x86 vDSO: new layout

/*

 * 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;

}

/*

 * 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 <asm/asm-offsets.h>

#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

}

/*

 * 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 */

}

/*

 * This controls what symbols we export from the DSO.

 */

VERSION

{

VERSION {

	LINUX_2.6 {

	global:

		clock_gettime;

	local: *;

	};

}

VDSO64_PRELINK = VDSO_PRELINK;

/*

 * Define VDSO64_x for each VEXTERN(x), for use via VDSO64_SYMBOL.

 */

#define VEXTERN(x)	VDSO64_ ## x = vdso_ ## x;

#include "vextern.h"

#undef	VEXTERN

#define VDSO_TEXT_OFFSET 0x600