Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752519AbZFAOF0 (ORCPT ); Mon, 1 Jun 2009 10:05:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750975AbZFAOFP (ORCPT ); Mon, 1 Jun 2009 10:05:15 -0400 Received: from cantor.suse.de ([195.135.220.2]:46830 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751008AbZFAOFO (ORCPT ); Mon, 1 Jun 2009 10:05:14 -0400 Subject: [PATCH] x86: clean up vdso-layout.lds.S From: Petr Tesarik To: LKML Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen Content-Type: text/plain Organization: SUSE LINUX Date: Mon, 01 Jun 2009 16:05:15 +0200 Message-Id: <1243865115.24278.8.camel@nathan.suse.cz> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3880 Lines: 128 The handling of various sections in the VDSO linker script looks pretty haphazard. This patch cleans it up in this regards: - re-order sections to more closely match the result of a normal shared link - discard sections which are not useful to user-space - issue a linker error if a section is encountered which is known not to work - check that the .got section is empty, except for the three entries defined by the ABI Signed-off-by: Petr Tesarik --- Makefile | 5 ++-- vdso-layout.lds.S | 57 +++++++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 51 insertions(+), 11 deletions(-) diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile index 16a9020..8c7f06a 100644 --- a/arch/x86/vdso/Makefile +++ b/arch/x86/vdso/Makefile @@ -23,7 +23,8 @@ $(obj)/vdso.o: $(obj)/vdso.so targets += vdso.so vdso.so.dbg vdso.lds $(vobjs-y) -export CPPFLAGS_vdso.lds += -P -C +vdso-cppflags = -P -C +export CPPFLAGS_vdso.lds += -m64 $(vdso-cppflags) VDSO_LDFLAGS_vdso.lds = -m elf_x86_64 -Wl,-soname=linux-vdso.so.1 \ -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096 @@ -68,7 +69,7 @@ vdso32.so-$(VDSO32-y) += sysenter vdso32-images = $(vdso32.so-y:%=vdso32-%.so) -CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds) +CPPFLAGS_vdso32.lds = -m32 $(vdso-cppflags) VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -Wl,-soname=linux-gate.so.1 # This makes sure the $(obj) subdirectory exists even though vdso32/ diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S index 634a2cf..1f4b215 100644 --- a/arch/x86/vdso/vdso-layout.lds.S +++ b/arch/x86/vdso/vdso-layout.lds.S @@ -22,16 +22,15 @@ SECTIONS .eh_frame : { KEEP (*(.eh_frame)) } :text .dynamic : { *(.dynamic) } :text :dynamic + .got : { *(.got.plt) *(.got) } :text - .rodata : { *(.rodata*) } :text + .rodata : { + *(.rodata .rodata.* .gnu.linkonce.r.*) + } .data : { - *(.data*) - *(.sdata*) - *(.got.plt) *(.got) - *(.gnu.linkonce.d.*) - *(.bss*) - *(.dynbss*) - *(.gnu.linkonce.b.*) + *(.data .data.* .gnu.linkonce.d.*) + *(.bss .bss.* .gnu.linkonce.b.*) + *(COMMON) } .altinstructions : { *(.altinstructions) } @@ -43,9 +42,49 @@ SECTIONS */ . = ALIGN(0x100); - .text : { *(.text*) } :text =0x90909090 + .text : { + *(.text .text.* .gnu.linkonce.t.*) + } :text =0x90909090 + + /* We would need a more sophisticated dynamic linker for the + * vDSO to make the following sections work. Put them into + * a special section and raise a link-time error if they get + * used. + */ + .broken : { + /* Code in the Procedure Linkage Table will segfault */ + *(.plt) + + /* Relocation will not be done, so any pointers will + * still point to the prelinked address, which is wrong + */ + *(.data.rel.ro*) + *(.gnu.linkonce.d.rel.ro.*) + + /* Initialization/termination won't work this way */ + *(.init) *(.fini) + *(.preinit_array) *(.init_array*) + *(.fini_array*) + + /* Thread-local data cannot be defined like this */ + *(.tdata .tdata.* .gnu.linkonce.td.*) + *(.tbss .tbss.* .gnu.linkonce.tb.*) + *(.tcommon) + } + + /* These sections are not useful */ + /DISCARD/ : { + *(.gnu.warning.*) + *(.note.GNU-stack) + } } +ASSERT(!SIZEOF(.broken), "VDSO contains sections that don't work properly"); + +/* Check that GOT has only the three entries defined by the ABI */ +ASSERT(SIZEOF(.got) == 3*__SIZEOF_POINTER__, + "Found extra GOT entries. Check your use of external vars."); + /* * Very old versions of ld do not recognize this name token; use the constant. */ -- 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/