percpu scheduling for perfcounters wants to take the context lock,
but that lock first needs to be initialized. Currently it is an
early_initcall() - but that is too late, the task tick runs much
sooner than that.

Call it explicitly from the scheduler init sequence instead.

[ Impact: fix access-before-init crash ]

LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This used to be unstable when we had the rq->lock dependencies,
but now that they are that of the past we can turn on percpu
counter RR too.

[ Impact: handle counter over-commit for per-CPU counters too ]

LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When two (or more) contexts output to the same buffer, it is possible
to observe half written output.

Suppose we have CPU0 doing perf_counter_mmap(), CPU1 doing
perf_counter_overflow(). If CPU1 does a wakeup and exposes head to
user-space, then CPU2 can observe the data CPU0 is still writing.

[ Impact: fix occasionally corrupted profiling records ]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090501102533.007821627@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This adds my name to the list of copyright holders on the core
perf_counter.c, since I have contributed a significant amount of the
code in there.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
LKML-Reference: <18936.59200.888049.746658@cargo.ozlabs.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch renames struct hw_perf_counter_ops into struct pmu. It
introduces a structure to describe a cpu specific pmu (performance
monitoring unit). It may contain ops and data. The new name of the
structure fits better, is shorter, and thus better to handle. Where it
was appropriate, names of function and variable have been changed too.

[ Impact: cleanup ]
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-7-git-send-email-robert.richter@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Needed for modular tracepoint support.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix perf-report output for /home mounted binaries, etc.

dentry_path() only provide path-names up to the mount root, which is
unsuited for out purpose, use d_path() instead.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.601794134@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add sysctl for paranoid/relaxed perfcounters policy

Allow the use of system wide perf counters to everybody, but provide
a sysctl to disable it for the paranoid security minded.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.514046352@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: performance optimization

The mmap/comm tracking code does quite a lot of work before it discovers
there's no interest in it, avoid that by keeping a counter.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.427173196@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

strlen() does not include the \0.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Paul suggested we allow for data addresses to be recorded along with
the traditional IPs as power can provide these.

For now, only the software pagefault events provide data addresses,
but in the future power might as well for some events.

x86 doesn't seem capable of providing this atm.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.394816925@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move PERF_RECORD_TIME so that all the fixed length items come before
the variable length ones.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.307926436@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Similar to the mmap data stream, add one that tracks the task COMM field,
so that the userspace reporting knows what to call a task.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.127422406@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Push the PERF_EVENT_COUNTER_OVERFLOW bit into the misc field so that
we can have the full 32bit for PERF_RECORD_ bits.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.891867663@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Limit the size of each record to 64k (or should we count in multiples
of u64 and have a 512K limit?), this gives 16 bits or spare room in the
header, which we can use for misc bits, so as to not have to grow the
record with u64 every time we have a few bits to report.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.769271806@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We should not be updating ctx->time from NMI context, work around that.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.681326666@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Push the update_context_time() calls up the stack so that we get less
invokations and thereby a less noisy output:

before:

 # ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null

 Performance counter stats for 'ls':

      10.163691  cpu clock ticks      (msecs)  (scaled from 98.94%)
      10.215360  task clock ticks     (msecs)  (scaled from 98.18%)
      10.185549  task clock ticks     (msecs)  (scaled from 98.53%)
      10.183581  task clock ticks     (msecs)  (scaled from 98.71%)

 Wall-clock time elapsed:    11.912858 msecs

after:

 # ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null

 Performance counter stats for 'ls':

       9.316630  cpu clock ticks      (msecs)
       9.280789  task clock ticks     (msecs)
       9.280789  task clock ticks     (msecs)
       9.280789  task clock ticks     (msecs)

 Wall-clock time elapsed:     9.574872 msecs
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.618876874@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Now that all the task runtime clock users are gone, remove the ugly
rq->lock usage from perf counters, which solves the nasty deadlock
seen when a software task clock counter was read from an NMI overflow
context.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.531137582@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Rework the task clock software counter to use the context time instead
of the task runtime clock, this removes the last such user.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.445450972@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Since perf_counter_context is switched along with tasks, we can
maintain the context time without using the task runtime clock.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.353552838@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently the definition of an event is slightly ambiguous. We have
wakeup events, for poll() and SIGIO, which are either generated
when a record crosses a page boundary (hw_events.wakeup_events == 0),
or every wakeup_events new records.

Now a record can be either a counter overflow record, or a number of
different things, like the mmap PROT_EXEC region notifications.

Then there is the PERF_COUNTER_IOC_REFRESH event limit, which only
considers counter overflows.

This patch changes then wakeup_events and SIGIO notification to only
consider overflow events. Furthermore it changes the SIGIO notification
to report SIGHUP when the event limit is reached and the counter will
be disabled.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.266679874@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Provide means to auto-disable the counter after 'n' overflow events.

Create the counter with hw_event.disabled = 1, and then issue an
ioctl(fd, PREF_COUNTER_IOC_REFRESH, n); to set the limit and enable
the counter.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.083139737@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

By popular request, provide means to log a timestamp along with the
counter overflow event.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.024173282@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Reading through the code I saw I forgot the finish the mlock accounting.
Do so now.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.899767331@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Prepare for more generic overflow handling. The new perf_counter_overflow()
method will handle the generic bits of the counter overflow, and can return
a !0 return value, in which case the counter should be (soft) disabled, so
that it won't count until it's properly disabled.

XXX: do powerpc and swcounter
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.812109629@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Prepare the pending infrastructure to do more than wakeups.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.634732847@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Provide support for fcntl() I/O availability signals.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.579788800@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Change the callchain context entries to u16, so as to gain some space.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.457320003@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Paul noted that we don't need SMP barriers for the mmap() counter read
because its always on the same cpu (otherwise you can't access the hw
counter anyway).

So remove the SMP barriers and replace them with regular compiler
barriers.

Further, update the comment to include a race free method of reading
said hardware counter. The primary change is putting the pmc_read
inside the seq-loop, otherwise we can still race and read rubbish.
Noticed-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.577951445@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Put in counts to tell which ips belong to what context.

  -----
   | |  hv
   | --
nr | |  kernel
   | --
   | |  user
  -----
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.493101305@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

By request, provide a way to request a wakeup every 'n' events instead
of every page of output.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.323309784@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Per suggestion from Paul, move the event overflow bits to record_type
and sanitize the enums a bit.

Breaks the ABI -- again ;-)
Suggested-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.151921176@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Provide the generic callchain support bits. If hw_event->callchain is
set the arch specific perf_callchain() function is called upon to
provide a perf_callchain_entry structure filled with the current
callchain.

If it does so, it is added to the overflow output event.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.254266860@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Breaks ABI yet again :-)

Change the event type so that [0, 2^31-1] are regular event types, but
[2^31, 2^32-1] forms a bitmask for overflow events.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.047961770@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move the nmi argument to the _begin() function, so that _end() only needs the
handle. This allows the _begin() function to generate a wakeup on event loss.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.959404268@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: better error reporting

At present, if hw_perf_counter_init encounters an error, all it can do
is return NULL, which causes sys_perf_counter_open to return an EINVAL
error to userspace.  This isn't very informative for userspace; it means
that userspace can't tell the difference between "sorry, oprofile is
already using the PMU" and "we don't support this CPU" and "this CPU
doesn't support the requested generic hardware event".

This commit uses the PTR_ERR/ERR_PTR/IS_ERR set of macros to let
hw_perf_counter_init return an error code on error rather than just NULL
if it wishes.  If it does so, that error code will be returned from
sys_perf_counter_open to userspace.  If it returns NULL, an EINVAL
error will be returned to userspace, as before.

This also adapts the powerpc hw_perf_counter_init to make use of this
to return ENXIO, EINVAL, EBUSY, or EOPNOTSUPP as appropriate.  It would
be good to add extra error numbers in future to allow userspace to
distinguish the various errors that are currently reported as EINVAL,
i.e. irq_period < 0, too many events in a group, conflict between
exclude_* settings in a group, and PMU resource conflict in a group.

[ v2: fix a bug pointed out by Corey Ashford where error returns from
      hw_perf_counter_init were not handled correctly in the case of
      raw hardware events.]
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Orig-LKML-Reference: <20090330171023.682428180@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently the profiling information returns userspace IPs but no way
to correlate them to userspace code. Userspace could look into
/proc/$pid/maps but that might not be current or even present anymore
at the time of analyzing the IPs.

Therefore provide means to track the mmap information and provide it
in the output stream.

XXX: only covers mmap()/munmap(), mremap() and mprotect() are missing.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Orig-LKML-Reference: <20090330171023.417259499@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It just occured to me it is possible to have multiple contending
updates of the userpage (mmap information vs overflow vs counter).
This would break the seqlock logic.

It appear the arch code uses this from NMI context, so we cannot
possibly serialize its use, therefore separate the data_head update
from it and let it return to its original use.

The arch code needs to make sure there are no contending callers by
disabling the counter before using it -- powerpc appears to do this
nicely.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.241410660@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While going over the wakeup code I noticed delayed wakeups only work
for hardware counters but basically all software counters rely on
them.

This patch unifies and generalizes the delayed wakeup to fix this
issue.

Since we're dealing with NMI context bits here, use a cmpxchg() based
single link list implementation to track counters that have pending
wakeups.

[ This should really be generic code for delayed wakeups, but since we
  cannot use cmpxchg()/xchg() in generic code, I've let it live in the
  perf_counter code. -- Eric Dumazet could use it to aggregate the
  network wakeups. ]

Furthermore, the x86 method of using TIF flags was flawed in that its
quite possible to end up setting the bit on the idle task, loosing the
wakeup.

The powerpc method uses per-cpu storage and does appear to be
sufficient.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.153932974@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>