With newer GNU binutils, linking with BFD produces warnings for vmlinux:
aarch64-linux-gnu-ld: warning: -z norelro ignored
BFD can produce this warning when the target emulation mode does not
support RELRO relocation types, and -z relro or -z norelro is passed.
Alan Modra clarifies:
The default linker emulation for an aarch64-linux ld.bfd is
-maarch64linux, the default for an aarch64-elf linker is
-maarch64elf. They are not equivalent. If you choose -maarch64elf
you get an emulation that doesn't support -z relro.
The ARCH=arm64 kernel prefers -maarch64elf, but may fall back to
-maarch64linux based on the toolchain configuration.
LLD will always create RELRO relocation types regardless of target
emulation.
To avoid the above warning when linking with BFD, pass -z norelro only
when linking with LLD or with -maarch64linux.
Cc: Alan Modra <amodra@xxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Fāng-ruì Sòng <maskray@xxxxxxxxxx>
Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE")
Reported-by: kernelci.org bot <bot@xxxxxxxxxxxx>
Reported-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---
arch/arm64/Makefile | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 6be9b3750250..90309208bb28 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -10,7 +10,7 @@
#
# Copyright (C) 1995-2001 by Russell King
-LDFLAGS_vmlinux :=--no-undefined -X -z norelro
+LDFLAGS_vmlinux :=--no-undefined -X
ifeq ($(CONFIG_RELOCATABLE), y)
# Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
@@ -115,16 +115,20 @@ KBUILD_CPPFLAGS += -mbig-endian
CHECKFLAGS += -D__AARCH64EB__
# Prefer the baremetal ELF build target, but not all toolchains include
# it so fall back to the standard linux version if needed.
-KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
+KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb -z norelro)
UTS_MACHINE := aarch64_be
else
KBUILD_CPPFLAGS += -mlittle-endian
CHECKFLAGS += -D__AARCH64EL__
# Same as above, prefer ELF but fall back to linux target if needed.
-KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux)
+KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro)
UTS_MACHINE := aarch64
endif
+ifeq ($(CONFIG_LD_IS_LLD), y)
+KBUILD_LDFLAGS += -z norelro
+endif
+
CHECKFLAGS += -D__aarch64__
ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
--
2.29.2.684.gfbc64c5ab5-goog
