Uncore PMU drivers face an awkward cyclic dependency wherein:
- They have to pick a valid online CPU to associate with before
registering the PMU device, since it will get exposed to userspace
immediately.
- The PMU registration has to be be at least partly complete before
hotplug events can be handled, since trying to migrate an
uninitialised context would be bad.
- The hotplug handler has to be ready as soon as a CPU is chosen, lest
it go offline without the user-visible cpumask value getting updated.
The arm-cci driver has tried to solve this by using get_cpu() to pick
the current CPU and prevent it from disappearing while both
registrations are performed, but that results in taking mutexes with
preemption disabled, which makes certain configurations very unhappy:
[ 1.983337] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:2004
[ 1.983340] in_atomic(): 1, irqs_disabled(): 0, pid: 1, name: swapper/0
[ 1.983342] Preemption disabled at:
[ 1.983353] [<ffffff80089801f4>] cci_pmu_probe+0x1dc/0x488
[ 1.983360] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.20-rt8-yocto-preempt-rt #1
[ 1.983362] Hardware name: ZynqMP ZCU102 Rev1.0 (DT)
[ 1.983364] Call trace:
[ 1.983369] dump_backtrace+0x0/0x158
[ 1.983372] show_stack+0x24/0x30
[ 1.983378] dump_stack+0x80/0xa4
[ 1.983383] ___might_sleep+0x138/0x160
[ 1.983386] __might_sleep+0x58/0x90
[ 1.983391] __rt_mutex_lock_state+0x30/0xc0
[ 1.983395] _mutex_lock+0x24/0x30
[ 1.983400] perf_pmu_register+0x2c/0x388
[ 1.983404] cci_pmu_probe+0x2bc/0x488
[ 1.983409] platform_drv_probe+0x58/0xa8
It is not feasible to resolve all the possible races outside of the perf
core itself, so address the immediate bug by following the example of
nearly every other PMU driver and not even trying to do so. Registering
the hotplug notifier first should minimise the window in which things
can go wrong, so that's about as much as we can reasonably do here. This
also revealed an additional race in assigning the global pointer too
late relative to the hotplug notifier, which gets fixed in the process.
Reported-by: Li, Meng <Meng.Li@windriver.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
PERF_PMU_CAP_NO_EXCLUDE capability. This ensures that perf will
prevent us from handling events where any exclusion flags are set.
Let's also remove the now unnecessary check for exclusion flags.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: robin.murphy@arm.com
Cc: suzuki.poulose@arm.com
Link: https://lkml.kernel.org/r/1547128414-50693-8-git-send-email-andrew.murray@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the quest to remove all stack VLA usage from the kernel[1], this
removes the VLA in favor of a maximum size and adds a sanity check
at registration time. The sizes are all explicitly enumerated already,
so this just collects them into macros.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When the arm-cci driver is enabled, but both CONFIG_ARM_CCI5xx_PMU and
CONFIG_ARM_CCI400_PMU are not, we get a warning about how parts of
the driver are never used:
drivers/perf/arm-cci.c:1454:29: error: 'cci_pmu_models' defined but not used [-Werror=unused-variable]
drivers/perf/arm-cci.c:693:16: error: 'cci_pmu_event_show' defined but not used [-Werror=unused-function]
drivers/perf/arm-cci.c:685:16: error: 'cci_pmu_format_show' defined but not used [-Werror=unused-function]
Marking all three functions as __maybe_unused avoids the warnings in
randconfig builds. I'm doing this lacking any ideas for a better fix.
Fixes: 3de6be7a3d ("drivers/bus: Split Arm CCI driver")
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Fill in the few extra bits and annotations needed to make the driver
work properly as a module, and jiggle the Kconfig to expose the
driver-level ARM_CCI_PMU option.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The CCI PMU driver bears some legacy remnants of the arm_pmu framework
from when it was split in c6f85cb430 ("bus: cci: move away from
arm_pmu framework"). In particular this perf_pmu_{dis,en}able() dance
around pmu->add which was fixed for arm_pmu in a9e469d1c8
("drivers/perf: arm_pmu: remove pointless PMU disabling").
For the exact same reasons (i.e. perf core already does this around the
call anyway), give cci_pmu_add() the exact same change, which also
prevents having to export those core functions to build it as a module.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The CCI/CCN drivers are licensed under GPLv2, but the MODULE_LICENSE()
tags are using the bare "GPL" string implying GPLv2 or later. Fix them
to match their actual file license.
Acked-by: Pawel Moll <pawel.moll@arm.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Since sampling events are rejected up-front by cci_pmu_event_init(), it
doesn't make much sense to go fiddling with the sampling period later.
This would seem to be just another leftover artefact of the arm_pmu
framwork, and as such can go.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The main addition this time around is the new ARM "SCMI" framework,
which is the latest in a series of standards coming from ARM to do power
management in a platform independent way. This has been through many
review cycles, and it relies on a rather interesting way of using the
mailbox subsystem, but in the end I agreed that Sudeep's version was
the best we could do after all.
Other changes include:
- the ARM CCN driver is moved out of drivers/bus into drivers/perf,
which makes more sense. Similarly, the performance monitoring
portion of the CCI driver are moved the same way and cleaned up
a little more.
- a series of updates to the SCPI framework
- support for the Mediatek mt7623a SoC in drivers/soc
- support for additional NVIDIA Tegra hardware in drivers/soc
- a new reset driver for Socionext Uniphier
- lesser bug fixes in drivers/soc, drivers/tee, drivers/memory, and
drivers/firmware and drivers/reset across platforms
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Merge tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC driver updates from Arnd Bergmann:
"The main addition this time around is the new ARM "SCMI" framework,
which is the latest in a series of standards coming from ARM to do
power management in a platform independent way.
This has been through many review cycles, and it relies on a rather
interesting way of using the mailbox subsystem, but in the end I
agreed that Sudeep's version was the best we could do after all.
Other changes include:
- the ARM CCN driver is moved out of drivers/bus into drivers/perf,
which makes more sense. Similarly, the performance monitoring
portion of the CCI driver are moved the same way and cleaned up a
little more.
- a series of updates to the SCPI framework
- support for the Mediatek mt7623a SoC in drivers/soc
- support for additional NVIDIA Tegra hardware in drivers/soc
- a new reset driver for Socionext Uniphier
- lesser bug fixes in drivers/soc, drivers/tee, drivers/memory, and
drivers/firmware and drivers/reset across platforms"
* tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (87 commits)
reset: uniphier: add ethernet reset control support for PXs3
reset: stm32mp1: Enable stm32mp1 reset driver
dt-bindings: reset: add STM32MP1 resets
reset: uniphier: add Pro4/Pro5/PXs2 audio systems reset control
reset: imx7: add 'depends on HAS_IOMEM' to fix unmet dependency
reset: modify the way reset lookup works for board files
reset: add support for non-DT systems
clk: scmi: use devm_of_clk_add_hw_provider() API and drop scmi_clocks_remove
firmware: arm_scmi: prevent accessing rate_discrete uninitialized
hwmon: (scmi) return -EINVAL when sensor information is unavailable
amlogic: meson-gx-socinfo: Update soc ids
soc/tegra: pmc: Use the new reset APIs to manage reset controllers
soc: mediatek: update power domain data of MT2712
dt-bindings: soc: update MT2712 power dt-bindings
cpufreq: scmi: add thermal dependency
soc: mediatek: fix the mistaken pointer accessed when subdomains are added
soc: mediatek: add SCPSYS power domain driver for MediaTek MT7623A SoC
soc: mediatek: avoid hardcoded value with bus_prot_mask
dt-bindings: soc: add header files required for MT7623A SCPSYS dt-binding
dt-bindings: soc: add SCPSYS binding for MT7623 and MT7623A SoC
...
Depending directly on the bus driver's global cci_ctrl_base variable
is a little unpleasant, and exporting it to allow the PMU driver to
be modular would be even more so. Let's make things a little better
abstracted by adding the control register block to the cci_pmu instance
data alongside the PMU register block, and communicating the mapped
address from the bus driver via platform data.
It's not practical to try the same thing for the bus driver itself,
given that the globals are entangled with the hairy assembly code for
port control, so we leave them be there. It would however be prudent
to move them to the __ro_after_init section in passing, since the
addresses really should never be changing once set.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Since I am the self-appointed of_device_get_match_data() police, it's
only right that I should clean up this driver while I'm otherwise
touching it. This also reveals that we're passing around a struct
platform_device in places where we only ever care about its regular
device, so straighten that out in the process.
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Realistically, systems with multiple CCIs are unlikely to ever exist,
and since the driver only actually supports a single instance anyway
there's really no need to do the multi-instance hotplug state dance.
Take the opportunity to simplify the hotplug-related code all over,
addressing the context-migration TODO in the process for good measure.
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The arm-cci driver is really two entirely separate drivers; one for MCPM
port control and the other for the performance monitors. Since they are
already relatively self-contained, let's take the plunge and move the
PMU parts out to drivers/perf where they belong these days. For non-MCPM
systems this leaves a small dependency on the remaining "bus" stub for
initial probing and discovery, but we end up with something that still
fits the general pattern of its fellow system PMU drivers to ease future
maintenance.
Moving code to a new file also offers a perfect excuse to modernise the
license/copyright headers and clean up some funky linewraps on the way.
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Robin Murphy
Andrew Murray
Kees Cook
Arnd Bergmann
Linus Torvalds