kernel.git/drivers/perf/arm-cci.c, branch linux-5.8.y

drivers/perf: Prevent forced unbinding of PMU drivers

2020-07-17T09:51:44Z

Forcefully unbinding PMU drivers during perf sampling will lead to a kernel panic, because the perf upper-layer framework call a NULL pointer in this situation. To solve this issue, "suppress_bind_attrs" should be set to true, so that bind/unbind can be disabled via sysfs and prevent unbinding PMU drivers during perf sampling. Signed-off-by: Qi Liu Reviewed-by: John Garry Link: https://lore.kernel.org/r/1594975763-32966-1-git-send-email-liuqi115@huawei.com Signed-off-by: Will Deacon

perf/arm-cci: use devm_platform_ioremap_resource() to simplify code

2019-10-01T11:28:47Z

Use devm_platform_ioremap_resource() to simplify the code a bit. This is detected by coccinelle. Signed-off-by: YueHaibing Signed-off-by: Will Deacon

perf/arm-cci: Remove broken race mitigation

2019-04-23T11:29:23Z

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] [] 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 Tested-by: Corentin Labbe Reviewed-by: Suzuki K Poulose Signed-off-by: Robin Murphy Signed-off-by: Will Deacon

For drivers that do not support context exclusion let's advertise the

2019-01-21T10:01:24Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Cc: Arnaldo Carvalho de Melo Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Ivan Kokshaysky Cc: Linus Torvalds Cc: Mark Rutland Cc: Matt Turner Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Richard Henderson Cc: Russell King Cc: Sascha Hauer Cc: Shawn Guo Cc: Thomas Gleixner 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

perf/arm-cci: Remove VLA usage

2018-07-02T11:50:03Z

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 Signed-off-by: Will Deacon

drivers/bus: arm-cci: fix build warnings

2018-05-29T15:38:16Z

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: 3de6be7a3dd8 ("drivers/bus: Split Arm CCI driver") Reviewed-by: Robin Murphy Signed-off-by: Arnd Bergmann Signed-off-by: Will Deacon

perf/arm-cci: Allow building as a module

2018-05-21T17:12:54Z

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 Signed-off-by: Will Deacon

perf/arm-cci: Remove pointless PMU disabling

2018-05-21T17:12:53Z

The CCI PMU driver bears some legacy remnants of the arm_pmu framework from when it was split in c6f85cb4305b ("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 a9e469d1c89b ("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 Signed-off-by: Robin Murphy Signed-off-by: Will Deacon

perf/arm-cc*: Fix MODULE_LICENSE() tags

2018-05-21T17:12:53Z

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 Acked-by: Suzuki K Poulose Signed-off-by: Robin Murphy Signed-off-by: Will Deacon

perf/arm-cci: Remove unnecessary period adjustment

2018-05-21T17:06:11Z

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 Signed-off-by: Robin Murphy Signed-off-by: Will Deacon