Messages in this thread | | | Date | Wed, 10 Feb 2021 12:00:27 -0700 | From | Mathieu Poirier <> | Subject | Re: [PATCH V3 11/14] coresight: sink: Add TRBE driver |
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On Wed, Jan 27, 2021 at 02:25:35PM +0530, Anshuman Khandual wrote: > Trace Buffer Extension (TRBE) implements a trace buffer per CPU which is > accessible via the system registers. The TRBE supports different addressing > modes including CPU virtual address and buffer modes including the circular > buffer mode. The TRBE buffer is addressed by a base pointer (TRBBASER_EL1), > an write pointer (TRBPTR_EL1) and a limit pointer (TRBLIMITR_EL1). But the > access to the trace buffer could be prohibited by a higher exception level > (EL3 or EL2), indicated by TRBIDR_EL1.P. The TRBE can also generate a CPU > private interrupt (PPI) on address translation errors and when the buffer > is full. Overall implementation here is inspired from the Arm SPE driver. > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > Changes in V3: > > - Added new DT bindings document TRBE.yaml > - Changed TRBLIMITR_TRIG_MODE_SHIFT from 2 to 3 > - Dropped isb() from trbe_reset_local() > - Dropped gap between (void *) and buf->trbe_base > - Changed 'int' to 'unsigned int' in is_trbe_available() > - Dropped unused function set_trbe_running(), set_trbe_virtual_mode(), > set_trbe_enabled() and set_trbe_limit_pointer() > - Changed get_trbe_flag_update(), is_trbe_programmable() and > get_trbe_address_align() to accept TRBIDR value > - Changed is_trbe_running(), is_trbe_abort(), is_trbe_wrap(), is_trbe_trg(), > is_trbe_irq(), get_trbe_bsc() and get_trbe_ec() to accept TRBSR value > - Dropped snapshot mode condition in arm_trbe_alloc_buffer() > - Exit arm_trbe_init() when arm64_kernel_unmapped_at_el0() is enabled > - Compute trbe_limit before trbe_write to get the updated handle > - Added trbe_stop_and_truncate_event() > - Dropped trbe_handle_fatal() > > Documentation/trace/coresight/coresight-trbe.rst | 39 + > arch/arm64/include/asm/sysreg.h | 1 + > drivers/hwtracing/coresight/Kconfig | 11 + > drivers/hwtracing/coresight/Makefile | 1 + > drivers/hwtracing/coresight/coresight-trbe.c | 1023 ++++++++++++++++++++++ > drivers/hwtracing/coresight/coresight-trbe.h | 160 ++++ > 6 files changed, 1235 insertions(+) > create mode 100644 Documentation/trace/coresight/coresight-trbe.rst > create mode 100644 drivers/hwtracing/coresight/coresight-trbe.c > create mode 100644 drivers/hwtracing/coresight/coresight-trbe.h > +
[...]
> +static void arm_trbe_probe_coresight_cpu(void *info) > +{ > + struct trbe_drvdata *drvdata = info; > + struct coresight_desc desc = { 0 }; > + int cpu = smp_processor_id(); > + struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu); > + struct coresight_device *trbe_csdev = per_cpu(csdev_sink, cpu); > + u64 trbidr = read_sysreg_s(SYS_TRBIDR_EL1); > + struct device *dev; > + > + if (WARN_ON(!cpudata)) > + goto cpu_clear;
There is already a check for this in arm_trbe_probe_coresight(), we couldn't be here if there was a problem with the allocation.
> + > + if (trbe_csdev) > + return;
Now that's a reason to have a WARN_ON(). If we are probing and a sink is already present in this cpu's slot, something went seriously wrong and we should be clear about it.
> + > + cpudata->cpu = smp_processor_id(); > + cpudata->drvdata = drvdata; > + dev = &cpudata->drvdata->pdev->dev; > + > + if (!is_trbe_available()) { > + pr_err("TRBE is not implemented on cpu %d\n", cpudata->cpu); > + goto cpu_clear; > + } > + > + if (!is_trbe_programmable(trbidr)) { > + pr_err("TRBE is owned in higher exception level on cpu %d\n", cpudata->cpu); > + goto cpu_clear; > + } > + desc.name = devm_kasprintf(dev, GFP_KERNEL, "%s%d", DRVNAME, smp_processor_id());
We will end up with "arm_trbe0", "arm_trbe1" and so on in sysfs... Is the "arm_" part absolutely needed? I think this should be like what we do for etmv3 and etmv4 where only "etmX" shows up in sysfs.
> + if (IS_ERR(desc.name)) > + goto cpu_clear; > + > + desc.type = CORESIGHT_DEV_TYPE_SINK; > + desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM; > + desc.ops = &arm_trbe_cs_ops; > + desc.pdata = dev_get_platdata(dev); > + desc.groups = arm_trbe_groups; > + desc.dev = dev; > + trbe_csdev = coresight_register(&desc); > + if (IS_ERR(trbe_csdev)) > + goto cpu_clear; > + > + dev_set_drvdata(&trbe_csdev->dev, cpudata); > + cpudata->trbe_dbm = get_trbe_flag_update(trbidr); > + cpudata->trbe_align = 1ULL << get_trbe_address_align(trbidr); > + if (cpudata->trbe_align > SZ_2K) { > + pr_err("Unsupported alignment on cpu %d\n", cpudata->cpu); > + goto cpu_clear;
Here coresight_unregister() should be called. The other option is to call coresight_register() when everything else is known to be fine, which is the favoured approach.
> + } > + per_cpu(csdev_sink, cpu) = trbe_csdev; > + trbe_reset_local(); > + enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE); > + return; > +cpu_clear: > + cpumask_clear_cpu(cpudata->cpu, &cpudata->drvdata->supported_cpus); > +} > + > +static void arm_trbe_remove_coresight_cpu(void *info) > +{ > + int cpu = smp_processor_id(); > + struct trbe_drvdata *drvdata = info; > + struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu); > + struct coresight_device *trbe_csdev = per_cpu(csdev_sink, cpu); > + > + if (trbe_csdev) {
In what scenario do you see not having a trbe_csdev and still needing to disable IRQs for the HW? If there is a such a case then a few lines of comment is needed.
> + coresight_unregister(trbe_csdev); > + cpudata->drvdata = NULL; > + per_cpu(csdev_sink, cpu) = NULL; > + } > + disable_percpu_irq(drvdata->irq); > + trbe_reset_local();
Theoretically this code shouldn't run when the TRBE is enabled, because the CS core will prevent that from happening. As sush disabling interrupts after coresight_unregister() has been called and setting cpudata->drvdata to NULL should be fine. But from an outsider's point of view it will look very bizarre. Either write a comment to explain all that or call the above two before doing the cleanup.
> +} > + > +static int arm_trbe_probe_coresight(struct trbe_drvdata *drvdata) > +{ > + drvdata->cpudata = alloc_percpu(typeof(*drvdata->cpudata)); > + if (IS_ERR(drvdata->cpudata)) > + return PTR_ERR(drvdata->cpudata);
As far as I can tell alloc_percpu() returns NULL on failure and nothing else.
> + > + arm_trbe_probe_coresight_cpu(drvdata); > + smp_call_function_many(&drvdata->supported_cpus, arm_trbe_probe_coresight_cpu, drvdata, 1);
The above two calls look racy to me. The executing process could be moved to another CPU between the call to arm_trbe_probe_coresight_cpu() and smp_call_function_many(), which would prevent the initialisation of the TRBE on the new CPU to be done. I suggest using a for_each_cpu() loop where smp_call_function_single() would be used. That way we are guaranteed all the TRBEs will be initialised.
> + return 0; > +} > + > +static int arm_trbe_remove_coresight(struct trbe_drvdata *drvdata) > +{ > + arm_trbe_remove_coresight_cpu(drvdata); > + smp_call_function_many(&drvdata->supported_cpus, arm_trbe_remove_coresight_cpu, drvdata, 1);
Same as above.
I'm out of time for today, more to come tomorrow.
Mathieu
> + free_percpu(drvdata->cpudata); > + return 0; > +} > + > +static int arm_trbe_cpu_startup(unsigned int cpu, struct hlist_node *node) > +{ > + struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct trbe_drvdata, hotplug_node); > + > + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) { > + if (!per_cpu(csdev_sink, cpu)) { > + arm_trbe_probe_coresight_cpu(drvdata); > + } else { > + trbe_reset_local(); > + enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE); > + } > + } > + return 0; > +} > + > +static int arm_trbe_cpu_teardown(unsigned int cpu, struct hlist_node *node) > +{ > + struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct trbe_drvdata, hotplug_node); > + > + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) { > + disable_percpu_irq(drvdata->irq); > + trbe_reset_local(); > + } > + return 0; > +} > + > +static int arm_trbe_probe_cpuhp(struct trbe_drvdata *drvdata) > +{ > + enum cpuhp_state trbe_online; > + > + trbe_online = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, DRVNAME, > + arm_trbe_cpu_startup, arm_trbe_cpu_teardown); > + if (trbe_online < 0) > + return -EINVAL; > + > + if (cpuhp_state_add_instance(trbe_online, &drvdata->hotplug_node)) > + return -EINVAL; > + > + drvdata->trbe_online = trbe_online; > + return 0; > +} > + > +static void arm_trbe_remove_cpuhp(struct trbe_drvdata *drvdata) > +{ > + cpuhp_remove_multi_state(drvdata->trbe_online); > +} > + > +static int arm_trbe_probe_irq(struct platform_device *pdev, > + struct trbe_drvdata *drvdata) > +{ > + drvdata->irq = platform_get_irq(pdev, 0); > + if (!drvdata->irq) { > + pr_err("IRQ not found for the platform device\n"); > + return -ENXIO; > + } > + > + if (!irq_is_percpu(drvdata->irq)) { > + pr_err("IRQ is not a PPI\n"); > + return -EINVAL; > + } > + > + if (irq_get_percpu_devid_partition(drvdata->irq, &drvdata->supported_cpus)) > + return -EINVAL; > + > + drvdata->handle = alloc_percpu(typeof(*drvdata->handle)); > + if (!drvdata->handle) > + return -ENOMEM; > + > + if (request_percpu_irq(drvdata->irq, arm_trbe_irq_handler, DRVNAME, drvdata->handle)) { > + free_percpu(drvdata->handle); > + return -EINVAL; > + } > + return 0; > +} > + > +static void arm_trbe_remove_irq(struct trbe_drvdata *drvdata) > +{ > + free_percpu_irq(drvdata->irq, drvdata->handle); > + free_percpu(drvdata->handle); > +} > + > +static int arm_trbe_device_probe(struct platform_device *pdev) > +{ > + struct coresight_platform_data *pdata; > + struct trbe_drvdata *drvdata; > + struct device *dev = &pdev->dev; > + int ret; > + > + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL); > + if (IS_ERR(drvdata)) > + return -ENOMEM; > + > + pdata = coresight_get_platform_data(dev); > + if (IS_ERR(pdata)) { > + kfree(drvdata); > + return -ENOMEM; > + } > + > + dev_set_drvdata(dev, drvdata); > + dev->platform_data = pdata; > + drvdata->pdev = pdev; > + ret = arm_trbe_probe_irq(pdev, drvdata); > + if (ret) > + goto irq_failed; > + > + ret = arm_trbe_probe_coresight(drvdata); > + if (ret) > + goto probe_failed; > + > + ret = arm_trbe_probe_cpuhp(drvdata); > + if (ret) > + goto cpuhp_failed; > + > + return 0; > +cpuhp_failed: > + arm_trbe_remove_coresight(drvdata); > +probe_failed: > + arm_trbe_remove_irq(drvdata); > +irq_failed: > + kfree(pdata); > + kfree(drvdata); > + return ret; > +} > + > +static int arm_trbe_device_remove(struct platform_device *pdev) > +{ > + struct coresight_platform_data *pdata = dev_get_platdata(&pdev->dev); > + struct trbe_drvdata *drvdata = platform_get_drvdata(pdev); > + > + arm_trbe_remove_coresight(drvdata); > + arm_trbe_remove_cpuhp(drvdata); > + arm_trbe_remove_irq(drvdata); > + kfree(pdata); > + kfree(drvdata); > + return 0; > +} > + > +static const struct of_device_id arm_trbe_of_match[] = { > + { .compatible = "arm,trace-buffer-extension"}, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, arm_trbe_of_match); > + > +static struct platform_driver arm_trbe_driver = { > + .driver = { > + .name = DRVNAME, > + .of_match_table = of_match_ptr(arm_trbe_of_match), > + .suppress_bind_attrs = true, > + }, > + .probe = arm_trbe_device_probe, > + .remove = arm_trbe_device_remove, > +}; > + > +static int __init arm_trbe_init(void) > +{ > + int ret; > + > + if (arm64_kernel_unmapped_at_el0()) { > + pr_err("TRBE wouldn't work if kernel gets unmapped at EL0\n"); > + return -EOPNOTSUPP; > + } > + > + ret = platform_driver_register(&arm_trbe_driver); > + if (!ret) > + return 0; > + > + pr_err("Error registering %s platform driver\n", DRVNAME); > + return ret; > +} > + > +static void __exit arm_trbe_exit(void) > +{ > + platform_driver_unregister(&arm_trbe_driver); > +} > +module_init(arm_trbe_init); > +module_exit(arm_trbe_exit); > + > +MODULE_AUTHOR("Anshuman Khandual <anshuman.khandual@arm.com>"); > +MODULE_DESCRIPTION("Arm Trace Buffer Extension (TRBE) driver"); > +MODULE_LICENSE("GPL v2"); > diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/hwtracing/coresight/coresight-trbe.h > new file mode 100644 > index 0000000..43308bc > --- /dev/null > +++ b/drivers/hwtracing/coresight/coresight-trbe.h > @@ -0,0 +1,160 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * This contains all required hardware related helper functions for > + * Trace Buffer Extension (TRBE) driver in the coresight framework. > + * > + * Copyright (C) 2020 ARM Ltd. > + * > + * Author: Anshuman Khandual <anshuman.khandual@arm.com> > + */ > +#include <linux/coresight.h> > +#include <linux/device.h> > +#include <linux/irq.h> > +#include <linux/kernel.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/smp.h> > + > +#include "coresight-etm-perf.h" > + > +DECLARE_PER_CPU(struct coresight_device *, csdev_sink); > + > +static inline bool is_trbe_available(void) > +{ > + u64 aa64dfr0 = read_sysreg_s(SYS_ID_AA64DFR0_EL1); > + unsigned int trbe = cpuid_feature_extract_unsigned_field(aa64dfr0, ID_AA64DFR0_TRBE_SHIFT); > + > + return trbe >= 0b0001; > +} > + > +static inline bool is_trbe_enabled(void) > +{ > + u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1); > + > + return trblimitr & TRBLIMITR_ENABLE; > +} > + > +#define TRBE_EC_OTHERS 0 > +#define TRBE_EC_STAGE1_ABORT 36 > +#define TRBE_EC_STAGE2_ABORT 37 > + > +static inline int get_trbe_ec(u64 trbsr) > +{ > + return (trbsr >> TRBSR_EC_SHIFT) & TRBSR_EC_MASK; > +} > + > +#define TRBE_BSC_NOT_STOPPED 0 > +#define TRBE_BSC_FILLED 1 > +#define TRBE_BSC_TRIGGERED 2 > + > +static inline int get_trbe_bsc(u64 trbsr) > +{ > + return (trbsr >> TRBSR_BSC_SHIFT) & TRBSR_BSC_MASK; > +} > + > +static inline void clr_trbe_irq(void) > +{ > + u64 trbsr = read_sysreg_s(SYS_TRBSR_EL1); > + > + trbsr &= ~TRBSR_IRQ; > + write_sysreg_s(trbsr, SYS_TRBSR_EL1); > +} > + > +static inline bool is_trbe_irq(u64 trbsr) > +{ > + return trbsr & TRBSR_IRQ; > +} > + > +static inline bool is_trbe_trg(u64 trbsr) > +{ > + return trbsr & TRBSR_TRG; > +} > + > +static inline bool is_trbe_wrap(u64 trbsr) > +{ > + return trbsr & TRBSR_WRAP; > +} > + > +static inline bool is_trbe_abort(u64 trbsr) > +{ > + return trbsr & TRBSR_ABORT; > +} > + > +static inline bool is_trbe_running(u64 trbsr) > +{ > + return !(trbsr & TRBSR_STOP); > +} > + > +#define TRBE_TRIG_MODE_STOP 0 > +#define TRBE_TRIG_MODE_IRQ 1 > +#define TRBE_TRIG_MODE_IGNORE 3 > + > +#define TRBE_FILL_MODE_FILL 0 > +#define TRBE_FILL_MODE_WRAP 1 > +#define TRBE_FILL_MODE_CIRCULAR_BUFFER 3 > + > +static inline void set_trbe_disabled(void) > +{ > + u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1); > + > + trblimitr &= ~TRBLIMITR_ENABLE; > + write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1); > +} > + > +static inline bool get_trbe_flag_update(u64 trbidr) > +{ > + return trbidr & TRBIDR_FLAG; > +} > + > +static inline bool is_trbe_programmable(u64 trbidr) > +{ > + return !(trbidr & TRBIDR_PROG); > +} > + > +static inline int get_trbe_address_align(u64 trbidr) > +{ > + return (trbidr >> TRBIDR_ALIGN_SHIFT) & TRBIDR_ALIGN_MASK; > +} > + > +static inline unsigned long get_trbe_write_pointer(void) > +{ > + u64 trbptr = read_sysreg_s(SYS_TRBPTR_EL1); > + unsigned long addr = (trbptr >> TRBPTR_PTR_SHIFT) & TRBPTR_PTR_MASK; > + > + return addr; > +} > + > +static inline void set_trbe_write_pointer(unsigned long addr) > +{ > + WARN_ON(is_trbe_enabled()); > + addr = (addr >> TRBPTR_PTR_SHIFT) & TRBPTR_PTR_MASK; > + write_sysreg_s(addr, SYS_TRBPTR_EL1); > +} > + > +static inline unsigned long get_trbe_limit_pointer(void) > +{ > + u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1); > + unsigned long limit = (trblimitr >> TRBLIMITR_LIMIT_SHIFT) & TRBLIMITR_LIMIT_MASK; > + unsigned long addr = limit << TRBLIMITR_LIMIT_SHIFT; > + > + WARN_ON(!IS_ALIGNED(addr, PAGE_SIZE)); > + return addr; > +} > + > +static inline unsigned long get_trbe_base_pointer(void) > +{ > + u64 trbbaser = read_sysreg_s(SYS_TRBBASER_EL1); > + unsigned long addr = (trbbaser >> TRBBASER_BASE_SHIFT) & TRBBASER_BASE_MASK; > + > + addr = addr << TRBBASER_BASE_SHIFT; > + WARN_ON(!IS_ALIGNED(addr, PAGE_SIZE)); > + return addr; > +} > + > +static inline void set_trbe_base_pointer(unsigned long addr) > +{ > + WARN_ON(is_trbe_enabled()); > + WARN_ON(!IS_ALIGNED(addr, (1UL << TRBLIMITR_LIMIT_SHIFT))); > + WARN_ON(!IS_ALIGNED(addr, PAGE_SIZE)); > + write_sysreg_s(addr, SYS_TRBBASER_EL1); > +} > -- > 2.7.4 >
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