Lu (4):
elf: Properly handle zero DT_RELA/DT_REL values
Add GLIBC_ABI_DT_RELR for DT_RELR support
Add --disable-default-dt-relr
NEWS: Mention DT_RELR support
INSTALL | 6 ++++
Makeconfig | 19 +++++++++++++
Makerules | 2 ++
NEWS | 3 +-
configure | 60 +++++++++++++++++++++++++++++++++++++++
configure.ac | 23 +++++++++++++++
elf/Makefile | 30 ++++++++++++++++++--
elf/Versions | 5 ++++
elf/dl-version.c | 33 ++++++++++++++++++++--
elf/dynamic-link.h | 40 +++++++++++++++++++++++++-
elf/elf.h | 13 +++++++--
elf/get-dynamic-info.h | 19 +++++++++++--
elf/tst-relr-pie.c | 1 +
elf/tst-relr.c | 64 ++++++++++++++++++++++++++++++++++++++++++
include/link.h | 6 ++++
manual/install.texi | 5 ++++
scripts/abilist.awk | 2 ++
scripts/versions.awk | 7 ++++-
18 files changed, 325 insertions(+), 13 deletions(-)
create mode 100644 elf/tst-relr-pie.c
create mode 100644 elf/tst-relr.c
--
2.35.1
next reply other threads:[~2022-03-10 20:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 20:03 H.J. Lu [this message]
2022-03-10 20:03 ` [PATCH v6 1/5] elf: Support DT_RELR relative relocation format [BZ #27924] H.J. Lu
2022-03-29 16:34 ` Adhemerval Zanella
2022-03-29 22:34 ` H.J. Lu
2022-03-10 20:03 ` [PATCH v6 2/5] elf: Properly handle zero DT_RELA/DT_REL values H.J. Lu
2022-03-29 16:38 ` Adhemerval Zanella
2022-03-29 22:30 ` H.J. Lu
2022-03-10 20:03 ` [PATCH v6 3/5] Add GLIBC_ABI_DT_RELR for DT_RELR support H.J. Lu
2022-03-29 16:52 ` Adhemerval Zanella
2022-03-29 22:29 ` H.J. Lu
2022-03-30 14:18 ` Adhemerval Zanella
2022-03-30 14:41 ` H.J. Lu
2022-03-30 17:17 ` Adhemerval Zanella
2022-03-30 17:32 ` H.J. Lu
2022-03-30 17:39 ` Adhemerval Zanella
2022-03-30 19:22 ` Joseph Myers
2022-03-30 20:38 ` Adhemerval Zanella
2022-03-30 21:32 ` Fangrui Song
2022-03-10 20:03 ` [PATCH v6 4/5] Add --disable-default-dt-relr H.J. Lu
2022-03-29 17:19 ` Adhemerval Zanella
2022-03-29 22:25 ` H.J. Lu
2022-03-10 20:03 ` [PATCH v6 5/5] NEWS: Mention DT_RELR support H.J. Lu
2022-03-29 17:25 ` Adhemerval Zanella
2022-03-29 22:22 ` H.J. Lu
2022-03-29 23:34 ` Fangrui Song
2022-03-30 14:20 ` Adhemerval Zanella
2022-03-10 20:09 ` [PATCH v6 0/5] Support DT_RELR relative relocation format Fangrui Song
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