alistair23-linux/arch/parisc/kernel/vmlinux.lds.S
Roland McGrath 0b0bf7a3cc [PATCH] vDSO hash-style fix
The latest toolchains can produce a new ELF section in DSOs and
dynamically-linked executables.  The new section ".gnu.hash" replaces
".hash", and allows for more efficient runtime symbol lookups by the
dynamic linker.  The new ld option --hash-style={sysv|gnu|both} controls
whether to produce the old ".hash", the new ".gnu.hash", or both.  In some
new systems such as Fedora Core 6, gcc by default passes --hash-style=gnu
to the linker, so that a standard invocation of "gcc -shared" results in
producing a DSO with only ".gnu.hash".  The new ".gnu.hash" sections need
to be dealt with the same way as ".hash" sections in all respects; only the
dynamic linker cares about their contents.  To work with older dynamic
linkers (i.e.  preexisting releases of glibc), a binary must have the old
".hash" section.  The --hash-style=both option produces binaries that a new
dynamic linker can use more efficiently, but an old dynamic linker can
still handle.

The new section runs afoul of the custom linker scripts used to build vDSO
images for the kernel.  On ia64, the failure mode for this is a boot-time
panic because the vDSO's PT_IA_64_UNWIND segment winds up ill-formed.

This patch addresses the problem in two ways.

First, it mentions ".gnu.hash" in all the linker scripts alongside ".hash".
 This produces correct vDSO images with --hash-style=sysv (or old tools),
with --hash-style=gnu, or with --hash-style=both.

Second, it passes the --hash-style=sysv option when building the vDSO
images, so that ".gnu.hash" is not actually produced.  This is the most
conservative choice for compatibility with any old userland.  There is some
concern that some ancient glibc builds (though not any known old production
system) might choke on --hash-style=both binaries.  The optimizations
provided by the new style of hash section do not really matter for a DSO
with a tiny number of symbols, as the vDSO has.  If someone wants to use
=gnu or =both for their vDSO builds and worry less about that
compatibility, just change the option and the linker script changes will
make any choice work fine.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-31 13:28:43 -07:00

215 lines
5.6 KiB
ArmAsm

/* Kernel link layout for various "sections"
*
* Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
* Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
* Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
* Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
* Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
* Copyright (C) 2003 James Bottomley <jejb with parisc-linux.org>
* Copyright (C) 2006 Helge Deller <deller@gmx.de>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <asm-generic/vmlinux.lds.h>
/* needed for the processor specific cache alignment size */
#include <asm/cache.h>
#include <asm/page.h>
#include <asm/asm-offsets.h>
/* ld script to make hppa Linux kernel */
#ifndef CONFIG_64BIT
OUTPUT_FORMAT("elf32-hppa-linux")
OUTPUT_ARCH(hppa)
#else
OUTPUT_FORMAT("elf64-hppa-linux")
OUTPUT_ARCH(hppa:hppa2.0w)
#endif
ENTRY(_stext)
#ifndef CONFIG_64BIT
jiffies = jiffies_64 + 4;
#else
jiffies = jiffies_64;
#endif
SECTIONS
{
. = KERNEL_BINARY_TEXT_START;
_text = .; /* Text and read-only data */
.text ALIGN(16) : {
*(.text)
SCHED_TEXT
LOCK_TEXT
*(.text.do_softirq)
*(.text.sys_exit)
*(.text.do_sigaltstack)
*(.text.do_fork)
*(.text.*)
*(.fixup)
*(.lock.text) /* out-of-line lock text */
*(.gnu.warning)
} = 0
_etext = .; /* End of text section */
RODATA
/* writeable */
. = ALIGN(ASM_PAGE_SIZE); /* Make sure this is page aligned so
that we can properly leave these
as writable */
data_start = .;
. = ALIGN(16); /* Exception table */
__start___ex_table = .;
__ex_table : { *(__ex_table) }
__stop___ex_table = .;
__start___unwind = .; /* unwind info */
.PARISC.unwind : { *(.PARISC.unwind) }
__stop___unwind = .;
/* rarely changed data like cpu maps */
. = ALIGN(16);
.data.read_mostly : { *(.data.read_mostly) }
. = ALIGN(L1_CACHE_BYTES);
.data : { /* Data */
*(.data)
CONSTRUCTORS
}
. = ALIGN(L1_CACHE_BYTES);
.data.cacheline_aligned : { *(.data.cacheline_aligned) }
/* PA-RISC locks requires 16-byte alignment */
. = ALIGN(16);
.data.lock_aligned : { *(.data.lock_aligned) }
. = ALIGN(ASM_PAGE_SIZE);
/* nosave data is really only used for software suspend...it's here
* just in case we ever implement it */
__nosave_begin = .;
.data_nosave : { *(.data.nosave) }
. = ALIGN(ASM_PAGE_SIZE);
__nosave_end = .;
_edata = .; /* End of data section */
__bss_start = .; /* BSS */
/* page table entries need to be PAGE_SIZE aligned */
. = ALIGN(ASM_PAGE_SIZE);
.data.vmpages : {
*(.data.vm0.pmd)
*(.data.vm0.pgd)
*(.data.vm0.pte)
}
.bss : { *(.bss) *(COMMON) }
__bss_stop = .;
/* assembler code expects init_task to be 16k aligned */
. = ALIGN(16384); /* init_task */
.data.init_task : { *(.data.init_task) }
/* The interrupt stack is currently partially coded, but not yet
* implemented */
. = ALIGN(16384);
init_istack : { *(init_istack) }
#ifdef CONFIG_64BIT
. = ALIGN(16); /* Linkage tables */
.opd : { *(.opd) } PROVIDE (__gp = .);
.plt : { *(.plt) }
.dlt : { *(.dlt) }
#endif
/* reserve space for interrupt stack by aligning __init* to 16k */
. = ALIGN(16384);
__init_begin = .;
.init.text : {
_sinittext = .;
*(.init.text)
_einittext = .;
}
.init.data : { *(.init.data) }
. = ALIGN(16);
__setup_start = .;
.init.setup : { *(.init.setup) }
__setup_end = .;
__initcall_start = .;
.initcall.init : {
*(.initcall1.init)
*(.initcall2.init)
*(.initcall3.init)
*(.initcall4.init)
*(.initcall5.init)
*(.initcall6.init)
*(.initcall7.init)
}
__initcall_end = .;
__con_initcall_start = .;
.con_initcall.init : { *(.con_initcall.init) }
__con_initcall_end = .;
SECURITY_INIT
/* alternate instruction replacement. This is a mechanism x86 uses
* to detect the CPU type and replace generic instruction sequences
* with CPU specific ones. We don't currently do this in PA, but
* it seems like a good idea... */
. = ALIGN(4);
__alt_instructions = .;
.altinstructions : { *(.altinstructions) }
__alt_instructions_end = .;
.altinstr_replacement : { *(.altinstr_replacement) }
/* .exit.text is discard at runtime, not link time, to deal with references
from .altinstructions and .eh_frame */
.exit.text : { *(.exit.text) }
.exit.data : { *(.exit.data) }
. = ALIGN(ASM_PAGE_SIZE);
__initramfs_start = .;
.init.ramfs : { *(.init.ramfs) }
__initramfs_end = .;
. = ALIGN(32);
__per_cpu_start = .;
.data.percpu : { *(.data.percpu) }
__per_cpu_end = .;
. = ALIGN(ASM_PAGE_SIZE);
__init_end = .;
/* freed after init ends here */
_end = . ;
/* Sections to be discarded */
/DISCARD/ : {
*(.exitcall.exit)
#ifdef CONFIG_64BIT
/* temporary hack until binutils is fixed to not emit these
for static binaries */
*(.interp)
*(.dynsym)
*(.dynstr)
*(.dynamic)
*(.hash)
*(.gnu.hash)
#endif
}
STABS_DEBUG
.note 0 : { *(.note) }
}