linux/arch/powerpc/kernel/vmlinux.lds.S
Fenghua Yu 5fb7dc37dc define new percpu interface for shared data
per cpu data section contains two types of data.  One set which is
exclusively accessed by the local cpu and the other set which is per cpu,
but also shared by remote cpus.  In the current kernel, these two sets are
not clearely separated out.  This can potentially cause the same data
cacheline shared between the two sets of data, which will result in
unnecessary bouncing of the cacheline between cpus.

One way to fix the problem is to cacheline align the remotely accessed per
cpu data, both at the beginning and at the end.  Because of the padding at
both ends, this will likely cause some memory wastage and also the
interface to achieve this is not clean.

This patch:

Moves the remotely accessed per cpu data (which is currently marked
as ____cacheline_aligned_in_smp) into a different section, where all the data
elements are cacheline aligned. And as such, this differentiates the local
only data and remotely accessed data cleanly.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00

246 lines
3.6 KiB
ArmAsm

#ifdef CONFIG_PPC64
#include <asm/page.h>
#define PROVIDE32(x) PROVIDE(__unused__##x)
#else
#define PAGE_SIZE 4096
#define KERNELBASE CONFIG_KERNEL_START
#define PROVIDE32(x) PROVIDE(x)
#endif
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
ENTRY(_stext)
#ifdef CONFIG_PPC64
OUTPUT_ARCH(powerpc:common64)
jiffies = jiffies_64;
#else
OUTPUT_ARCH(powerpc:common)
jiffies = jiffies_64 + 4;
#endif
SECTIONS
{
/* Sections to be discarded. */
/DISCARD/ : {
*(.exitcall.exit)
*(.exit.data)
}
. = KERNELBASE;
/*
* Text, read only data and other permanent read-only sections
*/
/* Text and gots */
.text : {
_text = .;
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
#ifdef CONFIG_PPC32
*(.got1)
__got2_start = .;
*(.got2)
__got2_end = .;
#endif /* CONFIG_PPC32 */
. = ALIGN(PAGE_SIZE);
_etext = .;
PROVIDE32 (etext = .);
}
/* Read-only data */
RODATA
/* Exception & bug tables */
__ex_table : {
__start___ex_table = .;
*(__ex_table)
__stop___ex_table = .;
}
BUG_TABLE
/*
* Init sections discarded at runtime
*/
. = ALIGN(PAGE_SIZE);
__init_begin = .;
.init.text : {
_sinittext = .;
*(.init.text)
_einittext = .;
}
/* .exit.text is discarded at runtime, not link time,
* to deal with references from __bug_table
*/
.exit.text : { *(.exit.text) }
.init.data : {
*(.init.data);
__vtop_table_begin = .;
*(.vtop_fixup);
__vtop_table_end = .;
__ptov_table_begin = .;
*(.ptov_fixup);
__ptov_table_end = .;
#ifdef CONFIG_PPC_ISERIES
__dt_strings_start = .;
*(.dt_strings);
__dt_strings_end = .;
#endif
}
. = ALIGN(16);
.init.setup : {
__setup_start = .;
*(.init.setup)
__setup_end = .;
}
.initcall.init : {
__initcall_start = .;
INITCALLS
__initcall_end = .;
}
.con_initcall.init : {
__con_initcall_start = .;
*(.con_initcall.init)
__con_initcall_end = .;
}
SECURITY_INIT
. = ALIGN(8);
__ftr_fixup : {
__start___ftr_fixup = .;
*(__ftr_fixup)
__stop___ftr_fixup = .;
}
#ifdef CONFIG_PPC64
. = ALIGN(8);
__fw_ftr_fixup : {
__start___fw_ftr_fixup = .;
*(__fw_ftr_fixup)
__stop___fw_ftr_fixup = .;
}
#endif
#ifdef CONFIG_BLK_DEV_INITRD
. = ALIGN(PAGE_SIZE);
.init.ramfs : {
__initramfs_start = .;
*(.init.ramfs)
__initramfs_end = .;
}
#endif
. = ALIGN(PAGE_SIZE);
.data.percpu : {
__per_cpu_start = .;
*(.data.percpu)
*(.data.percpu.shared_aligned)
__per_cpu_end = .;
}
. = ALIGN(8);
.machine.desc : {
__machine_desc_start = . ;
*(.machine.desc)
__machine_desc_end = . ;
}
/* freed after init ends here */
. = ALIGN(PAGE_SIZE);
__init_end = .;
/*
* And now the various read/write data
*/
. = ALIGN(PAGE_SIZE);
_sdata = .;
#ifdef CONFIG_PPC32
.data :
{
DATA_DATA
*(.sdata)
*(.got.plt) *(.got)
}
#else
.data : {
*(.data .data.rel* .toc1)
*(.branch_lt)
}
.opd : {
*(.opd)
}
.got : {
__toc_start = .;
*(.got)
*(.toc)
}
#endif
. = ALIGN(PAGE_SIZE);
_edata = .;
PROVIDE32 (edata = .);
/* The initial task and kernel stack */
#ifdef CONFIG_PPC32
. = ALIGN(8192);
#else
. = ALIGN(16384);
#endif
.data.init_task : {
*(.data.init_task)
}
. = ALIGN(PAGE_SIZE);
.data.page_aligned : {
*(.data.page_aligned)
}
.data.cacheline_aligned : {
*(.data.cacheline_aligned)
}
. = ALIGN(L1_CACHE_BYTES);
.data.read_mostly : {
*(.data.read_mostly)
}
. = ALIGN(PAGE_SIZE);
__data_nosave : {
__nosave_begin = .;
*(.data.nosave)
. = ALIGN(PAGE_SIZE);
__nosave_end = .;
}
/*
* And finally the bss
*/
.bss : {
__bss_start = .;
*(.sbss) *(.scommon)
*(.dynbss)
*(.bss)
*(COMMON)
__bss_stop = .;
}
. = ALIGN(PAGE_SIZE);
_end = . ;
PROVIDE32 (end = .);
}