Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756409AbXKSWE3 (ORCPT ); Mon, 19 Nov 2007 17:04:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755845AbXKSWEH (ORCPT ); Mon, 19 Nov 2007 17:04:07 -0500 Received: from mx1.redhat.com ([66.187.233.31]:33896 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756271AbXKSWEE (ORCPT ); Mon, 19 Nov 2007 17:04:04 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Andrew Morton , Linus Torvalds , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org X-Fcc: ~/Mail/linus Subject: [PATCH 04/18] x86 vDSO: new layout In-Reply-To: Roland McGrath's message of Monday, 19 November 2007 13:59:43 -0800 <20071119215944.01B7C26F8BE@magilla.localdomain> References: <20071119215944.01B7C26F8BE@magilla.localdomain> X-Shopping-List: (1) Fantastic rotation livers (2) Chromatic mauve logs (3) Periodical pincushions Message-Id: <20071119220319.5C73426F8BE@magilla.localdomain> Date: Mon, 19 Nov 2007 14:03:19 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6496 Lines: 218 This revamps the vDSO linker script to lay things out with the best packing of the data and good, separate alignment of the code. The rigid layout using VDSO_TEXT_OFFSET no longer matters to the kernel. I've moved the layout parts of the linker script into a new include file, vdso-layout.lds.S; this is in preparation for sharing the script for the 32-bit vDSO builds too. Signed-off-by: Roland McGrath --- arch/x86/vdso/vdso-layout.lds.S | 64 ++++++++++++++++++++++++ arch/x86/vdso/vdso.lds.S | 102 ++++++++++----------------------------- arch/x86/vdso/voffset.h | 1 - 3 files changed, 89 insertions(+), 78 deletions(-) create mode 100644 arch/x86/vdso/vdso-layout.lds.S delete mode 100644 arch/x86/vdso/voffset.h diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S new file mode 100644 index 0000000..634a2cf --- /dev/null +++ b/arch/x86/vdso/vdso-layout.lds.S @@ -0,0 +1,64 @@ +/* + * Linker script for vDSO. This is an ELF shared object prelinked to + * its virtual address, and with only one read-only segment. + * This script controls its layout. + */ + +SECTIONS +{ + . = VDSO_PRELINK + SIZEOF_HEADERS; + + .hash : { *(.hash) } :text + .gnu.hash : { *(.gnu.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .gnu.version : { *(.gnu.version) } + .gnu.version_d : { *(.gnu.version_d) } + .gnu.version_r : { *(.gnu.version_r) } + + .note : { *(.note.*) } :text :note + + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr + .eh_frame : { KEEP (*(.eh_frame)) } :text + + .dynamic : { *(.dynamic) } :text :dynamic + + .rodata : { *(.rodata*) } :text + .data : { + *(.data*) + *(.sdata*) + *(.got.plt) *(.got) + *(.gnu.linkonce.d.*) + *(.bss*) + *(.dynbss*) + *(.gnu.linkonce.b.*) + } + + .altinstructions : { *(.altinstructions) } + .altinstr_replacement : { *(.altinstr_replacement) } + + /* + * Align the actual code well away from the non-instruction data. + * This is the best thing for the I-cache. + */ + . = ALIGN(0x100); + + .text : { *(.text*) } :text =0x90909090 +} + +/* + * Very old versions of ld do not recognize this name token; use the constant. + */ +#define PT_GNU_EH_FRAME 0x6474e550 + +/* + * We must supply the ELF program headers explicitly to get just one + * PT_LOAD segment, and set the flags explicitly to make segments read-only. + */ +PHDRS +{ + text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */ + dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ + note PT_NOTE FLAGS(4); /* PF_R */ + eh_frame_hdr PT_GNU_EH_FRAME; +} diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S index d40d0e9..4e5dd3b 100644 --- a/arch/x86/vdso/vdso.lds.S +++ b/arch/x86/vdso/vdso.lds.S @@ -1,89 +1,37 @@ /* - * Linker script for vsyscall DSO. The vsyscall page is an ELF shared - * object prelinked to its virtual address, and with only one read-only - * segment (that fits in one page). This script controls its layout. + * Linker script for 64-bit vDSO. + * We #include the file to define the layout details. + * Here we only choose the prelinked virtual address. + * + * This file defines the version script giving the user-exported symbols in + * the DSO. We can define local symbols here called VDSO* to make their + * values visible using the asm-x86/vdso.h macros from the kernel proper. */ -#include -#include "voffset.h" #define VDSO_PRELINK 0xffffffffff700000 +#include "vdso-layout.lds.S" /* - * Symbols we define here called VDSO* get their values into vdso-syms.lds - * and become visible to the kernel itself. + * This controls what userland symbols we export from the vDSO. */ -VDSO64_PRELINK = VDSO_PRELINK; - -#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x; -#include "vextern.h" -#undef VEXTERN - -SECTIONS -{ - . = VDSO_PRELINK + SIZEOF_HEADERS; - - .hash : { *(.hash) } :text - .gnu.hash : { *(.gnu.hash) } - .dynsym : { *(.dynsym) } - .dynstr : { *(.dynstr) } - .gnu.version : { *(.gnu.version) } - .gnu.version_d : { *(.gnu.version_d) } - .gnu.version_r : { *(.gnu.version_r) } - - /* This linker script is used both with -r and with -shared. - For the layouts to match, we need to skip more than enough - space for the dynamic symbol table et al. If this amount - is insufficient, ld -shared will barf. Just increase it here. */ - . = VDSO_PRELINK + VDSO_TEXT_OFFSET; - - .text : { *(.text*) } :text - .rodata : { *(.rodata*) } :text - .data : { - *(.data*) - *(.sdata*) - *(.bss*) - *(.dynbss*) - } :text - - .altinstructions : { *(.altinstructions) } :text - .altinstr_replacement : { *(.altinstr_replacement) } :text - - .note : { *(.note.*) } :text :note - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr - .eh_frame : { KEEP (*(.eh_frame)) } :text - .dynamic : { *(.dynamic) } :text :dynamic - .useless : { - *(.got.plt) *(.got) - *(.gnu.linkonce.d.*) - *(.gnu.linkonce.b.*) - } :text +VERSION { + LINUX_2.6 { + global: + clock_gettime; + __vdso_clock_gettime; + gettimeofday; + __vdso_gettimeofday; + getcpu; + __vdso_getcpu; + local: *; + }; } -/* - * We must supply the ELF program headers explicitly to get just one - * PT_LOAD segment, and set the flags explicitly to make segments read-only. - */ -PHDRS -{ - text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */ - dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ - note PT_NOTE FLAGS(4); /* PF_R */ - eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */ -} +VDSO64_PRELINK = VDSO_PRELINK; /* - * This controls what symbols we export from the DSO. + * Define VDSO64_x for each VEXTERN(x), for use via VDSO64_SYMBOL. */ -VERSION -{ - LINUX_2.6 { - global: - clock_gettime; - __vdso_clock_gettime; - gettimeofday; - __vdso_gettimeofday; - getcpu; - __vdso_getcpu; - local: *; - }; -} +#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x; +#include "vextern.h" +#undef VEXTERN diff --git a/arch/x86/vdso/voffset.h b/arch/x86/vdso/voffset.h deleted file mode 100644 index 4af67c7..0000000 --- a/arch/x86/vdso/voffset.h +++ /dev/null @@ -1 +0,0 @@ -#define VDSO_TEXT_OFFSET 0x600 - 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/