Messages in this thread Patch in this message | | | Date | Mon, 10 Oct 2022 15:17:39 +0100 | Subject | Re: [PATCH V3 4/7] driver/perf/arm_pmu_platform: Add support for BRBE attributes detection | From | James Clark <> |
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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? 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:
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 ...
> 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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