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authorHauke Mehrtens2025-11-06 22:08:04 +0000
committerHauke Mehrtens2025-11-18 22:17:09 +0000
commita2a78c04f807806d81dde1d146d3688707a375de (patch)
treec67fe683c712817dfca3592313b5edec8d11bc50
parent08997df4753470811829ea09eec7a5c3366aac63 (diff)
downloadopenwrt-a2a78c04f807806d81dde1d146d3688707a375de.tar.gz
build: Add support for linking with DT_RELR
This adds the -Wl,-z,pack-relative-relocs linking options. This reduces the size of some binaries. This is only supported on i386, x86_64, aarch64 and loongarch64 in binutils. This feature is not support for MIPS. musl libc supports it since version 1.2.4 . glibc supports it since vesion 2.36. binutils ld supports it since version 2.38 for x86 and since version 2.43 for LoongArch. This reduces the size of the armsr default root file system from 5,262,198 bytes to 5,200,950 bytes by 61,248 bytes. Link: https://github.com/openwrt/openwrt/pull/20679 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
-rw-r--r--config/Config-build.in9
-rw-r--r--include/hardening.mk8
2 files changed, 17 insertions, 0 deletions
diff --git a/config/Config-build.in b/config/Config-build.in
index 2d08f4ccd2..caeae79944 100644
--- a/config/Config-build.in
+++ b/config/Config-build.in
@@ -383,6 +383,15 @@ menu "Global build settings"
bool "Full"
endchoice
+ config PKG_DT_RELR
+ bool "Link with relative relocations (RELR)"
+ depends on (aarch64 || i386 || loongarch64 || x86_64)
+ default y
+ help
+ Link all applications with -Wl,-z,pack-relative-relocs.
+ This will reduce the size of many applications.
+ This is only supported on a limited number of architectures.
+
config TARGET_ROOTFS_SECURITY_LABELS
bool
select KERNEL_SQUASHFS_XATTR
diff --git a/include/hardening.mk b/include/hardening.mk
index a2be5eabd0..1565e5aa27 100644
--- a/include/hardening.mk
+++ b/include/hardening.mk
@@ -8,6 +8,7 @@ PKG_ASLR_PIE_REGULAR ?= 0
PKG_SSP ?= 1
PKG_FORTIFY_SOURCE ?= 1
PKG_RELRO ?= 1
+PKG_DT_RELR ?= 1
ifdef CONFIG_PKG_CHECK_FORMAT_SECURITY
ifeq ($(strip $(PKG_CHECK_FORMAT_SECURITY)),1)
@@ -69,3 +70,10 @@ ifdef CONFIG_PKG_RELRO_FULL
endif
endif
+ifdef CONFIG_PKG_DT_RELR
+ ifeq ($(strip $(PKG_DT_RELR)),1)
+ TARGET_CFLAGS += -Wl,-z,pack-relative-relocs
+ TARGET_LDFLAGS += -zpack-relative-relocs
+ endif
+endif
+