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  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. 31 Jul, 2015 4 commits
    • 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
    • Sudeep Holla's avatar
      ARM: perf: replace arch_find_n_match_cpu_physical_id with of_cpu_device_node_get · bc1e3c46
      Sudeep Holla authored
      arch_find_n_match_cpu_physical_id parses the device tree to get the
      device node for a given logical cpu index. However, since ARM PMUs get
      probed after the CPU device nodes are stashed while registering the
      cpus, we can use of_cpu_device_node_get to avoid another DT parse.
      
      This patch replaces arch_find_n_match_cpu_physical_id with
      of_cpu_device_node_get to reuse the stashed value directly instead.
      
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      bc1e3c46
    • Will Deacon's avatar
      ARM: perf: extend interrupt-affinity property for PPIs · b6c084d7
      Will Deacon authored
      On systems containing multiple, heterogeneous clusters we need a way to
      associate a PMU "device" with the CPU(s) on which it exists. For PMUs
      that signal overflow with SPIs, this relationship is determined via the
      "interrupt-affinity" property, which contains a list of phandles to CPU
      nodes for the PMU. For PMUs using PPIs, the per-cpu nature of the
      interrupt isn't enough to determine the set of CPUs which actually
      contain the device.
      
      This patch allows the interrupt-affinity property to be specified on a
      PMU node irrespective of the interrupt type. For PPIs, it identifies
      the set of CPUs signalling the PPI in question.
      
      Tested-by: Stephen Boyd <sboyd@codeaurora.org> # Krait PMU
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      b6c084d7
    • Stephen Boyd's avatar
      arm: perf: Set affinity for PPI based PMUs · 8ae81c25
      Stephen Boyd authored
      For PPI based PMUs, we bail out early in of_pmu_irq_cfg() without
      setting the PMU's supported_cpus bitmap. This causes the
      smp_call_function_any() in armv7_probe_num_events() to fail. Set
      the bitmap to be all CPUs so that we properly probe PMUs that use
      PPIs.
      
      Fixes: cc88116d ("arm: perf: treat PMUs as CPU affine")
      Cc: Mark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      8ae81c25
  11. 17 Jul, 2015 1 commit
  12. 10 Jul, 2015 1 commit
  13. 28 May, 2015 2 commits
  14. 27 May, 2015 2 commits
    • Mark Rutland's avatar
      arm: perf: filter unschedulable events · c904e32a
      Mark Rutland authored
      Different CPU microarchitectures implement different PMU events, and
      thus events which can be scheduled on one microarchitecture cannot be
      scheduled on another, and vice-versa. Some archicted events behave
      differently across microarchitectures, and thus cannot be meaningfully
      summed. Due to this, we reject the scheduling of an event on a CPU of a
      different microarchitecture to that the event targets.
      
      When the core perf code is scheduling events and encounters an event
      which cannot be scheduled, it stops attempting to schedule events. As
      the perf core periodically rotates the list of events, for some
      proportion of the time events which are unschedulable will block events
      which are schedulable, resulting in low utilisation of the hardware
      counters.
      
      This patch implements a pmu::filter_match callback such that we can
      detect and skip such events while scheduling early, before they can
      block the schedulable events. This prevents the low HW counter
      utilisation issue.
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      c904e32a
    • Mark Rutland's avatar
      arm: perf: treat PMUs as CPU affine · cc88116d
      Mark Rutland authored
      In multi-cluster systems, the PMUs can be different across clusters, and
      so our logical PMU may not be able to schedule events on all CPUs.
      
      This patch adds a cpumask to encode which CPUs a PMU driver supports
      controlling events for, and limits the driver to scheduling events on
      those CPUs, and enabling and disabling the physical PMUs on those CPUs.
      The cpumask is built based on the interrupt-affinity property, and in
      the absence of such a property a homogenous system is assumed.
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      cc88116d
  15. 19 Mar, 2015 1 commit
    • Suzuki K. Poulose's avatar
      ARM: perf: reject groups spanning multiple hardware PMUs · e429817b
      Suzuki K. Poulose authored
      The perf core implicitly rejects events spanning multiple HW PMUs, as in
      these cases the event->ctx will differ. However this validation is
      performed after pmu::event_init() is called in perf_init_event(), and
      thus pmu::event_init() may be called with a group leader from a
      different HW PMU.
      
      The ARM PMU driver does not take this fact into account, and when
      validating groups assumes that it can call to_arm_pmu(event->pmu) for
      any HW event. When the event in question is from another HW PMU this is
      wrong, and results in dereferencing garbage.
      
      This patch updates the ARM PMU driver to first test for and reject
      events from other PMUs, moving the to_arm_pmu and related logic after
      this test. Fixes a crash triggered by perf_fuzzer on Linux-4.0-rc2, with
      a CCI PMU present:
      
       ---
      CPU: 0 PID: 1527 Comm: perf_fuzzer Not tainted 4.0.0-rc2 #57
      Hardware name: ARM-Versatile Express
      task: bd8484c0 ti: be676000 task.ti: be676000
      PC is at 0xbf1bbc90
      LR is at validate_event+0x34/0x5c
      pc : [<bf1bbc90>]    lr : [<80016060>]    psr: 00000013
      ...
      [<80016060>] (validate_event) from [<80016198>] (validate_group+0x28/0x90)
      [<80016198>] (validate_group) from [<80016398>] (armpmu_event_init+0x150/0x218)
      [<80016398>] (armpmu_event_init) from [<800882e4>] (perf_try_init_event+0x30/0x48)
      [<800882e4>] (perf_try_init_event) from [<8008f544>] (perf_init_event+0x5c/0xf4)
      [<8008f544>] (perf_init_event) from [<8008f8a8>] (perf_event_alloc+0x2cc/0x35c)
      [<8008f8a8>] (perf_event_alloc) from [<8009015c>] (SyS_perf_event_open+0x498/0xa70)
      [<8009015c>] (SyS_perf_event_open) from [<8000e420>] (ret_fast_syscall+0x0/0x34)
      Code: bf1be000 bf1bb380 802a2664 00000000 (00000002)
      ---[ end trace 01aff0ff00926a0a ]---
      
      Also cleans up the code to use the arm_pmu only when we know that
      we are dealing with an arm pmu event.
      
      Cc: Will Deacon <will.deacon@arm.com>
      Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
      Acked-by: default avatarPeter Ziljstra (Intel) <peterz@infradead.org>
      Signed-off-by: default avatarSuzuki K. Poulose <suzuki.poulose@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      e429817b
  16. 12 Jan, 2015 1 commit
    • Daniel Thompson's avatar
      ARM: 8255/1: perf: Prevent wraparound during overflow · 2d9ed740
      Daniel Thompson authored
      If the overflow threshold for a counter is set above or near the
      0xffffffff boundary then the kernel may lose track of the overflow
      causing only events that occur *after* the overflow to be recorded.
      Specifically the problem occurs when the value of the performance counter
      overtakes its original programmed value due to wrap around.
      
      Typical solutions to this problem are either to avoid programming in
      values likely to be overtaken or to treat the overflow bit as the 33rd
      bit of the counter.
      
      Its somewhat fiddly to refactor the code to correctly handle the 33rd bit
      during irqsave sections (context switches for example) so instead we take
      the simpler approach of avoiding values likely to be overtaken.
      
      We set the limit to half of max_period because this matches the limit
      imposed in __hw_perf_event_init(). This causes a doubling of the interrupt
      rate for large threshold values, however even with a very fast counter
      ticking at 4GHz the interrupt rate would only be ~1Hz.
      Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      2d9ed740
  17. 12 Dec, 2014 1 commit
  18. 30 Oct, 2014 5 commits
    • Mark Rutland's avatar
      arm: perf: fold percpu_pmu into pmu_hw_events · 5ebd9200
      Mark Rutland authored
      Currently the percpu_pmu pointers used as percpu_irq dev_id values are
      defined separately from the other per-cpu accounting data, which make
      dynamically allocating the data (as will be required for systems with
      heterogeneous CPUs) difficult.
      
      This patch moves the percpu_pmu pointers into pmu_hw_events (which is
      itself allocated per cpu), which will allow for easier dynamic
      allocation. Both percpu and regular irqs are requested using percpu_pmu
      pointers as tokens, freeing us from having to know whether an irq is
      percpu within the handler, and thus avoiding a radix tree lookup on the
      handler path.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
      Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Tested-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      5ebd9200
    • Mark Rutland's avatar
      arm: perf: kill get_hw_events() · 11679250
      Mark Rutland authored
      Now that the arm pmu code is limited to CPU PMUs the get_hw_events()
      function is superfluous, as we'll always have a set of per-cpu
      pmu_hw_events structures.
      
      This patch removes the get_hw_events() function, replacing it with
      a percpu hw_events pointer. Uses of get_hw_events are updated to use
      this_cpu_ptr.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
      Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      11679250
    • Mark Rutland's avatar
      arm: perf: limit size of accounting data · a4560846
      Mark Rutland authored
      Commit 3fc2c830 (ARM: perf: remove event limit from pmu_hw_events) got
      rid of the upper limit on the number of events an arm_pmu could handle,
      but introduced additional complexity and places a burden on each PMU
      driver to allocate accounting data somehow. So far this has not
      generally been useful as the only users of arm_pmu are the CPU backend
      and the CCI driver.
      
      Now that the CCI driver plugs into the perf subsystem directly, we can
      remove some of the complexities that get in the way of supporting
      heterogeneous CPU PMUs.
      
      This patch restores the original limits on pmu_hw_events fields such
      that the pmu_hw_events data can be allocated as a contiguous block. This
      will simplify dynamic pmu_hw_events allocation in later patches.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
      Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Tested-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      a4560846
    • Mark Rutland's avatar
      arm: perf: use IDR types for CPU PMUs · 67b4305a
      Mark Rutland authored
      For systems with heterogeneous CPUs (e.g. big.LITTLE systems) the PMUs
      can be different in each cluster, and not all events can be migrated
      between clusters. To allow userspace to deal with this, it must be
      possible to address each PMU independently.
      
      This patch changes PMUs to be registered with dynamic (IDR) types,
      allowing them to be targeted individually. Each PMU's type can be found
      in ${SYSFS_ROOT}/bus/event_source/devices/${PMU_NAME}/type.
      
      From userspace, raw events can be targeted at a specific PMU:
      $ perf stat -e ${PMU_NAME}/config=V,config1=V1,.../
      
      Doing this does not break existing tools which use existing perf types:
      when perf core can't find a PMU of matching type (in perf_init_event)
      it'll iterate over the set of all PMUs. If a compatible PMU exists,
      it'll be found eventually. If more than one compatible PMU exists, the
      event will be handled by whichever PMU happens to be earlier in the pmus
      list (which currently will be the last compatible PMU registered).
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      67b4305a
    • Mark Rutland's avatar
      arm: perf: factor out callchain code · d39976f0
      Mark Rutland authored
      The ARM callchain handling code is currently bundled with the ARM PMU
      management code, despite the two having no dependency on each other.
      This bundling has the unfortunate property of making callchain handling
      depend on CONFIG_HW_PERF_EVENTS, even though the callchain handling
      could be applied to software events in the absence of PMU hardware
      support.
      
      This patch separates the two, placing the callchain handling in
      perf_callchain.c and making it depend on CONFIG_PERF_EVENTS rather than
      CONFIG_HW_PERF_EVENTS, enabling callchain recording on kernels built
      without hardware perf event support.
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      d39976f0
  19. 18 Jul, 2014 1 commit
  20. 09 Jul, 2014 2 commits
    • Jean Pihet's avatar
      ARM: perf: disable the pagefault handler when reading from user space · 4b2974fa
      Jean Pihet authored
      Under perf, the fp unwinding scheme requires access to user space memory
      and can provoke a pagefault via call to __copy_from_user_inatomic from
      user_backtrace. This unwinding can take place in response to an interrupt
      (__perf_event_overflow). This is undesirable as we may already have
      mmap_sem held for write. One example being a process that calls mprotect
      just as a the PMU counters overflow.
      
      An example that can provoke this behaviour:
      perf record -e event:tocapture --call-graph fp ./application_to_test
      
      This patch addresses this issue by disabling pagefaults briefly in
      user_backtrace (as is done in the other architectures: ARM64, x86, Sparc etc.).
      
      Without the patch a deadlock occurs when __perf_event_overflow is called
      while reading the data from the user space:
      
       [ INFO: possible recursive locking detected ]
       3.16.0-rc2-00038-g0ed7ff6 #46 Not tainted
       ---------------------------------------------
       stress/1634 is trying to acquire lock:
       (&mm->mmap_sem){++++++}, at: [<c001dc04>] do_page_fault+0xa8/0x428
      
       but task is already holding lock:
       (&mm->mmap_sem){++++++}, at: [<c00f4098>] SyS_mprotect+0xa8/0x1c8
      
       other info that might help us debug this:
       Possible unsafe locking scenario:
      
             CPU0
             ----
        lock(&mm->mmap_sem);
        lock(&mm->mmap_sem);
      
       *** DEADLOCK ***
      
       May be due to missing lock nesting notation
      
       2 locks held by stress/1634:
       #0:  (&mm->mmap_sem){++++++}, at: [<c00f4098>] SyS_mprotect+0xa8/0x1c8
       #1:  (rcu_read_lock){......}, at: [<c00c29dc>] __perf_event_overflow+0x120/0x294
      
       stack backtrace:
       CPU: 1 PID: 1634 Comm: stress Not tainted 3.16.0-rc2-00038-g0ed7ff6 #46
       [<c0017c8c>] (unwind_backtrace) from [<c0012eec>] (show_stack+0x20/0x24)
       [<c0012eec>] (show_stack) from [<c04de914>] (dump_stack+0x7c/0x98)
       [<c04de914>] (dump_stack) from [<c006a360>] (__lock_acquire+0x1484/0x1cf0)
       [<c006a360>] (__lock_acquire) from [<c006b14c>] (lock_acquire+0xa4/0x11c)
       [<c006b14c>] (lock_acquire) from [<c04e3880>] (down_read+0x40/0x7c)
       [<c04e3880>] (down_read) from [<c001dc04>] (do_page_fault+0xa8/0x428)
       [<c001dc04>] (do_page_fault) from [<c00084ec>] (do_DataAbort+0x44/0xa8)
       [<c00084ec>] (do_DataAbort) from [<c0013a1c>] (__dabt_svc+0x3c/0x60)
       Exception stack(0xed7c5ae0 to 0xed7c5b28)
       5ae0: ed7c5b5c b6dadff4 ffffffec 00000000 b6dadff4 ebc08000 00000000 ebc08000
       5b00: 0000007e 00000000 ed7c4000 ed7c5b94 00000014 ed7c5b2c c001a438 c0236c60
       5b20: 00000013 ffffffff
       [<c0013a1c>] (__dabt_svc) from [<c0236c60>] (__copy_from_user+0xa4/0x3a4)
      Acked-by: default avatarSteve Capper <steve.capper@linaro.org>
      Signed-off-by: default avatarJean Pihet <jean.pihet@linaro.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      4b2974fa
    • Jean Pihet's avatar
      ARM: perf: Check that current->mm is alive before getting user callchain · a7cc9100
      Jean Pihet authored
      An event may occur when an mm is already released.
      
      As per commit 20afc60f
       'x86, perf: Check that current->mm is alive before getting user callchain'
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarJean Pihet <jean.pihet@linaro.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      a7cc9100
  21. 05 Jun, 2014 1 commit
  22. 21 Feb, 2014 3 commits
  23. 17 Dec, 2013 1 commit
  24. 09 Oct, 2013 1 commit
    • Will Deacon's avatar
      ARM: perf: fix group validation for mixed software and hardware groups · 2dfcb802
      Will Deacon authored
      Since software events can always be scheduled, perf allows software and
      hardware events to be mixed together in the same event group. There are
      two ways in which this can come about:
      
        (1) A SW event is added to a HW group. This validates using the HW PMU
            of the group leader.
      
        (2) A HW event is added to a SW group. This inserts the SW events and
            the new HW event into a HW context, but the SW event remains the
            group leader.
      
      When validating the latter case, we would ideally compare the PMU of
      each event in the group with the relevant HW PMU. The problem is, in the
      face of potentially multiple HW PMUs, we don't have a handle on the
      relevant structure. Commit 7b9f72c6 ("ARM: perf: clean up event
      group validation") attempting to resolve this issue, but actually made
      things *worse* by comparing with the leader PMU. If the leader is a SW
      event, then we automatically `pass' all the HW events during validation!
      
      This patch removes the check against the leader PMU. Whilst this will
      allow events from multiple HW PMUs to be grouped together, that should
      probably be dealt with in perf core as the result of a later patch.
      Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      2dfcb802
  25. 13 Aug, 2013 2 commits
    • Stephen Boyd's avatar
      perf/arm: Fix armpmu_map_hw_event() · b88a2595
      Stephen Boyd authored
      Fix constraint check in armpmu_map_hw_event().
      Reported-and-tested-by: default avatarVince Weaver <vincent.weaver@maine.edu>
      Cc: <stable@kernel.org>
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b88a2595
    • Stephen Boyd's avatar
      ARM: 7810/1: perf: Fix array out of bounds access in armpmu_map_hw_event() · d9f96635
      Stephen Boyd authored
      Vince Weaver reports an oops in the ARM perf event code while
      running his perf_fuzzer tool on a pandaboard running v3.11-rc4.
      
      Unable to handle kernel paging request at virtual address 73fd14cc
      pgd = eca6c000
      [73fd14cc] *pgd=00000000
      Internal error: Oops: 5 [#1] SMP ARM
      Modules linked in: snd_soc_omap_hdmi omapdss snd_soc_omap_abe_twl6040 snd_soc_twl6040 snd_soc_omap snd_soc_omap_hdmi_card snd_soc_omap_mcpdm snd_soc_omap_mcbsp snd_soc_core snd_compress regmap_spi snd_pcm snd_page_alloc snd_timer snd soundcore
      CPU: 1 PID: 2790 Comm: perf_fuzzer Not tainted 3.11.0-rc4 #6
      task: eddcab80 ti: ed892000 task.ti: ed892000
      PC is at armpmu_map_event+0x20/0x88
      LR is at armpmu_event_init+0x38/0x280
      pc : [<c001c3e4>]    lr : [<c001c17c>]    psr: 60000013
      sp : ed893e40  ip : ecececec  fp : edfaec00
      r10: 00000000  r9 : 00000000  r8 : ed8c3ac0
      r7 : ed8c3b5c  r6 : edfaec00  r5 : 00000000  r4 : 00000000
      r3 : 000000ff  r2 : c0496144  r1 : c049611c  r0 : edfaec00
      Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
      Control: 10c5387d  Table: aca6c04a  DAC: 00000015
      Process perf_fuzzer (pid: 2790, stack limit = 0xed892240)
      Stack: (0xed893e40 to 0xed894000)
      3e40: 00000800 c001c17c 00000002 c008a748 00000001 00000000 00000000 c00bf078
      3e60: 00000000 edfaee50 00000000 00000000 00000000 edfaec00 ed8c3ac0 edfaec00
      3e80: 00000000 c073ffac ed893f20 c00bf180 00000001 00000000 c00bf078 ed893f20
      3ea0: 00000000 ed8c3ac0 00000000 00000000 00000000 c0cb0818 eddcab80 c00bf440
      3ec0: ed893f20 00000000 eddcab80 eca76800 00000000 eca76800 00000000 00000000
      3ee0: 00000000 ec984c80 eddcab80 c00bfe68 00000000 00000000 00000000 00000080
      3f00: 00000000 ed892000 00000000 ed892030 00000004 ecc7e3c8 ecc7e3c8 00000000
      3f20: 00000000 00000048 ecececec 00000000 00000000 00000000 00000000 00000000
      3f40: 00000000 00000000 00297810 00000000 00000000 00000000 00000000 00000000
      3f60: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
      3f80: 00000002 00000002 000103a4 00000002 0000016c c00128e8 ed892000 00000000
      3fa0: 00090998 c0012700 00000002 000103a4 00090ab8 00000000 00000000 0000000f
      3fc0: 00000002 000103a4 00000002 0000016c 00090ab0 00090ab8 000107a0 00090998
      3fe0: bed92be0 bed92bd0 0000b785 b6e8f6d0 40000010 00090ab8 00000000 00000000
      [<c001c3e4>] (armpmu_map_event+0x20/0x88) from [<c001c17c>] (armpmu_event_init+0x38/0x280)
      [<c001c17c>] (armpmu_event_init+0x38/0x280) from [<c00bf180>] (perf_init_event+0x108/0x180)
      [<c00bf180>] (perf_init_event+0x108/0x180) from [<c00bf440>] (perf_event_alloc+0x248/0x40c)
      [<c00bf440>] (perf_event_alloc+0x248/0x40c) from [<c00bfe68>] (SyS_perf_event_open+0x4f4/0x8fc)
      [<c00bfe68>] (SyS_perf_event_open+0x4f4/0x8fc) from [<c0012700>] (ret_fast_syscall+0x0/0x48)
      Code: 0a000005 e3540004 0a000016 e3540000 (0791010c)
      
      This is because event->attr.config in armpmu_event_init()
      contains a very large number copied directly from userspace and
      is never checked against the size of the array indexed in
      armpmu_map_hw_event(). Fix the problem by checking the value of
      config before indexing the array and rejecting invalid config
      values.
      Reported-by: default avatarVince Weaver <vincent.weaver@maine.edu>
      Tested-by: default avatarVince Weaver <vincent.weaver@maine.edu>
      Acked-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      d9f96635