sched: Force sleep on consecutive sched_yields

If a task sched_yields to itself continuously, force the task to
sleep in sched_yield. This will lower the CPU load of this task
thereby lowering the cpu frequency and improving power.

Added a stat variable to track how many times we sleep due these
consecutive sched_yields. Also added sysctl knobs to control the number
of consecutive sched_yields before which the sleep kicks in and the
duration fo the sleep in us.

Bug 1424617

Signed-off-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Wen Yi <wyi@nvidia.com>
Reviewed-by: Peter Zu <pzu@nvidia.com>
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
ARM: cleanup undefined instruction entry code

We don't need to keep reloading the thread into into r10 - we can do
this once and keep the value cached in the register.  Also, schedule
some instructions better so that the pipeline doesn't stall after a
load in the neon code.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: Remove unnecessary CMO in Cortex A15 startup

Cortex-A15 flush L2 cache after reset, there is no need to do this
in software, if L2 is already invalidated in bootloader and
cache is disabled. For secondary startup, there is no reason to
flush L2 as well.

This change assumes the setup code is always entered as the result
of CPU reset.

Signed-off-by: Bo Yan <byan@nvidia.com>
Reviewed-by: Mrutyunjay Sawant <msawant@nvidia.com>
Tested-by: Mrutyunjay Sawant <msawant@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: Skip I-cache invalidate for Cortex-A15 boot

This is not required since cache is invalidated by HW in the reset
sequence. Bootloader is supposed to do the same before it hands
over control to kernel.

Signed-off-by: Bo Yan <byan@nvidia.com>
Reviewed-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: remove unnecessary dcache_clean_area

Cortex-A9 has PIPT D-cache which do not require clean the cache
on creating page table.

Reviewed-by: Heechul Yun <hyun@nvidia.com>
Tested-by: Heechul Yun <hyun@nvidia.com>
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Reviewed-by: Scott Williams <scwilliams@nvidia.com>

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: LPAE: Invalidate the TLB for module addresses during translation fault

During the free_pgtables() call all user and modules/pkmap entries are
removed. If a translation fault for the modules/pkmap area occurs before
we switched away from the current pgd, do_translation_fault() would copy
the init_mm pud into the user pud.

There is a small window between pud_clear() and pmd_free_tlb() in
free_pmd_range() where the pud entry was cleared but the TLB has not
been invalidated yet and the CPU may have cached the original (valid)
pud entry in the TLB. A scenario like below would get stuck in
continuous prefetch abort:

1. Current process exiting. The modules pmd entries not populated
2. exit_mmap() -> ... -> pmd_free_tlb()
3. pud_clear() for the 1GB pud containing user stack and modules (no TLB
   invalidation yet)
4. Interrupt -> module interrupt routine
5. Level 2 (pmd) translation fault occurs when executing the module
   interrupt routine. The CPU previously cached (TLB) the old valid pud
   value for the modules area, so we don't get a level 1 translation
   fault
6. do_translation fault() copies the pud_k into the pud
7. Linux returns to the faulty instruction. Goes back to 5

At point 7, since the CPU still has the old pud value, it goes back to
point 5 and never gets out of this loop. With this patch, the stale pud
TLB entry is invalidated after point 6 and the subsequent prefetch abort
doesn't occur.

Reported-by: Tony Thompson <Anthony.Thompson@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: cache-l2x0: Implement outer_clean_all()

There is already implemented full outer clean routine in
arch/arm/mm/cache-l2x0.c.

Make it possible to use it through outer_cache interface,
like other outer maintenance functions.

bug 983964

Reviewed-by: Kirill Artamonov <kartamonov@nvidia.com>
Tested-by: Kirill Artamonov <kartamonov@nvidia.com>
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Reviewed-by: Justin Paver <jpaver@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: dma: Drop GFP_COMP for DMA-IOMMU memory allocations

dma_alloc_coherent wants to split pages after allocation in order to
reduce the memory footprint. This does not work well with GFP_COMP
pages, so drop this flag before allocation.

This patch is ported from arch/avr32

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: cache-l2x0: get size of outer cache

Implement interface for getting size of outer cache.

bug 983964

Signed-off-by: Kirill Artamonov <kartamonov@nvidia.com>
Reviewed-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7650/1: mm: replace direct access to mm->context.id with new macro

The mmid macro is meant to be used to get the mm->context.id data
from the mm structure, but it seems to have been missed in a cuple
of files.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: enable non-cacheable streaming enhancement

This is cortex-a15 specific

bug 1178938

Signed-off-by: Bo Yan <byan@nvidia.com>
Reviewed-by: Mrutyunjay Sawant <msawant@nvidia.com>
Tested-by: Mrutyunjay Sawant <msawant@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: Enable NCSE feature for A15 only

Signed-off-by: Bo Yan <byan@nvidia.com>
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: adding a check for slab objects in flush_dcache_page

A page struct obtained via virt_to_page from a slab object may be passed to
the flush_dcache_page function. However, slab allocation is a kernel feature
(can only be done in kernel space) and thus slab objects are never mapped into
user space. However, slab allocators may use the mapping field for their own
purposes and as a result mapping may not be NULL although the page is not
mapped. For this purpose there is a BUG_ON inside page_mapping() to check for
slab objects. So, using NULL for this special case and avoiding calling
page_mapping() on slab objects to avoid the BUG_ON.

Bug 845618.
Bug 1154527.

Signed-off-by: Vishal Singh <vissingh@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: Export LoUIS flush

Export flushing to LoUIS.

Signed-off-by: Antti P Miettinen <amiettinen@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: kgdb: ignore breakpoint instructions from user mode

Avoid conflicts with user mode usage of the same instructions, as with
Clang -ftrapv.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: Honor udelay convention for timer-based delay

Replaced strict "below" comparison in timer delay function with "below
or equal". The former may result in actual delay time below requested
(if the delay happens to start just before cycle counter advance). The
latter guarantees actual delay at/above requested.

Signed-off-by: Alex Frid <afrid@nvidia.com>
Reviewed-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-by: Bo Yan <byan@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
alarmtimer: Do not check for wake capability in registration

Removed the check if device has wakeup capablity
while registration as the wakeup policy has to come from
user space as per Documentation/power/devices.txt

Bug 1219152

Signed-off-by: Chaitanya Bandi <bandik@nvidia.com>
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
freezer: set PF_SUSPEND_TASK flag on tasks that call freeze_processes

Calling freeze_processes sets a global flag that will cause any
process that calls try_to_freeze to enter the refrigerator.  It
skips sending a signal to the current task, but if the current
task ever hits try_to_freeze, all threads will be frozen and the
system will deadlock.

Set a new flag, PF_SUSPEND_TASK, on the task that calls
freeze_processes.  The flag notifies the freezer that the thread
is involved in suspend and should not be frozen.  Also add a
WARN_ON in thaw_processes if the caller does not have the
PF_SUSPEND_TASK flag set to catch if a different task calls
thaw_processes than the one that called freeze_processes, leaving
a task with PF_SUSPEND_TASK permanently set on it.

Threads that spawn off a task with PF_SUSPEND_TASK set (which
swsusp does) will also have PF_SUSPEND_TASK set, preventing them
from freezing while they are helping with suspend, but they need
to be dead by the time suspend is triggered, otherwise they may
run when userspace is expected to be frozen.  Add a WARN_ON in
thaw_processes if more than one thread has the PF_SUSPEND_TASK
flag set.

Reported-and-tested-by: Michael Leun <lkml20130126@newton.leun.net>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Tested-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
kernel: power: Add PM_USERSPACE_FROZEN workqueue

Some device drivers require a callback to be called after the userspace
processes are frozen. This patch adds PM_USERSPACE_FROZEN workqueue
which is called after userspace processes are frozen but when the
kernel threads are still functioning.

Bug 1344551

Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Tested-by: Sang-Hun Lee <sanlee@nvidia.com>
Reviewed-by: Kevin Huang (Eng-SW) <kevinh@nvidia.com>
Reviewed-by: Mitch Luban <mluban@nvidia.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
suspend: enable freeze timeout configuration through sys

At present, the value of timeout for freezing is 20s, which is
meaningless in case that one thread is frozen with mutex locked
and another thread is trying to lock the mutex, as this time of
freezing will fail unavoidably.
And if there is no new wakeup event registered, the system will
waste at most 20s for such meaningless trying of freezing.

With this patch, the value of timeout can be configured to smaller
value, so such meaningless trying of freezing will be aborted in
earlier time, and later freezing can be also triggered in earlier
time. And more power will be saved.
In normal case on mobile phone, it costs real little time to freeze
processes. On some platform, it only costs about 20ms to freeze
user space processes and 10ms to freeze kernel freezable threads.

Signed-off-by: Liu Chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Li Fei <fei.li@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>