Platforms like Moorestown require early setup and want to avoid the
call to reserve_ebda_region. The x86_init override is too late when
the MRST detection happens in setup_arch. Move the default i386
x86_init overrides and the call to reserve_ebda_region into a separate
function which is called as the default of a switch case depending on
the hardware_subarch id in boot params. This allows us to add a case
for MRST and let MRST have its own early setup function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
reserve_ebda_region needs to be called befor start_kernel. Moorestown
needs to override it. Make it a x86_init_ops function and initialize
it with the default reserve_ebda_region.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Impact: new interface
Add a brk()-like allocator which effectively extends the bss in order
to allow very early code to do dynamic allocations. This is better than
using statically allocated arrays for data in subsystems which may never
get used.
The space for brk allocations is in the bss ELF segment, so that the
space is mapped properly by the code which maps the kernel, and so
that bootloaders keep the space free rather than putting a ramdisk or
something into it.
The bss itself, delimited by __bss_stop, ends before the brk area
(__brk_base to __brk_limit). The kernel text, data and bss is reserved
up to __bss_stop.
Any brk-allocated data is reserved separately just before the kernel
pagetable is built, as that code allocates from unreserved spaces
in the e820 map, potentially allocating from any unused brk memory.
Ultimately any unused memory in the brk area is used in the general
kernel memory pool.
Initially the brk space is set to 1MB, which is probably much larger
than any user needs (the largest current user is i386 head_32.S's code
to build the pagetables to map the kernel, which can get fairly large
with a big kernel image and no PSE support). So long as the system
has sufficient memory for the bootloader to reserve the kernel+1MB brk,
there are no bad effects resulting from an over-large brk.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: cleanup
Copy the code to cpu_init() to satisfy the requirement that the cpu
be reinitialized. Remove all other calls, since the segments are
already initialized in head_64.S.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Do the following cleanups:
* kill x86_64_init_pda() which now is equivalent to pda_init()
* use per_cpu_offset() instead of cpu_pda() when initializing
initial_gs
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[ Based on original patch from Christoph Lameter and Mike Travis. ]
As pda is now allocated in percpu area, it can easily be made a proper
percpu variable. Make it so by defining per cpu symbol from linker
script and declaring it in C code for SMP and simply defining it for
UP. This change cleans up code and brings SMP and UP closer a bit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Now that pda is allocated as part of percpu, percpu doesn't need to be
accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP
one. Other than the segment register, operand size and the base of
percpu symbols, they behave identical now.
This patch replaces now unnecessary pda->data_offset with a dummy
field which is necessary to keep stack_canary at its place. This
patch also moves per_cpu_offset initialization out of init_gdt() into
setup_per_cpu_areas(). Note that this change also necessitates
explicit per_cpu_offset initializations in voyager_smp.c.
With this change, x86_OP_percpu()'s are as efficient on x86_64 as on
x86_32 and also x86_64 can use assembly PER_CPU macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[ Based on original patch from Christoph Lameter and Mike Travis. ]
Currently pdas and percpu areas are allocated separately. %gs points
to local pda and percpu area can be reached using pda->data_offset.
This patch folds pda into percpu area.
Due to strange gcc requirement, pda needs to be at the beginning of
the percpu area so that pda->stack_canary is at %gs:40. To achieve
this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is
added and used to reserve pda sized chunk at the start of the percpu
area.
After this change, for boot cpu, %gs first points to pda in the
data.init area and later during setup_per_cpu_areas() gets updated to
point to the actual pda. This means that setup_per_cpu_areas() need
to reload %gs for CPU0 while clearing pda area for other cpus as cpu0
already has modified it when control reaches setup_per_cpu_areas().
This patch also removes now unnecessary get_local_pda() and its call
sites.
A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into
per cpu area" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
_cpu_pda array first uses statically allocated storage in data.init
and then switches to allocated bootmem to conserve space. However,
after folding pda area into percpu area, _cpu_pda array will be
removed completely. Drop the reallocation part to simplify the code
for soon-to-follow changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[ Based on original patch from Christoph Lameter and Mike Travis. ]
CPU startup code in head_64.S loaded address of a zero page into %gs
for temporary use till pda is loaded but address to the actual pda is
available at the point. Load the real address directly instead.
This will help unifying percpu and pda handling later on.
This patch is mostly taken from Mike Travis' "x86_64: Fold pda into
per cpu area" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
[ Based on original patch from Christoph Lameter and Mike Travis. ]
This patch makes percpu symbols zerobased on x86_64 SMP by adding
PERCPU_VADDR() to vmlinux.lds.h which helps setting explicit vaddr on
the percpu output section and using it in vmlinux_64.lds.S. A new
PHDR is added as existing ones cannot contain sections near address
zero. PERCPU_VADDR() also adds a new symbol __per_cpu_load which
always points to the vaddr of the loaded percpu data.init region.
The following adjustments have been made to accomodate the address
change.
* code to locate percpu gdt_page in head_64.S is updated to add the
load address to the gdt_page offset.
* __per_cpu_load is used in places where access to the init data area
is necessary.
* pda->data_offset is initialized soon after C code is entered as zero
value doesn't work anymore.
This patch is mostly taken from Mike Travis' "x86_64: Base percpu
variables at zero" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The pda rework (commit 3461b0af02)
to remove static boot cpu pdas introduced a performance bug.
_boot_cpu_pda is the actual pda used by the boot cpu and is definitely
not "__read_mostly" and ended up polluting the read mostly section with
writes. This bug caused regression of about 8-10% on certain syscall
intensive workloads.
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Acked-by: Mike Travis <travis@sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix trampoline sizing bug, save space
While debugging a suspend-to-RAM related issue it occured to me that
if the trampoline code had grown past 4 KB, we would have been
allocating too little memory for it, since the 4 KB size of the
trampoline is hardcoded into arch/x86/kernel/e820.c . Change that
by making the kernel compute the trampoline size and allocate as much
memory as necessary.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Plus add a build time check so this doesn't go unnoticed again.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As a stopgap until Mike Travis's x86-64 gs-based percpu patches are
ready, provide workaround functions for x86_read/write_percpu for
Xen's use.
Specifically, this means that we can't really make use of vcpu
placement, because we can't use a single gs-based memory access to get
to vcpu fields. So disable all that for now.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ying Huang would like setup_data to be reserved, but not included in the
no save range.
Here we try to modify the e820 table to reserve that range early.
also add that in early_res in case bootloader messes up with the ramdisk.
other solution would be
1. add early_res_to_highmem...
2. early_res_to_e820...
but they could reserve another type memory wrongly, if early_res has some
resource reserved early, and not needed later, but it is not removed from
early_res in time. Like the RAMDISK (already handled).
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: andi@firstfloor.org
Tested-by: Huang, Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Split x86_64_start_kernel() into two pieces:
The first essentially cleans up after head_64.S. It clears the
bss, zaps low identity mappings, sets up some early exception
handlers.
The second part preserves the boot data, reserves the kernel's
text/data/bss, pagetables and ramdisk, and then starts the kernel
proper.
This split is so that Xen can call the second part to do the set up it
needs done. It doesn't need any of the first part setups, because it
doesn't boot via head_64.S, and its redundant or actively damaging.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Remove the boot_cpu_pda array and pointer table from the data section.
Allocate the pointer table and array during init. do_boot_cpu()
will reallocate the pda in node local memory and if the cpu is being
brought up before the bootmem array is released (after_bootmem = 0),
then it will free the initial pda. This will happen for all cpus
present at system startup.
This removes 512k + 32k bytes from the data section.
For inclusion into sched-devel/latest tree.
Based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
+ sched-devel/latest .../mingo/linux-2.6-sched-devel.git
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds a field of 64-bit physical pointer to NULL terminated
single linked list of struct setup_data to real-mode kernel
header. This is used as a more extensible boot parameters passing
mechanism.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Thomas Gleixner
Jeremy Fitzhardinge
Brian Gerst
Tejun Heo
Ravikiran G Thirumalai
Rafael J. Wysocki
dcg
Bill Nottingham
Jan Beulich
Jeremy Fitzhardinge
Yinghai Lu
Ingo Molnar
Mike Travis
Huang, Ying