Since the IDT is referenced from a fixmap, make sure it is page aligned.
Merge with 32-bit one, since it was already aligned to deal with F00F
bug. Since bss is cleared before IDT setup, it can live there. This also
moves the other *_idt_table variables into common locations.

This avoids the risk of the IDT ever being moved in the bss and having
the mapping be offset, resulting in calling incorrect handlers. In the
current upstream kernel this is not a manifested bug, but heavily patched
kernels (such as those using the PaX patch series) did encounter this bug.

The tables other than idt_table technically do not need to be page
aligned, at least not at the current time, but using a common
declaration avoids mistakes.  On 64 bits the table is exactly one page
long, anyway.
Signed-off-by: NKees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.netReported-by: NPaX Team <pageexec@gmail.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

[Purpose of this patch]

As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.

http://www.spinics.net/lists/mm-commits/msg85707.html

<snip>
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled.  They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.

There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers.  Tracing such events gives
us the information about IRQ interaction with other system events.

The trace also tells where the system is spending its time.  We want to
know which cores are handling interrupts and how they are affecting other
processes in the system.  Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
<snip>

On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.

I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.

[Patch Description]

Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.

So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
   - local_timer_vector
   - reschedule_vector
   - call_function_vector
   - call_function_single_vector
   - irq_work_entry_vector
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
 - Create trace irq handlers with entering_irq()/exiting_irq().
 - Create a new IDT, trace_idt_table, at boot time by adding a logic to
   _set_gate(). It is just a copy of original idt table.
 - Register the new handlers for tracpoints to the new IDT by introducing
   macros to alloc_intr_gate() called at registering time of irq_vector handlers.
 - Add checking, whether irq vector tracing is on/off, into load_current_idt().
   This has to be done below debug checking for these reasons.
   - Switching to debug IDT may be kicked while tracing is enabled.
   - On the other hands, switching to trace IDT is kicked only when debugging
     is disabled.

In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.
Signed-off-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

Rename variables for debugging to describe meaning of them precisely.

Also, introduce a generic way to switch IDT by checking a current state,
debug on/off.
Signed-off-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323A8.7050905@hds.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

In head_64.S, a switchover has been used to handle kernel crossing
1G, 512G boundaries.

And commit 8170e6be
    x86, 64bit: Use a #PF handler to materialize early mappings on demand
said:
    During the switchover in head_64.S, before #PF handler is available,
    we use three pages to handle kernel crossing 1G, 512G boundaries with
    sharing page by playing games with page aliasing: the same page is
    mapped twice in the higher-level tables with appropriate wraparound.

But from the switchover code, when we set up the PUD table:
114         addq    $4096, %rdx
115         movq    %rdi, %rax
116         shrq    $PUD_SHIFT, %rax
117         andl    $(PTRS_PER_PUD-1), %eax
118         movq    %rdx, (4096+0)(%rbx,%rax,8)
119         movq    %rdx, (4096+8)(%rbx,%rax,8)

It seems line 119 has a potential bug there. For example,
if the kernel is loaded at physical address 511G+1008M, that is
    000000000 111111111 111111000 000000000000000000000
and the kernel _end is 512G+2M, that is
    000000001 000000000 000000001 000000000000000000000
So in this example, when using the 2nd page to setup PUD (line 114~119),
rax is 511.
In line 118, we put rdx which is the address of the PMD page (the 3rd page)
into entry 511 of the PUD table. But in line 119, the entry we calculate from
(4096+8)(%rbx,%rax,8) has exceeded the PUD page. IMO, the entry in line
119 should be wraparound into entry 0 of the PUD table.

The patch fixes the bug.
Signed-off-by: NZhang Yanfei <zhangyanfei@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/5191DE5A.3020302@cn.fujitsu.comSigned-off-by: NYinghai Lu <yinghai@kernel.org>
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

During early init, we would incorrectly set the NX bit even if the NX
feature was not supported.  Instead, only set this bit if NX is
actually available and enabled.  We already do very early detection of
the NX bit to enable it in EFER, this simply extends this detection to
the early page table mask.
Reported-by: NFernando Luis Vázquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1367476850.5660.2.camel@nexus
Cc: <stable@vger.kernel.org> v3.9

The AMD64 Architecture Programmer's Manual Volume 2, on page
89 mentions: "If the processor is running in 64-bit mode (L=1),
the only valid setting of the D bit is 0." This matches
with what the code does.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1361825650-14031-4-git-send-email-konrad.wilk@oracle.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The code requires the use of the proper per-exception-vector stub
functions (set up as the early_idt_handlers[] array - note the 's') that
make sure to set up the error vector number.  This is true regardless of
whether CONFIG_EARLY_PRINTK is set or not.

Why? The stack offset for the comparison of __KERNEL_CS won't be right
otherwise, nor will the new check (from commit 8170e6be: "x86,
64bit: Use a #PF handler to materialize early mappings on demand") for
the page fault exception vector.
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Linear mode (CR0.PG = 0) is mutually exclusive with 64-bit mode; all
64-bit code has to use page tables.  This makes it awkward before we
have first set up properly all-covering page tables to access objects
that are outside the static kernel range.

So far we have dealt with that simply by mapping a fixed amount of
low memory, but that fails in at least two upcoming use cases:

1. We will support load and run kernel, struct boot_params, ramdisk,
   command line, etc. above the 4 GiB mark.
2. need to access ramdisk early to get microcode to update that as
   early possible.

We could use early_iomap to access them too, but it will make code to
messy and hard to be unified with 32 bit.

Hence, set up a #PF table and use a fixed number of buffers to set up
page tables on demand.  If the buffers fill up then we simply flush
them and start over.  These buffers are all in __initdata, so it does
not increase RAM usage at runtime.

Thus, with the help of the #PF handler, we can set the final kernel
mapping from blank, and switch to init_level4_pgt later.

During the switchover in head_64.S, before #PF handler is available,
we use three pages to handle kernel crossing 1G, 512G boundaries with
sharing page by playing games with page aliasing: the same page is
mapped twice in the higher-level tables with appropriate wraparound.
The kernel region itself will be properly mapped; other mappings may
be spurious.

early_make_pgtable is using kernel high mapping address to access pages
to set page table.

-v4: Add phys_base offset to make kexec happy, and add
	init_mapping_kernel()   - Yinghai
-v5: fix compiling with xen, and add back ident level3 and level2 for xen
     also move back init_level4_pgt from BSS to DATA again.
     because we have to clear it anyway.  - Yinghai
-v6: switch to init_level4_pgt in init_mem_mapping. - Yinghai
-v7: remove not needed clear_page for init_level4_page
     it is with fill 512,8,0 already in head_64.S  - Yinghai
-v8: we need to keep that handler alive until init_mem_mapping and don't
     let early_trap_init to trash that early #PF handler.
     So split early_trap_pf_init out and move it down. - Yinghai
-v9: switchover only cover kernel space instead of 1G so could avoid
     touch possible mem holes. - Yinghai
-v11: change far jmp back to far return to initial_code, that is needed
     to fix failure that is reported by Konrad on AMD systems.  - Yinghai
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-12-git-send-email-yinghai@kernel.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

start_cpu0() is defined in head_64.S for 64-bit. The function sets up stack and
jumps to start_secondary() for CPU0 wake up.
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1352835171-3958-8-git-send-email-fenghua.yu@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Migrated SMP trampoline code to the real mode blob.
SMP trampoline code is not yet removed from
.x86_trampoline because it is needed by the wakeup
code.

[ hpa: always enable compiling startup_32_smp in head_32.S... it is
  only a few instructions which go into .init on UP builds, and it makes
  the rest of the code less #ifdef ugly. ]
Signed-off-by: NJarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-6-git-send-email-jarkko.sakkinen@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

If we get an exception during early boot, walk the exception table to
see if we should intercept it.  The main use case for this is to allow
rdmsr_safe()/wrmsr_safe() during CPU initialization.

Since the exception table is currently sorted at runtime, and fairly
late in startup, this code walks the exception table linearly.  We
obviously don't need to worry about modules, however: none have been
loaded at this point.

[ v2: Use early_fixup_exception() instead of linear search ]

Link: http://lkml.kernel.org/r/1334794610-5546-5-git-send-email-hpa@zytor.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

GET_CR2_INTO_RCX is asinine: it is only used in one place, the actual
paravirt call returns the value in %rax, not %rcx; and the one place
that wants it wants the result in %r9.  We actually generate as a
result of this call:

       call ...
       movq %rax, %rcx
       xorq %rax, %rax		/* this value isn't even used... */
       movq %rcx, %r9

At least make the macro do what the paravirt call does, which is put
the value into %rax.

Nevermind the fact that the macro clobbers all the volatile registers.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1334794610-5546-4-git-send-email-hpa@zytor.com
Cc: Glauber de Oliveira Costa <glommer@parallels.com>

Add a symbolic constant for the bitmask which states which exceptions
carry an error code.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1334794610-5546-3-git-send-email-hpa@zytor.com

We want to allow NMI handlers to have breakpoints to be able to
remove stop_machine from ftrace, kprobes and jump_labels. But if
an NMI interrupts a current breakpoint, and then it triggers a
breakpoint itself, it will switch to the breakpoint stack and
corrupt the data on it for the breakpoint processing that it
interrupted.

Instead, have the NMI check if it interrupted breakpoint processing
by checking if the stack that is currently used is a breakpoint
stack. If it is, then load a special IDT that changes the IST
for the debug exception to keep the same stack in kernel context.
When the NMI is done, it puts it back.

This way, if the NMI does trigger a breakpoint, it will keep
using the same stack and not stomp on the breakpoint data for
the breakpoint it interrupted.
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Common infrastructure for low memory trampolines.  This code installs
the trampolines permanently in low memory very early.  It also permits
multiple pieces of code to be used for this purpose.

This code also introduces a standard infrastructure for computing
symbol addresses in the trampoline code.

The only change to the actual SMP trampolines themselves is that the
64-bit trampoline has been made reusable -- the previous version would
overwrite the code with a status variable; this moves the status
variable to a separate location.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>

Load initial_gs as two 32-bit values instead of splitting a 64-bit value.
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
LKML-Reference: <1279371808-24804-3-git-send-email-brgerst@gmail.com>
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.
Signed-off-by: NDaniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This prevents kernel threads from inheriting non-null segment
selectors, and causing optimizations in __switch_to() to be
ineffective.
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Cc: Tim Blechmann <tim@klingt.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jan Beulich <JBeulich@novell.com>
LKML-Reference: <1259165856-3512-1-git-send-email-brgerst@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In the first 2MB, kernel text is co-located with kernel static
page tables setup by head_64.S.  CONFIG_DEBUG_RODATA chops this
2MB large page mapping to small 4KB pages as we mark the kernel text as RO,
leaving the static page tables as RW.

With CONFIG_DEBUG_RODATA disabled, OLTP run on NHM-EP shows 1% improvement
with 2% reduction in system time and 1% improvement in iowait idle time.

To recover this, move the kernel static page tables to .data section, so that
we don't have to break the first 2MB of kernel text to small pages with
CONFIG_DEBUG_RODATA.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20091014220254.063193621@sbs-t61.sc.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

This patch changes the remaining direct references to
.bss.page_aligned in C and assembly code to use the macros in
include/linux/linkage.h.
Signed-off-by: NTim Abbott <tabbott@ksplice.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: NPaul Mundt <lethal@linux-sh.org>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

This has the consequence of changing the section name use for head
code from ".text.head" to ".head.text".  It also eliminates the
".text.head" output section (instead placing head code at the start of
the .text output section), which should be harmless.

This patch only changes the sections in the actual kernel, not those
in the compressed boot loader.
Signed-off-by: NTim Abbott <tabbott@ksplice.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

asm/desc.h is included in three assembly files, but the only macro
it defines, GET_DESC_BASE, is never used. This patch removes the
includes, removes the macro GET_DESC_BASE and the ASSEMBLY guard
from asm/desc.h.
Signed-off-by: NAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Impact: cleanup
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: heukelum@fastmail.fm
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

NEXT_PAGE already has 'balign' so no
need to keep this redundant one.
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: heukelum@fastmail.fm
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup and bug fix

Use the linker to create symbols for certain per-cpu variables
that are offset by __per_cpu_load.  This allows the removal of
the runtime fixup of the GDT pointer, which fixes a bug with
resume reported by Jiri Slaby.
Reported-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Acked-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: x86_64 percpu area layout change, irq_stack now at the beginning

Now that the PDA is empty except for the stack canary, it can be removed.
The irqstack is moved to the start of the per-cpu section.  If the stack
protector is enabled, the canary overlaps the bottom 48 bytes of the irqstack.

tj: * updated subject
    * dropped asm relocation of irq_stack_ptr
    * updated comments a bit
    * rebased on top of stack canary changes
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

Impact: cleanup

Use cpu_number to determine if the adjustment is necessary.
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

[ 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: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo 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: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo 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: NTejun 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: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix debug/crash printout

Since errorcode is popped out, RIP is on the top of the stack.
Use real RIP value instead of wrong CS.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: arjan@linux.intel.com
Cc: venkatesh.pallipadi@intel.com
Cc: jeremy@goop.org
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit 033786969d1d1b5af12a32a19d3a760314d05329.

Suresh Siddha reported that this broke booting on his 2GB testbox.
Reported-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add the Xen entrypoint and ELF notes to head_64.S.  Adapts xen-head.S
to compile either 32-bit or 64-bit.
Signed-off-by: NJeremy 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: NIngo Molnar <mingo@elte.hu>

Early fixmap will allocate its own L1 pagetable page for fixmap
mappings, so there's no need to preallocate one.
Signed-off-by: NJeremy 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: NIngo Molnar <mingo@elte.hu>

Consistently set _PAGE_GLOBAL in _PAGE_KERNEL flags.  This makes 32-
and 64-bit code consistent, and removes some special cases where
__PAGE_KERNEL* did not have _PAGE_GLOBAL set, causing confusion as a
result of the inconsistencies.

This patch only affects x86-64, which generally always supports PGD.
The x86-32 patch is next.
Signed-off-by: NJeremy 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: NIngo Molnar <mingo@elte.hu>

Ingo Molnar wrote:
> -tip auto-testing found pagetable corruption (CPA self-test failure):
>
> [   32.956015] CPA self-test:
> [   32.958822]  4k 2048 large 508 gb 0 x 2556[ffff880000000000-ffff88003fe00000] miss 0
> [   32.964000] CPA ffff88001d54e000: bad pte 1d4000e3
> [   32.968000] CPA ffff88001d54e000: unexpected level 2
> [   32.972000] CPA ffff880022c5d000: bad pte 22c000e3
> [   32.976000] CPA ffff880022c5d000: unexpected level 2
> [   32.980000] CPA ffff8800200ce000: bad pte 200000e3
> [   32.984000] CPA ffff8800200ce000: unexpected level 2
> [   32.988000] CPA ffff8800210f0000: bad pte 210000e3
>
> config and full log can be found at:
>
>  http://redhat.com/~mingo/misc/config-Mon_Jun_30_11_11_51_CEST_2008.bad
>  http://redhat.com/~mingo/misc/log-Mon_Jun_30_11_11_51_CEST_2008.bad

Phew.  OK, I've worked this out.  Short version is that's it's a false
alarm, and there was no real failure here.  Long version:

    * I changed the code to create the physical mapping pagetables to
      reuse any existing mapping rather than replace it.   Specifically,
      reusing an pud pointed to by the pgd caused this symptom to appear.
    * The specific PUD being reused is the one created statically in
      head_64.S, which creates an initial 1GB mapping.
    * That mapping doesn't have _PAGE_GLOBAL set on it, due to the
      inconsistency between __PAGE_* and PAGE_*.
    * The CPA test attempts to clear _PAGE_GLOBAL, and then checks to
      see that the resulting range is 1) shattered into 4k pages, and 2)
      has no _PAGE_GLOBAL.
    * However, since it didn't have _PAGE_GLOBAL on that range to start
      with, change_page_attr_clear() had nothing to do, and didn't
      bother shattering the range,
    * resulting in the reported messages

The simple fix is to set _PAGE_GLOBAL in level2_ident_pgt.

An additional fix to make CPA testing more robust by using some other
pagetable bit (one of the unused available-to-software ones).  This
would solve spurious CPA test warnings under Xen which uses _PAGE_GLOBAL
for its own purposes (ie, not under guest control).

Also, we should revisit the use of _PAGE_GLOBAL in asm-x86/pgtable.h,
and use it consistently, and drop MAKE_GLOBAL.  The first time I
proposed it it caused breakages in the very early CPA code; with luck
that's all fixed now.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Set __PAGE_OFFSET to the most negative possible address +
16*PGDIR_SIZE.  The gap is to allow a space for a hypervisor to fit.
The gap is more or less arbitrary, but it's what Xen needs.

When booting native, kernel/head_64.S has a set of compile-time
generated pagetables used at boot time.  This patch removes their
absolutely hard-coded layout, and makes it parameterised on
__PAGE_OFFSET (and __START_KERNEL_map).
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NJeremy 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: NIngo Molnar <mingo@elte.hu>

i386 and x86_64 used two different schemes for maintaining the gdt.
With this patch, x86_64 initial gdt table is defined in a .c file,
same way as i386 is now. Also, we call it "gdt_page", and the descriptor,
"early_gdt_descr". This way we achieve common naming, which can allow for
more code integration.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>