Commit fbe34298 authored Dec 17, 2020 by Nick Desaulniers Committed by Lee Jones Feb 01, 2023

BACKPORT: arm64: link with -z norelro for LLD or aarch64-elf



With GNU binutils 2.35+, 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 program headers, 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 program header regardless of target
emulation.

To avoid the above warning when linking with BFD, pass -z norelro only
when linking with LLD or with -maarch64linux.

Bug: 254441685
Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE")
Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options")
Cc: <stable@vger.kernel.org> # 5.0.x-
Reported-by: kernelci.org bot <bot@kernelci.org>
Reported-by: Quentin Perret <qperret@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Alan Modra <amodra@gmail.com>
Cc: Fāng-ruì Sòng <maskray@google.com>
Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@google.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Ie2c90e7d869ca08ce22eaf57421a6f33b9b74735

parent 44cfba49

arch/arm64/Makefile

+7 −3

Original line number	Diff line number	Diff line
		@@ -10,7 +10,7 @@
		#
		# Copyright (C) 1995-2001 by Russell King

		LDFLAGS_vmlinux :=--no-undefined -X -z norelro
		LDFLAGS_vmlinux :=--no-undefined -X
		CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
		GZFLAGS :=-9

		@@ -67,17 +67,21 @@ CHECKFLAGS += -D__AARCH64EB__
		AS += -EB
		# 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__
		AS += -EL
		# 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_ARM64_MODULE_PLTS),y)