4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ard Biesheuvel <ard.biesheu...@linaro.org> commit 91ee5b21ee026c49e4e7483de69b55b8b47042be upstream. Clang may emit absolute symbol references when building in non-PIC mode, even when using the default 'small' code model, which is already mostly position independent to begin with, due to its use of adrp/add pairs that have a relative range of +/- 4 GB. The remedy is to pass the -fpie flag, which can be done safely now that the code has been updated to avoid GOT indirections (which may be emitted due to the compiler assuming that the PIC/PIE code may end up in a shared library that is subject to ELF symbol preemption) Passing -fpie when building code that needs to execute at an a priori unknown offset is arguably an improvement in any case, and given that the recent visibility changes allow the PIC build to pass with GCC as well, let's add -fpie for all arm64 builds rather than only for Clang. Tested-by: Matthias Kaehlcke <m...@chromium.org> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170818194947.19347-5-ard.biesheu...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulni...@google.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/firmware/efi/libstub/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -10,7 +10,7 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__K -fPIC -fno-strict-aliasing -mno-red-zone \ -mno-mmx -mno-sse -cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) +cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ -fno-builtin -fpic -mno-single-pic-base
