Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

Pull powerpc updates from Ben Herrenschmidt:
 "This is the powerpc changes for the 3.11 merge window.  In addition to
  the usual bug fixes and small updates, the main highlights are:

   - Support for transparent huge pages by Aneesh Kumar for 64-bit
     server processors.  This allows the use of 16M pages as transparent
     huge pages on kernels compiled with a 64K base page size.

   - Base VFIO support for KVM on power by Alexey Kardashevskiy

   - Wiring up of our nvram to the pstore infrastructure, including
     putting compressed oopses in there by Aruna Balakrishnaiah

   - Move, rework and improve our "EEH" (basically PCI error handling
     and recovery) infrastructure.  It is no longer specific to pseries
     but is now usable by the new "powernv" platform as well (no
     hypervisor) by Gavin Shan.

   - I fixed some bugs in our math-emu instruction decoding and made it
     usable to emulate some optional FP instructions on processors with
     hard FP that lack them (such as fsqrt on Freescale embedded
     processors).

   - Support for Power8 "Event Based Branch" facility by Michael
     Ellerman.  This facility allows what is basically "userspace
     interrupts" for performance monitor events.

   - A bunch of Transactional Memory vs.  Signals bug fixes and HW
     breakpoint/watchpoint fixes by Michael Neuling.

  And more ...  I appologize in advance if I've failed to highlight
  something that somebody deemed worth it."

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (156 commits)
  pstore: Add hsize argument in write_buf call of pstore_ftrace_call
  powerpc/fsl: add MPIC timer wakeup support
  powerpc/mpic: create mpic subsystem object
  powerpc/mpic: add global timer support
  powerpc/mpic: add irq_set_wake support
  powerpc/85xx: enable coreint for all the 64bit boards
  powerpc/8xx: Erroneous double irq_eoi() on CPM IRQ in MPC8xx
  powerpc/fsl: Enable CONFIG_E1000E in mpc85xx_smp_defconfig
  powerpc/mpic: Add get_version API both for internal and external use
  powerpc: Handle both new style and old style reserve maps
  powerpc/hw_brk: Fix off by one error when validating DAWR region end
  powerpc/pseries: Support compression of oops text via pstore
  powerpc/pseries: Re-organise the oops compression code
  pstore: Pass header size in the pstore write callback
  powerpc/powernv: Fix iommu initialization again
  powerpc/pseries: Inform the hypervisor we are using EBB regs
  powerpc/perf: Add power8 EBB support
  powerpc/perf: Core EBB support for 64-bit book3s
  powerpc/perf: Drop MMCRA from thread_struct
  powerpc/perf: Don't enable if we have zero events
  ...

1 files changed, 137 insertions, 0 deletions

diff --git a/Documentation/powerpc/pmu-ebb.txt b/Documentation/powerpc/pmu-ebb.txt
new file mode 100644
index 00000000000..73cd163dbfb
--- /dev/null
+++ b/Documentation/powerpc/pmu-ebb.txt
@@ -0,0 +1,137 @@
+PMU Event Based Branches
+========================
+
+Event Based Branches (EBBs) are a feature which allows the hardware to
+branch directly to a specified user space address when certain events occur.
+
+The full specification is available in Power ISA v2.07:
+
+  https://www.power.org/documentation/power-isa-version-2-07/
+
+One type of event for which EBBs can be configured is PMU exceptions. This
+document describes the API for configuring the Power PMU to generate EBBs,
+using the Linux perf_events API.
+
+
+Terminology
+-----------
+
+Throughout this document we will refer to an "EBB event" or "EBB events". This
+just refers to a struct perf_event which has set the "EBB" flag in its
+attr.config. All events which can be configured on the hardware PMU are
+possible "EBB events".
+
+
+Background
+----------
+
+When a PMU EBB occurs it is delivered to the currently running process. As such
+EBBs can only sensibly be used by programs for self-monitoring.
+
+It is a feature of the perf_events API that events can be created on other
+processes, subject to standard permission checks. This is also true of EBB
+events, however unless the target process enables EBBs (via mtspr(BESCR)) no
+EBBs will ever be delivered.
+
+This makes it possible for a process to enable EBBs for itself, but not
+actually configure any events. At a later time another process can come along
+and attach an EBB event to the process, which will then cause EBBs to be
+delivered to the first process. It's not clear if this is actually useful.
+
+
+When the PMU is configured for EBBs, all PMU interrupts are delivered to the
+user process. This means once an EBB event is scheduled on the PMU, no non-EBB
+events can be configured. This means that EBB events can not be run
+concurrently with regular 'perf' commands, or any other perf events.
+
+It is however safe to run 'perf' commands on a process which is using EBBs. The
+kernel will in general schedule the EBB event, and perf will be notified that
+its events could not run.
+
+The exclusion between EBB events and regular events is implemented using the
+existing "pinned" and "exclusive" attributes of perf_events. This means EBB
+events will be given priority over other events, unless they are also pinned.
+If an EBB event and a regular event are both pinned, then whichever is enabled
+first will be scheduled and the other will be put in error state. See the
+section below titled "Enabling an EBB event" for more information.
+
+
+Creating an EBB event
+---------------------
+
+To request that an event is counted using EBB, the event code should have bit
+63 set.
+
+EBB events must be created with a particular, and restrictive, set of
+attributes - this is so that they interoperate correctly with the rest of the
+perf_events subsystem.
+
+An EBB event must be created with the "pinned" and "exclusive" attributes set.
+Note that if you are creating a group of EBB events, only the leader can have
+these attributes set.
+
+An EBB event must NOT set any of the "inherit", "sample_period", "freq" or
+"enable_on_exec" attributes.
+
+An EBB event must be attached to a task. This is specified to perf_event_open()
+by passing a pid value, typically 0 indicating the current task.
+
+All events in a group must agree on whether they want EBB. That is all events
+must request EBB, or none may request EBB.
+
+EBB events must specify the PMC they are to be counted on. This ensures
+userspace is able to reliably determine which PMC the event is scheduled on.
+
+
+Enabling an EBB event
+---------------------
+
+Once an EBB event has been successfully opened, it must be enabled with the
+perf_events API. This can be achieved either via the ioctl() interface, or the
+prctl() interface.
+
+However, due to the design of the perf_events API, enabling an event does not
+guarantee that it has been scheduled on the PMU. To ensure that the EBB event
+has been scheduled on the PMU, you must perform a read() on the event. If the
+read() returns EOF, then the event has not been scheduled and EBBs are not
+enabled.
+
+This behaviour occurs because the EBB event is pinned and exclusive. When the
+EBB event is enabled it will force all other non-pinned events off the PMU. In
+this case the enable will be successful. However if there is already an event
+pinned on the PMU then the enable will not be successful.
+
+
+Reading an EBB event
+--------------------
+
+It is possible to read() from an EBB event. However the results are
+meaningless. Because interrupts are being delivered to the user process the
+kernel is not able to count the event, and so will return a junk value.
+
+
+Closing an EBB event
+--------------------
+
+When an EBB event is finished with, you can close it using close() as for any
+regular event. If this is the last EBB event the PMU will be deconfigured and
+no further PMU EBBs will be delivered.
+
+
+EBB Handler
+-----------
+
+The EBB handler is just regular userspace code, however it must be written in
+the style of an interrupt handler. When the handler is entered all registers
+are live (possibly) and so must be saved somehow before the handler can invoke
+other code.
+
+It's up to the program how to handle this. For C programs a relatively simple
+option is to create an interrupt frame on the stack and save registers there.
+
+Fork
+----
+
+EBB events are not inherited across fork. If the child process wishes to use
+EBBs it should open a new event for itself. Similarly the EBB state in
+BESCR/EBBHR/EBBRR is cleared across fork().