diff options
Diffstat (limited to 'arch/s390/kernel/perf_cpum_cf.c')
-rw-r--r-- | arch/s390/kernel/perf_cpum_cf.c | 580 |
1 files changed, 580 insertions, 0 deletions
diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c new file mode 100644 index 000000000..dddb32e53 --- /dev/null +++ b/arch/s390/kernel/perf_cpum_cf.c @@ -0,0 +1,580 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Performance event support for s390x - CPU-measurement Counter Facility + * + * Copyright IBM Corp. 2012, 2019 + * Author(s): Hendrik Brueckner <brueckner@linux.ibm.com> + */ +#define KMSG_COMPONENT "cpum_cf" +#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt + +#include <linux/kernel.h> +#include <linux/kernel_stat.h> +#include <linux/percpu.h> +#include <linux/notifier.h> +#include <linux/init.h> +#include <linux/export.h> +#include <asm/cpu_mcf.h> + +static enum cpumf_ctr_set get_counter_set(u64 event) +{ + int set = CPUMF_CTR_SET_MAX; + + if (event < 32) + set = CPUMF_CTR_SET_BASIC; + else if (event < 64) + set = CPUMF_CTR_SET_USER; + else if (event < 128) + set = CPUMF_CTR_SET_CRYPTO; + else if (event < 288) + set = CPUMF_CTR_SET_EXT; + else if (event >= 448 && event < 496) + set = CPUMF_CTR_SET_MT_DIAG; + + return set; +} + +static int validate_ctr_version(const struct hw_perf_event *hwc) +{ + struct cpu_cf_events *cpuhw; + int err = 0; + u16 mtdiag_ctl; + + cpuhw = &get_cpu_var(cpu_cf_events); + + /* check required version for counter sets */ + switch (hwc->config_base) { + case CPUMF_CTR_SET_BASIC: + case CPUMF_CTR_SET_USER: + if (cpuhw->info.cfvn < 1) + err = -EOPNOTSUPP; + break; + case CPUMF_CTR_SET_CRYPTO: + if ((cpuhw->info.csvn >= 1 && cpuhw->info.csvn <= 5 && + hwc->config > 79) || + (cpuhw->info.csvn >= 6 && hwc->config > 83)) + err = -EOPNOTSUPP; + break; + case CPUMF_CTR_SET_EXT: + if (cpuhw->info.csvn < 1) + err = -EOPNOTSUPP; + if ((cpuhw->info.csvn == 1 && hwc->config > 159) || + (cpuhw->info.csvn == 2 && hwc->config > 175) || + (cpuhw->info.csvn >= 3 && cpuhw->info.csvn <= 5 + && hwc->config > 255) || + (cpuhw->info.csvn >= 6 && hwc->config > 287)) + err = -EOPNOTSUPP; + break; + case CPUMF_CTR_SET_MT_DIAG: + if (cpuhw->info.csvn <= 3) + err = -EOPNOTSUPP; + /* + * MT-diagnostic counters are read-only. The counter set + * is automatically enabled and activated on all CPUs with + * multithreading (SMT). Deactivation of multithreading + * also disables the counter set. State changes are ignored + * by lcctl(). Because Linux controls SMT enablement through + * a kernel parameter only, the counter set is either disabled + * or enabled and active. + * + * Thus, the counters can only be used if SMT is on and the + * counter set is enabled and active. + */ + mtdiag_ctl = cpumf_ctr_ctl[CPUMF_CTR_SET_MT_DIAG]; + if (!((cpuhw->info.auth_ctl & mtdiag_ctl) && + (cpuhw->info.enable_ctl & mtdiag_ctl) && + (cpuhw->info.act_ctl & mtdiag_ctl))) + err = -EOPNOTSUPP; + break; + } + + put_cpu_var(cpu_cf_events); + return err; +} + +static int validate_ctr_auth(const struct hw_perf_event *hwc) +{ + struct cpu_cf_events *cpuhw; + u64 ctrs_state; + int err = 0; + + cpuhw = &get_cpu_var(cpu_cf_events); + + /* Check authorization for cpu counter sets. + * If the particular CPU counter set is not authorized, + * return with -ENOENT in order to fall back to other + * PMUs that might suffice the event request. + */ + ctrs_state = cpumf_ctr_ctl[hwc->config_base]; + if (!(ctrs_state & cpuhw->info.auth_ctl)) + err = -ENOENT; + + put_cpu_var(cpu_cf_events); + return err; +} + +/* + * Change the CPUMF state to active. + * Enable and activate the CPU-counter sets according + * to the per-cpu control state. + */ +static void cpumf_pmu_enable(struct pmu *pmu) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + int err; + + if (cpuhw->flags & PMU_F_ENABLED) + return; + + err = lcctl(cpuhw->state); + if (err) { + pr_err("Enabling the performance measuring unit " + "failed with rc=%x\n", err); + return; + } + + cpuhw->flags |= PMU_F_ENABLED; +} + +/* + * Change the CPUMF state to inactive. + * Disable and enable (inactive) the CPU-counter sets according + * to the per-cpu control state. + */ +static void cpumf_pmu_disable(struct pmu *pmu) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + int err; + u64 inactive; + + if (!(cpuhw->flags & PMU_F_ENABLED)) + return; + + inactive = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1); + err = lcctl(inactive); + if (err) { + pr_err("Disabling the performance measuring unit " + "failed with rc=%x\n", err); + return; + } + + cpuhw->flags &= ~PMU_F_ENABLED; +} + + +/* Number of perf events counting hardware events */ +static atomic_t num_events = ATOMIC_INIT(0); +/* Used to avoid races in calling reserve/release_cpumf_hardware */ +static DEFINE_MUTEX(pmc_reserve_mutex); + +/* Release the PMU if event is the last perf event */ +static void hw_perf_event_destroy(struct perf_event *event) +{ + if (!atomic_add_unless(&num_events, -1, 1)) { + mutex_lock(&pmc_reserve_mutex); + if (atomic_dec_return(&num_events) == 0) + __kernel_cpumcf_end(); + mutex_unlock(&pmc_reserve_mutex); + } +} + +/* CPUMF <-> perf event mappings for kernel+userspace (basic set) */ +static const int cpumf_generic_events_basic[] = { + [PERF_COUNT_HW_CPU_CYCLES] = 0, + [PERF_COUNT_HW_INSTRUCTIONS] = 1, + [PERF_COUNT_HW_CACHE_REFERENCES] = -1, + [PERF_COUNT_HW_CACHE_MISSES] = -1, + [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1, + [PERF_COUNT_HW_BRANCH_MISSES] = -1, + [PERF_COUNT_HW_BUS_CYCLES] = -1, +}; +/* CPUMF <-> perf event mappings for userspace (problem-state set) */ +static const int cpumf_generic_events_user[] = { + [PERF_COUNT_HW_CPU_CYCLES] = 32, + [PERF_COUNT_HW_INSTRUCTIONS] = 33, + [PERF_COUNT_HW_CACHE_REFERENCES] = -1, + [PERF_COUNT_HW_CACHE_MISSES] = -1, + [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1, + [PERF_COUNT_HW_BRANCH_MISSES] = -1, + [PERF_COUNT_HW_BUS_CYCLES] = -1, +}; + +static int __hw_perf_event_init(struct perf_event *event, unsigned int type) +{ + struct perf_event_attr *attr = &event->attr; + struct hw_perf_event *hwc = &event->hw; + enum cpumf_ctr_set set; + int err = 0; + u64 ev; + + switch (type) { + case PERF_TYPE_RAW: + /* Raw events are used to access counters directly, + * hence do not permit excludes */ + if (attr->exclude_kernel || attr->exclude_user || + attr->exclude_hv) + return -EOPNOTSUPP; + ev = attr->config; + break; + + case PERF_TYPE_HARDWARE: + if (is_sampling_event(event)) /* No sampling support */ + return -ENOENT; + ev = attr->config; + /* Count user space (problem-state) only */ + if (!attr->exclude_user && attr->exclude_kernel) { + if (ev >= ARRAY_SIZE(cpumf_generic_events_user)) + return -EOPNOTSUPP; + ev = cpumf_generic_events_user[ev]; + + /* No support for kernel space counters only */ + } else if (!attr->exclude_kernel && attr->exclude_user) { + return -EOPNOTSUPP; + + /* Count user and kernel space */ + } else { + if (ev >= ARRAY_SIZE(cpumf_generic_events_basic)) + return -EOPNOTSUPP; + ev = cpumf_generic_events_basic[ev]; + } + break; + + default: + return -ENOENT; + } + + if (ev == -1) + return -ENOENT; + + if (ev > PERF_CPUM_CF_MAX_CTR) + return -ENOENT; + + /* Obtain the counter set to which the specified counter belongs */ + set = get_counter_set(ev); + switch (set) { + case CPUMF_CTR_SET_BASIC: + case CPUMF_CTR_SET_USER: + case CPUMF_CTR_SET_CRYPTO: + case CPUMF_CTR_SET_EXT: + case CPUMF_CTR_SET_MT_DIAG: + /* + * Use the hardware perf event structure to store the + * counter number in the 'config' member and the counter + * set number in the 'config_base'. The counter set number + * is then later used to enable/disable the counter(s). + */ + hwc->config = ev; + hwc->config_base = set; + break; + case CPUMF_CTR_SET_MAX: + /* The counter could not be associated to a counter set */ + return -EINVAL; + }; + + /* Initialize for using the CPU-measurement counter facility */ + if (!atomic_inc_not_zero(&num_events)) { + mutex_lock(&pmc_reserve_mutex); + if (atomic_read(&num_events) == 0 && __kernel_cpumcf_begin()) + err = -EBUSY; + else + atomic_inc(&num_events); + mutex_unlock(&pmc_reserve_mutex); + } + if (err) + return err; + event->destroy = hw_perf_event_destroy; + + /* Finally, validate version and authorization of the counter set */ + err = validate_ctr_auth(hwc); + if (!err) + err = validate_ctr_version(hwc); + + return err; +} + +/* Events CPU_CYLCES and INSTRUCTIONS can be submitted with two different + * attribute::type values: + * - PERF_TYPE_HARDWARE: + * - pmu->type: + * Handle both type of invocations identical. They address the same hardware. + * The result is different when event modifiers exclude_kernel and/or + * exclude_user are also set. + */ +static int cpumf_pmu_event_type(struct perf_event *event) +{ + u64 ev = event->attr.config; + + if (cpumf_generic_events_basic[PERF_COUNT_HW_CPU_CYCLES] == ev || + cpumf_generic_events_basic[PERF_COUNT_HW_INSTRUCTIONS] == ev || + cpumf_generic_events_user[PERF_COUNT_HW_CPU_CYCLES] == ev || + cpumf_generic_events_user[PERF_COUNT_HW_INSTRUCTIONS] == ev) + return PERF_TYPE_HARDWARE; + return PERF_TYPE_RAW; +} + +static int cpumf_pmu_event_init(struct perf_event *event) +{ + unsigned int type = event->attr.type; + int err; + + if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_RAW) + err = __hw_perf_event_init(event, type); + else if (event->pmu->type == type) + /* Registered as unknown PMU */ + err = __hw_perf_event_init(event, cpumf_pmu_event_type(event)); + else + return -ENOENT; + + if (unlikely(err) && event->destroy) + event->destroy(event); + + return err; +} + +static int hw_perf_event_reset(struct perf_event *event) +{ + u64 prev, new; + int err; + + do { + prev = local64_read(&event->hw.prev_count); + err = ecctr(event->hw.config, &new); + if (err) { + if (err != 3) + break; + /* The counter is not (yet) available. This + * might happen if the counter set to which + * this counter belongs is in the disabled + * state. + */ + new = 0; + } + } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev); + + return err; +} + +static void hw_perf_event_update(struct perf_event *event) +{ + u64 prev, new, delta; + int err; + + do { + prev = local64_read(&event->hw.prev_count); + err = ecctr(event->hw.config, &new); + if (err) + return; + } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev); + + delta = (prev <= new) ? new - prev + : (-1ULL - prev) + new + 1; /* overflow */ + local64_add(delta, &event->count); +} + +static void cpumf_pmu_read(struct perf_event *event) +{ + if (event->hw.state & PERF_HES_STOPPED) + return; + + hw_perf_event_update(event); +} + +static void cpumf_pmu_start(struct perf_event *event, int flags) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + struct hw_perf_event *hwc = &event->hw; + + if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED))) + return; + + if (WARN_ON_ONCE(hwc->config == -1)) + return; + + if (flags & PERF_EF_RELOAD) + WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE)); + + hwc->state = 0; + + /* (Re-)enable and activate the counter set */ + ctr_set_enable(&cpuhw->state, hwc->config_base); + ctr_set_start(&cpuhw->state, hwc->config_base); + + /* The counter set to which this counter belongs can be already active. + * Because all counters in a set are active, the event->hw.prev_count + * needs to be synchronized. At this point, the counter set can be in + * the inactive or disabled state. + */ + hw_perf_event_reset(event); + + /* increment refcount for this counter set */ + atomic_inc(&cpuhw->ctr_set[hwc->config_base]); +} + +static void cpumf_pmu_stop(struct perf_event *event, int flags) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + struct hw_perf_event *hwc = &event->hw; + + if (!(hwc->state & PERF_HES_STOPPED)) { + /* Decrement reference count for this counter set and if this + * is the last used counter in the set, clear activation + * control and set the counter set state to inactive. + */ + if (!atomic_dec_return(&cpuhw->ctr_set[hwc->config_base])) + ctr_set_stop(&cpuhw->state, hwc->config_base); + event->hw.state |= PERF_HES_STOPPED; + } + + if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) { + hw_perf_event_update(event); + event->hw.state |= PERF_HES_UPTODATE; + } +} + +static int cpumf_pmu_add(struct perf_event *event, int flags) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + + /* Check authorization for the counter set to which this + * counter belongs. + * For group events transaction, the authorization check is + * done in cpumf_pmu_commit_txn(). + */ + if (!(cpuhw->txn_flags & PERF_PMU_TXN_ADD)) + if (validate_ctr_auth(&event->hw)) + return -ENOENT; + + ctr_set_enable(&cpuhw->state, event->hw.config_base); + event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED; + + if (flags & PERF_EF_START) + cpumf_pmu_start(event, PERF_EF_RELOAD); + + perf_event_update_userpage(event); + + return 0; +} + +static void cpumf_pmu_del(struct perf_event *event, int flags) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + + cpumf_pmu_stop(event, PERF_EF_UPDATE); + + /* Check if any counter in the counter set is still used. If not used, + * change the counter set to the disabled state. This also clears the + * content of all counters in the set. + * + * When a new perf event has been added but not yet started, this can + * clear enable control and resets all counters in a set. Therefore, + * cpumf_pmu_start() always has to reenable a counter set. + */ + if (!atomic_read(&cpuhw->ctr_set[event->hw.config_base])) + ctr_set_disable(&cpuhw->state, event->hw.config_base); + + perf_event_update_userpage(event); +} + +/* + * Start group events scheduling transaction. + * Set flags to perform a single test at commit time. + * + * We only support PERF_PMU_TXN_ADD transactions. Save the + * transaction flags but otherwise ignore non-PERF_PMU_TXN_ADD + * transactions. + */ +static void cpumf_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + + WARN_ON_ONCE(cpuhw->txn_flags); /* txn already in flight */ + + cpuhw->txn_flags = txn_flags; + if (txn_flags & ~PERF_PMU_TXN_ADD) + return; + + perf_pmu_disable(pmu); + cpuhw->tx_state = cpuhw->state; +} + +/* + * Stop and cancel a group events scheduling tranctions. + * Assumes cpumf_pmu_del() is called for each successful added + * cpumf_pmu_add() during the transaction. + */ +static void cpumf_pmu_cancel_txn(struct pmu *pmu) +{ + unsigned int txn_flags; + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + + WARN_ON_ONCE(!cpuhw->txn_flags); /* no txn in flight */ + + txn_flags = cpuhw->txn_flags; + cpuhw->txn_flags = 0; + if (txn_flags & ~PERF_PMU_TXN_ADD) + return; + + WARN_ON(cpuhw->tx_state != cpuhw->state); + + perf_pmu_enable(pmu); +} + +/* + * Commit the group events scheduling transaction. On success, the + * transaction is closed. On error, the transaction is kept open + * until cpumf_pmu_cancel_txn() is called. + */ +static int cpumf_pmu_commit_txn(struct pmu *pmu) +{ + struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); + u64 state; + + WARN_ON_ONCE(!cpuhw->txn_flags); /* no txn in flight */ + + if (cpuhw->txn_flags & ~PERF_PMU_TXN_ADD) { + cpuhw->txn_flags = 0; + return 0; + } + + /* check if the updated state can be scheduled */ + state = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1); + state >>= CPUMF_LCCTL_ENABLE_SHIFT; + if ((state & cpuhw->info.auth_ctl) != state) + return -ENOENT; + + cpuhw->txn_flags = 0; + perf_pmu_enable(pmu); + return 0; +} + +/* Performance monitoring unit for s390x */ +static struct pmu cpumf_pmu = { + .task_ctx_nr = perf_sw_context, + .capabilities = PERF_PMU_CAP_NO_INTERRUPT, + .pmu_enable = cpumf_pmu_enable, + .pmu_disable = cpumf_pmu_disable, + .event_init = cpumf_pmu_event_init, + .add = cpumf_pmu_add, + .del = cpumf_pmu_del, + .start = cpumf_pmu_start, + .stop = cpumf_pmu_stop, + .read = cpumf_pmu_read, + .start_txn = cpumf_pmu_start_txn, + .commit_txn = cpumf_pmu_commit_txn, + .cancel_txn = cpumf_pmu_cancel_txn, +}; + +static int __init cpumf_pmu_init(void) +{ + int rc; + + if (!kernel_cpumcf_avail()) + return -ENODEV; + + cpumf_pmu.attr_groups = cpumf_cf_event_group(); + rc = perf_pmu_register(&cpumf_pmu, "cpum_cf", -1); + if (rc) + pr_err("Registering the cpum_cf PMU failed with rc=%i\n", rc); + return rc; +} +subsys_initcall(cpumf_pmu_init); |