Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756085AbbGPBoc (ORCPT ); Wed, 15 Jul 2015 21:44:32 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55872 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754791AbbGPBLF (ORCPT ); Wed, 15 Jul 2015 21:11:05 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Will Deacon , Catalin Marinas , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 142/251] arm64: vdso: work-around broken ELF toolchains in Makefile Date: Wed, 15 Jul 2015 18:07:43 -0700 Message-Id: <1437008972-9140-143-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437008972-9140-1-git-send-email-kamal@canonical.com> References: <1437008972-9140-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2027 Lines: 53 3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon commit 6f1a6ae87c0c60d7c462ef8fd071f291aa7a9abb upstream. When building the kernel with a bare-metal (ELF) toolchain, the -shared option may not be passed down to collect2, resulting in silent corruption of the vDSO image (in particular, the DYNAMIC section is omitted). The effect of this corruption is that the dynamic linker fails to find the vDSO symbols and libc is instead used for the syscalls that we intended to optimise (e.g. gettimeofday). Functionally, there is no issue as the sigreturn trampoline is still intact and located by the kernel. This patch fixes the problem by explicitly passing -shared to the linker when building the vDSO. Reported-by: Szabolcs Nagy Reported-by: James Greenlaigh Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/kernel/vdso/Makefile | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index ff3bdde..f6fe17d 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -15,6 +15,10 @@ ccflags-y := -shared -fno-common -fno-builtin ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \ $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) +# Workaround for bare-metal (ELF) toolchains that neglect to pass -shared +# down to collect2, resulting in silent corruption of the vDSO image. +ccflags-y += -Wl,-shared + obj-y += vdso.o extra-y += vdso.lds vdso-offsets.h CPPFLAGS_vdso.lds += -P -C -U$(ARCH) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/