From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.9 31/59] efi/libstub/arm64: Set -fpie when building the EFI stub Date: Wed, 21 Nov 2018 20:06:46 +0100 Message-ID: <20181121183509.471221312@linuxfoundation.org> References: <20181121183508.262873520@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181121183508.262873520@linuxfoundation.org> Sender: stable-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthias Kaehlcke , Ard Biesheuvel , Linus Torvalds , Matt Fleming , Peter Zijlstra , Thomas Gleixner , linux-efi@vger.kernel.org, Ingo Molnar , Nick Desaulniers List-Id: linux-efi@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ard Biesheuvel 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 Signed-off-by: Ard Biesheuvel Cc: Linus Torvalds Cc: Matt Fleming Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170818194947.19347-5-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman --- 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