From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:54088 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754698AbbIKWui (ORCPT ); Fri, 11 Sep 2015 18:50:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Agner , Nathan Lynch , Russell King , Alexander Kochetkov Subject: [PATCH 4.1 33/78] ARM: 8384/1: VDSO: force use of BFD linker Date: Fri, 11 Sep 2015 15:49:34 -0700 Message-Id: <20150911224611.073064696@linuxfoundation.org> In-Reply-To: <20150911224606.758437370@linuxfoundation.org> References: <20150911224606.758437370@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nathan Lynch commit d2b30cd4b7223a96e606dfc8120626f66d81e091 upstream. When using a toolchain with gold as the default linker, the VDSO build fails: VDSO arch/arm/vdso/vdso.so.raw HOSTCC arch/arm/vdso/vdsomunge MUNGE arch/arm/vdso/vdso.so.dbg OBJCOPY arch/arm/vdso/vdso.so BFD: arch/arm/vdso/vdso.so: Not enough room for program headers, try linking with -N For whatever reason, ld.gold is omitting an exidx program header that ld.bfd emits, and even when I work around that, I don't get a working VDSO. For now, instead of supporting gold (which will fail to link the kernel anyway since it does not implement --pic-veneer), direct the compiler to use the traditional bfd linker. This is accomplished by using -fuse-ld, which is implemented in GCC 4.8 and later. Note: one limitation of this is that if the toolchain is configured to use gold by default, and the bfd linker is not in $PATH, the VDSO build will fail: VDSO arch/arm/vdso/vdso.so.raw collect2: fatal error: cannot find 'ld' This will happen if CROSS_COMPILE begins with a path such as /opt/bin/arm-linux-gnu- but /opt/bin is not in $PATH. This is considered an acceptable corner-case limitation and is easily worked around. Additonal note: we use cc-option instead of cc-ldoption so that -fuse-ld=bfd is placed in the command line if the compiler recognizes the option. Using cc-ldoption results in an attempt to link, which fails in the situation just described, causing -fuse-ld=bfd to be omitted and gold to be used for the VDSO link, which is what we're trying to prevent. Reported-by: Stefan Agner Signed-off-by: Nathan Lynch Signed-off-by: Russell King Cc: Alexander Kochetkov Signed-off-by: Greg Kroah-Hartman --- arch/arm/vdso/Makefile | 1 + 1 file changed, 1 insertion(+) --- a/arch/arm/vdso/Makefile +++ b/arch/arm/vdso/Makefile @@ -14,6 +14,7 @@ VDSO_LDFLAGS += -Wl,-z,max-page-size=409 VDSO_LDFLAGS += -nostdlib -shared VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--build-id) +VDSO_LDFLAGS += $(call cc-option, -fuse-ld=bfd) obj-$(CONFIG_VDSO) += vdso.o extra-$(CONFIG_VDSO) += vdso.lds