[PATCH 12/15] arm64: add a workaround for GNU gold with ARM64_MODULE_PLTS

From: Sami Tolvanen
Date: Fri Nov 03 2017 - 13:14:35 EST


CONFIG_CLANG_LTO depends on GNU gold and due to a known bug, the
linker crashes when ARM64_MODULE_PLTS is enabled:

https://sourceware.org/bugzilla/show_bug.cgi?id=14592

To work around the problem, this change:

1) Enables ARM64_MODULE_PLTS only when it's needed, i.e. when
RANDOMIZE_MODULE_REGION_FULL is selected,

2) and disables RANDOMIZE_MODULE_REGION_FULL with clang LTO.

Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
---
arch/arm64/Kconfig | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 43ccddb7c8ec..a301fdc90319 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -997,8 +997,8 @@ config RELOCATABLE

config RANDOMIZE_BASE
bool "Randomize the address of the kernel image"
- select ARM64_MODULE_PLTS if MODULES
select RELOCATABLE
+ select ARM64_MODULE_PLTS if RANDOMIZE_MODULE_REGION_FULL
help
Randomizes the virtual address at which the kernel image is
loaded, as a security feature that deters exploit attempts
@@ -1016,7 +1016,7 @@ config RANDOMIZE_BASE

config RANDOMIZE_MODULE_REGION_FULL
bool "Randomize the module region independently from the core kernel"
- depends on RANDOMIZE_BASE
+ depends on RANDOMIZE_BASE && !CLANG_LTO
default y
help
Randomizes the location of the module region without considering the
--
2.15.0.403.gc27cc4dac6-goog