Messages in this thread | | | Date | Tue, 11 Oct 2022 14:51:44 +0530 | Subject | Re: [PATCH V3 4/7] driver/perf/arm_pmu_platform: Add support for BRBE attributes detection | From | Anshuman Khandual <> |
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On 10/10/22 19:47, James Clark wrote: > > > On 06/10/2022 14:37, James Clark wrote: >> >> >> On 29/09/2022 08:58, Anshuman Khandual wrote: >>> This adds arm pmu infrastrure to probe BRBE implementation's attributes via >>> driver exported callbacks later. The actual BRBE feature detection will be >>> added by the driver itself. >>> >>> CPU specific BRBE entries, cycle count, format support gets detected during >>> PMU init. This information gets saved in per-cpu struct pmu_hw_events which >>> later helps in operating BRBE during a perf event context. >>> >>> Cc: Will Deacon <will@kernel.org> >>> Cc: Mark Rutland <mark.rutland@arm.com> >>> Cc: linux-arm-kernel@lists.infradead.org >>> Cc: linux-kernel@vger.kernel.org >>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >>> --- >>> drivers/perf/arm_pmu_platform.c | 34 +++++++++++++++++++++++++++++++++ >>> 1 file changed, 34 insertions(+) >>> >>> diff --git a/drivers/perf/arm_pmu_platform.c b/drivers/perf/arm_pmu_platform.c >>> index 933b96e243b8..acdc445081aa 100644 >>> --- a/drivers/perf/arm_pmu_platform.c >>> +++ b/drivers/perf/arm_pmu_platform.c >>> @@ -172,6 +172,36 @@ static int armpmu_request_irqs(struct arm_pmu *armpmu) >>> return err; >>> } >>> >>> +static void arm_brbe_probe_cpu(void *info) >>> +{ >>> + struct pmu_hw_events *hw_events; >>> + struct arm_pmu *armpmu = info; >>> + >>> + /* >>> + * Return from here, if BRBE driver has not been >>> + * implemented for this PMU. This helps prevent >>> + * kernel crash later when brbe_probe() will be >>> + * called on the PMU. >>> + */ >>> + if (!armpmu->brbe_probe) >>> + return; >>> + >>> + hw_events = per_cpu_ptr(armpmu->hw_events, smp_processor_id()); >>> + armpmu->brbe_probe(hw_events); >>> +} >>> + >>> +static int armpmu_request_brbe(struct arm_pmu *armpmu) >>> +{ >>> + int cpu, err = 0; >>> + >>> + for_each_cpu(cpu, &armpmu->supported_cpus) { >>> + err = smp_call_function_single(cpu, arm_brbe_probe_cpu, armpmu, 1); >> >> Hi Anshuman, >> >> I have LOCKDEP on and the patchset applied to perf/core (82aad7ff7) on >> git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git and I get > > Can you confirm if this is currently the correct place to apply this to?
This series applied on v6.0-rc5 after the perf ABI changes, both in kernel and in user space tools.
> I'm only getting 0 length branch stacks now. Seems like it could be > something to do with the layout of perf samples because I know that was > done in separate commits:
Right, might be.
> > sudo ./perf record -j any_call -- ls > ./perf report -D | grep "branch stack" > ... branch stack: nr:0 > ... branch stack: nr:0 > ... branch stack: nr:0 > ... branch stack: nr:0
I am planning to respin the series on 6.1-rc1 next week which should solve these multiple moving parts problem.
> ... > >> this: >> >> armv8-pmu pmu: hw perfevents: no interrupt-affinity property, guessing. >> brbe: implementation found on cpu 0 >> >> ============================= >> [ BUG: Invalid wait context ] >> 6.0.0-rc7 #38 Not tainted >> ----------------------------- >> kworker/u8:0/9 is trying to lock: >> ffff000800855898 (&port_lock_key){....}-{3:3}, at: >> pl011_console_write+0x148/0x240 >> other info that might help us debug this: >> context-{2:2} >> 5 locks held by kworker/u8:0/9: >> #0: ffff00080032a138 ((wq_completion)eval_map_wq){+.+.}-{0:0}, at: >> process_one_work+0x200/0x6b0 >> #1: ffff80000807bde0 >> ((work_completion)(&eval_map_work)){+.+.}-{0:0}, at: >> process_one_work+0x200/0x6b0 >> #2: ffff80000aa3db70 (trace_event_sem){+.+.}-{4:4}, at: >> trace_event_eval_update+0x28/0x420 >> #3: ffff80000a9afe58 (console_lock){+.+.}-{0:0}, at: >> vprintk_emit+0x130/0x380 >> #4: ffff80000a9aff78 (console_owner){-...}-{0:0}, at: >> console_emit_next_record.constprop.0+0x128/0x338 >> stack backtrace: >> CPU: 0 PID: 9 Comm: kworker/u8:0 Not tainted 6.0.0-rc7 #38 >> Hardware name: Foundation-v8A (DT) >> Workqueue: eval_map_wq eval_map_work_func >> Call trace: >> dump_backtrace+0x114/0x120 >> show_stack+0x20/0x58 >> dump_stack_lvl+0x9c/0xd8 >> dump_stack+0x18/0x34 >> __lock_acquire+0x17cc/0x1920 >> lock_acquire+0x138/0x3b8 >> _raw_spin_lock+0x58/0x70 >> pl011_console_write+0x148/0x240 >> console_emit_next_record.constprop.0+0x194/0x338 >> console_unlock+0x18c/0x208 >> vprintk_emit+0x24c/0x380 >> vprintk_default+0x40/0x50 >> vprintk+0xd4/0xf0 >> _printk+0x68/0x90 >> arm64_pmu_brbe_probe+0x10c/0x128 >> armv8pmu_brbe_probe+0x18/0x28 >> arm_brbe_probe_cpu+0x44/0x58 >> __flush_smp_call_function_queue+0x1d0/0x440 >> generic_smp_call_function_single_interrupt+0x20/0x78 >> ipi_handler+0x98/0x368 >> handle_percpu_devid_irq+0xc0/0x3a8 >> generic_handle_domain_irq+0x34/0x50 >> gic_handle_irq+0x58/0x138 >> call_on_irq_stack+0x2c/0x58 >> do_interrupt_handler+0x88/0x90 >> el1_interrupt+0x40/0x78 >> el1h_64_irq_handler+0x18/0x28 >> el1h_64_irq+0x64/0x68 >> trace_event_eval_update+0x114/0x420 >> eval_map_work_func+0x30/0x40 >> process_one_work+0x298/0x6b0 >> worker_thread+0x54/0x408 >> kthread+0x118/0x128 >> ret_from_fork+0x10/0x20 >> brbe: implementation found on cpu 1 >> brbe: implementation found on cpu 2 >> brbe: implementation found on cpu 3 >> >>> + if (err) >>> + return err; >>> + } >>> + return err; >>> +} >>> + >>> static void armpmu_free_irqs(struct arm_pmu *armpmu) >>> { >>> int cpu; >>> @@ -229,6 +259,10 @@ int arm_pmu_device_probe(struct platform_device *pdev, >>> if (ret) >>> goto out_free_irqs; >>> >>> + ret = armpmu_request_brbe(pmu); >>> + if (ret) >>> + goto out_free_irqs; >>> + >>> ret = armpmu_register(pmu); >>> if (ret) { >>> dev_err(dev, "failed to register PMU devices!\n");
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