linux-toradex.git/arch/arm/kernel/perf_event.c, branch v3.0.63

ARM: 6989/1: perf: do not start the PMU when no events are present

2011-07-05T11:37:23+00:00

armpmu_enable can be called in situations where no events are present
(for example, from the event rotation tick after a profiled task has
exited). In this case, we currently start the PMU anyway which may
leave it active inevitably without any events being monitored.

This patch adds a simple check to the enabling code so that we avoid
starting the PMU when no events are present.

Cc: 
Reported-by: Ashwin Chaugle 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 6902/1: perf: Remove erroneous check on active_events

2011-05-20T21:39:17+00:00

When initialising a PMU, there is a check to protect against races with
other CPUs filling all of the available event slots. Since armpmu_add
checks that an event can be scheduled, we do not need to do this at
initialisation time. Furthermore the current code is broken because it
assumes that atomic_inc_not_zero will unconditionally increment
active_counts and then tries to decrement it again on failure.

This patch removes the broken, redundant code.

Signed-off-by: Mark Rutland 
Acked-by: Will Deacon 
Cc: Jamie Iles 
Signed-off-by: Russell King

ARM: 6884/1: Fix infinite loop in ARM user perf_event backtrace code

2011-04-27T21:02:46+00:00

The ARM user backtrace code can get into an infinite loop if it
runs into an invalid stack frame which points back to itself.
This situation has been observed in practice.  Fix it by capping
the number of entries in the backtrace.  This is also what other
architectures do in their backtrace code.

Signed-off-by: Sonny Rao 
Acked-by: Jamie Iles 
Acked-by: Olof Johansson 
Signed-off-by: Russell King

ARM: 6865/1: perf: ensure pass through zero is counted on overflow

2011-04-10T20:13:35+00:00

Commit a737823d ("ARM: perf: ensure overflows aren't missed due to IRQ
latency") changed the way that event deltas are calculated on overflow
so that we don't miss events when the new count value overtakes the
previous one.

Unfortunately, we forget to count the event that passes through zero so
we end up being off by 1. This patch adds on the correction.

Reported-by: Chris Moore 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 6835/1: perf: ensure overflows aren't missed due to IRQ latency

2011-03-26T10:06:09+00:00

If a counter overflows during a perf stat profiling run it may overtake
the last known value of the counter:

    0        prev     new                0xffffffff
    |----------|-------|----------------------|

In this case, the number of events that have occurred is
(0xffffffff - prev) + new. Unfortunately, the event update code will
not realise an overflow has occurred and will instead report the event
delta as (new - prev) which may be considerably smaller than the real
count.

This patch adds an extra argument to armpmu_event_update which indicates
whether or not an overflow has occurred. If an overflow has occurred
then we use the maximum period of the counter to calculate the elapsed
events.

Acked-by: Jamie Iles 
Reported-by: Ashwin Chaugule 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 6834/1: perf: reset counters on all CPUs during initialisation

2011-03-26T10:06:09+00:00

ARMv7 dictates that the interrupt-enable and count-enable registers for
each PMU counter are UNKNOWN following core reset.

This patch adds a new (optional) function pointer to struct arm_pmu for
resetting the PMU state during init. The reset function is called on
each CPU via an arch_initcall in the generic ARM perf_event code and
allows the PMU backend to write sane values to any UNKNOWN registers.

Acked-by: Jean Pihet 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

Merge branch 'pmu-for-rmk' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-stericsson into devel-stable

2011-02-19T09:44:55+00:00

ARM: perf_event: allow platform-specific interrupt handler

2011-02-17T12:55:45+00:00

Allow a platform-specific IRQ handler to be specified via platform data.
This will be used to implement the single-irq workaround for the DB8500.

Signed-off-by: Rabin Vincent 
Acked-by: Lee Jones 
Acked-by: Will Deacon 
Signed-off-by: Linus Walleij

ARM: 6654/1: perf/oprofile: fix off-by-one in stack check

2011-02-10T15:29:03+00:00

Since tail is the previous fp - 1, we need to compare the new fp with tail + 1
to ensure that we don't end up passing in the same tail again, in order to
avoid a potential infinite loop in the perf interrupt handler (which has been
observed to occur).  A similar fix seems to be needed in the OProfile code.

Acked-by: Will Deacon 
Signed-off-by: Rabin Vincent 
Signed-off-by: Russell King

Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm

2011-01-07T00:50:35+00:00

* 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm: (416 commits)
  ARM: DMA: add support for DMA debugging
  ARM: PL011: add DMA burst threshold support for ST variants
  ARM: PL011: Add support for transmit DMA
  ARM: PL011: Ensure IRQs are disabled in UART interrupt handler
  ARM: PL011: Separate hardware FIFO size from TTY FIFO size
  ARM: PL011: Allow better handling of vendor data
  ARM: PL011: Ensure error flags are clear at startup
  ARM: PL011: include revision number in boot-time port printk
  ARM: vexpress: add sched_clock() for Versatile Express
  ARM i.MX53: Make MX53 EVK bootable
  ARM i.MX53: Some bug fix about MX53 MSL code
  ARM: 6607/1: sa1100: Update platform device registration
  ARM: 6606/1: sa1100: Fix platform device registration
  ARM i.MX51: rename IPU irqs
  ARM i.MX51: Add ipu clock support
  ARM: imx/mx27_3ds: Add PMIC support
  ARM: DMA: Replace page_to_dma()/dma_to_page() with pfn_to_dma()/dma_to_pfn()
  mx51: fix usb clock support
  MX51: Add support for usb host 2
  arch/arm/plat-mxc/ehci.c: fix errors/typos
  ...