Currently, running SetVirtualAddressMap() and passing the physical
address of the virtual map array was working only by a lucky coincidence
because the memory was present in the EFI page table too. Until Toshi
went and booted this on a big HP box - the krealloc() manner of resizing
the memmap we're doing did allocate from such physical addresses which
were not mapped anymore and boom:

http://lkml.kernel.org/r/1386806463.1791.295.camel@misato.fc.hp.com



One way to take care of that issue is to reimplement the krealloc thing
but with pages. We start with contiguous pages of order 1, i.e. 2 pages,
and when we deplete that memory (shouldn't happen all that often but you
know firmware) we realloc the next power-of-two pages.

Having the pages, it is much more handy and easy to map them into the
EFI page table with the already existing mapping code which we're using
for building the virtual mappings.

Thanks to Toshi Kani and Matt for the great debugging help.

Reported-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

We will use it in efi so expose it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

This is very useful for debugging issues with the recently added
pagetable switching code for EFI virtual mode.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

With reusing the ->trampoline_pgd page table for mapping EFI regions in
order to use them after having switched to EFI virtual mode, it is very
useful to be able to dump aforementioned page table in dmesg. This adds
that functionality through the walk_pgd_level() interface which can be
called from somewhere else.

The original functionality of dumping to debugfs remains untouched.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

Coalesce formats and remove spaces before tabs.
Move __initdata after the variable declaration.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

For now we only ensure about 5kb free space for avoiding our board
refusing boot. But the comment lies that we retain 50% space.

Signed-off-by: Madper Xie <cxie@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

It makes more sense to set the feature flag in the success path of the
detection function than it does to rely on the caller doing it. Apart
from it being more logical to group the code and data together, it sets
a much better example for new EFI architectures.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

As we grow support for more EFI architectures they're going to want the
ability to query which EFI features are available on the running system.
Instead of storing this information in an architecture-specific place,
stick it in the global 'struct efi', which is already the central
location for EFI state.

While we're at it, let's change the return value of efi_enabled() to be
bool and replace all references to 'facility' with 'feature', which is
the usual word used to describe the attributes of the running system.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

This reverts commit 01ab1167, it is
incorrect, a future patch will fix this up properly.

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This fixes the build breakage introduced by
c07a0191 and adds support for the device
control API and save/restore of the VGIC state for ARMv8.

The defines were simply missing from the arm64 header files and
uaccess.h must be implicitly imported from somewhere else on arm.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Madper reported seeing the following crash,

  BUG: unable to handle kernel paging request at ffffffffff340003
  IP: [<ffffffff81d85ba4>] efi_bgrt_init+0x9d/0x133
  Call Trace:
   [<ffffffff81d8525d>] efi_late_init+0x9/0xb
   [<ffffffff81d68f59>] start_kernel+0x436/0x450
   [<ffffffff81d6892c>] ? repair_env_string+0x5c/0x5c
   [<ffffffff81d68120>] ? early_idt_handlers+0x120/0x120
   [<ffffffff81d685de>] x86_64_start_reservations+0x2a/0x2c
   [<ffffffff81d6871e>] x86_64_start_kernel+0x13e/0x14d

This is caused because the layout of the ACPI BGRT header on this system
doesn't match the definition from the ACPI spec, and so we get a bogus
physical address when dereferencing ->image_address in efi_bgrt_init().

Luckily the status field in the BGRT header clearly marks it as invalid,
so we can check that field and skip BGRT initialisation.

Reported-by: Madper Xie <cxie@redhat.com>
Suggested-by: Toshi Kani <toshi.kani@hp.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

We do not enable the new efi memmap on 32-bit and thus we need to run
runtime_code_page_mkexec() unconditionally there. Fix that.

Reported-and-tested-by: Lejun Zhu <lejun.zhu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

If CONFIG_X86_SMAP is disabled, smap_violation() tests for conditions
which are incorrect (as the AC flag doesn't matter), causing spurious
faults.

The dynamic disabling of SMAP (nosmap on the command line) is fine
because it disables X86_FEATURE_SMAP, therefore causing the
static_cpu_has() to return false.

Found by Fengguang Wu's test system.

[ v3: move all predicates into smap_violation() ]
[ v2: use IS_ENABLED() instead of #ifdef ]

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.7+

If SMAP support is not compiled into the kernel, don't enable SMAP in
CR4 -- in fact, we should clear it, because the kernel doesn't contain
the proper STAC/CLAC instructions for SMAP support.

Found by Fengguang Wu's test system.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.7+

When the conversion was made to remove stop machine and use the breakpoint
logic instead, the modification of the function graph caller is still
done directly as though it was being done under stop machine.

As it is not converted via stop machine anymore, there is a possibility
that the code could be layed across cache lines and if another CPU is
accessing that function graph call when it is being updated, it could
cause a General Protection Fault.

Convert the update of the function graph caller to use the breakpoint
method as well.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: stable@vger.kernel.org # 3.5+
Fixes: 08d636b6 "ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Commit 70b41abc
"ARM: ux500: move MSP pin control to the device tree"
accidentally activated MSP2, giving rise to a boot scroll
scream as the kernel attempts to probe a driver for it and
fails to obtain DMA channel 14.

Fix this up by marking the node disabled again.

Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

This patch adds the support for to create a direct iommu "bypass"
window on IODA2 bridges (such as Power8) allowing to bypass iommu
page translation completely for 64-bit DMA capable devices, thus
significantly improving DMA performances.

Additionally, this adds a hook to the struct iommu_table so that
the IOMMU API / VFIO can disable the bypass when external ownership
is requested, since in that case, the device will be used by an
environment such as userspace or a KVM guest which must not be
allowed to bypass translations.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We expose a number of OF properties in the kexec and crash dump code
and these need to be big endian.

Cc: stable@vger.kernel.org # v3.13
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We would allocate one specific exception stack for each kind of
non-base exceptions for every CPU. For ppc32 the CPU hard ID is
used as the subscript to get the specific exception stack for
one CPU. But for an UP kernel, there is only one element in the
each kind of exception stack array. We would get stuck if the
CPU hard ID is not equal to '0'. So in this case we should use the
subscript '0' no matter what the CPU hard ID is.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Currently we set our cpu's bit in cpus_in_xmon, and then we take the
output lock and print the exception information.

This can race with the master cpu entering the command loop and printing
the backtrace. The result is that the backtrace gets garbled with
another cpu's exception print out.

Fix it by delaying the set of cpus_in_xmon until we are finished
printing.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

As far as I can tell, our 70s era timeout loop in get_output_lock() is
generating no code.

This leads to the hostile takeover happening more or less simultaneously
on all cpus. The result is "interesting", some example output that is
more readable than most:

    cpu 0x1: Vector: 100 (Scypsut e0mx bR:e setV)e catto xc0p:u[ c 00
    c0:0  000t0o0V0erc0td:o5 rfc28050000]0c00 0 0  0 6t(pSrycsV1ppuot
    uxe 1m 2 0Rx21e3:0s0ce000c00000t00)00 60602oV2SerucSayt0y 0p 1sxs

Fix it by using udelay() in the timeout loop. The wait time and check
frequency are arbitrary, but seem to work OK. We already rely on
udelay() working so this is not a new dependency.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

If we enter with xmon_speaker != 0 we skip the first cmpxchg(), we also
skip the while loop because xmon_speaker != last_speaker (0) - meaning we
skip the second cmpxchg() also.

Following that code path the compiler sees no memory barriers and so is
within its rights to never reload xmon_speaker. The end result is we loop
forever.

This manifests as all cpus being in xmon ('c' command), but they refuse
to take control when you switch to them ('c x' for cpu # x).

I have seen this deadlock in practice and also checked the generated code to
confirm this is what's happening.

The simplest fix is just to always try the cmpxchg().

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Right now the config_bhrb() PMU specific call happens after
write_mmcr0(), which actually enables the PMU for event counting and
interrupts. So there is a small window of time where the PMU and BHRB
runs without the required HW branch filter (if any) enabled in BHRB.

This can cause some of the branch samples to be collected through BHRB
without any filter applied and hence affects the correctness of
the results. This patch moves the BHRB config function call before
enabling interrupts.

Here are some data points captured via trace prints which depicts how we
could get PMU interrupts with BHRB filter NOT enabled with a standard
perf record command line (asking for branch record information as well).

    $ perf record -j any_call ls

Before the patch:-

    ls-1962  [003] d...  2065.299590: .perf_event_interrupt: MMCRA: 40000000000
    ls-1962  [003] d...  2065.299603: .perf_event_interrupt: MMCRA: 40000000000
    ...

    All the PMU interrupts before this point did not have the requested
    HW branch filter enabled in the MMCRA.

    ls-1962  [003] d...  2065.299647: .perf_event_interrupt: MMCRA: 40040000000
    ls-1962  [003] d...  2065.299662: .perf_event_interrupt: MMCRA: 40040000000

After the patch:-

    ls-1850  [008] d...   190.311828: .perf_event_interrupt: MMCRA: 40040000000
    ls-1850  [008] d...   190.311848: .perf_event_interrupt: MMCRA: 40040000000

    All the PMU interrupts have the requested HW BHRB branch filter
    enabled in MMCRA.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
[mpe: Fixed up whitespace and cleaned up changelog]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We have a driver for the ARCH_RANDOM hook in rng.c, so we should select
ARCH_RANDOM on pseries.

Without this the build breaks if you turn ARCH_RANDOM off.

This hasn't broken the build because pseries_defconfig doesn't specify a
value for PPC_POWERNV, which is default y, and selects ARCH_RANDOM.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Relocation's code is not working in little endian mode because the r_info
field, which is a 64 bits value, should be read from the right offset.

The current code is optimized to read the r_info field as a 32 bits value
starting at the middle of the double word (offset 12). When running in LE
mode, the read value is not correct since only the MSB is read.

This patch removes this optimization which consist to deal with a 32 bits
value instead of a 64 bits one. This way it works in big and little endian
mode.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

On p8 systems, with relocation on exception feature enabled we are seeing
kdump kernel hang at interrupt vector 0xc*4400. The reason is, with this
feature enabled, exception are raised with MMU (IR=DR=1) ON with the
default offset of 0xc*4000. Since exception is raised in virtual mode it
requires the vector region to be executable without which it fails to
fetch and execute instruction at 0xc*4xxx. For default kernel since kernel
is loaded at real 0, the htab mappings sets the entire kernel text region
executable. But for relocatable kernel (e.g. kdump case) we only copy
interrupt vectors down to real 0 and never marked that region as
executable because in p7 and below we always get exception in real mode.

This patch fixes this issue by marking htab mapping range as executable
that overlaps with the interrupt vector region for relocatable kernel.

Thanks to Ben who helped me to debug this issue and find the root cause.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Disable relocation on exception while going down even in kdump case. This
is because we are about clear htab mappings while kexec-ing into kdump
kernel and we may run into issues if we still have AIL ON.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Commit f5c57710 ("powerpc/eeh: Use
partial hotplug for EEH unaware drivers") introduces eeh_rmv_device,
which may grab a reference to a driver, but not release it.

That prevents a driver from being removed after it has gone through EEH
recovery.

This patch drops the reference if it was taken.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 446f6d06 ("powerpc/mpic: Properly
set default triggers") breaks the mpc7447_hpc_defconfig as follows:

  CC      arch/powerpc/sysdev/mpic.o
arch/powerpc/sysdev/mpic.c: In function 'mpic_set_irq_type':
arch/powerpc/sysdev/mpic.c:886:9: error: case label does not reduce to an integer constant
arch/powerpc/sysdev/mpic.c:890:9: error: case label does not reduce to an integer constant
arch/powerpc/sysdev/mpic.c:894:9: error: case label does not reduce to an integer constant
arch/powerpc/sysdev/mpic.c:898:9: error: case label does not reduce to an integer constant

Looking at the cpp output (gcc 4.7.3), I see:

   case mpic->hw_set[MPIC_IDX_VECPRI_SENSE_EDGE] |
        mpic->hw_set[MPIC_IDX_VECPRI_POLARITY_POSITIVE]:

The pointer into an array appears because CONFIG_MPIC_WEIRD=y is set
for this platform, thus enabling the following:

  -------------------
  #ifdef CONFIG_MPIC_WEIRD
  static u32 mpic_infos[][MPIC_IDX_END] = {
        [0] = { /* Original OpenPIC compatible MPIC */

  [...]

  #define MPIC_INFO(name) mpic->hw_set[MPIC_IDX_##name]

  #else /* CONFIG_MPIC_WEIRD */

  #define MPIC_INFO(name) MPIC_##name

  #endif /* CONFIG_MPIC_WEIRD */
  -------------------

Here we convert the case section to if/else if, and also add
the equivalent of a default case to warn about unknown types.
Boot tested on sbc8548, build tested on all defconfigs.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Steven Noonan forwarded a users report where they had a problem starting
vsftpd on a Xen paravirtualized guest, with this in dmesg:

  BUG: Bad page map in process vsftpd  pte:8000000493b88165 pmd:e9cc01067
  page:ffffea00124ee200 count:0 mapcount:-1 mapping:     (null) index:0x0
  page flags: 0x2ffc0000000014(referenced|dirty)
  addr:00007f97eea74000 vm_flags:00100071 anon_vma:ffff880e98f80380 mapping:          (null) index:7f97eea74
  CPU: 4 PID: 587 Comm: vsftpd Not tainted 3.12.7-1-ec2 #1
  Call Trace:
    dump_stack+0x45/0x56
    print_bad_pte+0x22e/0x250
    unmap_single_vma+0x583/0x890
    unmap_vmas+0x65/0x90
    exit_mmap+0xc5/0x170
    mmput+0x65/0x100
    do_exit+0x393/0x9e0
    do_group_exit+0xcc/0x140
    SyS_exit_group+0x14/0x20
    system_call_fastpath+0x1a/0x1f
  Disabling lock debugging due to kernel taint
  BUG: Bad rss-counter state mm:ffff880e9ca60580 idx:0 val:-1
  BUG: Bad rss-counter state mm:ffff880e9ca60580 idx:1 val:1

The issue could not be reproduced under an HVM instance with the same
kernel, so it appears to be exclusive to paravirtual Xen guests.  He
bisected the problem to commit 1667918b ("mm: numa: clear numa
hinting information on mprotect") that was also included in 3.12-stable.

The problem was related to how xen translates ptes because it was not
accounting for the _PAGE_NUMA bit.  This patch splits pte_present to add
a pteval_present helper for use by xen so both bare metal and xen use
the same code when checking if a PTE is present.

[mgorman@suse.de: wrote changelog, proposed minor modifications]
[akpm@linux-foundation.org: fix typo in comment]
Reported-by: Steven Noonan <steven@uplinklabs.net>
Tested-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Elena Ufimtseva <ufimtseva@gmail.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Reserve space from 0x0 - __pa(swapper_pg_dir),
if kernel is loaded from 0, which is not DMAable.
It is causing problem with MMC driver and others
which want to add dma buffers to this space.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

Select CONFIG_SOC_DRA7XX so that we can boot dra7-evm.
DRA7 family are A15 based processors that supports LPAE and an
evolutionary update to the OMAP5 generation of processors.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

Since commit 9e8147bb
"ARM: imx6q: move low-power code out of clock driver"
the kernel fails to boot on i.MX6Q/D if preemption is
enabled (CONFIG_PREEMPT=y). The kernel just hangs
before the console comes up.

The above commit moved the initalization of the low-power
mode setting (enabling clocked WAIT states), which was
introduced in commit 83ae2098
"ARM: imx: correct low-power mode setting", from
imx6q_clks_init to imx6q_pm_init. Now it is called
much later, after all cores are enabled.

This patch moves the low-power mode initialization back
to imx6q_clks_init again (and to imx6sl_clks_init).

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

Due to commit 88f718e3
"ARM: pxa: delete the custom GPIO header" some drivers fail
compilation, for example like this:

In file included from sound/soc/pxa/spitz.c:28:0:
sound/soc/pxa/spitz.c: In function ‘spitz_ext_control’:
arch/arm/mach-pxa/include/mach/spitz.h:111:30: error:
‘PXA_NR_BUILTIN_GPIO’ undeclared (first use in this function)
 #define SPITZ_SCP_GPIO_BASE (PXA_NR_BUILTIN_GPIO)
(etc.)

This is caused by implicit inclusion of <mach/irqs.h> from
various board-specific headers under <mach/*> in the PXA
platform. So we take a sweep over these, and for every such
header that uses PXA_NR_BUILTIN_GPIO or PXA_GPIO_TO_IRQ()
we explicitly #include "irqs.h" so that we satisfy the
dependency in the board include file alone.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Kevin Hilman <khilman@linaro.org>

This board fails compilation like this:
arch/arm/mach-pxa/am300epd.c: In function ‘am300_cleanup’:
arch/arm/mach-pxa/am300epd.c:179:2: error: implicit declaration
of function ‘PXA_GPIO_TO_IRQ’ [-Werror=implicit-function-declaration]
  free_irq(PXA_GPIO_TO_IRQ(RDY_GPIO_PIN), par);

This was caused by commit 88f718e3
"ARM: pxa: delete the custom GPIO header"

This is because it was previously getting the macro PXA_GPIO_TO_IRQ
implicitly from <linux/gpio.h> which in turn implicitly included
<mach/gpio.h> which in turn included <mach/irqs.h>.

Add the missing include so that the board compiles again.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

Correct a typo causing the stack protector to be left enabled.
0xFFFFFFF -> 0xFFFFFFFF

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Some drivers check if readq/writeq functions are defined.
If not internal driver functions are used which cause
compilation failures.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Add missing param.h header because of HZ macro.
It is causing compilation failure:
In file included from include/linux/delay.h:14:0,
                    from drivers/clk/qcom/reset.c:18:
drivers/clk/qcom/reset.c: In function 'qcom_reset':
arch/microblaze/include/asm/delay.h:39:35: error: 'HZ'
 undeclared (first use in this function)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

When debug preempt is enabled, preempt_disable() can be traced by
function and function graph tracing.

There's a place in the function graph tracer that calls trace_clock()
which eventually calls cycles_2_ns() outside of the recursion
protection. When cycles_2_ns() calls preempt_disable() it gets traced
and the graph tracer will go into a recursive loop causing a crash or
worse, a triple fault.

Simple fix is to use preempt_disable_notrace() in cycles_2_ns, which
makes sense because the preempt_disable() tracing may use that code
too, and it tracing it, even with recursion protection is rather
pointless.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140204141315.2a968a72@gandalf.local.home


Signed-off-by: Ingo Molnar <mingo@kernel.org>