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 v2 0/7] Support DT_RELR relative relocation format
Date: Sat, 5 Feb 2022 09:24:39 -0800 [thread overview]
Message-ID: <20220205172446.652011-1-hjl.tools@gmail.com> (raw)
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
nd the architecture defines SUPPORT_DT_RELR in config.h. At the moment,
only x86 targets define SUPPORT_DT_RELR.
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 (6):
elf: Properly handle zero DT_RELA/DT_REL values
Add GLIBC_ABI_DT_RELR for DT_RELR support
x86/configure.ac: Define PI_STATIC_AND_HIDDEN/SUPPORT_STATIC_PIE
x86: Define SUPPORT_DT_RELR
Add --disable-default-dt-relr
NEWS: Mention DT_RELR support
INSTALL | 6 +++
Makeconfig | 19 +++++++++
Makerules | 2 +
NEWS | 2 +-
config.h.in | 3 ++
configure | 80 +++++++++++++++++++++++++++++++++++++
configure.ac | 33 +++++++++++++++
elf/Makefile | 36 +++++++++++++++--
elf/Versions | 5 +++
elf/dl-version.c | 33 ++++++++++++++-
elf/dynamic-link.h | 40 ++++++++++++++++++-
elf/elf.h | 13 +++++-
elf/get-dynamic-info.h | 19 +++++++--
elf/libc-abi-version.exp | 1 +
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 +++-
sysdeps/i386/configure | 6 ---
sysdeps/i386/configure.ac | 7 ----
sysdeps/x86/configure | 9 +++++
sysdeps/x86/configure.ac | 10 +++++
sysdeps/x86_64/configure | 6 ---
sysdeps/x86_64/configure.ac | 7 ----
26 files changed, 383 insertions(+), 39 deletions(-)
create mode 100644 elf/libc-abi-version.exp
create mode 100644 elf/tst-relr-pie.c
create mode 100644 elf/tst-relr.c
--
2.34.1
next reply other threads:[~2022-02-05 17:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-05 17:24 H.J. Lu [this message]
2022-02-05 17:24 ` [PATCH v2 1/7] elf: Support DT_RELR relative relocation format [BZ #27924] H.J. Lu
2022-02-05 17:24 ` [PATCH v2 2/7] elf: Properly handle zero DT_RELA/DT_REL values H.J. Lu
2022-02-05 17:24 ` [PATCH v2 3/7] Add GLIBC_ABI_DT_RELR for DT_RELR support H.J. Lu
2022-02-05 17:24 ` [PATCH v2 4/7] x86/configure.ac: Define PI_STATIC_AND_HIDDEN/SUPPORT_STATIC_PIE H.J. Lu
2022-02-05 17:24 ` [PATCH v2 5/7] x86: Define SUPPORT_DT_RELR H.J. Lu
2022-02-05 17:24 ` [PATCH v2 6/7] Add --disable-default-dt-relr H.J. Lu
2022-02-05 17:24 ` [PATCH v2 7/7] NEWS: Mention DT_RELR support H.J. Lu
2022-02-07 20:27 ` [PATCH v2 0/7] Support DT_RELR relative relocation format Joseph Myers
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