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Subject[PATCH 7/9] powerpc/perf_counter: Add generic support for POWER-family PMU hardware
This provides the architecture-specific functions needed to access
PMU hardware on the 64-bit PowerPC processors. It has been designed
for the IBM POWER family (POWER 4/4+/5/5+/6 and PPC970) but will
hopefully also suit other 64-bit PowerPC machines (although probably
not Cell given how different it is in this area). This doesn't
include back-ends for any specific processors.

This implements a system which allows back-ends to express the
constraints that their hardware has on what events can be counted
simultaneously. The constraints are expressed as a 64-bit mask +
64-bit value for each event, and the encoding is capable of
expressing the constraints arising from having a set of multiplexers
feeding an event bus, with some events being available through
multiple multiplexer settings, such as we get on POWER4 and PPC970.
Furthermore, the back-end can supply alternative event codes for
each event, and the constraint checking code will try all possible
combinations of alternative event codes to try to find a combination
that will fit.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
diff --git a/arch/powerpc/include/asm/perf_counter.h b/arch/powerpc/include/asm/perf_counter.h
index 59530ae..9d7ff6d 100644
--- a/arch/powerpc/include/asm/perf_counter.h
+++ b/arch/powerpc/include/asm/perf_counter.h
@@ -8,3 +8,65 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/types.h>
+
+#define MAX_HWCOUNTERS 8
+#define MAX_EVENT_ALTERNATIVES 8
+
+/*
+ * This struct provides the constants and functions needed to
+ * describe the PMU on a particular POWER-family CPU.
+ */
+struct power_pmu {
+ int n_counter;
+ int max_alternatives;
+ u64 add_fields;
+ u64 test_adder;
+ int (*compute_mmcr)(unsigned int events[], int n_ev,
+ unsigned int hwc[], u64 mmcr[]);
+ int (*get_constraint)(unsigned int event, u64 *mskp, u64 *valp);
+ int (*get_alternatives)(unsigned int event, unsigned int alt[]);
+ void (*disable_pmc)(unsigned int pmc, u64 mmcr[]);
+ int n_generic;
+ int *generic_events;
+};
+
+extern struct power_pmu *ppmu;
+
+/*
+ * The power_pmu.get_constraint function returns a 64-bit value and
+ * a 64-bit mask that express the constraints between this event and
+ * other events.
+ *
+ * The value and mask are divided up into (non-overlapping) bitfields
+ * of three different types:
+ *
+ * Select field: this expresses the constraint that some set of bits
+ * in MMCR* needs to be set to a specific value for this event. For a
+ * select field, the mask contains 1s in every bit of the field, and
+ * the value contains a unique value for each possible setting of the
+ * MMCR* bits. The constraint checking code will ensure that two events
+ * that set the same field in their masks have the same value in their
+ * value dwords.
+ *
+ * Add field: this expresses the constraint that there can be at most
+ * N events in a particular class. A field of k bits can be used for
+ * N <= 2^(k-1) - 1. The mask has the most significant bit of the field
+ * set (and the other bits 0), and the value has only the least significant
+ * bit of the field set. In addition, the 'add_fields' and 'test_adder'
+ * in the struct power_pmu for this processor come into play. The
+ * add_fields value contains 1 in the LSB of the field, and the
+ * test_adder contains 2^(k-1) - 1 - N in the field.
+ *
+ * NAND field: this expresses the constraint that you may not have events
+ * in all of a set of classes. (For example, on PPC970, you can't select
+ * events from the FPU, ISU and IDU simultaneously, although any two are
+ * possible.) For N classes, the field is N+1 bits wide, and each class
+ * is assigned one bit from the least-significant N bits. The mask has
+ * only the most-significant bit set, and the value has only the bit
+ * for the event's class set. The test_adder has the least significant
+ * bit set in the field.
+ *
+ * If an event is not subject to the constraint expressed by a particular
+ * field, then it will have 0 in both the mask and value for that field.
+ */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 1308a86..fde190b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -94,6 +94,7 @@ obj-$(CONFIG_AUDIT) += audit.o
obj64-$(CONFIG_AUDIT) += compat_audit.o

obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
+obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o

obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o

diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c
new file mode 100644
index 0000000..4f2d6ea
--- /dev/null
+++ b/arch/powerpc/kernel/perf_counter.c
@@ -0,0 +1,735 @@
+/*
+ * Performance counter support - powerpc architecture code
+ *
+ * Copyright 2008-2009 Paul Mackerras, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_counter.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <asm/reg.h>
+#include <asm/pmc.h>
+
+struct cpu_hw_counters {
+ int n_counters;
+ int n_percpu;
+ int disabled;
+ int n_added;
+ struct perf_counter *counter[MAX_HWCOUNTERS];
+ unsigned int events[MAX_HWCOUNTERS];
+ u64 mmcr[3];
+};
+DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters);
+
+struct power_pmu *ppmu;
+
+void perf_counter_print_debug(void)
+{
+}
+
+/*
+ * Return 1 for a software counter, 0 for a hardware counter
+ */
+static inline int is_software_counter(struct perf_counter *counter)
+{
+ return !counter->hw_event.raw && counter->hw_event.type < 0;
+}
+
+/*
+ * Read one performance monitor counter (PMC).
+ */
+static unsigned long read_pmc(int idx)
+{
+ unsigned long val;
+
+ switch (idx) {
+ case 1:
+ val = mfspr(SPRN_PMC1);
+ break;
+ case 2:
+ val = mfspr(SPRN_PMC2);
+ break;
+ case 3:
+ val = mfspr(SPRN_PMC3);
+ break;
+ case 4:
+ val = mfspr(SPRN_PMC4);
+ break;
+ case 5:
+ val = mfspr(SPRN_PMC5);
+ break;
+ case 6:
+ val = mfspr(SPRN_PMC6);
+ break;
+ case 7:
+ val = mfspr(SPRN_PMC7);
+ break;
+ case 8:
+ val = mfspr(SPRN_PMC8);
+ break;
+ default:
+ printk(KERN_ERR "oops trying to read PMC%d\n", idx);
+ val = 0;
+ }
+ return val;
+}
+
+/*
+ * Write one PMC.
+ */
+static void write_pmc(int idx, unsigned long val)
+{
+ switch (idx) {
+ case 1:
+ mtspr(SPRN_PMC1, val);
+ break;
+ case 2:
+ mtspr(SPRN_PMC2, val);
+ break;
+ case 3:
+ mtspr(SPRN_PMC3, val);
+ break;
+ case 4:
+ mtspr(SPRN_PMC4, val);
+ break;
+ case 5:
+ mtspr(SPRN_PMC5, val);
+ break;
+ case 6:
+ mtspr(SPRN_PMC6, val);
+ break;
+ case 7:
+ mtspr(SPRN_PMC7, val);
+ break;
+ case 8:
+ mtspr(SPRN_PMC8, val);
+ break;
+ default:
+ printk(KERN_ERR "oops trying to write PMC%d\n", idx);
+ }
+}
+
+/*
+ * Check if a set of events can all go on the PMU at once.
+ * If they can't, this will look at alternative codes for the events
+ * and see if any combination of alternative codes is feasible.
+ * The feasible set is returned in event[].
+ */
+static int power_check_constraints(unsigned int event[], int n_ev)
+{
+ u64 mask, value, nv;
+ unsigned int alternatives[MAX_HWCOUNTERS][MAX_EVENT_ALTERNATIVES];
+ u64 amasks[MAX_HWCOUNTERS][MAX_EVENT_ALTERNATIVES];
+ u64 avalues[MAX_HWCOUNTERS][MAX_EVENT_ALTERNATIVES];
+ u64 smasks[MAX_HWCOUNTERS], svalues[MAX_HWCOUNTERS];
+ int n_alt[MAX_HWCOUNTERS], choice[MAX_HWCOUNTERS];
+ int i, j;
+ u64 addf = ppmu->add_fields;
+ u64 tadd = ppmu->test_adder;
+
+ if (n_ev > ppmu->n_counter)
+ return -1;
+
+ /* First see if the events will go on as-is */
+ for (i = 0; i < n_ev; ++i) {
+ alternatives[i][0] = event[i];
+ if (ppmu->get_constraint(event[i], &amasks[i][0],
+ &avalues[i][0]))
+ return -1;
+ choice[i] = 0;
+ }
+ value = mask = 0;
+ for (i = 0; i < n_ev; ++i) {
+ nv = (value | avalues[i][0]) + (value & avalues[i][0] & addf);
+ if ((((nv + tadd) ^ value) & mask) != 0 ||
+ (((nv + tadd) ^ avalues[i][0]) & amasks[i][0]) != 0)
+ break;
+ value = nv;
+ mask |= amasks[i][0];
+ }
+ if (i == n_ev)
+ return 0; /* all OK */
+
+ /* doesn't work, gather alternatives... */
+ if (!ppmu->get_alternatives)
+ return -1;
+ for (i = 0; i < n_ev; ++i) {
+ n_alt[i] = ppmu->get_alternatives(event[i], alternatives[i]);
+ for (j = 1; j < n_alt[i]; ++j)
+ ppmu->get_constraint(alternatives[i][j],
+ &amasks[i][j], &avalues[i][j]);
+ }
+
+ /* enumerate all possibilities and see if any will work */
+ i = 0;
+ j = -1;
+ value = mask = nv = 0;
+ while (i < n_ev) {
+ if (j >= 0) {
+ /* we're backtracking, restore context */
+ value = svalues[i];
+ mask = smasks[i];
+ j = choice[i];
+ }
+ /*
+ * See if any alternative k for event i,
+ * where k > j, will satisfy the constraints.
+ */
+ while (++j < n_alt[i]) {
+ nv = (value | avalues[i][j]) +
+ (value & avalues[i][j] & addf);
+ if ((((nv + tadd) ^ value) & mask) == 0 &&
+ (((nv + tadd) ^ avalues[i][j])
+ & amasks[i][j]) == 0)
+ break;
+ }
+ if (j >= n_alt[i]) {
+ /*
+ * No feasible alternative, backtrack
+ * to event i-1 and continue enumerating its
+ * alternatives from where we got up to.
+ */
+ if (--i < 0)
+ return -1;
+ } else {
+ /*
+ * Found a feasible alternative for event i,
+ * remember where we got up to with this event,
+ * go on to the next event, and start with
+ * the first alternative for it.
+ */
+ choice[i] = j;
+ svalues[i] = value;
+ smasks[i] = mask;
+ value = nv;
+ mask |= amasks[i][j];
+ ++i;
+ j = -1;
+ }
+ }
+
+ /* OK, we have a feasible combination, tell the caller the solution */
+ for (i = 0; i < n_ev; ++i)
+ event[i] = alternatives[i][choice[i]];
+ return 0;
+}
+
+static void power_perf_read(struct perf_counter *counter)
+{
+ long val, delta, prev;
+
+ if (!counter->hw.idx)
+ return;
+ /*
+ * Performance monitor interrupts come even when interrupts
+ * are soft-disabled, as long as interrupts are hard-enabled.
+ * Therefore we treat them like NMIs.
+ */
+ do {
+ prev = atomic64_read(&counter->hw.prev_count);
+ barrier();
+ val = read_pmc(counter->hw.idx);
+ } while (atomic64_cmpxchg(&counter->hw.prev_count, prev, val) != prev);
+
+ /* The counters are only 32 bits wide */
+ delta = (val - prev) & 0xfffffffful;
+ atomic64_add(delta, &counter->count);
+ atomic64_sub(delta, &counter->hw.period_left);
+}
+
+/*
+ * Disable all counters to prevent PMU interrupts and to allow
+ * counters to be added or removed.
+ * Interrupts should have been disabled by the caller.
+ */
+u64 hw_perf_save_disable(void)
+{
+ struct cpu_hw_counters *cpuhw;
+ unsigned long ret;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ cpuhw = &__get_cpu_var(cpu_hw_counters);
+
+ ret = cpuhw->disabled;
+ if (!ret) {
+ cpuhw->disabled = 1;
+ cpuhw->n_added = 0;
+
+ /*
+ * Set the 'freeze counters' bit.
+ * The barrier is to make sure the mtspr has been
+ * executed and the PMU has frozen the counters
+ * before we return.
+ */
+ mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC);
+ mb();
+ }
+ local_irq_restore(flags);
+ return ret;
+}
+
+/*
+ * Re-enable all counters if disable == 0.
+ * If we were previously disabled and counters were added, then
+ * put the new config on the PMU.
+ */
+void hw_perf_restore(u64 disable)
+{
+ struct perf_counter *counter;
+ struct cpu_hw_counters *cpuhw;
+ unsigned long flags;
+ long i;
+ unsigned long val;
+ s64 left;
+ unsigned int hwc_index[MAX_HWCOUNTERS];
+
+ if (disable)
+ return;
+ local_irq_save(flags);
+ cpuhw = &__get_cpu_var(cpu_hw_counters);
+ cpuhw->disabled = 0;
+
+ /*
+ * If we didn't change anything, or only removed counters,
+ * no need to recalculate MMCR* settings and reset the PMCs.
+ * Just reenable the PMU with the current MMCR* settings
+ * (possibly updated for removal of counters).
+ */
+ if (!cpuhw->n_added) {
+ mtspr(SPRN_MMCRA, cpuhw->mmcr[2]);
+ mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
+ mtspr(SPRN_MMCR0, cpuhw->mmcr[0]);
+ goto out;
+ }
+
+ /*
+ * Compute MMCR* values for the new set of counters
+ */
+ if (ppmu->compute_mmcr(cpuhw->events, cpuhw->n_counters, hwc_index,
+ cpuhw->mmcr)) {
+ /* shouldn't ever get here */
+ printk(KERN_ERR "oops compute_mmcr failed\n");
+ goto out;
+ }
+
+ /*
+ * Write the new configuration to MMCR* with the freeze
+ * bit set and set the hardware counters to their initial values.
+ * Then unfreeze the counters.
+ */
+ mtspr(SPRN_MMCRA, cpuhw->mmcr[2]);
+ mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
+ mtspr(SPRN_MMCR0, (cpuhw->mmcr[0] & ~(MMCR0_PMC1CE | MMCR0_PMCjCE))
+ | MMCR0_FC);
+
+ /*
+ * Read off any pre-existing counters that need to move
+ * to another PMC.
+ */
+ for (i = 0; i < cpuhw->n_counters; ++i) {
+ counter = cpuhw->counter[i];
+ if (counter->hw.idx && counter->hw.idx != hwc_index[i] + 1) {
+ power_perf_read(counter);
+ write_pmc(counter->hw.idx, 0);
+ counter->hw.idx = 0;
+ }
+ }
+
+ /*
+ * Initialize the PMCs for all the new and moved counters.
+ */
+ for (i = 0; i < cpuhw->n_counters; ++i) {
+ counter = cpuhw->counter[i];
+ if (counter->hw.idx)
+ continue;
+ val = 0;
+ if (counter->hw_event.irq_period) {
+ left = atomic64_read(&counter->hw.period_left);
+ if (left < 0x80000000L)
+ val = 0x80000000L - left;
+ }
+ atomic64_set(&counter->hw.prev_count, val);
+ counter->hw.idx = hwc_index[i] + 1;
+ write_pmc(counter->hw.idx, val);
+ }
+ mb();
+ cpuhw->mmcr[0] |= MMCR0_PMXE | MMCR0_FCECE;
+ mtspr(SPRN_MMCR0, cpuhw->mmcr[0]);
+
+ out:
+ local_irq_restore(flags);
+}
+
+static int collect_events(struct perf_counter *group, int max_count,
+ struct perf_counter *ctrs[], unsigned int *events)
+{
+ int n = 0;
+ struct perf_counter *counter;
+
+ if (!is_software_counter(group)) {
+ if (n >= max_count)
+ return -1;
+ ctrs[n] = group;
+ events[n++] = group->hw.config;
+ }
+ list_for_each_entry(counter, &group->sibling_list, list_entry) {
+ if (!is_software_counter(counter) &&
+ counter->state != PERF_COUNTER_STATE_OFF) {
+ if (n >= max_count)
+ return -1;
+ ctrs[n] = counter;
+ events[n++] = counter->hw.config;
+ }
+ }
+ return n;
+}
+
+static void counter_sched_in(struct perf_counter *counter, int cpu)
+{
+ counter->state = PERF_COUNTER_STATE_ACTIVE;
+ counter->oncpu = cpu;
+ if (is_software_counter(counter))
+ counter->hw_ops->enable(counter);
+}
+
+/*
+ * Called to enable a whole group of counters.
+ * Returns 1 if the group was enabled, or -EAGAIN if it could not be.
+ * Assumes the caller has disabled interrupts and has
+ * frozen the PMU with hw_perf_save_disable.
+ */
+int hw_perf_group_sched_in(struct perf_counter *group_leader,
+ struct perf_cpu_context *cpuctx,
+ struct perf_counter_context *ctx, int cpu)
+{
+ struct cpu_hw_counters *cpuhw;
+ long i, n, n0;
+ struct perf_counter *sub;
+
+ cpuhw = &__get_cpu_var(cpu_hw_counters);
+ n0 = cpuhw->n_counters;
+ n = collect_events(group_leader, ppmu->n_counter - n0,
+ &cpuhw->counter[n0], &cpuhw->events[n0]);
+ if (n < 0)
+ return -EAGAIN;
+ if (power_check_constraints(cpuhw->events, n + n0))
+ return -EAGAIN;
+ cpuhw->n_counters = n0 + n;
+ cpuhw->n_added += n;
+
+ /*
+ * OK, this group can go on; update counter states etc.,
+ * and enable any software counters
+ */
+ for (i = n0; i < n0 + n; ++i)
+ cpuhw->counter[i]->hw.config = cpuhw->events[i];
+ n = 1;
+ counter_sched_in(group_leader, cpu);
+ list_for_each_entry(sub, &group_leader->sibling_list, list_entry) {
+ if (sub->state != PERF_COUNTER_STATE_OFF) {
+ counter_sched_in(sub, cpu);
+ ++n;
+ }
+ }
+ cpuctx->active_oncpu += n;
+ ctx->nr_active += n;
+
+ return 1;
+}
+
+/*
+ * Add a counter to the PMU.
+ * If all counters are not already frozen, then we disable and
+ * re-enable the PMU in order to get hw_perf_restore to do the
+ * actual work of reconfiguring the PMU.
+ */
+static int power_perf_enable(struct perf_counter *counter)
+{
+ struct cpu_hw_counters *cpuhw;
+ unsigned long flags;
+ u64 pmudis;
+ int n0;
+ int ret = -EAGAIN;
+
+ local_irq_save(flags);
+ pmudis = hw_perf_save_disable();
+
+ /*
+ * Add the counter to the list (if there is room)
+ * and check whether the total set is still feasible.
+ */
+ cpuhw = &__get_cpu_var(cpu_hw_counters);
+ n0 = cpuhw->n_counters;
+ if (n0 >= ppmu->n_counter)
+ goto out;
+ cpuhw->counter[n0] = counter;
+ cpuhw->events[n0] = counter->hw.config;
+ if (power_check_constraints(cpuhw->events, n0 + 1))
+ goto out;
+
+ counter->hw.config = cpuhw->events[n0];
+ ++cpuhw->n_counters;
+ ++cpuhw->n_added;
+
+ ret = 0;
+ out:
+ hw_perf_restore(pmudis);
+ local_irq_restore(flags);
+ return ret;
+}
+
+/*
+ * Remove a counter from the PMU.
+ * If all counters are already frozen, we can defer updating the
+ * hardware config until counters get re-enabled.
+ */
+static void power_perf_disable(struct perf_counter *counter)
+{
+ struct cpu_hw_counters *cpuhw;
+ long i;
+
+ cpuhw = &__get_cpu_var(cpu_hw_counters);
+ ppmu->disable_pmc(counter->hw.idx, cpuhw->mmcr);
+ if (!cpuhw->disabled)
+ mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC);
+ power_perf_read(counter);
+ write_pmc(counter->hw.idx, 0);
+ counter->hw.idx = 0;
+ for (i = 0; i < cpuhw->n_counters; ++i) {
+ if (counter == cpuhw->counter[i]) {
+ while (++i < cpuhw->n_counters)
+ cpuhw->counter[i-1] = cpuhw->counter[i];
+ --cpuhw->n_counters;
+ break;
+ }
+ }
+ if (!cpuhw->disabled) {
+ mtspr(SPRN_MMCRA, cpuhw->mmcr[2]);
+ mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
+ mtspr(SPRN_MMCR0, cpuhw->mmcr[0]);
+ }
+}
+
+struct hw_perf_counter_ops power_perf_ops = {
+ .enable = power_perf_enable,
+ .disable = power_perf_disable,
+ .read = power_perf_read
+};
+
+const struct hw_perf_counter_ops *
+hw_perf_counter_init(struct perf_counter *counter)
+{
+ unsigned long ev;
+ struct perf_counter *ctrs[MAX_HWCOUNTERS];
+ unsigned int events[MAX_HWCOUNTERS];
+ int n;
+
+ if (!ppmu)
+ return NULL;
+ ev = counter->hw_event.type;
+ if (!counter->hw_event.raw) {
+ if (ev >= ppmu->n_generic ||
+ ppmu->generic_events[ev] == 0)
+ return NULL;
+ ev = ppmu->generic_events[ev];
+ }
+ counter->hw.config_base = ev;
+ counter->hw.idx = 0;
+
+ /*
+ * If this is in a group, check if it can go on with all the
+ * other hardware counters in the group. We assume the counter
+ * hasn't been linked into its leader's sibling list at this point.
+ */
+ n = 0;
+ if (counter->group_leader != counter) {
+ n = collect_events(counter->group_leader, ppmu->n_counter - 1,
+ ctrs, events);
+ if (n < 0)
+ return NULL;
+ }
+ events[n++] = ev;
+ if (power_check_constraints(events, n))
+ return NULL;
+
+ counter->hw.config = events[n - 1];
+ atomic64_set(&counter->hw.period_left, counter->hw_event.irq_period);
+ return &power_perf_ops;
+}
+
+/*
+ * Handle wakeups.
+ */
+void perf_counter_do_pending(void)
+{
+ int i;
+ struct cpu_hw_counters *ctrs = &__get_cpu_var(cpu_hw_counters);
+ struct perf_counter *counter;
+
+ set_perf_counter_pending(0);
+ for (i = 0; i < ppmu->n_counter; ++i) {
+ counter = ctrs->counter[i];
+ if (counter && counter->wakeup_pending) {
+ counter->wakeup_pending = 0;
+ wake_up(&counter->waitq);
+ }
+ }
+}
+
+/*
+ * Record data for an irq counter.
+ * This function was lifted from the x86 code; maybe it should
+ * go in the core?
+ */
+static void perf_store_irq_data(struct perf_counter *counter, u64 data)
+{
+ struct perf_data *irqdata = counter->irqdata;
+
+ if (irqdata->len > PERF_DATA_BUFLEN - sizeof(u64)) {
+ irqdata->overrun++;
+ } else {
+ u64 *p = (u64 *) &irqdata->data[irqdata->len];
+
+ *p = data;
+ irqdata->len += sizeof(u64);
+ }
+}
+
+/*
+ * Record all the values of the counters in a group
+ */
+static void perf_handle_group(struct perf_counter *counter)
+{
+ struct perf_counter *leader, *sub;
+
+ leader = counter->group_leader;
+ list_for_each_entry(sub, &leader->sibling_list, list_entry) {
+ if (sub != counter)
+ sub->hw_ops->read(sub);
+ perf_store_irq_data(counter, sub->hw_event.type);
+ perf_store_irq_data(counter, atomic64_read(&sub->count));
+ }
+}
+
+/*
+ * A counter has overflowed; update its count and record
+ * things if requested. Note that interrupts are hard-disabled
+ * here so there is no possibility of being interrupted.
+ */
+static void record_and_restart(struct perf_counter *counter, long val,
+ struct pt_regs *regs)
+{
+ s64 prev, delta, left;
+ int record = 0;
+
+ /* we don't have to worry about interrupts here */
+ prev = atomic64_read(&counter->hw.prev_count);
+ delta = (val - prev) & 0xfffffffful;
+ atomic64_add(delta, &counter->count);
+
+ /*
+ * See if the total period for this counter has expired,
+ * and update for the next period.
+ */
+ left = atomic64_read(&counter->hw.period_left) - delta;
+ if (left <= 0 && counter->hw_event.irq_period) {
+ left += counter->hw_event.irq_period;
+ if (left <= 0)
+ left = counter->hw_event.irq_period;
+ record = 1;
+ }
+ val = 0;
+ if (counter->hw_event.irq_period && left < 0x80000000L)
+ val = 0x80000000L - left;
+ write_pmc(counter->hw.idx, val);
+ atomic64_set(&counter->hw.prev_count, val);
+ atomic64_set(&counter->hw.period_left, left);
+
+ /*
+ * Finally record data if requested.
+ */
+ if (record) {
+ switch (counter->hw_event.record_type) {
+ case PERF_RECORD_SIMPLE:
+ break;
+ case PERF_RECORD_IRQ:
+ perf_store_irq_data(counter, instruction_pointer(regs));
+ counter->wakeup_pending = 1;
+ break;
+ case PERF_RECORD_GROUP:
+ perf_handle_group(counter);
+ counter->wakeup_pending = 1;
+ break;
+ }
+ }
+}
+
+/*
+ * Performance monitor interrupt stuff
+ */
+static void perf_counter_interrupt(struct pt_regs *regs)
+{
+ int i;
+ struct cpu_hw_counters *ctrs = &__get_cpu_var(cpu_hw_counters);
+ struct perf_counter *counter;
+ long val;
+ int need_wakeup = 0;
+
+ for (i = 0; i < ppmu->n_counter; ++i) {
+ counter = ctrs->counter[i];
+ if (!counter)
+ continue;
+ val = read_pmc(i + 1);
+ if ((int)val < 0) {
+ /* counter has overflowed */
+ record_and_restart(counter, val, regs);
+ if (counter->wakeup_pending)
+ need_wakeup = 1;
+ }
+ }
+
+ /*
+ * Clear FC (freeze counters) and PMAO (perf mon alert occurred) bits
+ * in order to start the counters again and reset the irq.
+ * XXX might want to use MSR.PM to keep the counters frozen until
+ * we get back out of this interrupt.
+ */
+ mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~(MMCR0_FC | MMCR0_PMAO));
+
+ /*
+ * If we need a wakeup, check whether interrupts were soft-enabled
+ * when we took the interrupt. If they were, we can wake stuff up
+ * immediately; otherwise we'll have to set a flag and do the
+ * wakeup when interrupts get soft-enabled.
+ */
+ if (need_wakeup) {
+ if (regs->softe) {
+ irq_enter();
+ perf_counter_do_pending();
+ irq_exit();
+ } else {
+ set_perf_counter_pending(1);
+ }
+ }
+}
+
+static int init_perf_counters(void)
+{
+ unsigned long pvr;
+
+ if (reserve_pmc_hardware(perf_counter_interrupt)) {
+ printk(KERN_ERR "Couldn't init performance monitor subsystem\n");
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
+arch_initcall(init_perf_counters);

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