Impact: fix potential miscompile (currently believed non-manifest)

As the comment explains, the VBE DDC call can clobber any register.
Tell the compiler about that fact.
Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1: make "target_kb" only accept and produce a memory size in kilobytes.
2: add a second "target" file which produces output in bytes, and will accept
   memparse input (scaled bytes)

This fixes the rather irritating problem that writing the same value
read back into target_kb would end up shrinking the domain by a factor
of 1024, with generally bad results.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>
Cc: "dan.magenheimer@oracle.com" <dan.magenheimer@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kerneloops.org is reporting a lot of these warnings that come due to
vmware not setting up any MTRRs for emulated CPUs:

| Reported 709 times (14696 total reports)
| BIOS bug (often in VMWare) where the MTRR's are set up incorrectly
| or not at all
|
| This warning was last seen in version 2.6.29-rc2-git1, and first
| seen in 2.6.24.
|
| More info:
|   http://www.kerneloops.org/searchweek.php?search=mtrr_trim_uncached_memory

Keep a one-liner KERN_INFO about it - so that we have so notice if empty
MTRRs are caused by native hardware/BIOS weirdness.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: re-enable CPUID unmasking on affected processors

As far as I am capable of discerning from the documentation,
MSR_IA32_MISC_ENABLE should be available for all family 0xf CPUs, as
well as family 6 for model >= 0xd (newer Pentium M).

The documentation on this isn't ideal, so we need to be on the lookout
for errors, still.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

The return value of xenbus_write_transaction can be uninitialised in
the success case leading to the userspace xenstore utilities failing.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Here function vmi_activate calls a init function activate_vmi , which
causes the following section mismatch warnings:

  LD      arch/x86/kernel/built-in.o
WARNING: arch/x86/kernel/built-in.o(.text+0x13ba9): Section mismatch
in reference from the function vmi_activate() to the function
.init.text:vmi_time_init()
The function vmi_activate() references
the function __init vmi_time_init().
This is often because vmi_activate lacks a __init
annotation or the annotation of vmi_time_init is wrong.

WARNING: arch/x86/kernel/built-in.o(.text+0x13bd1): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_bsp_init()
The function vmi_activate() references
the function __devinit vmi_time_bsp_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_bsp_init is wrong.

WARNING: arch/x86/kernel/built-in.o(.text+0x13bdb): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_ap_init()
The function vmi_activate() references
the function __devinit vmi_time_ap_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_ap_init is wrong.

Fix it by marking vmi_activate() as __init too.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix boot hang on pre-model-15 Intel CPUs

rdmsrl_safe() does not work in very early bootup code yet, because we
dont have the pagefault handler installed yet so exception section
does not get parsed. rdmsr_safe() will just crash and hang the bootup.

So limit the MSR_IA32_MISC_ENABLE MSR read to those CPU types that
support it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

In the absence of PAT, PAGE_KERNEL_WC ends up mapping to a memory type that
gets UC behavior even in the presence of a WC MTRR covering the area in
question.  By swapping to PAGE_KERNEL_UC_MINUS, we can get the actual
behavior the caller wanted (WC if you can manage it, UC otherwise).

This recovers the 40% performance improvement of using WC in the DRM
to upload vertex data.
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

the RDC and ELAN platforms use slighly different PIT clocks, resulting in
a timex.h hack that changes PIT_TICK_RATE during build time. But if a
tester enables any of these platform support .config options, the PIT
will be miscalibrated on standard PC platforms.

So use one frequency - in a subsequent patch we'll add a quirk to allow
x86 platforms to define different PIT frequencies.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Commit 1058a75f ("xen: actually release
memory when shrinking domain") causes a crash if the page being released
is a highmem page.

If a page is highmem then there is no need to unmap it.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

On -rt we were seeing spurious bad page states like:

Bad page state in process 'firefox'
page:c1bc2380 flags:0x40000000 mapping:c1bc2390 mapcount:0 count:0
Trying to fix it up, but a reboot is needed
Backtrace:
Pid: 503, comm: firefox Not tainted 2.6.26.8-rt13 #3
[<c043d0f3>] ? printk+0x14/0x19
[<c0272d4e>] bad_page+0x4e/0x79
[<c0273831>] free_hot_cold_page+0x5b/0x1d3
[<c02739f6>] free_hot_page+0xf/0x11
[<c0273a18>] __free_pages+0x20/0x2b
[<c027d170>] __pte_alloc+0x87/0x91
[<c027d25e>] handle_mm_fault+0xe4/0x733
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c0218875>] do_page_fault+0x36f/0x88a

This is the case where a concurrent fault already installed the PTE and
we get to free the newly allocated one.

This is due to pgtable_page_ctor() doing the spin_lock_init(&page->ptl)
which is overlaid with the {private, mapping} struct.

union {
    struct {
        unsigned long private;
        struct address_space *mapping;
    };
    spinlock_t ptl;
    struct kmem_cache *slab;
    struct page *first_page;
};

Normally the spinlock is small enough to not stomp on page->mapping, but
PREEMPT_RT=y has huge 'spin'locks.

But lockdep kernels should also be able to trigger this splat, as the
lock tracking code grows the spinlock to cover page->mapping.

The obvious fix is calling pgtable_page_dtor() like the regular pte free
path __pte_free_tlb() does.

It seems all architectures except x86 and nm10300 already do this, and
nm10300 doesn't seem to use pgtable_page_ctor(), which suggests it
doesn't do SMP or simply doesnt do MMU at all or something.
Signed-off-by: Peter Zijlstra <a.p.zijlsta@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>

Fix this:

> It appears that in the upstream balloon driver,
> the call to HYPERVISOR_update_va_mapping is missing
> from decrease_reservation.  I think as a result,
> the balloon driver is eating memory but not
> releasing it to Xen, thus rendering the balloon
> driver essentially useless.  (Can be observed via xentop.)
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: Fixes crashes with misconfigured BIOSes on XSAVE hardware

Avuton Olrich reported early boot crashes with v2.6.28 and
bisected it down to dc1e35c6
("x86, xsave: enable xsave/xrstor on cpus with xsave support").

If the CPUID limit bit in MSR_IA32_MISC_ENABLE is set, clear it to
make all CPUID information available.  This is required for some
features to work, in particular XSAVE.
Reported-and-bisected-by: Avuton Olrich <avuton@gmail.com>
Tested-by: Avuton Olrich <avuton@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Impact: None (new bit definitions currently unused)

Add bit definitions for the MSR_IA32_MISC_ENABLE MSRs to
<asm/msr-index.h>.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Beschorner Daniel reported:
> hwinfo problem since 2.6.28, showing this in the oops:
>	Corrupted page table at address 7fd04de3ec00

Also, PaX Team reported a regression with this commit:

>	commit 9542ada8
>	Author: Suresh Siddha <suresh.b.siddha@intel.com>
>	Date:   Wed Sep 24 08:53:33 2008 -0700
>
>	    x86: track memtype for RAM in page struct

This commit breaks mapping any RAM page through /dev/mem, as the
reserve_memtype() was not initializing the return attribute type and as such
corrupting the PTE entry that was setup with the return attribute type.

Because of this bug, application mapping this RAM page through /dev/mem
will die with "Corrupted page table at address xxxx" message in the kernel
log and also the kernel identity mapping which maps the underlying RAM
page gets converted to UC.

Fix this by initializing the return attribute type before calling
reserve_ram_pages_type()
Reported-by: PaX Team <pageexec@freemail.hu>
Reported-and-tested-by: Beschorner Daniel <Daniel.Beschorner@facton.com>
Tested-and-Acked-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

while looking at:

  http://bugzilla.kernel.org/show_bug.cgi?id=11541

I realized that the mtrr.show param cannot work, because
the code is processed much too early.

This patch:
 - Declares mtrr.show as early_param
 - Stays consistent with the previous param (which I doubt
   that it ever worked), so mtrr.show=1 would still work
 - Declares mtrr_show as initdata
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix sporadic slowdowns and warning messages

This patch fixes a performance issue reported by Linus on his
Nehalem system. While Linus reverted the PAT patch (commit
58dab916) which exposed the issue,
existing cpa() code can potentially still cause wrong(page attribute
corruption) behavior.

This patch also fixes the "WARNING: at arch/x86/mm/pageattr.c:560" that
various people reported.

In 64bit kernel, kernel identity mapping might have holes depending
on the available memory and how e820 reports the address range
covering the RAM, ACPI, PCI reserved regions. If there is a 2MB/1GB hole
in the address range that is not listed by e820 entries, kernel identity
mapping will have a corresponding hole in its 1-1 identity mapping.

If cpa() happens on the kernel identity mapping which falls into these holes,
existing code fails like this:

	__change_page_attr_set_clr()
		__change_page_attr()
			returns 0 because of if (!kpte). But doesn't
			set cpa->numpages and cpa->pfn.
		cpa_process_alias()
			uses uninitialized cpa->pfn (random value)
			which can potentially lead to changing the page
			attribute of kernel text/data, kernel identity
			mapping of RAM pages etc. oops!

This bug was easily exposed by another PAT patch which was doing
cpa() more often on kernel identity mapping holes (physical range between
max_low_pfn_mapped and 4GB), where in here it was setting the
cache disable attribute(PCD) for kernel identity mappings aswell.

Fix cpa() to handle the kernel identity mapping holes. Retain
the WARN() for cpa() calls to other not present address ranges
(kernel-text/data, ioremap() addresses)
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This reverts commit 4217458d.

Justin Madru bisected this commit, it was causing weird Firefox
crashes.

The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.

So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.

Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505Reported-and-bisected-by: Justin Madru <jdm64@gawab.com>
Tested-by: Justin Madru <jdm64@gawab.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix rare (but currently harmless) miscompile with certain configs and gcc versions

Hugh Dickins noticed that strncpy_from_user() was miscompiled
in some circumstances with gcc 4.3.

Thanks to Hugh's excellent analysis it was easy to track down.

Hugh writes:

> Try building an x86_64 defconfig 2.6.29-rc1 kernel tree,
> except not quite defconfig, switch CONFIG_PREEMPT_NONE=y
> and CONFIG_PREEMPT_VOLUNTARY off (because it expands a
> might_fault() there, which hides the issue): using a
> gcc 4.3.2 (I've checked both openSUSE 11.1 and Fedora 10).
>
> It generates the following:
>
> 0000000000000000 <__strncpy_from_user>:
>    0:   48 89 d1                mov    %rdx,%rcx
>    3:   48 85 c9                test   %rcx,%rcx
>    6:   74 0e                   je     16 <__strncpy_from_user+0x16>
>    8:   ac                      lods   %ds:(%rsi),%al
>    9:   aa                      stos   %al,%es:(%rdi)
>    a:   84 c0                   test   %al,%al
>    c:   74 05                   je     13 <__strncpy_from_user+0x13>
>    e:   48 ff c9                dec    %rcx
>   11:   75 f5                   jne    8 <__strncpy_from_user+0x8>
>   13:   48 29 c9                sub    %rcx,%rcx
>   16:   48 89 c8                mov    %rcx,%rax
>   19:   c3                      retq
>
> Observe that "sub %rcx,%rcx; mov %rcx,%rax", whereas gcc 4.2.1
> (and many other configs) say "sub %rcx,%rdx; mov %rdx,%rax".
> Isn't it returning 0 when it ought to be returning strlen?

The asm constraints for the strncpy_from_user() result were missing an
early clobber, which tells gcc that the last output arguments
are written before all input arguments are read.

Also add more early clobbers in the rest of the file and fix 32-bit
usercopy.c in the same way.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
[ since this API is rarely used and no in-kernel user relies on a 'len'
  return value (they only rely on negative return values) this miscompile
  was never noticed in the field. But it's worth fixing it nevertheless. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix crash with memory hotplug enabled

kernel_physical_mapping_init() is called during memory hotplug
so it does not belong in the init section.

If the kernel is built with CONFIG_DEBUG_SECTION_MISMATCH=y on
the make command line, arch/x86/mm/init_64.c is compiled with
the -fno-inline-functions-called-once gcc option defeating
inlining of kernel_physical_mapping_init() within init_memory_mapping().

When kernel_physical_mapping_init() is not inlined it is placed
in the .init.text section according to the __init in it's current
declaration.  A later call to kernel_physical_mapping_init() during
a memory hotplug operation encounters an int3 trap because the
.init.text section memory has been freed.

This patch eliminates the crash caused by the int3 trap by moving the
non-inlined kernel_physical_mapping_init() from .init.text to .meminit.text.
Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

-tip testing found this crash:

> [   35.258515] calling  acpi_cpufreq_init+0x0/0x127 @ 1
> [   35.264127] BUG: unable to handle kernel NULL pointer dereference at (null)
> [   35.267554] IP: [<ffffffff80478092>] __bitmap_intersects+0x48/0x73
> [   35.267554] PGD 0
> [   35.267554] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC

arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c is still broken: there's no
allocation of the variable mask, so we pass in an uninitialized cmd.mask
field to drv_read(), which then passes it to the scheduler which then
crashes ...

Switch it over to the much simpler constant-cpumask-pointers approach.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: use new work_on_cpu function to reduce stack usage

Replace the saving of current->cpus_allowed and set_cpus_allowed_ptr() with
a work_on_cpu function for drv_read() and drv_write().

Basically converts do_drv_{read,write} into "work_on_cpu" functions that
are now called by drv_read and drv_write.

Note: This patch basically reverts 50c668d6 which reverted 7503bfba, now
that the work_on_cpu() function is more stable.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Tested-by: Dieter Ries <clip2@gmx.de>
Tested-by: Maciej Rutecki <maciej.rutecki@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: <cpufreq@vger.kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: remove potential clashes with generic kevent workqueue

Annoyingly, some places we want to use work_on_cpu are already in
workqueues.  As per Ingo's suggestion, we create a different workqueue
for work_on_cpu.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: remove potential circular lock dependency with cpu hotplug lock

This has caused more problems than it solved, with a pile of cpu
hotplug locking issues.

Followup patches will get_online_cpus() in callers that need it, but
if they don't do it they're no worse than before when they were using
set_cpus_allowed without locking.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The function setup_cpu_local_masks() has been marked __init, in
order to remove the following section mismatch messages:

WARNING: vmlinux.o(.text+0x3c2c7): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2d3): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2df): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2eb): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.
Signed-off-by: Leonardo Potenza <lpotenza@inwind.it>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: add debug warning

Fire off one message if two apic's discovered with different
apic versions. (this code is only called during CPU init)

The goal of this is to pave the way of the removal of the apic_version[]
array. We dont expect any apic version incompatibilities in the x86
landscape of systems [if so we dont handle them very well and probably
never will handle deep apic version assymetries well], but it's prudent
to have a debug check for one kernel cycle nevertheless.
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Commit da4276b8 changed a dependency
for FRAME_POINTER from X86 to ARCH_WANT_FRAME_POINTERS, but didn't
actually define it.

This patch adds the definition for ARCH_WANT_FRAME_POINTERS. Without it,
FRAME_POINTER can't be enabled on x86.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Debugging and original patch from Nick Piggin <npiggin@suse.de>

The early fixmap pmd entry inserted at the very top of the KVA is causing the
subsequent fixmap mapping code to not provide physically linear pte pages over
the kmap atomic portion of the fixmap (which relies on said property to
calculate pte addresses).

This has caused weird boot failures in kmap_atomic much later in the boot
process (initial userspace faults) on a 32-bit PAE system with a larger number
of CPUs (smaller CPU counts tend not to run over into the next page so don't
show up the problem).

Solve this by attempting to clear out the page table, and copy any of its
entries to the new one. Also, add a bug if a nonlinear condition is encountered
and can't be resolved, which might save some hours of debugging if this fragile
scheme ever breaks again...

Once we have such logic, we can also use it to eliminate the early ioremap
trickery around the page table setup for the fixmap area. This also fixes
potential issues with FIX_* entries sharing the leaf page table with the early
ioremap ones getting discarded by early_ioremap_clear() and not restored by
early_ioremap_reset(). It at once eliminates the temporary (and configuration,
namely NR_CPUS, dependent) unavailability of early fixed mappings during the
time the fixmap area page tables get constructed.

Finally, also replace the hard coded calculation of the initial table space
needed for the fixmap area with a proper one, allowing kernels configured for
large CPU counts to actually boot.

Based-on: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The function uv_wait_completion() spins on reads of a memory-mapped
register, waiting for completion of BAU hardware replies.

It should call "cpu_relax()" between those reads to improve performance
on hyperthreaded configurations.
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Acked-by: Jack Steiner <steiner@sgi.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

E.g. when called due to an early panic.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Thierry Vignaud reported:
> http://bugzilla.kernel.org/show_bug.cgi?id=12372
>
> On P4 with an SiS motherboard (video card is a SiS 651)
> X server fails to start with error:
> xf86MapVidMem: Could not mmap framebuffer (0x00000000,0x2000) (Invalid
> argument)

Here X is trying to map first 8KB of memory using /dev/mem. Existing
code treats first 0-4KB of memory as non-RAM and 4KB-8KB as RAM. Recent
code changes don't allow to map memory with different attributes
at the same time.

Fix this by treating the first 1MB legacy region as special and always
track the attribute requests with in this region using linear linked
list (and don't bother if the range is RAM or non-RAM or mixed)
Reported-and-tested-by: Thierry Vignaud <tvignaud@mandriva.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: reduce kernel image size

Hugh Dickins noticed that older gcc versions when the kernel
is built for code size didn't inline some of the bitops.

Mark all complex x86 bitops that have more than a single
asm statement or two as always inline to avoid this problem.

Probably should be done for other architectures too.

Ingo then found a better fix that only requires
a single line change, but it unfortunately only
works on gcc 4.3.

On older gccs the original patch still makes a ~0.3% defconfig
difference with CONFIG_OPTIMIZE_INLINING=y.

With gcc 4.1 and a defconfig like build:

    61169987 1138540  883788 8139326  7c323e vmlinux-oi-with-patch
    6137043 1138540  883788 8159371  7c808b vmlinux-optimize-inlining

~20k / 0.3% difference.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix potential boot crash on MAXSMP

Remove code left over by:

  50c668d6: Revert "cpumask: use work_on_cpu in acpi-cpufreq.c for drv_read

That cmd.cpumask is not allocated anymore. No impact on default !MAXSMP
kernels.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This reverts commit e0c73175.

This patch was wrong, as lockdep (and thus the irq state tracer)
aren't nmi safe. People are already seeing lockdep warnings due
to this.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This reverts commit 7503bfba.

Dieter Ries reported bootup soft-hangs and bisected it back to
this commit, and reverting this commit gave him a working system.

The commit introduces work_on_cpu() use into the cpufreq code,
but that is subtly problematic from a lock hierarchy POV: the
hotplug-cpu lock is an highlevel lock that is taken before
lowlevel locks, and in this codepath we are called with the
policy lock taken.

Dieter did not have lockdep enabled so we dont have a nice stack
trace proof for this, but using work_on_cpu() in such a lowlevel
place certainly looks wrong, so we revert the patch.

work_on_cpu() needs to be reworked to be more generally usable.
Reported-by: Dieter Ries <clip2@gmx.de>
Tested-by: Dieter Ries <clip2@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix this by reintroducing asm/smp.h include in apic.c - later on
I will fix this by removing non-smp data from smp.h

Also fix the __inquire_remote_apic() prototype/inline.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix this by reintroducing asm/smp.h include in mpparse.c - later on
I will fix this by removing non-smp data from smp.h.
Reported-by: Petr Titera <P.Titera@century.cz>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Ajith Kumar noticed:

 I was going through the vmalloc fault handling for x86_64 and am unclear
 about the following lines in the vmalloc_fault() function.

 pgd = pgd_offset(current->mm ?: &init_mm, address);
 pgd_ref = pgd_offset_k(address);

 Here the intention is to get the pgd corresponding to the current process
 and sync it up with the pgd in init_mm(obtained from pgd_offset_k).
 However, for kernel threads current->mm is NULL and hence pgd =
 pgd_offset(init_mm, address) = pgd_ref which means the fault handler
 returns without setting the pgd entry in the MM structure in the context
 of which the kernel thread has faulted.  This could lead to never-ending
 faults and busy looping of kernel threads like pdflush.  So, shouldn't the
 pgd = pgd_offset(current->mm ?: &init_mm, address); be pgd =
 pgd_offset(current->active_mm ?: &init_mm, address);

We can use active_mm unconditionally because it should be always set.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>