From: Nick Desaulniers <ndesaulniers@google.com>

Date: Thu, 17 Dec 2020 16:24:32 -0800

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

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Git-commit: 311bea3cb9ee20ef150ca76fc60a592bf6b159f5

Patch-mainline: v5.11-rc3

References: git-fixes

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.

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>

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>

---

 arch/arm64/Makefile |   10 +++++++---

 1 file changed, 7 insertions(+), 3 deletions(-)

--- 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

 CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)

 GZFLAGS		:=-9

@@ -83,17 +83,21 @@ 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)