On 4 September 2017 at 19:11, Nicolas Pitre [off-list ref] wrote:

On Sun, 3 Sep 2017, Ard Biesheuvel wrote:

quoted

Update the build flags and linker script to allow vmlinux to be built
as a PIE  binary, which retains relocation information about absolute
symbol references so that they can be fixed up at runtime. This will
be used for implementing KASLR,

Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Ard Biesheuvel <redacted>
---
 arch/arm/Kconfig                 |  4 ++++
 arch/arm/Makefile                |  5 +++++
 arch/arm/include/asm/assembler.h |  2 +-
 arch/arm/kernel/vmlinux.lds.S    |  9 +++++++++
 include/linux/hidden.h           | 20 ++++++++++++++++++++
 scripts/module-common.lds        |  1 +
 6 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 61a0cb15067e..300add3b8023 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig

@@ -2085,6 +2085,10 @@ config DMI
        firmware need to be enabled. This would require the DMI subsystem
        to be enabled much earlier than we do on ARM, which is non-trivial.

+config RELOCATABLE
+     bool
+     select HAVE_ARCH_PREL32_RELOCATIONS
+

You should probably make it depend on !XIP_KERNEL.

Indeed.

Other than that

Acked-by: Nicolas Pitre <redacted>

Thanks.