Allow user to select CONFIG_FG_KASLR if dependencies are met. Change the make file to build with -ffunction-sections if CONFIG_FG_KASLR Signed-off-by: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx> Tested-by: Tony Luck <tony.luck@xxxxxxxxx> --- Makefile | 4 ++++ arch/x86/Kconfig | 13 +++++++++++++ 2 files changed, 17 insertions(+) diff --git a/Makefile b/Makefile index 04f5662ae61a..28e515baa824 100644 --- a/Makefile +++ b/Makefile @@ -862,6 +862,10 @@ ifdef CONFIG_LIVEPATCH KBUILD_CFLAGS += $(call cc-option, -flive-patching=inline-clone) endif +ifdef CONFIG_FG_KASLR +KBUILD_CFLAGS += -ffunction-sections +endif + # arch Makefile may override CC so keep this after arch Makefile is included NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2d3f963fd6f1..50e83ea57d70 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2183,6 +2183,19 @@ config RANDOMIZE_BASE If unsure, say Y. +config FG_KASLR + bool "Function Granular Kernel Address Space Layout Randomization" + depends on $(cc-option, -ffunction-sections) + depends on RANDOMIZE_BASE && X86_64 + help + This option improves the randomness of the kernel text + over basic Kernel Address Space Layout Randomization (KASLR) + by reordering the kernel text at boot time. This feature + uses information generated at compile time to re-layout the + kernel text section at boot time at function level granularity. + + If unsure, say N. + # Relocation on x86 needs some additional build support config X86_NEED_RELOCS def_bool y -- 2.20.1
