This is the MIPS part of the following commit by Peter Zijlstra:

- e360adbe
    irq_work: Add generic hardirq context callbacks

    Provide a mechanism that allows running code in IRQ context. It is
    most useful for NMI code that needs to interact with the rest of the
    system -- like wakeup a task to drain buffers.

    Perf currently has such a mechanism, so extract that and provide it as
    a generic feature, independent of perf so that others may also
    benefit.

    The IRQ context callback is generated through self-IPIs where
    possible, or on architectures like powerpc the decrementer (the
    built-in timer facility) is set to generate an interrupt immediately.

    Architectures that don't have anything like this get to do with a
    callback from the timer tick. These architectures can call
    irq_work_run() at the tail of any IRQ handlers that might enqueue such
    work (like the perf IRQ handler) to avoid undue latencies in
    processing the work.

For MIPSXX, we need to call irq_work_run() at the tail of the perf IRQ
handler as described above.
Reported-by: NWu Zhangjin <wuzhangjin@gmail.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NDavid Daney <ddaney@caviumnetworks.com>
Signed-off-by: NDeng-Cheng Zhu <dengcheng.zhu@gmail.com>
To: fweisbec@gmail.com
To: will.deacon@arm.com
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: paulus@samba.org
Cc: mingo@elte.hu
Cc: acme@redhat.com
Cc: matt@console-pimps.org
Cc: sshtylyov@mvista.com,
Patchwork: http://patchwork.linux-mips.org/patch/2011/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

The perf hardware pmu got initialized at various points in the boot,
some before early_initcall() some after (notably arch_initcall).

The problem is that the NMI lockup detector is ran from early_initcall()
and expects the hardware pmu to be present.

Sanitize this by moving all architecture hardware pmu implementations to
initialize at early_initcall() and move the lockup detector to an explicit
initcall right after that.

Cc: paulus <paulus@samba.org>
Cc: davem <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Acked-by: NPaul Mundt <lethal@linux-sh.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1290707759.2145.119.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch adds the mipsxx Perf-events support based on the skeleton.
Generic hardware events and cache events are now fully implemented for
the 24K/34K/74K/1004K cores. To support other cores in mipsxx (such as
R10000/SB1), the generic hardware event tables and cache event tables
need to be filled out. To support other CPUs which have different PMU
than mipsxx, such as RM9000 and LOONGSON2, the additional files
perf_event_$cpu.c need to be created.

Raw event is an important part of Perf-events. It helps the user collect
performance data for events that are not listed as the generic hardware
events and cache events but ARE supported by the CPU's PMU.

This patch also adds this feature for mipsxx 24K/34K/74K/1004K. For how to
use it, please refer to processor core software user's manual and the
comments for mipsxx_pmu_map_raw_event() for more details.

Please note that this is a "precise" implementation, which means the
kernel will check whether the requested raw events are supported by this
CPU and which hardware counters can be assigned for them.

To test the functionality of Perf-event, you may want to compile the tool
"perf" for your MIPS platform. You can refer to the following URL:
http://www.linux-mips.org/archives/linux-mips/2010-10/msg00126.html

You also need to customize the CFLAGS and LDFLAGS in tools/perf/Makefile
for your libs, includes, etc.

In case you encounter the boot failure in SMVP kernel on multi-threading
CPUs, you may take a look at:
http://www.linux-mips.org/git?p=linux-mti.git;a=commitdiff;h=5460815027d802697b879644c74f0e8365254020Signed-off-by: NDeng-Cheng Zhu <dengcheng.zhu@gmail.com>
To: linux-mips@linux-mips.org
Cc: a.p.zijlstra@chello.nl
Cc: paulus@samba.org
Cc: mingo@elte.hu
Cc: acme@redhat.com
Cc: jamie.iles@picochip.com
Cc: ddaney@caviumnetworks.com
Cc: matt@console-pimps.org
Patchwork: https://patchwork.linux-mips.org/patch/1689/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

 create mode 100644 arch/mips/kernel/perf_event_mipsxx.c