/* * Hardware performance events for the Alpha. * * We implement HW counts on the EV67 and subsequent CPUs only. * * (C) 2010 Michael J. Cree * * Somewhat based on the Sparc code, and to a lesser extent the PowerPC and * ARM code, which are copyright by their respective authors. */ #include #include #include #include #include #include #include #include #include #include #include #include #include /* The maximum number of PMCs on any Alpha CPU whatsoever. */ #define MAX_HWEVENTS 3 #define PMC_NO_INDEX -1 /* For tracking PMCs and the hw events they monitor on each CPU. */ struct cpu_hw_events { int enabled; /* Number of events scheduled; also number entries valid in arrays below. */ int n_events; /* Number events added since last hw_perf_disable(). */ int n_added; /* Events currently scheduled. */ struct perf_event *event[MAX_HWEVENTS]; /* Event type of each scheduled event. */ unsigned long evtype[MAX_HWEVENTS]; /* Current index of each scheduled event; if not yet determined * contains PMC_NO_INDEX. */ int current_idx[MAX_HWEVENTS]; /* The active PMCs' config for easy use with wrperfmon(). */ unsigned long config; /* The active counters' indices for easy use with wrperfmon(). */ unsigned long idx_mask; }; DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events); /* * A structure to hold the description of the PMCs available on a particular * type of Alpha CPU. */ struct alpha_pmu_t { /* Mapping of the perf system hw event types to indigenous event types */ const int *event_map; /* The number of entries in the event_map */ int max_events; /* The number of PMCs on this Alpha */ int num_pmcs; /* * All PMC counters reside in the IBOX register PCTR. This is the * LSB of the counter. */ int pmc_count_shift[MAX_HWEVENTS]; /* * The mask that isolates the PMC bits when the LSB of the counter * is shifted to bit 0. */ unsigned long pmc_count_mask[MAX_HWEVENTS]; /* The maximum period the PMC can count. */ unsigned long pmc_max_period[MAX_HWEVENTS]; /* * The maximum value that may be written to the counter due to * hardware restrictions is pmc_max_period - pmc_left. */ long pmc_left[3]; /* Subroutine for allocation of PMCs. Enforces constraints. */ int (*check_constraints)(struct perf_event **, unsigned long *, int); }; /* * The Alpha CPU PMU description currently in operation. This is set during * the boot process to the specific CPU of the machine. */ static const struct alpha_pmu_t *alpha_pmu; #define HW_OP_UNSUPPORTED -1 /* * The hardware description of the EV67, EV68, EV69, EV7 and EV79 PMUs * follow. Since they are identical we refer to them collectively as the * EV67 henceforth. */ /* * EV67 PMC event types * * There is no one-to-one mapping of the possible hw event types to the * actual codes that are used to program the PMCs hence we introduce our * own hw event type identifiers. */ enum ev67_pmc_event_type { EV67_CYCLES = 1, EV67_INSTRUCTIONS, EV67_BCACHEMISS, EV67_MBOXREPLAY, EV67_LAST_ET }; #define EV67_NUM_EVENT_TYPES (EV67_LAST_ET-EV67_CYCLES) /* Mapping of the hw event types to the perf tool interface */ static const int ev67_perfmon_event_map[] = { [PERF_COUNT_HW_CPU_CYCLES] = EV67_CYCLES, [PERF_COUNT_HW_INSTRUCTIONS] = EV67_INSTRUCTIONS, [PERF_COUNT_HW_CACHE_REFERENCES] = HW_OP_UNSUPPORTED, [PERF_COUNT_HW_CACHE_MISSES] = EV67_BCACHEMISS, }; struct ev67_mapping_t { int config; int idx; }; /* * The mapping used for one event only - these must be in same order as enum * ev67_pmc_event_type definition. */ static const struct ev67_mapping_t ev67_mapping[] = { {EV67_PCTR_INSTR_CYCLES, 1}, /* EV67_CYCLES, */ {EV67_PCTR_INSTR_CYCLES, 0}, /* EV67_INSTRUCTIONS */ {EV67_PCTR_INSTR_BCACHEMISS, 1}, /* EV67_BCACHEMISS */ {EV67_PCTR_CYCLES_MBOX, 1} /* EV67_MBOXREPLAY */ }; /* * Check that a group of events can be simultaneously scheduled on to the * EV67 PMU. Also allocate counter indices and config. */ static int ev67_check_constraints(struct perf_event **event, unsigned long *evtype, int n_ev) { int idx0; unsigned long config; idx0 = ev67_mapping[evtype[0]-1].idx; config = ev67_mapping[evtype[0]-1].config; if (n_ev == 1) goto success; BUG_ON(n_ev != 2); if (evtype[0] == EV67_MBOXREPLAY || evtype[1] == EV67_MBOXREPLAY) { /* MBOX replay traps must be on PMC 1 */ idx0 = (evtype[0] == EV67_MBOXREPLAY) ? 1 : 0; /* Only cycles can accompany MBOX replay traps */ if (evtype[idx0] == EV67_CYCLES) { config = EV67_PCTR_CYCLES_MBOX; goto success; } } if (evtype[0] == EV67_BCACHEMISS || evtype[1] == EV67_BCACHEMISS) { /* Bcache misses must be on PMC 1 */ idx0 = (evtype[0] == EV67_BCACHEMISS) ? 1 : 0; /* Only instructions can accompany Bcache misses */ if (evtype[idx0] == EV67_INSTRUCTIONS) { config = EV67_PCTR_INSTR_BCACHEMISS; goto success; } } if (evtype[0] == EV67_INSTRUCTIONS || evtype[1] == EV67_INSTRUCTIONS) { /* Instructions must be on PMC 0 */ idx0 = (evtype[0] == EV67_INSTRUCTIONS) ? 0 : 1; /* By this point only cycles can accompany instructions */ if (evtype[idx0^1] == EV67_CYCLES) { config = EV67_PCTR_INSTR_CYCLES; goto success; } } /* Otherwise, darn it, there is a conflict. */ return -1; success: event[0]->hw.idx = idx0; event[0]->hw.config_base = config; if (n_ev == 2) { event[1]->hw.idx = idx0 ^ 1; event[1]->hw.config_base = config; } return 0; } static const struct alpha_pmu_t ev67_pmu = { .event_map = ev67_perfmon_event_map, .max_events = ARRAY_SIZE(ev67_perfmon_event_map), .num_pmcs = 2, .pmc_count_shift = {EV67_PCTR_0_COUNT_SHIFT, EV67_PCTR_1_COUNT_SHIFT, 0}, .pmc_count_mask = {EV67_PCTR_0_COUNT_MASK, EV67_PCTR_1_COUNT_MASK, 0}, .pmc_max_period = {(1UL<<20) - 1, (1UL<<20) - 1, 0}, .pmc_left = {16, 4, 0}, .check_constraints = ev67_check_constraints }; /* * Helper routines to ensure that we read/write only the correct PMC bits * when calling the wrperfmon PALcall. */ static inline void alpha_write_pmc(int idx, unsigned long val) { val &= alpha_pmu->pmc_count_mask[idx]; val <<= alpha_pmu->pmc_count_shift[idx]; val |= (1<>= alpha_pmu->pmc_count_shift[idx]; val &= alpha_pmu->pmc_count_mask[idx]; return val; } /* Set a new period to sample over */ static int alpha_perf_event_set_period(struct perf_event *event, struct hw_perf_event *hwc, int idx) { long left = local64_read(&hwc->period_left); long period = hwc->sample_period; int ret = 0; if (unlikely(left <= -period)) { left = period; local64_set(&hwc->period_left, left); hwc->last_period = period; ret = 1; } if (unlikely(left <= 0)) { left += period; local64_set(&hwc->period_left, left); hwc->last_period = period; ret = 1; } /* * Hardware restrictions require that the counters must not be * written with values that are too close to the maximum period. */ if (unlikely(left < alpha_pmu->pmc_left[idx])) left = alpha_pmu->pmc_left[idx]; if (left > (long)alpha_pmu->pmc_max_period[idx]) left = alpha_pmu->pmc_max_period[idx]; local64_set(&hwc->prev_count, (unsigned long)(-left)); alpha_write_pmc(idx, (unsigned long)(-left)); perf_event_update_userpage(event); return ret; } /* * Calculates the count (the 'delta') since the last time the PMC was read. * * As the PMCs' full period can easily be exceeded within the perf system * sampling period we cannot use any high order bits as a guard bit in the * PMCs to detect overflow as is done by other architectures. The code here * calculates the delta on the basis that there is no overflow when ovf is * zero. The value passed via ovf by the interrupt handler corrects for * overflow. * * This can be racey on rare occasions -- a call to this routine can occur * with an overflowed counter just before the PMI service routine is called. * The check for delta negative hopefully always rectifies this situation. */ static unsigned long alpha_perf_event_update(struct perf_event *event, struct hw_perf_event *hwc, int idx, long ovf) { long prev_raw_count, new_raw_count; long delta; again: prev_raw_count = local64_read(&hwc->prev_count); new_raw_count = alpha_read_pmc(idx); if (local64_cmpxchg(&hwc->prev_count, prev_raw_count, new_raw_count) != prev_raw_count) goto again; delta = (new_raw_count - (prev_raw_count & alpha_pmu->pmc_count_mask[idx])) + ovf; /* It is possible on very rare occasions that the PMC has overflowed * but the interrupt is yet to come. Detect and fix this situation. */ if (unlikely(delta < 0)) { delta += alpha_pmu->pmc_max_period[idx] + 1; } local64_add(delta, &event->count); local64_sub(delta, &hwc->period_left); return new_raw_count; } /* * Collect all HW events into the array event[]. */ static int collect_events(struct perf_event *group, int max_count, struct perf_event *event[], unsigned long *evtype, int *current_idx) { struct perf_event *pe; int n = 0; if (!is_software_event(group)) { if (n >= max_count) return -1; event[n] = group; evtype[n] = group->hw.event_base; current_idx[n++] = PMC_NO_INDEX; } list_for_each_entry(pe, &group->sibling_list, group_entry) { if (!is_software_event(pe) && pe->state != PERF_EVENT_STATE_OFF) { if (n >= max_count) return -1; event[n] = pe; evtype[n] = pe->hw.event_base; current_idx[n++] = PMC_NO_INDEX; } } return n; } /* * Check that a group of events can be simultaneously scheduled on to the PMU. */ static int alpha_check_constraints(struct perf_event **events, unsigned long *evtypes, int n_ev) { /* No HW events is possible from hw_perf_group_sched_in(). */ if (n_ev == 0) return 0; if (n_ev > alpha_pmu->num_pmcs) return -1; return alpha_pmu->check_constraints(events, evtypes, n_ev); } /* * If new events have been scheduled then update cpuc with the new * configuration. This may involve shifting cycle counts from one PMC to * another. */ static void maybe_change_configuration(struct cpu_hw_events *cpuc) { int j; if (cpuc->n_added == 0) return; /* Find counters that are moving to another PMC and update */ for (j = 0; j < cpuc->n_events; j++) { struct perf_event *pe = cpuc->event[j]; if (cpuc->current_idx[j] != PMC_NO_INDEX && cpuc->current_idx[j] != pe->hw.idx) { alpha_perf_event_update(pe, &pe->hw, cpuc->current_idx[j], 0); cpuc->current_idx[j] = PMC_NO_INDEX; } } /* Assign to counters all unassigned events. */ cpuc->idx_mask = 0; for (j = 0; j < cpuc->n_events; j++) { struct perf_event *pe = cpuc->event[j]; struct hw_perf_event *hwc = &pe->hw; int idx = hwc->idx; if (cpuc->current_idx[j] == PMC_NO_INDEX) { alpha_perf_event_set_period(pe, hwc, idx); cpuc->current_idx[j] = idx; } if (!(hwc->state & PERF_HES_STOPPED)) cpuc->idx_mask |= (1<current_idx[j]); } cpuc->config = cpuc->event[0]->hw.config_base; } /* Schedule perf HW event on to PMU. * - this function is called from outside this module via the pmu struct * returned from perf event initialisation. */ static int alpha_pmu_add(struct perf_event *event, int flags) { struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); struct hw_perf_event *hwc = &event->hw; int n0; int ret; unsigned long irq_flags; /* * The Sparc code has the IRQ disable first followed by the perf * disable, however this can lead to an overflowed counter with the * PMI disabled on rare occasions. The alpha_perf_event_update() * routine should detect this situation by noting a negative delta, * nevertheless we disable the PMCs first to enable a potential * final PMI to occur before we disable interrupts. */ perf_pmu_disable(event->pmu); local_irq_save(irq_flags); /* Default to error to be returned */ ret = -EAGAIN; /* Insert event on to PMU and if successful modify ret to valid return */ n0 = cpuc->n_events; if (n0 < alpha_pmu->num_pmcs) { cpuc->event[n0] = event; cpuc->evtype[n0] = event->hw.event_base; cpuc->current_idx[n0] = PMC_NO_INDEX; if (!alpha_check_constraints(cpuc->event, cpuc->evtype, n0+1)) { cpuc->n_events++; cpuc->n_added++; ret = 0; } } hwc->state = PERF_HES_UPTODATE; if (!(flags & PERF_EF_START)) hwc->state |= PERF_HES_STOPPED; local_irq_restore(irq_flags); perf_pmu_enable(event->pmu); return ret; } /* Disable performance monitoring unit * - this function is called from outside this module via the pmu struct * returned from perf event initialisation. */ static void alpha_pmu_del(struct perf_event *event, int flags) { struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); struct hw_perf_event *hwc = &event->hw; unsigned long irq_flags; int j; perf_pmu_disable(event->pmu); local_irq_save(irq_flags); for (j = 0; j < cpuc->n_events; j++) { if (event == cpuc->event[j]) { int idx = cpuc->current_idx[j]; /* Shift remaining entries down into the existing * slot. */ while (++j < cpuc->n_events) { cpuc->event[j - 1] = cpuc->event[j]; cpuc->evtype[j - 1] = cpuc->evtype[j]; cpuc->current_idx[j - 1] = cpuc->current_idx[j]; } /* Absorb the final count and turn off the event. */ alpha_perf_event_update(event, hwc, idx, 0); perf_event_update_userpage(event); cpuc->idx_mask &= ~(1UL<n_events--; break; } } local_irq_restore(irq_flags); perf_pmu_enable(event->pmu); } static void alpha_pmu_read(struct perf_event *event) { struct hw_perf_event *hwc = &event->hw; alpha_perf_event_update(event, hwc, hwc->idx, 0); } static void alpha_pmu_stop(struct perf_event *event, int flags) { struct hw_perf_event *hwc = &event->hw; struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (!(hwc->state & PERF_HES_STOPPED)) { cpuc->idx_mask &= ~(1UL<idx); hwc->state |= PERF_HES_STOPPED; } if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) { alpha_perf_event_update(event, hwc, hwc->idx, 0); hwc->state |= PERF_HES_UPTODATE; } if (cpuc->enabled) wrperfmon(PERFMON_CMD_DISABLE, (1UL<idx)); } static void alpha_pmu_start(struct perf_event *event, int flags) { struct hw_perf_event *hwc = &event->hw; struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED))) return; if (flags & PERF_EF_RELOAD) { WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE)); alpha_perf_event_set_period(event, hwc, hwc->idx); } hwc->state = 0; cpuc->idx_mask |= 1UL<idx; if (cpuc->enabled) wrperfmon(PERFMON_CMD_ENABLE, (1UL<idx)); } /* * Check that CPU performance counters are supported. * - currently support EV67 and later CPUs. * - actually some later revisions of the EV6 have the same PMC model as the * EV67 but we don't do suffiently deep CPU detection to detect them. * Bad luck to the very few people who might have one, I guess. */ static int supported_cpu(void) { struct percpu_struct *cpu; unsigned long cputype; /* Get cpu type from HW */ cpu = (struct percpu_struct *)((char *)hwrpb + hwrpb->processor_offset); cputype = cpu->type & 0xffffffff; /* Include all of EV67, EV68, EV7, EV79 and EV69 as supported. */ return (cputype >= EV67_CPU) && (cputype <= EV69_CPU); } static void hw_perf_event_destroy(struct perf_event *event) { /* Nothing to be done! */ return; } static int __hw_perf_event_init(struct perf_event *event) { struct perf_event_attr *attr = &event->attr; struct hw_perf_event *hwc = &event->hw; struct perf_event *evts[MAX_HWEVENTS]; unsigned long evtypes[MAX_HWEVENTS]; int idx_rubbish_bin[MAX_HWEVENTS]; int ev; int n; /* We only support a limited range of HARDWARE event types with one * only programmable via a RAW event type. */ if (attr->type == PERF_TYPE_HARDWARE) { if (attr->config >= alpha_pmu->max_events) return -EINVAL; ev = alpha_pmu->event_map[attr->config]; } else if (attr->type == PERF_TYPE_HW_CACHE) { return -EOPNOTSUPP; } else if (attr->type == PERF_TYPE_RAW) { ev = attr->config & 0xff; } else { return -EOPNOTSUPP; } if (ev < 0) { return ev; } /* The EV67 does not support mode exclusion */ if (attr->exclude_kernel || attr->exclude_user || attr->exclude_hv || attr->exclude_idle) { return -EPERM; } /* * We place the event type in event_base here and leave calculation * of the codes to programme the PMU for alpha_pmu_enable() because * it is only then we will know what HW events are actually * scheduled on to the PMU. At that point the code to programme the * PMU is put into config_base and the PMC to use is placed into * idx. We initialise idx (below) to PMC_NO_INDEX to indicate that * it is yet to be determined. */ hwc->event_base = ev; /* Collect events in a group together suitable for calling * alpha_check_constraints() to verify that the group as a whole can * be scheduled on to the PMU. */ n = 0; if (event->group_leader != event) { n = collect_events(event->group_leader, alpha_pmu->num_pmcs - 1, evts, evtypes, idx_rubbish_bin); if (n < 0) return -EINVAL; } evtypes[n] = hwc->event_base; evts[n] = event; if (alpha_check_constraints(evts, evtypes, n + 1)) return -EINVAL; /* Indicate that PMU config and idx are yet to be determined. */ hwc->config_base = 0; hwc->idx = PMC_NO_INDEX; event->destroy = hw_perf_event_destroy; /* * Most architectures reserve the PMU for their use at this point. * As there is no existing mechanism to arbitrate usage and there * appears to be no other user of the Alpha PMU we just assume * that we can just use it, hence a NO-OP here. * * Maybe an alpha_reserve_pmu() routine should be implemented but is * anything else ever going to use it? */ if (!hwc->sample_period) { hwc->sample_period = alpha_pmu->pmc_max_period[0]; hwc->last_period = hwc->sample_period; local64_set(&hwc->period_left, hwc->sample_period); } return 0; } /* * Main entry point to initialise a HW performance event. */ static int alpha_pmu_event_init(struct perf_event *event) { int err; switch (event->attr.type) { case PERF_TYPE_RAW: case PERF_TYPE_HARDWARE: case PERF_TYPE_HW_CACHE: break; default: return -ENOENT; } if (!alpha_pmu) return -ENODEV; /* Do the real initialisation work. */ err = __hw_perf_event_init(event); return err; } /* * Main entry point - enable HW performance counters. */ static void alpha_pmu_enable(struct pmu *pmu) { struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (cpuc->enabled) return; cpuc->enabled = 1; barrier(); if (cpuc->n_events > 0) { /* Update cpuc with information from any new scheduled events. */ maybe_change_configuration(cpuc); /* Start counting the desired events. */ wrperfmon(PERFMON_CMD_LOGGING_OPTIONS, EV67_PCTR_MODE_AGGREGATE); wrperfmon(PERFMON_CMD_DESIRED_EVENTS, cpuc->config); wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); } } /* * Main entry point - disable HW performance counters. */ static void alpha_pmu_disable(struct pmu *pmu) { struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (!cpuc->enabled) return; cpuc->enabled = 0; cpuc->n_added = 0; wrperfmon(PERFMON_CMD_DISABLE, cpuc->idx_mask); } static struct pmu pmu = { .pmu_enable = alpha_pmu_enable, .pmu_disable = alpha_pmu_disable, .event_init = alpha_pmu_event_init, .add = alpha_pmu_add, .del = alpha_pmu_del, .start = alpha_pmu_start, .stop = alpha_pmu_stop, .read = alpha_pmu_read, }; /* * Main entry point - don't know when this is called but it * obviously dumps debug info. */ void perf_event_print_debug(void) { unsigned long flags; unsigned long pcr; int pcr0, pcr1; int cpu; if (!supported_cpu()) return; local_irq_save(flags); cpu = smp_processor_id(); pcr = wrperfmon(PERFMON_CMD_READ, 0); pcr0 = (pcr >> alpha_pmu->pmc_count_shift[0]) & alpha_pmu->pmc_count_mask[0]; pcr1 = (pcr >> alpha_pmu->pmc_count_shift[1]) & alpha_pmu->pmc_count_mask[1]; pr_info("CPU#%d: PCTR0[%06x] PCTR1[%06x]\n", cpu, pcr0, pcr1); local_irq_restore(flags); } /* * Performance Monitoring Interrupt Service Routine called when a PMC * overflows. The PMC that overflowed is passed in la_ptr. */ static void alpha_perf_event_irq_handler(unsigned long la_ptr, struct pt_regs *regs) { struct cpu_hw_events *cpuc; struct perf_sample_data data; struct perf_event *event; struct hw_perf_event *hwc; int idx, j; __get_cpu_var(irq_pmi_count)++; cpuc = &__get_cpu_var(cpu_hw_events); /* Completely counting through the PMC's period to trigger a new PMC * overflow interrupt while in this interrupt routine is utterly * disastrous! The EV6 and EV67 counters are sufficiently large to * prevent this but to be really sure disable the PMCs. */ wrperfmon(PERFMON_CMD_DISABLE, cpuc->idx_mask); /* la_ptr is the counter that overflowed. */ if (unlikely(la_ptr >= alpha_pmu->num_pmcs)) { /* This should never occur! */ irq_err_count++; pr_warning("PMI: silly index %ld\n", la_ptr); wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } idx = la_ptr; perf_sample_data_init(&data, 0); for (j = 0; j < cpuc->n_events; j++) { if (cpuc->current_idx[j] == idx) break; } if (unlikely(j == cpuc->n_events)) { /* This can occur if the event is disabled right on a PMC overflow. */ wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } event = cpuc->event[j]; if (unlikely(!event)) { /* This should never occur! */ irq_err_count++; pr_warning("PMI: No event at index %d!\n", idx); wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } hwc = &event->hw; alpha_perf_event_update(event, hwc, idx, alpha_pmu->pmc_max_period[idx]+1); data.period = event->hw.last_period; if (alpha_perf_event_set_period(event, hwc, idx)) { if (perf_event_overflow(event, &data, regs)) { /* Interrupts coming too quickly; "throttle" the * counter, i.e., disable it for a little while. */ alpha_pmu_stop(event, 0); } } wrperfmon(PERFMON_CMD_ENABLE, cpuc->idx_mask); return; } /* * Init call to initialise performance events at kernel startup. */ int __init init_hw_perf_events(void) { pr_info("Performance events: "); if (!supported_cpu()) { pr_cont("No support for your CPU.\n"); return 0; } pr_cont("Supported CPU type!\n"); /* Override performance counter IRQ vector */ perf_irq = alpha_perf_event_irq_handler; /* And set up PMU specification */ alpha_pmu = &ev67_pmu; perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW); return 0; } early_initcall(init_hw_perf_events);