1. 03 Jun, 2016 3 commits
  2. 05 May, 2016 1 commit
    • Mark Rutland's avatar
      perf/arm: Special-case hetereogeneous CPUs · 5101ef20
      Mark Rutland authored
      Commit:
      
        26657848 ("perf/core: Verify we have a single perf_hw_context PMU")
      
      forcefully prevents multiple PMUs from sharing perf_hw_context, as this
      generally doesn't make sense. It is a common bug for uncore PMUs to
      use perf_hw_context rather than perf_invalid_context, which this detects.
      
      However, systems exist with heterogeneous CPUs (and hence heterogeneous
      HW PMUs), for which sharing perf_hw_context is necessary, and possible
      in some limited cases.
      
      To make this work we have to perform some gymnastics, as we did in these
      commits:
      
        66eb579e ("perf: allow for PMU-specific event filtering")
        c904e32a ("arm: perf: filter unschedulable events")
      
      To allow those systems to work, we must allow PMUs for heterogeneous
      CPUs to share perf_hw_context, though we must still disallow sharing
      otherwise to detect the common misuse of perf_hw_context.
      
      This patch adds a new PERF_PMU_CAP_HETEROGENEOUS_CPUS for this, updates
      the core logic to account for this, and makes use of it in the arm_pmu
      code that is used for systems with heterogeneous CPUs. Comments are
      added to make the rationale clear and hopefully avoid accidental abuse.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Jiri Olsa <jolsa@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Stephane Eranian <eranian@google.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Vince Weaver <vincent.weaver@maine.edu>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: linux-arm-kernel@lists.infradead.org
      Link: http://lkml.kernel.org/r/20160426103346.GA20836@leverpostejSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      5101ef20
  3. 21 Apr, 2016 1 commit
    • Lorenzo Pieralisi's avatar
      drivers/perf: arm-pmu: fix RCU usage on pmu resume from low-power · cbcc72e0
      Lorenzo Pieralisi authored
      Commit da4e4f18 ("drivers/perf: arm_pmu: implement CPU_PM notifier")
      added code in the arm perf infrastructure that allows the kernel to
      save/restore perf counters whenever the CPU enters a low-power
      state. The kernel saves/restores the counters for each active event
      through the armpmu_{stop/start} ARM pmu API, so that the low-power state
      enter/exit cycle is emulated through pmu start/stop operations for each
      event in use.
      
      However, calling armpmu_start() for each active event on power up
      executes code that requires RCU locking (perf_event_update_userpage())
      to be functional, so, given that the core may call the CPU_PM notifiers
      while running the idle thread in an quiescent RCU state this is not
      allowed as detected through the following splat when kernel is run with
      CONFIG_PROVE_LOCKING enabled:
      
      [   49.293286]
      [   49.294761] ===============================
      [   49.298895] [ INFO: suspicious RCU usage. ]
      [   49.303031] 4.6.0-rc3+ #421 Not tainted
      [   49.306821] -------------------------------
      [   49.310956] include/linux/rcupdate.h:872 rcu_read_lock() used
      illegally while idle!
      [   49.318530]
      [   49.318530] other info that might help us debug this:
      [   49.318530]
      [   49.326451]
      [   49.326451] RCU used illegally from idle CPU!
      [   49.326451] rcu_scheduler_active = 1, debug_locks = 0
      [   49.337209] RCU used illegally from extended quiescent state!
      [   49.342892] 2 locks held by swapper/2/0:
      [   49.346768]  #0:  (cpu_pm_notifier_lock){......}, at:
      [<ffffff8008163c28>] cpu_pm_exit+0x18/0x80
      [   49.355492]  #1:  (rcu_read_lock){......}, at: [<ffffff800816dc38>]
      perf_event_update_userpage+0x0/0x260
      
      This patch wraps the armpmu_start() call (that indirectly calls
      perf_event_update_userpage()) on CPU_PM notifier power state exit (or
      failed entry) within the RCU_NONIDLE() macro so that the RCU subsystem
      is made aware the calling cpu is not idle from an RCU perspective for
      the armpmu_start() call duration, therefore fixing the issue.
      
      Fixes: da4e4f18 ("drivers/perf: arm_pmu: implement CPU_PM notifier")
      Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
      Reported-by: default avatarJames Morse <james.morse@arm.com>
      Suggested-by: default avatarKevin Hilman <khilman@baylibre.com>
      Cc: Ashwin Chaugule <ashwin.chaugule@linaro.org>
      Cc: Kevin Hilman <khilman@baylibre.com>
      Cc: Sudeep Holla <sudeep.holla@arm.com>
      Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
      Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
      Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
      Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      cbcc72e0
  4. 21 Mar, 2016 1 commit
  5. 26 Feb, 2016 1 commit
    • Lorenzo Pieralisi's avatar
      drivers/perf: arm_pmu: implement CPU_PM notifier · da4e4f18
      Lorenzo Pieralisi authored
      When a CPU is suspended (either through suspend-to-RAM or CPUidle),
      its PMU registers content can be lost, which means that counters
      registers values that were initialized on power down entry have to be
      reprogrammed on power-up to make sure the counters set-up is preserved
      (ie on power-up registers take the reset values on Cold or Warm reset,
      which can be architecturally UNKNOWN).
      
      To guarantee seamless profiling conditions across a core power down
      this patch adds a CPU PM notifier to ARM pmus, that upon CPU PM
      entry/exit from low-power states saves/restores the pmu registers
      set-up (by using the ARM perf API), so that the power-down/up cycle does
      not affect the perf behaviour (apart from a black-out period between
      power-up/down CPU PM notifications that is unavoidable).
      
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Sudeep Holla <sudeep.holla@arm.com>
      Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
      Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Acked-by: default avatarAshwin Chaugule <ashwin.chaugule@linaro.org>
      Acked-by: default avatarKevin Hilman <khilman@baylibre.com>
      Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      da4e4f18
  6. 09 Feb, 2016 1 commit
    • Dirk Behme's avatar
      drivers/perf: arm_pmu: make info messages more verbose · c6b90653
      Dirk Behme authored
      On a big.LITTLE system e.g. with Cortex A57 and A53 in case not all cores
      are online at PMU probe time we might get
      
      hw perfevents: failed to probe PMU!
      hw perfevents: failed to register PMU devices!
      
      making it unclear which cores failed, here.
      
      Add the device tree full name which failed and the error value resulting
      in a more verbose and helpful message like
      
      hw perfevents: /soc/pmu_a53: failed to probe PMU! Error -6
      hw perfevents: /soc/pmu_a53: failed to register PMU devices! Error -6
      Signed-off-by: default avatarDirk Behme <dirk.behme@de.bosch.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      c6b90653
  7. 25 Jan, 2016 1 commit
  8. 16 Nov, 2015 1 commit
    • Mark Rutland's avatar
      drivers/perf: kill armpmu_register · b916b785
      Mark Rutland authored
      Nothing outside of drivers/perf/arm_pmu.c should call armpmu_register
      any more, so it no longer needs to be in include/linux/perf/arm_pmu.h.
      Additionally, by folding it in to arm_pmu_device_probe we can allow
      drivers to override struct pmu fields without getting blatted by the
      armpmu code.
      
      This patch folds armpmu_register into arm_pmu_device_probe. The logging
      to the console is moved to after the PMU is successfully registered with
      the core perf code.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Suggested-by: default avatarWill Deacon <will.deacon@arm.com>
      Cc: Drew Richardson <drew.richardson@arm.com>
      Cc: Pawel Moll <pawel.moll@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      b916b785
  9. 15 Oct, 2015 1 commit
  10. 07 Oct, 2015 1 commit
  11. 31 Jul, 2015 1 commit
    • Mark Rutland's avatar
      arm: perf: factor arm_pmu core out to drivers · fa8ad788
      Mark Rutland authored
      To enable sharing of the arm_pmu code with arm64, this patch factors it
      out to drivers/perf/. A new drivers/perf directory is added for
      performance monitor drivers to live under.
      
      MAINTAINERS is updated accordingly. Files added previously without a
      corresponsing MAINTAINERS update (perf_regs.c, perf_callchain.c, and
      perf_event.h) are also added.
      
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Linus Walleij <linus.walleij@linaro.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Will Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      [will: augmented Kconfig help slightly]
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      fa8ad788