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 v3 0/5] Support DT_RELR relative relocation format
Date: Mon, 7 Feb 2022 15:51:22 -0800 [thread overview]
Message-ID: <20220207235127.1807294-1-hjl.tools@gmail.com> (raw)
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 | 2 +-
configure | 60 +++++++++++++++++++++++++++++++++++++
configure.ac | 23 +++++++++++++++
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 ++++-
19 files changed, 331 insertions(+), 13 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:[~2022-02-07 23:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 23:51 H.J. Lu [this message]
2022-02-07 23:51 ` [PATCH v3 1/5] elf: Support DT_RELR relative relocation format [BZ #27924] H.J. Lu
2022-02-07 23:51 ` [PATCH v3 2/5] elf: Properly handle zero DT_RELA/DT_REL values H.J. Lu
2022-02-07 23:51 ` [PATCH v3 3/5] Add GLIBC_ABI_DT_RELR for DT_RELR support H.J. Lu
2022-03-01 4:22 ` Fangrui Song
2022-03-01 14:42 ` H.J. Lu
2022-03-01 15:10 ` H.J. Lu
2022-03-01 19:13 ` Fangrui Song
2022-02-07 23:51 ` [PATCH v3 4/5] Add --disable-default-dt-relr H.J. Lu
2022-03-01 4:25 ` Fangrui Song
2022-02-07 23:51 ` [PATCH v3 5/5] NEWS: Mention DT_RELR support H.J. Lu
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