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2016-09-02drivers/perf: arm_pmu: Fix NULL pointer dereference during probeStefan Wahren
Patch 7f1d642fbb5c ("drivers/perf: arm-pmu: Fix handling of SPI lacking interrupt-affinity property") unintended also fixes perf_event support for bcm2835 which doesn't have PMU interrupts. Unfortunately this change introduce a NULL pointer dereference on bcm2835, because irq_is_percpu always expected to be called with a valid IRQ. So fix this regression by validating the IRQ before. Tested-by: Kevin Hilman <khilman@baylibre.com> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> Fixes: 7f1d642fbb5c ("drivers/perf: arm-pmu: Fix handling of SPI lacking "interrupt-affinity" property") Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-09-02drivers/perf: arm_pmu: Fix leak in error pathStefan Wahren
In case of a IRQ type mismatch in of_pmu_irq_cfg() the device node for interrupt affinity isn't freed. So fix this issue by calling of_node_put(). Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> Fixes: fa8ad7889d83 ("arm: perf: factor arm_pmu core out to drivers") Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-08-09drivers/perf: arm-pmu: Fix handling of SPI lacking "interrupt-affinity" propertyMarc Zyngier
Patch 19a469a58720 ("drivers/perf: arm-pmu: Handle per-interrupt affinity mask") added support for partitionned PPI setups, but inadvertently broke setups using SPIs without the "interrupt-affinity" property (which is the case for UP platforms). This patch restore the broken functionnality by testing whether the interrupt is percpu or not instead of relying on the using_spi flag that really means "SPI *and* interrupt-affinity property". Acked-by: Mark Rutland <mark.rutland@arm.com> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Fixes: 19a469a58720 ("drivers/perf: arm-pmu: Handle per-interrupt affinity mask") Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-08-09drivers/perf: arm-pmu: convert arm_pmu_mutex to spinlockSudeep Holla
arm_pmu_mutex is never held long and we don't want to sleep while the lock is being held as it's executed in the context of hotplug notifiers. So it can be converted to a simple spinlock instead. Without this patch we get the following warning: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620 in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/2 no locks held by swapper/2/0. irq event stamp: 381314 hardirqs last enabled at (381313): _raw_spin_unlock_irqrestore+0x7c/0x88 hardirqs last disabled at (381314): cpu_die+0x28/0x48 softirqs last enabled at (381294): _local_bh_enable+0x28/0x50 softirqs last disabled at (381293): irq_enter+0x58/0x78 CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.7.0 #12 Call trace: dump_backtrace+0x0/0x220 show_stack+0x24/0x30 dump_stack+0xb4/0xf0 ___might_sleep+0x1d8/0x1f0 __might_sleep+0x5c/0x98 mutex_lock_nested+0x54/0x400 arm_perf_starting_cpu+0x34/0xb0 cpuhp_invoke_callback+0x88/0x3d8 notify_cpu_starting+0x78/0x98 secondary_start_kernel+0x108/0x1a8 This patch converts the mutex to spinlock to eliminate the above warnings. This constraints pmu->reset to be non-blocking call which is the case with all the ARM PMU backends. Cc: Stephen Boyd <sboyd@codeaurora.org> Fixes: 37b502f121ad ("arm/perf: Fix hotplug state machine conversion") Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-07-29Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull smp hotplug updates from Thomas Gleixner: "This is the next part of the hotplug rework. - Convert all notifiers with a priority assigned - Convert all CPU_STARTING/DYING notifiers The final removal of the STARTING/DYING infrastructure will happen when the merge window closes. Another 700 hundred line of unpenetrable maze gone :)" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits) timers/core: Correct callback order during CPU hot plug leds/trigger/cpu: Move from CPU_STARTING to ONLINE level powerpc/numa: Convert to hotplug state machine arm/perf: Fix hotplug state machine conversion irqchip/armada: Avoid unused function warnings ARC/time: Convert to hotplug state machine clocksource/atlas7: Convert to hotplug state machine clocksource/armada-370-xp: Convert to hotplug state machine clocksource/exynos_mct: Convert to hotplug state machine clocksource/arm_global_timer: Convert to hotplug state machine rcu: Convert rcutree to hotplug state machine KVM/arm/arm64/vgic-new: Convert to hotplug state machine smp/cfd: Convert core to hotplug state machine x86/x2apic: Convert to CPU hotplug state machine profile: Convert to hotplug state machine timers/core: Convert to hotplug state machine hrtimer: Convert to hotplug state machine x86/tboot: Convert to hotplug state machine arm64/armv8 deprecated: Convert to hotplug state machine hwtracing/coresight-etm4x: Convert to hotplug state machine ...
2016-07-20arm/perf: Fix hotplug state machine conversionSebastian Andrzej Siewior
Mark Rutland pointed out that this commit is incomplete: 7d88eb695a1f ("arm/perf: Convert to hotplug state machine") The problem is that: > We may have multiple PMUs (e.g. two in big.LITTLE systems), and > __oprofile_cpu_pmu only contains one of these. So this conversion is not > correct. > > We were relying on the notifier list implicitly containing a list of > those PMUs. It seems like we need an explicit list here. > > We keep __oprofile_cpu_pmu around for legacy 32-bit users of OProfile > (on non-hetereogeneous systems), and that's all that the variable should > be used for. Introduce arm_pmu_list to correctly handle multiple PMUs in the system. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-tip-commits@vger.kernel.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160719111733.GA22911@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15arm/perf: Convert to hotplug state machineThomas Gleixner
Straight forward conversion w/o bells and whistles. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153335.794097159@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-08drivers/perf: arm-pmu: Handle per-interrupt affinity maskMarc Zyngier
On a big-little system, PMUs can be wired to CPUs using per CPU interrups (PPI). In this case, it is important to make sure that the enable/disable do happen on the right set of CPUs. So instead of relying on the interrupt-affinity property, we can use the actual percpu affinity that DT exposes as part of the interrupt specifier. The DT binding is also updated to reflect the fact that the interrupt-affinity property shouldn't be used in that case. Acked-by: Rob Herring <robh@kernel.org> Tested-by: Caesar Wang <wxt@rock-chips.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-06-15arm: pmu: Fix non-devicetree probingMark Salter
There is a problem in the non-devicetree PMU probing where some probe functions may get the number of supported events through smp_call_function_any() using the arm_pmu supported_cpus mask. But at the time the probe function is called, the supported_cpus mask is empty so the call fails. This patch makes sure the mask is set before calling the init function rather than after. Signed-off-by: Mark Salter <msalter@redhat.com> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-06-03drivers/perf: arm_pmu: Avoid leaking pmu->irq_affinity on errorJulien Grall
pmu->irq_affinity will not be freed if an error occurred within arm_pmu_device_probe after of_pmu_irq_cfg has been called. Note that in the case of_pmu_irq_cfg is returning an error, pmu->irq_affinity will not be set, but it should be NULL as pmu was kzalloc'd. Therefore the result kfree(NULL) is benign. Signed-off-by: Julien Grall <julien.grall@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-06-03drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmuJulien Grall
The global variable __oprofile_cpu_pmu is set before the PMU is fully initialized. If an error occurs before the end of the initialization, the PMU will be freed and the variable will contain an invalid pointer. This will result in a kernel crash when perf will be used. Fix it by moving the setting of __oprofile_cpu_pmu when the PMU is fully initialized (i.e when it is no longer possible to fail). Cc: <stable@vger.kernel.org> Signed-off-by: Julien Grall <julien.grall@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-06-03drivers/perf: arm_pmu: Fix reference count of a device_node in of_pmu_irq_cfgJulien Grall
The only function called by of_pmu_irq_cfg that will increment the reference count on dn is of_parse_phandle. Each time we successfully parse a possible CPU from an interrupt-affinity property, we increment the refcount of that CPU node once via of_parse_handle. After validating the CPU is possible, we decrement the refcount once. Subsequently, we decrement the refcount again, either as part of an early break if we don't have a matching SPI, or as part of the end of the loop body. This will lead to decrementing twice the refcounnt. Remove the second pairs of call to of_node_put as nobody is using dn between the first and second call to of_node_put. Signed-off-by: Julien Grall <julien.grall@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-05-05perf/arm: Special-case hetereogeneous CPUsMark Rutland
Commit: 26657848502b7847 ("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: 66eb579e66ecfea5 ("perf: allow for PMU-specific event filtering") c904e32a69b7c779 ("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: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter 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@leverpostej Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-21drivers/perf: arm-pmu: fix RCU usage on pmu resume from low-powerLorenzo Pieralisi
Commit da4e4f18afe0 ("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: da4e4f18afe0 ("drivers/perf: arm_pmu: implement CPU_PM notifier") Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reported-by: James Morse <james.morse@arm.com> Suggested-by: Kevin 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: Mark Rutland <mark.rutland@arm.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-03-21drivers/perf: arm_pmu: avoid NULL dereference when not using devicetreeWill Deacon
Commit c6b90653f1f7 ("drivers/perf: arm_pmu: make info messages more verbose") breaks booting on systems where the PMU is probed without devicetree (e.g by inspecting the MIDR of the current CPU). In this case, pdev->dev.of_node is NULL and we shouldn't try to access its ->fullname field when printing probe error messages. This patch fixes the probing code to use of_node_full_name, which safely handles NULL nodes and removes the "Error %i" part of the string, since it's not terribly useful. Reported-by: Guenter Roeck <private@roeck-us.net> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-26drivers/perf: arm_pmu: implement CPU_PM notifierLorenzo Pieralisi
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: Ashwin Chaugule <ashwin.chaugule@linaro.org> Acked-by: Kevin Hilman <khilman@baylibre.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-09drivers/perf: arm_pmu: make info messages more verboseDirk Behme
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: Dirk Behme <dirk.behme@de.bosch.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-25ARM: perf: Set ARMv7 SDER SUNIDEN bitMartin Fuzzey
ARMv7 counters other than the CPU cycle counter only work if the Secure Debug Enable Register (SDER) SUNIDEN bit is set. Since access to the SDER is only possible in secure state, it will only be done if the device tree property "secure-reg-access" is set. Without this: Performance counter stats for 'sleep 1': 14606094 cycles # 0.000 GHz 0 instructions # 0.00 insns per cycle After applying: Performance counter stats for 'sleep 1': 5843809 cycles 2566484 instructions # 0.44 insns per cycle 1.020144000 seconds time elapsed Some platforms (eg i.MX53) may also need additional platform specific setup. Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com> Signed-off-by: Pooya Keshavarzi <Pooya.Keshavarzi@de.bosch.com> Signed-off-by: George G. Davis <george_davis@mentor.com> [will: add warning if property is found on arm64] Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-11-16drivers/perf: kill armpmu_registerMark Rutland
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: Mark Rutland <mark.rutland@arm.com> Suggested-by: Will Deacon <will.deacon@arm.com> Cc: Drew Richardson <drew.richardson@arm.com> Cc: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-11-04Merge tag 'arm64-upstream' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 updates from Catalin Marinas: - "genirq: Introduce generic irq migration for cpu hotunplugged" patch merged from tip/irq/for-arm to allow the arm64-specific part to be upstreamed via the arm64 tree - CPU feature detection reworked to cope with heterogeneous systems where CPUs may not have exactly the same features. The features reported by the kernel via internal data structures or ELF_HWCAP are delayed until all the CPUs are up (and before user space starts) - Support for 16KB pages, with the additional bonus of a 36-bit VA space, though the latter only depending on EXPERT - Implement native {relaxed, acquire, release} atomics for arm64 - New ASID allocation algorithm which avoids IPI on roll-over, together with TLB invalidation optimisations (using local vs global where feasible) - KASan support for arm64 - EFI_STUB clean-up and isolation for the kernel proper (required by KASan) - copy_{to,from,in}_user optimisations (sharing the memcpy template) - perf: moving arm64 to the arm32/64 shared PMU framework - L1_CACHE_BYTES increased to 128 to accommodate Cavium hardware - Support for the contiguous PTE hint on kernel mapping (16 consecutive entries may be able to use a single TLB entry) - Generic CONFIG_HZ now used on arm64 - defconfig updates * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (91 commits) arm64/efi: fix libstub build under CONFIG_MODVERSIONS ARM64: Enable multi-core scheduler support by default arm64/efi: move arm64 specific stub C code to libstub arm64: page-align sections for DEBUG_RODATA arm64: Fix build with CONFIG_ZONE_DMA=n arm64: Fix compat register mappings arm64: Increase the max granular size arm64: remove bogus TASK_SIZE_64 check arm64: make Timer Interrupt Frequency selectable arm64/mm: use PAGE_ALIGNED instead of IS_ALIGNED arm64: cachetype: fix definitions of ICACHEF_* flags arm64: cpufeature: declare enable_cpu_capabilities as static genirq: Make the cpuhotplug migration code less noisy arm64: Constify hwcap name string arrays arm64/kvm: Make use of the system wide safe values arm64/debug: Make use of the system wide safe value arm64: Move FP/ASIMD hwcap handling to common code arm64/HWCAP: Use system wide safe values arm64/capabilities: Make use of system wide safe value arm64: Delay cpu feature capability checks ...
2015-10-15drivers/perf: arm_pmu: avoid CPU device_node reference leakWill Deacon
of_cpu_device_node_get increments the reference count on the CPU device_node, so we must take care to of_node_put once we've finished with it. This patch fixes the perf IRQ probing code to avoid the leak. Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2015-10-07arm64: perf: move to shared arm_pmu frameworkMark Rutland
Now that the arm_pmu framework has been factored out to drivers/perf we can make use of it for arm64, gaining support for heterogeneous PMUs and unifying the two codebases before they diverge further. The as yet unused PMU name for PMUv3 is changed to armv8_pmuv3, matching the style previously applied to the 32-bit PMUs. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-07-31arm: perf: factor arm_pmu core out to driversMark Rutland
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: Mark Rutland <mark.rutland@arm.com> [will: augmented Kconfig help slightly] Signed-off-by: Will Deacon <will.deacon@arm.com>